Talk:Redshift/Archive 7

peer reviewed papers contra non peer reviewed?

Note that those particular papers of the last dicussion belong in tired light and not here; but I got the impression that ScienceApologist in the last discussion rejected the opinions of three peer reviewed papers plus an apparently non peer-reviewed web article, based on the opinion of another apparently non peer-reviewed web article. IMO that's not in accord with Wikipedia rules. Harald88 08:34, 22 December 2005 (UTC)

I am happy to continue the discussion at the other article. --ScienceApologist 15:43, 30 December 2005 (UTC)

Please reestablish the focus of this talk page

I think more discretion is required about what's posted here. The topic "More hypocrisy from..." does not focus on improving the associated article. The topics "Raman redshift" and "Intrinsic redshift" pick out individual examples from a list previously submitted as an RfC that was discussed at length. Heavy usage of a talk page is OK, but not if it only consists of bringing up the same topics over and over in different groupings. Flying Jazz 04:12, 22 December 2005 (UTC)

Leadership! My own introverted personality is better suited for quality control. Art LaPella 15:09, 22 December 2005 (UTC)

Time to bow out

It's time to bow of the redshift article for several reasons. While scattering and redshift was certainly discussed in the RfC, "intrinsic redshift" appears to have been mentioned only in relation to Arp, I can find no further discussion. That it is further suggested that "intrinsic redshift" only applies to Arp, and I can demonstrate with references that that is not the case, and this evidence is consigned to an Archive within a few ours, bothers me.

But what quite disturbs me, is the Disneyesque presentaion of the redshift article. Even if it doesn't say so implicitly, the article presents itself as if 100% of scientists acknowledge that there are only three kinds of "true" redshift, and that it is fully understood and accepted 100%. It's not as if we are discussing a subject where one or two non-qualified individuals have some pet-theories. That there are other scientists who dare question redshift/cosmology [1], who actually produce peer-reviewed articles questioning redshift, and that they are labelled "woo woos", "pseudoscientists", and "pathological sceptics", and merely mentioning this is considered dissent by just one or two people, is disprectful at best, and not on the spirit of scientific endevour at worst.

Are there non-Doppler redshift? I have no idea. But the American Physics Society deems the subject worth of discussion [2]; that's not my theory, that's a reflection of what is going on in science on redshift. It's a shame that the editor(s) of the redshift article also can't reflect what's going on in the world.

I'm sorry if this sounds like sour grapes, but it's meant as a genuine criticism.

I'll be removing my Request for Arbitration, though I can't suport the support for Peer Review because I think the article also requires addition work (historic mention of Doppler, Ballot, Fizeau, Huggins, etc [3], and a note on how redshift is actually measured). And I believe that the article needs to be converted from what I think is a scientific article, to something more appealing to non-scientists (as an example, read out the first sentence to a non-scientist, and gague the expression).

Joshua, and all the other editors, I have enjoyed many of your contributions, even though some of them are quite exasperating. I apologise to all those that have been upset with my comments over the months. I hope you all have a very merry Christmas (I'm a Jewish atheist myself), but I digress. --Iantresman 16:51, 22 December 2005 (UTC)

Improving a criterium of selection of the proposals for Doppler-like redshifts

Message posted in Archive 6 by JMO 08:55, 24 December 2005 (UTC)

Welcome to Wikipedia! Your contribution to this article follows a period of long wrangling over similar topics, and I hope you're able to peer through the archived talk pages to see what was discussed before. I have a few problems with the new section:

1) It mixes observables (no blurring) with causes (no excitation of the matter to cause blurring) and other things (obey the principles of thermodynamics).

2) Obvious truisms should not be included in an encylopedia. Any theory proposed for (almost) anything must obey the principles of thermodynamics! The fact that it was placed in an article about an observable seems defensive and argumentative.

3) It describes only interactions with matter, and so falls under the category shifts due to scattering.

4) A theory is mentioned without saying what it is a theory of other than a theory that can describe a doppler-like redshift due to scattering.

5) The phrases used elesewhere describe blurring as line broadening.

6) There is no mention of these changes occuring over the whole spectrum which would be required for a redshift to truly be Doppler-like. Even though I'm no expert, it seems like if "energy is exchanged between light beams" then some light would increase in energy and experience a blueshift.

I've removed this section because I think the statement: Except possibly under carefully controlled conditions, scattering does not produce the same relative change in wavelength across the whole spectrum covers this topic.

More importantly, this article is about redshift, an observable. Causes of redshift are secondary. Theory that explains causes of redshift are of tertiary importance and should really be avoided. Criteria for theory that explain causes of redshift should never be here at all in my opinion. Having said all that, I might be wrong. But we recently completed a period of intense discussion here that seemed to lead to a consensus that this was the way to go. I hope you contribute to the CREIL page and other pages on causes and theory related to redshift. Flying Jazz 16:40, 24 December 2005 (UTC)

I approve of the removal for a number of reasons. Just one example: The claim Planck's law, which gives the temperature of a beam, shows that, generally, the light beams are hot while the radio beams are cold. is wrong. The thermodynamic temperature of a high-power maser beam can be higher than a low-power or spectrally broad optical beam. --Art Carlson 20:33, 24 December 2005 (UTC)

Why I removed the link to tired light

During the recent RfC, it was suggested that a list of 9 non-standard causes for redshift be included (Brillouin scattering, Compton scattering, Raman scattering, Wolf effect, Neutrino redshift, tired light, non-Doppler redshifts, non-Cosmological redshifts, and intrinsic redshifts). People who opposed the list said it was arbitrary. More could be included or excluded from a list of non-standard causes (or explanations or usages or theories) of redshift. Since that time, those who opposed the list as arbitrary have been vindicated by the sheer number of perturbations and selections, expansions (no pun intended) and individual elements and subsets of this list that have been proposed for inclusion in the article repeatedly. The list has varied in number from 1 (including just tired light like now or just Brillouin) or 2 (just CREIL and plasma as above) to a maximum of 37 or 38 non-standard usages of redshift. If you wish to include tired light in this article, please provide your reasoning for excluding all the other "non-standard redshifts", and if there's support for this reasoning, the link to tired light should be put back. I think the link off Wikipedia for an article saying what is wrong with tired light should also be removed for the same reason: picking out one thing to debunk is as arbitrary as picking out one thing to list. Flying Jazz 00:14, 27 December 2005 (UTC)

Tired light has a special position because it is the only item on the laundry list that is not based on scattering, and it is the only one that suggests new physics. The scattering mechanisms are covered by a link to the article on scattering. If I come to the redshift article, I would like to have a way to find out about tired light. I think a link should be included, either in a single sentence in the text, or else in "See also". --Art Carlson 11:33, 27 December 2005 (UTC)

I'm seriously confused for several reasons. The current Tired light article describes the hypothesis this way:

"the energy of photons of light decreases slowly as it travels through space due to some interaction with matter along the way" (seems like scattering)

"photons are thought to lose energy as they travel from distant objects through the gas, dust, other photons, gravity, or vacuum" (Covers all the bases, but all are scattering except the last three.)

"photons lose energy by interacting with electrons and other particles." (scattering!)

"a related scatter model predicts Compton scattering with a higher accuracy than the original Compton model" (related to scattering?)

Also the current Wolf Effect article describes it as taking place in free space with no scattering (but I wouldn't include the Wolf effect either). I also don't know what you mean by new physics since something called tired light seems to have been proposed in the 1920s. Ian was arguing in the archives for the inclusion of tired light because it was old and of historical importance! Does new physics mean physics that hasn't been shown to exist yet in the actual universe? Isn't that true of many of the other alternatives? I'm not a physicist and I don't have a dog in this race. I'm just trying to get a handle on what's really going on with the discussion. Other people here think that if someone came to the redshift article, they should have a way to find out about CREIL or plasma cosmology or intrinsic redshifts or something else. It just seems like different people have their favorites from the list about what should be included and excluded and the encylcopedic thing to do would be either to exclude them all or refer to another article that includes them all instead of picking favorites. Flying Jazz 13:41, 27 December 2005 (UTC)

It is good to have links; before seeing this discussion I noticed the negative reference to tired light while any mention of tired light was lacking, so I replaced the reference by a link. If the total number of links would take up a too long part of the page, a subpage could be made with such links. Harald88 20:18, 27 December 2005 (UTC)

I'm surprised that the reason "It is good to have links" was given instead of addressing my concern. I'll just try stating my concern again. There are a large number of theories and causes for redshift that have "no plausible experimental basis" and which most physicists and astronomers "do not believe" (these are quotes from the current tired light article). What is it about tired light that makes it more worthy to be included than the other 2 or 8 or 37 other things that could be listed and linked to? I don't want to exclude these links because they will take up space on the page. I want to exclude them because there is no reason for an encyclopedia to single out an implausible explanation without also including all the other implausible explanations, and including all possible implausible explanations for an observable would be ridiculous and impossible. Please address my reason for removing the link instead of simply reverting it because "it is good" your way because I don't think it's good that way. So we could go back and forth saying "good" "not good" "good" "not good" over and over. Or we could talk about the reasoning behind those opinions. Flying Jazz 22:43, 27 December 2005 (UTC)

Perhaps you think that there is "no plausible experimental basis" for "tired light", due to the biased POV that the tired light article gave until very recently. Instead, bremsstrahlung is IMO just as established as scattering, and it is good to add links to articles about mechanisms that may cause different kinds of redshift - starting of course with the best known ones, which are doppler and time dilation. I don't know about 37 other things, but if there are 37 plausible mechanisms (that is, as published in peer reviewed journals and not proved to be faulty), I expect a good encyclopedia to lead me to them. And of course links to notable past explanations for cosmological redshift can be helpful to readers. Harald88 15:43, 28 December 2005 (UTC)

I think the major reason for keeping tired light in the article is notability. Indeed, tired light is extremely well-known as a hypothesis for explaining cosmological redshifts. The other "37" explanations are not well known, and some of them as proposals for explaining redshifts are already included in the article (as most, if not all, are due to some sort of scattering). There may be a few other ideas floating around about redshifts, but none of them rise to nearly the notability of tired light. --ScienceApologist 15:40, 29 December 2005 (UTC)

Well....OK. That's enough people who want it kept in for different reasons to convince me that maybe I was being too pedantic. Flying Jazz 05:55, 31 December 2005 (UTC)

The link is already there in the body of the text. No need for it to be in the "see also" section. --ScienceApologist 15:21, 2 January 2006 (UTC)

Tired light is not an only a notable (but out-of-date) explanation for Hubble's constant, but also a redshift mechanism. The term does not appear in the article, and the link only appears anonymously in a phrase about no-name not being relevant for Hubble. Thus: revert. Harald88 17:03, 2 January 2006 (UTC)

The term now appears in the article. Thus remove from "see also". --ScienceApologist 20:25, 2 January 2006 (UTC)

That's fine! Harald88 22:45, 2 January 2006 (UTC)

Olbers' Paradox and 'Gravitational' redshift

I have two main comments on the current edit, which I'll open for discussion here before editing the article itself. Firstly, Olbers' Paradox is very interesting and worth a mention, but it does not in itself require a Big Bang. A de Sitter universe (H=constant, e.g. a cosmological constant dominated universe) has no big bang, but has (1+z)^4 surface brightness dimming.

Excellent point. --ScienceApologist 14:06, 4 January 2006 (UTC)

Secondly, I'm not sure it's right for the two GR causes to be 'Relativistic effects' and 'Expansion of space'. Isn't the latter surely an example of the former? Really, gravitational redshift is about the temporal metric element g_00 being non-constant, while redshift from space expansion is about the spatial metric components g_ab being non-constant. These aren't exactly catchy titles though. (Merging the two into one section on all non-constant metric elements would be a mistake in my view, as these physically distinct situations are worth discussing separately.) So, my vote would be for the two GR causes to be discussed separately and called 'Gravitational redshift' and 'Expansion of space'. I would also put the (special) relativistic Doppler effect back into the section on the Doppler effect, because it is very different to gravitational redshift and is largely used in the context of the Minkowski metric, rather than the more general metrics seen in GR.--Serjeant 14:04, 4 January 2006 (UTC)

I also agree with this suggestion. --ScienceApologist 14:06, 4 January 2006 (UTC)

Marmet garbage

This is not exactly a timely contribution to the discussion, but I finally got around to looking at Marmet's papers. In my professional opinion, they're garbage from the word go. In the second sentence of the abstract of A New Non-Doppler Redshift he cites the difference between emission and absorption redshifts in quasars as incontrovertible evidence that they cannot be explained by Doppler shifts. Aside from the fact that his theory cannot explain these results at all, he must be blissfully unaware of the Lyman-alpha forest. But going for the meat, his theory is based on the idea that a photon transfers all of its momentum to an electron momentarily, which then re-emits the photon, of course redshifted. This is a blatant violation of the conservation of energy. Red card. Out of the game. Art Carlson 20:34, 2 March 2006 (UTC)

Hi Art, welcome back with your original research - as it happens, I just returned from vacation. Apparently you think to have spotted an error that the plasma physicists missed, and that I also didn't notice so far. But your reading of Marmet differs from mine (which I sketched to you some time ago). For example, he claimed, contrary to your reading, that a small part of the momentum is imparted to the nucleus. You don't claim that an atom can't absorb and emit radiation, right? If you like to elaborate, I'm interested to see it (perhaps a calculation example that differs from that of Marmet?). His basic point taken from Rohrlich (also according to you "out of the game"?):

"with the emission of a single photon [...]: The simultaneous emission of very soft photons [...] is always present even in the so-called elastic scattering".

Cheers, Harald88 19:38, 3 March 2006 (UTC)

please include the wolf effect

please include the wolf effect in this article. it is a very interesting 4th red shift which has been observed in the lab and in quasars. This is quite significant, and interesting! Wikipedia needs to be complete, i tried months ago to get this incoroprated in the page to no avail. please make wikipedia good! -- 06:48, 2006 March 9 66.251.27.40

Why stop there? We could also include

1. Brillouin scattering
2. Compton scattering
3. CREIL (Coherent Raman Effect on Incoherent Light)
4. Raman scattering
5. Rayleigh scattering
6. Rutherford scattering
7. Thomson scattering

We discussed this before and decided that there is no reason to single out any one scattering effect, and that the individual effects are sufficiently convered by the cross reference to Scattering. BTW, the idea that the Wolf effect has been observed in quasars is a fringe belief. --Art Carlson 09:11, 9 March 2006 (UTC)

• Except that the Wolf effect is not a scattering effect per se, it is a radiative effect. As James writes in his 1998 paper PDF, "The Wolf effect is the name given to several closely related phenomena in radiation physics [..] analogous effects may occur in the scattering of light".
• As James and Wolf note in their 1990 paper PDF, p.169 "We see that just in the case when the shift is due to the Doppler effect, the relative frequency shift z induced by this mechanism is independent of frequency and can take on any value in the range -1<z<[infinity], even though the source, the medium, and the observor are at rest with respect to one another.
• Wolf's original 1987 paper has received over 100 citations; while it may be considered "fringe" by those unfamiliar with the science, it mainstream in optics (as a rough comparison, there are 20 papers that mention the Wolf Effect, compared to 5 papers that mention the transverse redshift).
• Since the Wolf effect (a) is not primarily a scattering effect, (b) it may produce distortion-free, full-spectrum, frequency independent redshifts, (c) it has been experimentally confirmed, (d) it is considered mainstream in optics, (e) even falls into the narrow astronomical definition of redshift, (f) all of this is verifiable, as demonstrated above, it deserves a section of its own. --Iantresman 15:55, 9 March 2006 (UTC)

It is unfortunate that the term is applied to so many loosely related effects. The radiative effect cannot result in redshifts greater than the order of the line width. To result in a significant z-value, a scattering effect is needed. There is a small but legitimate interest in Wolf's original effect. There may have been a bit of interest at one time in the application of that effect to quasars. I stand by my description of the present state of affairs, that the idea that the Wolf effect has been observed in quasars is a fringe belief, and by the statement, that the only type of Wolf effect that could be significant in relation to redshift is the scattering effect. --Art Carlson 16:29, 9 March 2006 (UTC)

I believe you are correct regarding the line width; nevertheless, it still produces a redshift, with a mechanism that is not described in the article. Indeed, there may also be an interest regarding quasars, but this is not a prerequisit for inclusion in an article on redshift. The Wolf effect is demonstrated, and does not rely on scattering. Even Tim Thompson acknowledges the Wolf effect --Iantresman 17:02, 9 March 2006 (UTC)

The Wolf Effect is not an important topic for discussion on the redshift page. This discussion has already happened. Please read the archives. --ScienceApologist 18:38, 9 March 2006 (UTC)

That was when it was classified (incorrectly) as a scattering effect. It isn't, so that make it important. You yourself described it as a "photon-phonon interactions"; it does NOT require a scattering medium, and will work in free space, unlike the scattering processes. --Iantresman 18:49, 9 March 2006 (UTC)

Ian, a phonon requires a medium. This effect does not work unless the emitting atom is physically connected to other atoms with which it can share momentum. Technically, the interactions between atoms are all governed by the electrostatic force which has the photon as a carrier and thus technically this is a scattering effect though it is scattering at the source rather than scattering through the trasmission of the signal. --ScienceApologist 19:00, 9 March 2006 (UTC)

That may be. But the Wolf effect does NOT require a medium, and may occur in free space [4]. It does NOT require scattering. --Iantresman 20:44, 9 March 2006 (UTC)

Ian, that site does not support your statement. It only says that the Wolf Effect occurs at the source and so doesn't require a scattering medium for the redshift to occur in transit. The Wolf Effect does require scattering of light at the source whether you want to admit it or not. It is basic physics. --ScienceApologist 12:50, 10 March 2006 (UTC)

The Wolf effect is a radiative effect, with analogues in scattering (see previous citation). It will also produce a frequency-independent shift, ie redshift, (see previous citation). This latter characteristic makes it a redshift, irrespective of whether it is a radiative effect, scattering effect, or any other effect. --Iantresman 13:55, 10 March 2006 (UTC)

Does not address the point above. Try again. --ScienceApologist 14:32, 12 March 2006 (UTC)

Please include the Wolf Effect in this article. It may not be mainstream in the sense that everyone who graduates with a PhD in physics is cognizant of it's existence, however that belies the fact that it is a type of red shift, and is important to include for the completeness of the article. Additionally regarding the wolf effect as a type of scattering suggests an unfamiliarly with the field, and an unnecessary unwillingness to review it. Because of the obsceneness of the wolf effect in mainstream physics, it is vital to include it in this article to make sure the knowledge can be propagated. Too many times in my physics career have I seen this sort of uneducated specialist’s rivalry ruin a brilliant collaboration.

I see good points on both sides for this particular issue, and the archives aren't entirely relevant I think. I agree with ScienceApologist that the Wolf Effect is not an important topic for discussion. The best argument for this is the line-width limitation. If my body moves less than one body-length, have I travelled enough to merit inclusion in an article on transportation? But I also agree with 66.251.24.248's and Ian's point that a complete and exhaustive treatment of redshift might have to include this effect because it's not due to scattering or other processes mentioned in the current article. I think erring on the side of including information is the way to go on this even if the information isn't important for the main point of the article. I hope a single sentence and link are added, maybe by renaming the ""Reddening" due to scattering" section to include Wolf shift. Flying Jazz 05:13, 10 March 2006 (UTC)

I don't want to sound like I'm pushing it, but shouldn't the Wolf effect appear in the same section as the Classical redshift? It will also occur in free space, and produce a redshift that corresponds to the definition given. In this respect, it is a fourth redshift mechanism. Of course I don't see the line-width as a "limitation", but as a characteristic. At the very least, I think we should mention a sentence about its prediction and discovery by Emil Wolf around 1986, its "characteristics" (line-width, analogues with scattering with no characteristic line width shift), it's limited application to astronomy. I make that three of four sentences at most, which is no more than "insterstellar redding" which the articles admits is not a true redshift. --Iantresman 09:20, 10 March 2006 (UTC)

We should not play pander to inaccurate descriptions of this effect by its proponents. I cannot for the life of me see why people who are in favor of the Wolf Effect know so little about physics, but that's neither here nor there. Wikipedia needs accuracy and this article does not need to mention every single out-of-the-way mechanism for creating frequency shifts by the undue weight section of NPOV policy. --ScienceApologist 12:50, 10 March 2006 (UTC)

That is precisely why Wiki policy prevents you and I from giving our opinion on the Wolf effect. Whether you consider it accurate, or fits your definition of redshift is of no importance. What is important is that the informaion is verifiable. I have provided peer review citations stating that the Wolf effect produces a redshift as defined in this article. There are over 100 citations to Wolf's original article. Previously I have had at least THREE PROFESSORS, including Prof. Daniel James himself, CONFIRM that indeed the Wolf effect will produce a redshift that may be indistinguiable from the Doppler redshift.

No one has to believe either you or I. But the citations say that the Wolf effect produce a GENUINE redshift, and it's up to us as editors to describe that accurately, neutrally and verifiably.

With so many peer reviewed citations describing or citing the Wolf effect, I would think that you should be able to find a couple that state that the Wolf effect is NOT a "true" redshift. --Iantresman 13:07, 10 March 2006 (UTC)

Contrary to subjects that can't be complete (e.g. about soccer), this one can be, and therefore there is no excuse for exclusion. But because of its limited use, and in view of the fact that an article on it already exists, for completeness one sentence with a link should do, IMO. Thus I agree with Flying Jazz. BTW, physical effects have nothing to do with proponents. Harald88 13:17, 10 March 2006 (UTC)

Read undue weight and original research. It's not about how many citations there are to Wolf's article, it's not about how many professors personally communicated with you, and it's certainly not about my opinion of the Wolf Effect (which is to say that it is one of many frequency-dependent material-based phenomena that can cause spectral distortions). What it's about is whether in a summary style article one phenomenon which has reached a certain level of popularity with an (admitted) extreme minority of cosmology advocates should be included. The answer seems to be clear from undue weight that we should not include it -- especially considering that there are at least a dozen more phenomena that produce similar effects that no one seems to be championing. We can describe the Wolf Effect on its own page, but it is too minor a phenomenon to warrant mention on the main redshift page. --ScienceApologist 13:22, 10 March 2006 (UTC)

This has nothing to do with undue weight in cosmology. This is an article about redshift. This is NOT an article about "cosmological redshift". See the Wiki policy on Word ownership, neither you nor I own the word "redshift" and can decide what goes in, and what does not. And we would both be rather arrogant to assume that redshift has an application only in cosmology.

Original research? Whose? Certainly not mine.

Other scattering phenomenon do NOT produce a frequency-independent redshift. This makes the Wolf effect DIFFERENT from the other shifts, and a FORTH mechanism for generating redshifts, EQUAL in significance to the other mechanisms, but obviously unequal in importance to cosmolgy... but this is not an article on cosmology. --Iantresman 13:55, 10 March 2006 (UTC)

You insistence that the Wolf Effect is of "EQUAL" significance is not backed up by any citations -- regardless of which context you look. --ScienceApologist 20:16, 10 March 2006 (UTC)

As a planet, Pluto is equal in significance to all the other planets, because it is a planet. We don't remove Pluto from the article on Planets because it is too small, too far away, not as significant as the Earth, nor as exciting as Saturn.

I wouldn't have the arrogance to judge the significance, nor importance of the Wolf effect. All I know is that the references say that the Wolf effect produces a redshift (corresponding to the definition in this article), and is has been verified in the laboratory. That you require this to be of importance to astronomers is quite a conceit. --Iantresman 20:53, 10 March 2006 (UTC)

We're done with this since it is clear that an adequate survey of redshift does not include the Wolf Effect as per undue weight. Nor does it include intrinsic redshifts or redshift quantization. --ScienceApologist 22:13, 10 March 2006 (UTC)

"We're" done, you and who else? You're the only person who has streadfastly refused to acknowledge the Wolf effect. (1) Wolf's original paper has over 100 citations. (2) The Wolf effect accounts for a quarter of the possible frequency-independent redshift mechanisms. You wouldn't be limiting your redshift survey to only astronomy sources? You need to get your head out of your astronomy textbooks. --Iantresman 23:54, 10 March 2006 (UTC)

You need to get your head out of the clouds and into some resources. There does not exist a single summary of redshifts from standard texts (astronomy or otherwise) which include these things that the POV-pushers are trying to link to. Therefore, we are right in excluding them. Wikipedia articles are not flea markets where you can just plop everything down and let the buyer beware. It is up to the editors to make sure that the policies are followed. Undue weight demands that those extreme minority perspectives on redshift be left to their own pages. --ScienceApologist 12:15, 11 March 2006 (UTC)

• References says that the Wolf effect causes as frequency-independent redshift. This is verifiable.
• References says that the Wolf effect is a radiative effect, with analogues in scattering. This is verifiable.
• References confirm that the Wolf effect has been demonstrated in the laboratory. This is verifiable.
• There are over a 100 citations to Wolf's papers on the Wolf shift. This is verifiable.

Unless you can provide a couple of verifiable peer-reviewed citations supporting your point of view, then all you have is a point of view. --Iantresman 13:41, 11 March 2006 (UTC)

I don't believe you can find a reference saying that the radiative version of the Wolf effect can cause a frequency-independent redshift, or even a redshift larger than the line width. I also believe that only the scattering version has been demonstrated in the laboratory. In other words the radiative version really isn't very interesting. Although I argue to include a brief reference to the radiative Wolf effect for completeness, I can understand why SA thinks even that gives it inappropriately much weight. --Art Carlson 15:12, 11 March 2006 (UTC)

I think you are correct that the radiative Wolf effect will not produce a shift greater than the line width. But I believe that Wolf's original work [5] on "source correlations" refers to the radiative form, and this was confirmed by experiment by Faklis and Morris in 1988, see " "Observation of frequency shifts of spectral lines due to source correlations". Subsequent work on scattering specifically mentions it, such as "James, Savedoff, Malcolm, and Wolf, Emil (1990). "Shifts of spectral lines caused by scattering from fluctuating random media" (my emphasis).

The undue weight arguement applies only if this article is about "redshift and its implication to cosmology"; it's not. It is about "redshift", as defined by the title and definition; this is why the Wolf effect, Intrinisic redshift, non-cosmological redshift and redshift quantization should all be included in the article. --Iantresman 16:52, 11 March 2006 (UTC)

The basic point is that if you look at any review of redshift mechanisms that treat the Doppler, Cosmological, and General Relativity effects as well as this article you will not find mention of the Wolf Effect or the other ideas you are trying to insert. This is clear indication that inclusion of these things is in violation of undue weight. --ScienceApologist 15:14, 11 March 2006 (UTC)

What, if you look at any review of X, Y and Z, you won't find W? I agree totally that reviews of Doppler, Cosmological, and General Relativity, generally exclude the Wolf effect. But this is an article on redshift, and the Wolf effect fits that category perfectly. If you want to change the title of this article to "Redshifts with application to cosmology", then I will happily bow out. But you do not have "Word ownership" over "redshift". --Iantresman 16:16, 11 March 2006 (UTC)

The point is, Ian, if you look for reviews on redshift mechanisms without bias towards any given one, you will not find the Wolf Effect. Thus undue weight demans we exclude it. This is totally independent of cosmology, astronomy, physics, or any other discipline you care to name. There are plenty of reviews of redshift available in all sorts of texts from general physical science to specialized texts. None of them include the Wolf Effect. --ScienceApologist

If you read the Wiki policy on Undue Weight is says that "If a viewpoint is held by a significant minority, then it should be easy to name prominent adherents"; let's see:

• Prof Emil Wolf, Wilson Professor of Optical Physics, Theoretical Optics
• Prof Daniel James, Theoretical Optical Physics and Quantum Information
• Dean Faklis and George Michael Morris, who confirmed the Wolf effect in the laboratory
• Over 100 citations to Wolf's orginal paper, ie. several dozen others who have heard of the Wolf effect

So I have now provided verifiable evidence that (a) references cite that the Wolf effect produces a redshift (b) that it produces a frequency-independent redshift per the definition on this article page (c) that the Wolf effect is held by a significant minority, per the Wiki policy definition. --Iantresman 18:09, 11 March 2006 (UTC)

You still haven't shown that inclusion on this page isn't in violation of undue weight. In particular, I have pointed out that this article while including the Wolf Effect is the only redshift summary that includes the Wolf Effect. That is poor reporting. --ScienceApologist 13:49, 12 March 2006 (UTC)

I disagree with the idea that being the only resource that mentions something constitutes poor reporting and undue weight. By including this effect using language that is appropriate and factually correct, Wikipedia might just be providing excellent and more comprehensive reporting than is available elsewhere. Part of the beauty of Wikipedia as a resource in science is its inclusion of what is new. This can lead to poor articles that place undue weight on the new. But it also can improve the knowledge base of the casual and the professional reader. Harald is right that we have an opportunity to be comprehensive while still being a summary by the addition of this single sentence. What can light do to redshift? It can "stretch out" in various ways that are mentioned in the bulk of the article, it can interfere with matter in various ways that are included by mentioning scattering, and it can experience a partial cancellation due to phase interactions that is included by mentioning this effect. Can you think of anything else? Can anyone? If not, then we have a comprehensive summary, and that is excellent reporting. Flying Jazz 14:06, 12 March 2006 (UTC)

I don't buy the "new and improved Wikipedia" argument because I've seen this argument dragged out time and time again only by people with particular agendas. It doesn't appear in any summary of redshifts I know of because it isn't generally considered to be a "redshift mechanism". The problem with being "comprehensive" is that redshift as a subject isn't comprehensive: it is used to describe a particular set of phenomena that is defined by basic intro science texts. To move the goalposts, as it were, is to really engage in original research and is a violation of undue weight. There is no problem with including on the Wolf Effect page that the authors describe it to be a redshift. There is also no problem with describing various other ideas that have been described similarly (see Art Carlson's list above -- so yes, there are many more things light can do to "redshift"). But to include this list on the redshift page is misleading because the phenomenon is summarized in basic texts.

I really fail to see why people are so demanding that the Wolf Effect be included directly on this page. The Wolf Effect as a phenomenon has been observed on three occasions that I know of in rather contrived laboratory experiments. It is mentioned on its own page. But it is clear that when there are 10,000s of pages on the other three mechanisms for redshift and maybe 100 citations to the Wolf Effect (many of which are works which do not even characterize it as a "redshift") including this effect here is only done to confuse the issue.

--ScienceApologist 14:29, 12 March 2006 (UTC)

It's very very easy. The Wolf effect produces a redshift. The title of this aricle is redshift. Period. As I highlighted earlier, this is not an under weight issue, because astronomy is not the centre of the academic universe; this article is about redshift as it occurs in both astronomy and optics, and should also include redshift from other disciplines. If I was an optics researcher, I might be tempted to ditch most of the material on cosmology, and leave it for an article on cosmology. Here is some mention of the Wolf effect and redshift, in academic textbooks, published by reputable publisher Springer:

• Gravitation and Cosmology: From the Hubble Radius to the Planck Scale, edited by Richard L. Amoroso, Geoffrey Hunter, Menas Mafatos, Jean-Pierre Vigier (publ. 2002, Springer, Kluwer Academic publishers). Page 104 mentions "... a mechanism was proposed by Wolf in the mid-eighties that has no connection with the relative motion and gravitation. The main features of this new mechanism for redshift, called the Wolf Effect, is as follows...." (my emphasis).

Not a summary. This article from a book of transaction proceedings looks at the Wolf Effect as a source of scattering redshifts. Totally not what I requested. --ScienceApologist 15:55, 12 March 2006 (UTC)

• The Universe: Visions and Perspectives, edited by Naresh Dadhich, Ajit Kembhavi (publ. 2000 by Springer, Kluwer Academic publishers). Page 99-100 mentions the Doppler effect, gravitation redshift, and the the spectral coherence effect of the Wolf effect, and other "Non-cosmological redshifts".

The Wolf Effect together with variable mass, and other nonstandard ideas are mentioned as a laundry list similar to the one provided by Art Carlson above. This is not the descriptive redshift summary I asked for: it is rather a discussion of nonstandard cosmological interpretations for the quasar "problems". --ScienceApologist 15:57, 12 March 2006 (UTC)

--Iantresman 15:07, 12 March 2006 (UTC)

ScienceApologist wrote: "[the Wolf effect] doesn't appear in any summary of redshifts I know of because it isn't generally considered to be a "redshift mechanism"." -- Citation please? --Iantresman 15:11, 12 March 2006 (UTC)

You don't need to cite items on the talkpage, Ian. And one cannot cite something that doesn't exist (i.e. it doesn't appear). --ScienceApologist 15:55, 12 March 2006 (UTC)

Wolf's redshift is cited extensively thoughout the optics world. It doesn't need the acknowledgement of astronomers to assess its importance.

If I asked Wolf, or Daniel James, or any of the prominent adherents listed above, to write an article on redshift, I suspect it would be quite different. Indeed, if I look up redshift in a book on optics, most of your article would have to go. --Iantresman 17:04, 12 March 2006 (UTC)

If those people have published summaries or surveys on redshift, let us know. Until then, according to WP:V and WP:NPOV's undue weight section we have no justification for including this as a "redshift". By the way, the issue isn't acknowledgement of astronomers: the issue is whether the summaries of redshift include the Wolf Effect. Go ahead and look up redshift in an optics book and let us know what the summary article appears as. --ScienceApologist 18:04, 12 March 2006 (UTC)

Show me Wiki policy that suggests we have to go by extenal documents that provide a redshift summary? I can find no such guidelines. In every respect, the Wolf effect meets Wiki policy. --Iantresman 18:30, 12 March 2006 (UTC)

Inclusion of the Wolf Effect in Wikipedia is fine. Inclusion of it by name in this summary article when there are no citations to it being used in that fashion by the majority of writers who summarize redshift is a violation of Undue Weight. I do not object to the Wolf Effect as a webpage. I simply object to it being included here for the reasons I have outlined. --ScienceApologist 18:45, 12 March 2006 (UTC)

Nope, I've already demonstrated that since there are prominent adherers that we can name, that it exceeds undue weight, and falls into significant minority. As I see it, there are no other editors who object. --Iantresman 20:39, 12 March 2006 (UTC)

"Prominent adherers" is meaningless. You haven't demonstrated that this phenomenon is important to summaries of the subject anywhere but your own head. Therefore it is clear it should be omitted. --ScienceApologist 20:43, 12 March 2006 (UTC)

I have made the change I suggested

Ian's idea that the Wolf Effect belongs in the main section of the article is nonsensical and would constitute undue weight. ScienceApologist's view that it should not be included at all would make sense if the effect were a scattering effect because scattering effects are already mentioned. But the fact that lines may be shifted ever-so-slightly in a vacuum by this effect seems to be generally accepted, and my view is that by including it in this way, the article is more complete and up-to-date without being on the fringe. It's an optical phenomenon that can cause a shift that was published in Nature, so it doesn't seem fringe to me. The fact that some people on the fringe might misuse the Wolf effect to make unsubstantiated claims is not a reason to exclude it. I've also included an additional caveat that Classical Redshift mechanisms require the ability to shift by a length larger than one linewidth. I have no physics or astronomical background to justify saying something like that, but it just seems to make sense to me based on my analogy to someone calling it transportation if they lean forward because the center of their location has changed. Honestly, the fact that my middle course makes both Ian and ScienceApologist uncomfortable makes me confident that it's a reasonable thing to include. Please let people at least comment about it for a brief period before reverting it. Flying Jazz 21:40, 11 March 2006 (UTC)

Sounds like a fair compromise to me. --Iantresman 22:46, 11 March 2006 (UTC)

This is unacceptable. Unless you can explain how a mechanical resonance effect occurs in a vacuum so that it is not scattering, please don't pollute this article with caveats and impossible physics. Your compromise makes Ian beam because it panders to him without addressing my fundamental concerns. I am reverting. --ScienceApologist 13:51, 12 March 2006 (UTC)

It's not up to us to interpret, give our points of view, and even understand why something works or does not work. Can you explain how the Big Bang, an action without a cause, occurs? It's up to us to report and describe the literature. And the literature says that the Wolf effect produces a redshift, albeit a minoroty viewpoint in astronomy (a major viewpoint in optics), but more importantly, this is all verifiable --Iantresman 14:21, 12 March 2006 (UTC)

Except no one has pointed to a summary article on redshift which mentions the Wolf Effect. I therefore continue to submit that inclusion of it is a violation of undue weight. --ScienceApologist 14:30, 12 March 2006 (UTC)

COntrary to your apparent intention, the scope of Wikipedia is not to be at best as good as other encyclopdia and/or encyclopedic articles. Instead, the aim of Wikipedia is to become the best source of summary information. Please stop your continuous efforts against that aim. BTW, on this one there is near consensus (I think only you disagree) to make this article comprehensive: simply because it's feasible without becoming too long. Harald88 20:44, 12 March 2006 (UTC)

The key phrase being the best source. Pandering to special interests like those which want to insert the Wolf Effect as "the fourth redshift mechanism" is ridiculous. We make mention of alternatives, leave it at that. --ScienceApologist 21:12, 12 March 2006 (UTC)

ScienceApologist...I'm disappointed by your rapid reversion with very little comment about the specific issue. I know from experience reading you and Ian in the past that if someone found the sort of summary article you mention, you would declare it to be the work of an Arp supporter or someone with a particular agenda. And I also know from reading some of those things myself that chances are, you would be correct. Please debate the issue on its merits. You wrote: "Unless you can explain how a mechanical resonance effect occurs in a vacuum so that it is not scattering, please don't pollute this article with caveats and impossible physics." You are setting up an imopssible and inappropriate set of limitations by this statement. You want me to explain a mechanical effect that is not scattering. The Wolf effect is not mechanical. It is optical. According to an editorial written in a special issue of "Pure and Applied Optics" in 1998, Wolf's inquires:

led to the discovery of a new mechanism by means of which the spectrum of radiation can be changed on propagation even in free space. In particular, spectral lines can be shifted independently of the relative motion of the source and the observer. This phenomenon, which has come to be known as `the Wolf effect', and is discussed in some of the articles of this special issue, may have very profound implications in cosmology. It also has applications to such fields as optical radiometric standards, communications and remote sensing.

Do I personally think that the Wolf effect has profound implications in cosmology? No. Like scattering effects, I think it has practically nothing to do with cosmology, and I think this editorial was inflating its importance, as editorials often do. I am not among the "people with particular agendas." Do I think this effect deserves mention in an article that defines redshift the way this article does? Yes. Every other item on ArtCarlson's list was a scattering effect. Art's list is not relevant because the Wolf effect is not a scattering effect. This is not impossible physics simply because it is relatively new physics, and it is not undue weight to mention it as a phenomenon that is not scattering and does shift spectral lines. Why haven't Wolf or James published a summary or survey on redshift as a general topic? Perhaps because they are in optics, not in astrophysics, and if they did so they would have to waste countless hours (or weeks or years) bickering with people like you and Ian about semantics, to the detriment of their careers and research. The issue is not about other summaries. It's about this one. I was recently part of a Group number of lanthanides and actinides debate that resulted in Wikipedia providing a more comprehensive summary of the reasons behind different periodic tables than any summary (to the best of my knowledge) that has ever been published anywhere previously. You and Ian are very knowledgeable about Wikipedia policies...much more than I am, but I don't think there is a policy that says "anything that hasn't already been summarized elsewhere constitutes original research" or one that says "if other summaries don't include it, Wikipedia shouldn't." You won't find that policy anywhere because it limits excellence in article-writing-by-consensus, which is precisely what we should be trying to do. The summary you describe hasn't appeared because in 2006, a forum like Wikipedia may be required to produce it. What EXACTLY are your fundamental concerns and reasons for reverting? Please list them and number them so they may be addressed. I am trying to resolve this reversion with you which I feel was unjustified. I am also a little upset that you called my good-faith effort "pollution," but based on other things I've read from you, I don't expect you to address matters of etiquette here in any serious way. Flying Jazz 20:36, 12 March 2006 (UTC)

First of all, it hasn't been established that the Wolf Effect can occur as a resonance without a scattering medium. Let's put it this way, let's say that we had two atoms that emitted a line-photon a wavelength apart. There would be diffraction as predicted by Young's Double Slit experiment, but this wouldn't correspond to the Wolf Effect but only a change in probabilities for observing the photon. So let's move to the geometrical optics limit and say we had two sources that were creating electromagnetic waves one wavelength away from each other. Again, no redshift or blueshift by the same rationale.

The only way we get a redshift/blueshift is through photon-phonon interactions which is technically scattering through a medium. Even if you have a place between the two sources that is free space, as soon as the photons interact with the source material it becomes a scattering. So I reject outright the contention that the Wolf Effect represents a novel radiative phenomenon. It doesn't -- it's still scattering.

But the main reason for reverting is because there are plenty of resources available on redshift that make no mention whatsoever regarding the Wolf Effect when summarizing redshift. To make a perfectly good analogy look at the Evolution article and see how much is written about Specified complexity which is a phenomenon associated with a critic of evolution and supposedly casts doubt on evolution mechanisms. There is nothing written in that article about specified complexity because of the WP:NPOV section on undue weight. Likewise, we omit the Wolf Effect from specific mention here due to undue weight. We mention that there are naysayers and we point readers in the direction of those articles that report on such ideas, but those ideas are rightly excluded from this article here.

--ScienceApologist 20:51, 12 March 2006 (UTC)

Naysayers to what? SA, you demonstrate that you again forget that this article is about redshift and not about some kind of ideology (which one?) that you apparently want to defend, at the cost of making Wikipedia the best (most comprehensive) encyclopedia ever. BTW, I checked "specified complexity" and it turned out that that is a bad example, for that is not about evolution. Harald88 21:02, 12 March 2006 (UTC)

Naysayers mostly to this article. I understand that you and FlyingJazz are not as familiar with these topics as either myself or perhaps even Iantresman, but please make no mistake that Ian has an agenda for including points that are not part of mainstream descriptions into articles about admittedly mainstream subjects. We mention that there are those people which describe redshifts thusly, but a) we have not established that the Wolf Effect is different than scattering despite Ian's advocacy for this and b) we include links to the alternatives as warranted by the undue weight section of WP:NPOV. I am only defending this article from the nuanced attacks of Ian Tresman. If you don't believe me that this is his intention, just read what he wrote on Halton Arp's message board about these topics.

In the same way that the Wolf Effect is not about redshift, specified complexity is not about evolution. Specified complexity claims that there are other mechanisms which must exist that cast doubt on evolution as a unifying principle. Likewise the proponents (and yes, they are proponents here) of the Wolf Effect claim that there are mechanisms which must exist that cast doubt on the summary of redshift here and mainstream-wise listed. The Wolf Effect is no more a significant minority of described redshifts than specified complexity is a significant minority of observed biological functions.

--ScienceApologist 21:09, 12 March 2006 (UTC)

According to the article on the Wolf effect, it can cause redshift. And you did not explain what "the Wolf effect"would be "naysaying" about redshift - quite to the contrary! BTW, according to that article, "In free space, the Wolf effect cannot produce shifts greater than the linewidth of the source spectral line, since it is a position-dependent change in the distribution of the source spectrum, not a method by which new frequencies may be generated."

SA claims above that that is wrong, and that the Wolf effect is scattering. If he can convince the editors of that page to change it, based on sources, then we should next consider to rank the Wolf effect under scattering. However, for now that has not happened, and I'd be surprised if it happens. Harald88 21:14, 12 March 2006 (UTC)

The Wolf Effect, as a subject, is not a person and so has no anthropomorphic qualities. Editors who wish to include the Wolf Effect in an article about redshift do so for two reasons: 1) they mistakenly think it is part of the mainstream comprehensive summaries on the subject, or 2) they're pissed off at scientists who use the redshift to support ideas related to the phenomenon. When the two groups come together, they pose a formidable obstacle to the WP:NPOV guidelines. We aren't here to give any one person a soapbox. If Ian wants to believe the Wolf Effect is important, let him write his own encyclopedia. As it is, there is no justifiable reason to include such a out-of-the-way optical effect in an article about a phenomenon that is so well-known as to be discussed in middle school texts.

I think the point is that the "in free space" comments really refer to scattering at the sources rather than through a phonon connected medium. It is a subtle but important distinction that makes it clear that the Wolf Effect is, in fact, a scattering mechanism. --ScienceApologist 21:19, 12 March 2006 (UTC)

Per your suggestion, Harald, I modified the Wolf Effect article to be more clear. --ScienceApologist 21:24, 12 March 2006 (UTC)

The Wolf effect is a redshift by definition. But it's not for us to establish whether the "Wolf Effect can occur as a resonance without a scattering medium". Verifiable references say that the wolf effect produces a radiative redshift, with analogies in scattering. Period. "The threshold for inclusion in Wikipedia is verifiability, not truth." [6]

Meaningless. If the Wolf Effect really is scattering then we talk about it thusly and the objection is moot. --ScienceApologist 21:19, 12 March 2006 (UTC)

It is verifiable that the Wolf effect is a radiative effect. Your interpretation is a point of view.

And while I think of it, the importance of the Wolf effect to cosmology, is secondary to its importance to redshift. But it is not for us to judge the importance of redshift to cosmology, only to note that Wolf himself noted a connection in his 1987 paper "Noncosmological redshifts of spectral lines" (as have several others), and that's something which Wiki policy suggests that "Debates are described, represented, and characterized, but not engaged in."[7]

Let's put Ian's last source into context. Emil Wolf wrote his paper in 1987, at the tail of the so-called quasar controversies showing that in certain localized phenomenon for a given coincidence of phenomenon his Wolf Effect could kick in thus providing a mechanism for creating the tremendous redshifts seen in quasars. This was an important idea back in 1987 when the jury was still sort-of out regarding whether quasars were really at cosmological distances. Wolf's idea was based on allowing for correlations between source fluctuations and the photons being emitted allowing for dramatic redshifts up to 0.1, 0.2, 0.3, etc. Since that time it has become clear that 1) there is no problem for quasars being distant since they can be powered by accretion and 2) Such an effect cannot account for the vast majority of quasars which are at truly cosmological distances as measured by host galaxy observations and noted by z that approach 7. Nevertheless, Wolf's optical phenonenon of a redshift associated with double sources resonating is a clever one and I'm glad that Nature accepted the work for publication. But this effect is not fundamentally different than any of the other scattering effects we see except when you get to the very microphysical scales. Redshift by scattering is all this is, and it can only occur "in free space" if there is enough material to allow the photon signals to interact and resonate thus dragging the frequencies down. This is scattering again. I have added points to the Wolf Effect page to illustrate this. --ScienceApologist 21:43, 12 March 2006 (UTC)

SA...I agree that IF the Wolf Effect is really a form of scattering then it does not belong in this article because in that case it would be a particular example of scattering that is singled out for no particular reason. Please help us to understand exactly where you are coming from. I, for one, can't imagine how two partially coherent light sources could be formed without some scattering process being involved to create the partial coherence. If one looks at the entire process from beginning to end, then perhaps it must involve a scattering medium. But the Wolf effect (from what I have read and based on my understanding which, as you say, is limited) is not the formation of those light sources. It is how those sources interact with each other once they are created, and that interaction can occur in a vacuum between sources that fluctuate in intensity. Thus, in my mind, the Wolf effect is not a scattering effect even if scattering must be involved prior to the effect occuring. Flying Jazz 21:38, 12 March 2006 (UTC)

Think of this in terms of the conservation of energy. Photons do not interact with each other in the Wolf Effect. You can only get photons to interact with matter to take away some of the energy. Effectively what happens in "free space" is that the photons interact with the source material at either source when there is a coincidental coherence due to the source positioning. Thus the photons from source A scatter at source B and vice versa -- resonating to produce a frequency shift. Photons cannot resonate in a vacuum by the law of superposition. There are no photon-photon interactions. --ScienceApologist 21:43, 12 March 2006 (UTC)

"Wolf found that the way in which atoms in a source are ordered affects the way they emit light and the way the light travels through space" [8] This is not scattering, otherwise it would be called scattering. --Iantresman 22:02, 12 March 2006 (UTC)

The way atoms in a source are ordered affects the way they emit light because atoms interact through electromagnetic forces which are mediated by the force-carrying photon. As the photons are emitted and absorbed carrying information about atom-ordering in a source, they are effectively scattered. --ScienceApologist 22:05, 12 March 2006 (UTC)

Nope, radiated. That's why optical physicists distingish between raditive and scattering processes. --Iantresman 22:26, 12 March 2006 (UTC)

SA...From a strict particle physics perspective, you may be absolutely right that the Wolf effect is due to the scattering that initiated the light beams (by what someone like me might call spooky-action-at-a-distance). I imagine that the act of measuring the beams before they meet destroys the superposition (or something similar to this) and gives the impression (from the strict particle perspective) that it is the beams themselves that are interacting. But, it's also obvious from fairly recent optics literature that physicists in optics without an axe to grind in cosmological debates still describe the effect as taking place in a vacuum between two "light beams with certain traits". They don't seem wrong by describing it as not-a-scattering effect and neither do you by describing it as a scattering effect at a distance. Thus, the core question remains as to whether the effect should be mentioned in this article. Do you think the optics people are just plain wrong or that they and you have a different perspective on the same phenomenon? And shouldn't that decision be left up to the reader? Flying Jazz 22:39, 12 March 2006 (UTC)

I'm pretty sure that the physical optics physicists do not describe the effect as one between two light beams but would gladly admit that the semi-coherence effects occur with respect to the material doing the emitting. Two photon physics only applies for high energy physics and can only react by pair production. This is obviously not what's going on here. I think that Ian is using the optics literature to claim something that they are not claiming -- namely that the Wolf Effect can exist without interactions between the photons and a medium with an index of refraction other than 1.00. --ScienceApologist 14:46, 13 March 2006 (UTC)

I am using the EXACT VERIFIABLE QUOTES, exactly as they read. I claim no more. The direct quotes say that (1) The Wolf effect produces a Doppler-like frequency independent redshift (2) That the Wolf effect is a radiative effect with analogues in scattering (3) That the scattering form of the Wolf effect will produce large redshifts, and these may also be distortion free (4) there is discussion with relevance to cosmology. --Iantresman 00:15, 14 March 2006 (UTC)

Summary:

Reason to include Wolf Effect
In favour	Against
Radiative form of Wolf effect produces a Doppler-like frequency-independent redshift (with Doppler-like shift smaller than spectral line width) [9] Confirmed in the laboratory [10] Significant minority view held by Wolf [11] et al [12] [13] [14] Significant view in the field of optics, with over 100 citations to Wolf's original paper [15] Scattering analogue of Wolf effect may also produces a Doppler-like frequency-independent redshift (with Doppler-like shift of any magnitude), with line broadening [16] [17] [18] which the astronomical redshifts ascribes to "thermal or mechanical motion of the source" [19] Wolf et al, have suggested a relevance to cosmology, and quasars [20] [21] [22] Conforms to Wiki policy on: Verifiability "The threshold for inclusion in Wikipedia is verifiability, not truth" [23] Undue weight "is held by a significant minority" [24] NPOV "representing views fairly and without bias" [25], and "Debates are described, represented, and characterized, but not engaged in" [26]	No mention of redshift in redshift summaries Radiative effect is considered to be scattering

--Iantresman 23:45, 12 March 2006 (UTC)

You have succeeded in summarizing a debate that has only occured in your own mind rather than following the actual conversation between others who are discussing this issue. Flying Jazz 01:43, 13 March 2006 (UTC)

Perhaps, though I seem to recall having discussions over every single one of the points as reasons to include, or not to inclde the Wolf effect. As per your latest query, that seems to be aimed at ScienceApologist who I am sure will be able to answer for himself. --Iantresman 07:49, 13 March 2006 (UTC)

You forgot to include the claim that it is just another form of scattering, so that it's covered by that subject (and in which case it should be described in the scattering article). Thus the key question is where to put the summary description: in redshift or in scattering. The cited literature seems not to support scattering, but perhaps I overlooked a citation by SA? Harald88 12:59, 13 March 2006 (UTC)

Can ScienceApologist provide a citation indicating that a radiative effect is considered to be scattering process? --Iantresman 13:52, 13 March 2006 (UTC)

The Wolf Effect article itself explains how the effect can only be due to scattering at the sources. There is no source that you have pointed to which claims that the Wolf Effect can work in, for example, two atoms emiting photons a wavelenght apart from one another. Misusing citations as you are is some pretty shoddy editting work, Ian. --ScienceApologist 14:46, 13 March 2006 (UTC)

• James writes in his 1998 paper PDF, "The Wolf effect is the name given to several closely related phenomena in radiation physics [..] analogous effects may occur in the scattering of light". (My emphasis).
• I can't find any such sentence in Wolf's papers indicating "source scattering"; he does mention that "... the basic equation for scattering is of the same form as the basic equation for radiation from primary sources" [27], so he is quite clear that he is discussing a radiative effect, and that there is also an analogy in scattering. ie. radiation and scattering are considered DIFFERENT phenomenon.
• Another paper by Wolf and James [28] features sections (4) and (5) on "Radiation" (with no mention of the word scattering), followed by section (6) on "Scattering", again showing a clear division been the two processes.
• So unless you can find a sentence in a citation confirming that a radiative source is "scattering" process, your interpretation is a personal point of view. --Iantresman 16:10, 13 March 2006 (UTC)

I suggest that Ian take a course or two in physics or physical science. His advocacy is getting harder and harder to take seriously due to his sincere lack of an education in this area. No amount of hiding behind Wikipedia policy makes up for his promotion of ignorance. --ScienceApologist 21:23, 13 March 2006 (UTC)

That's not a particularly strong argument. may I point out that:

• You said that the Wolf effect does not produce a Doppler-like redshift. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided
• You said that the Wolf effect does not produce a frequency-independent redshift. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided.
• You said that the Wolf effect does not produce a redshift that is consistent with the definition on this page. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided.
• You said that the Wolf effect is a scattering mechanism, which effectively the same as a radiative one, but have been unable to prvoide a verifiable quote supporting this view. --Iantresman 08:33, 14 March 2006 (UTC)

Clarification from Emil Wolf

Date: 12/03/06 From: Ian Tresman To: Emil Wolf I wonder if you could clarify the following point: Is the Wolf effect primarily a radiative effect, or is it really just a form of scattering that requires a scattering medium? By itself, the Wolf effect can not produce spectral shifts greater than the line width? And if there is a shift greater than the line width, then scattering must be involved, which implies a distortion of the spectra?

Wolf replied (though I don't think he quite clarifies the question on scattering). I've added a link to the paper he refers to, which is on Daniel James' Web site:

Date: Mon, 13 Mar 2006 11:22:27 -0500 To: Ian Tresman From: Emil Wolf I am writing in response to our e-mail of March 12th, concerning the redshift and the Wolf effect. It seems, that the term "the Wolf effect" has now been adopted for the phenomena of changes in the spectrum of either a radiated or a scattered field, caused either by source correlations, or by correlations in the physical properties (e.g. the refractive index) of a scattering medium. You are right in saying that under certain circumstances the Wolf effect cannot produce spectral shift shifts greater than the line width. But this is only true for radiation from simple sources or from scattering on what is called static media i.e. media for which the physical properties do not change in time. For scattering on media where the physical property do change in time (one then speaks of dynamic scattering), appreciable changes may be generated. Some examples are given in a paper which I am attaching to this e-mail. Please note that figure 2 in the paper provides an example where the shift is many times greater than the width of the spectrum. You say that if there is a shift greater than the line width then scattering must be involved which implies a distortion of the spectra. That is actually not necessary so. In the figure I just mentioned there is some distortion but it is relatively small. In this connection I should also mention that when astronomers talk about shift of a spectral line, they usually refer to the shift of the its peak. The exact profiles of the lines can be very seldom be determined in astronomy.

He does mention "... a radiated or a scattered field,...", which to me implies that radiation is not scattering, and the introduction to paper he mentions, also separates "radiation from primary sources .. secondary sources" and "scattering processes". --Iantresman 16:38, 13 March 2006 (UTC)

This confirms what I have been saying (or at least meaning) all along, that there is a form of the Wolf effect that does not depend on scattering, but the size of this effect is so small (only comparable to the line width) that it is little more than a curiousity in any field, and even less than that in cosmology. It is in the category of the redshift in solar spectral lines at sunset due to the wavelength-dependence of Rayleigh scattering. --Art Carlson 17:41, 13 March 2006 (UTC)

Indeed, the radiative Wolf effect produces a tiny shift, which by itself might be insignificant to cosmology. But this is an article primarily on redshift, rather than cosmology. Anyway, the scattering analogue of the radiative Wolf effect will produce large frequency-independent shifts that may not be disorted, and is directly relevant to cosmology, as discussed in the paper, and others. --Iantresman 18:10, 13 March 2006 (UTC)

that there is a form of the Wolf effect that does not depend on scattering It looks to me like Wolf is saying that there are no forms of the Wolf Effect which do not depends on scattering. They instead correspond to scattering at the source rather than scattering through a medium. --ScienceApologist 18:32, 13 March 2006 (UTC)

Sorry, where does Wolf say that? If you read the first paragraph of Wolf's email, he says it's a phenomenon in radiative OR scattering spectra, caused by source correlations OR by correlations in scattering medium. Nowhere does he imply that source correlations in radiative spectra is anything to do with scattering. --Iantresman 19:03, 13 March 2006 (UTC)

When Wolf says "But this is only true for radiation from simple sources or from scattering on what is called static media i.e. media for which the physical properties do not change in time." he is positing an equivalence between radiation from simple sources and scattering on a static medium. This only makes sense if the radiation from the simple sources is affected by scattering at the sources. The only way to get a change in frequency is to transfer some photon energy to a medium, in the case of simple sources it is the medium at the source. --ScienceApologist 19:07, 13 March 2006 (UTC)

If a radiative spectrum imparts some of its momemtum to the source, that's fine, it's still not scattering (even if there are similarities), it still produces a Doppler-like frequency-independent redshifts, and scattering analogues of the Wolf effect may still produce large distortion-free Doppler-like redshifts, which Wolf and other significant adherents discuss in a redshift/cosmology setting, AND IT'S ALL VERIFIABLE. --Iantresman 19:31, 13 March 2006 (UTC)

Since the radiative spectrum only imparts its momentum onto other sources, it is scattering. --ScienceApologist 19:35, 13 March 2006 (UTC)

So provide some sources containing "radiative" and "scattering" in the same sentence that makes this clear. --Iantresman 19:40, 13 March 2006 (UTC)

Rybicki and Lightman treat scattering through the radiation and absorption of photons through a medium in the first look they do in their text. --ScienceApologist 19:42, 13 March 2006 (UTC)

Title, page number, quote? --Iantresman 20:07, 13 March 2006 (UTC)

Chapter and verse are irrelevant for the purposes of this argument. The citation is to the first few chapters of the book on radiative processes. Read the book and get back to me. I'm not going to spoon-feed you information -- especially considering that this reference has zero-chance of making it into the article. --ScienceApologist 21:21, 13 March 2006 (UTC)

I would have put it this way: "Title, Radiative Processes in Astrophysics. Page number and quote, the first few chapters in general." Art LaPella 23:19, 13 March 2006 (UTC)

Scattering is mentioned on pages 8, 11 and 14, but I can find no confirmation of your view. Scattering is then mentioned on page 33 in the section on scattering, so I can find not verification of your point of view. Wolf and James say that "The Wolf effect is the name given to several closely related phenomena in radiation physics [..] analogous effects may occur in the scattering of light". This is verifiable PDF. As a radiative process, this is different from scattering, it says so in black and white. --Iantresman 00:11, 14 March 2006 (UTC)

The more I think about it, the crazier this is. This should have nothing to do with whether the Wolf effect is a radiative, or scattering process. Semantics should not be the deciding factor. The main criteria should be whether it produces an observable Doppler-like frequency-independent redshift, and all the references say that it does (unlike any of the other scattering processes). The secondary criteria is whether there is any relevance to cosmology, and yet again, the papers by Wolf, James, Roy, etc, all discuss it in this context. Finally, it meets Wiki policy requirements: Significant minority interest, and verifiability. --Iantresman 20:26, 13 March 2006 (UTC)

You're forgetting the undue weight section of NPOV. That's why it is excluded. We already mention effects that account for the optical phenomena that the Wolf Effect describes in the article. --ScienceApologist 21:21, 13 March 2006 (UTC)

We're going around in circles. It has already been demonstrated that there are prominent adherers as defined in Wiki's section on Under Weight. Emil Wolf himself is listed as one of the Top 1000 Scientists of all time. This has nothing to do with whether the Wolf Effect is considered important, or even merely considered, by astronomers. --Iantresman 21:41, 13 March 2006 (UTC)

This is getting beyond a joke. Every piece of information I have provided is VERIFIABLE. ScienceApologist has provided NO VERIFIABLE information. As far as I can tell, there are NO OTHER EDITORS who are so vehemently against including the Wolf effect.

Every piece of information I have provided is not only verifiable, but is backed up with a direct quote. ScienceApologist has provided NO QUOTES. --Iantresman 00:11, 14 March 2006 (UTC)

Direct verifiable quotations supporting the Wolf effect

• Direct quotations suporting that the Wolf effect produces a redshift

• "Non-cosmological redshifts of spectral lines" [29]
• "Here, we demonstrate that under certain circumstances the modification of the normalized spectrum of the emitted light caused by the correlations between the source fluctuations within the source region can produce redshifts of spectral lines in the emitted light". [30]

• Direct quotations suporting that the Wolf effect produces a frequency-independent Doppler-like redshift

• "In 1986, Wolf introduced the scaling law, which is a condition upon the spatial coherence properties of a source under which the radiated field has the same normalized spectrum as the source; in other words, if the source obeys the scaling law, the radiation pattern is independent of wavelength." PDF
• "A review is also presented of recent research, which has revealed that under certain circumstances the changes in the spectrum of light scattered on random media may imitate the Doppler effect, even though the source, the medium and the observer are all at rest with respect to one another. In the final section" PDF
• "Doppler-like Frequency Shifts Generated by Dynamic Scattering,”" [31]

• Direct quotations suporting that the Wolf effect produces large redshifts

• We see that, just as in the case when the shift is due to the Doppler effect, the relative frequency shift z induced by this mechanism is independent of frequency and can take on any value in the range —1 < z< [infinity], even though the source, the medium and the observer are at rest with respect to each other. [32]
• "Very recently it was predicted (Wolf 1989a, b) that the frequency shifts induced by scattering from time-dependent random media with suitable correlation properties may imitate a Doppler shift of any magnitude," PDF

• Direct quotations suporting that Wolf effect is due to a radiative process

• "The Wolf effect is the name given to several closely related phenomena in radiation physics..." PDF
• "For radiation from primary sources, the spectral changes are induced by correlations" PDF

• Direct quotations suporting that radiative effects are analogous to (hence not the same as) scattering

• "There is a well known analogy between the processes of radiation from primary sources and scattering of light by media of finite extent." PDF
• "Because of the well known analogy between radiation and scattering,.." PDF
• "For radiation from primary sources, the spectral changes are induced by correlations..." [..] "for radiation from secondary sources..." [..] "In scattering processes the changes in the spectrum are induced by correlations" PDF

• Direct quotations suporting that Wolf effect is significant in science

• "more than 100 papers on this subject, both theoretical and experimental, have been published" PDF
• "Since then over 100 papers have appeared on this and related topics..." PDF

• Direct quotations suporting that Wolf effect has relevence to cosmology

• "Non-cosmological redshifts of spectral lines" [33]
• "Some remarks about potential implications of correlation-induced spectral shifts for cosmology may perhaps be appropriate here." PDF
• "Spectral shifts and cosmology" PDF
• "It seems therefore possible, in principle, that this effect may contribute toward the redshifts observed in the spectra of some astronomical objects. PDF
• " the ' evidence' for non-cosmological redshifts..." PDF

(Please don't break up to list) --Iantresman 01:15, 14 March 2006 (UTC)

Please stop confounding the radiative Wolf effect (if I may use that terminology), that cannot produce large or frequency-independent redshifts, with the scattering Wolf effect, which does not occur in vacuum. There is not one Wolf effect. --Art Carlson 08:54, 14 March 2006 (UTC)

Attempting to maintain focus on the scattering issue

Building an encyclopedia is an inherently semantic exercise. We have an article on redshift that currently divides up phenomena called redshift in a certain way. The current article delivers readers who might actually be interested in bathochromic shifts to one destination, and a little lower down, it delivers readers who might actually be interested in reddening due to scattering to another destination. The goal of these alternative destinations is to focus the article on what the current version calls "Classical redshift mechanisms," and a good article on redshift will have only three of these because, despite what Ian has posted in the past, there are no more. If the Wolf effect in a vacuum is actually a scattering effect then the article is fine as is because it delivers anyone who might be interested in one effect or another to a destination where that effect could be included. An effect occuring in a vacuum can be due to events that actually took place away from a vacuum and were due to scattering. This line of thinking requires a certain mindset that non-physics people like me can only sustain for a few minutes per decade. Neverthelesss, we can do it. So that's where the semantics come in about whether the Wolf effect is always due to scattering. I don't care whether the Wolf effect is mentioned in the article. I just want an article that can deliver everyone to other destinations where they can learn more about what can cause light to increase in wavelength. Imagine someone who does not call the Wolf effect in free space a scattering effect. Many people do not call it this. What would they call it? It's been described as an interference effect in partially coherent light. SA..if you are dead-set against mentioning the effect explicitly, what would you think of changing the title of the relevant section to ""Reddening" due to scattering and to partially coherent interference" or ""Reddening" due to scattering and interference" to provide additional focus and to provide readers with additional destinations to learn more about what can increase wavelengths? Informing the reader is my goal. (Please (Ian) maintain focus on this topic while posting in this subsection) Flying Jazz 01:53, 14 March 2006 (UTC)

Thanks for the perspective Flying Jazz. It seems like it is the most level-headed commentary yet (including my own).

Expanding the Reddening section sounds like a good idea (there is often confusion that people have about whether reddening is actually redshifting) but going in the direction of "interference" is problematic because most interference effects are about amplitude and not frequency (this includes diffraction patterns, double slit experiments, etc.). I doubt anyone is going to look up redshift when they're really looking for radiative interference effects. It seems to me that what is really "interfering" in the Wolf Effect are waves propogated through emitting media rather than photons directly. The photons emit at different frequencies because media-resonances are excited and carry energy away before the coherent photons have a chance to show their true colors, as it were.

Currently the Wolf Effect is listed under the scattering page (and rightly so). Just like we wouldn't list Compton Scattering here we shouldn't list the Wolf Effect here.

The Wolf Effect is really due to resonance of photons with media which is succinctly described as "scattering". I really don't know how else to put it: singling the Wolf Effect out makes it seem like it is some novel phenomenon that is independent of other scattering mechanisms. In reality, for all but the most contrived situations it will occur with a whole host of other kinds of scattering which can also cause reddening to occur.

--ScienceApologist 02:12, 14 March 2006 (UTC)

You may be right that the Wolf effect is similar or even identical to effects that are called scattering. However, my impression is that distinctions between scattering and interference are no longer set in stone in physics in terms of amplitude and frequency, and I doubt they ever were set in stone this way. If one person calls a phenomenon that alters a wavelength a "partially coherent interference in a vacuum," another person can call the exact same phenomenon "scattering effects interacting while separated by a vacuum" and maybe neither person is wrong. However, only scattering is mentioned in the current redshift article. I am not talking about singling out the Wolf effect. I am talking about mentioning interference, and ideally, partially coherent interference because I suspect that this is the flavor that is required for a wavelength to shift regardless of whether the shift is due to the Wolf effect or another effect (that may also be labelled as scattering or as interference). Also, people often are most interested in the most contrived situations. Most of the interest is mere curiosity, but sometimes what is viewed during one century as a contrived situation is viewed during the next as a very common situation. I doubt that will happen with the Wolf effect, but withholding information about anything from the reader, even if it is the most contrived situation, is not a good idea. Flying Jazz 02:53, 14 March 2006 (UTC)

Wave interference as a subject would need some substantial changing if we are to take your idealization of what interference can do to frequency. If I understand you correctly, you are suggesting that the Wolf Effect serves as a kind of Fourier analysis of multiple resonant waves due to the partially coherent character of the waveforms. The formalism of such an effect is interesting, but I was always taught that the superposition of two different coherent modes brought about beat phenomena and not changes to the wave frequency. This whole discussion is beginning to look a lot like the ambiguity between phase vs. group velocity -- I think that ultimately the conservation of energy is the clearest indicator of whether the perspective makes sense. What is fundamentally different about an interference effect which conspires to look exactly like scattering and a scattering effect that can be described through the superposition of electromagnetic waves as a Fourier decomposition and subsequent absorption and transmission of resonant frequencies? Are we really willing to bring Wikipedia readers down the garden path when there isn't a clear distinction made? Can you tell the difference between the two formulations? Because to me they look the same, they act the same, so they must be the same. The Wolf Effect must be a form of scattering. --ScienceApologist 03:31, 14 March 2006 (UTC)

I think the Wolf effect involves the superposition of two different coherent modes that are also fluctuating in intensity. And conservation of energy occurs because of anisotropy. In some directions, there's a blueshift and in others there's a redshift. And I would only be pretending if I said I understood the math or even if I said I tried to understand it. I am considering this from the standpoint of the sociology of different scientific subdisciplines and the words that each use. What is ambiguous in one subfield may be clear in another. My rebuttal is along the lines of "If it's just like the other girls then why isn't it called Wolf Scattering instead of the Wolf Effect?" Most of what you wrote is beyond me. I do like gardening, but I only want to lead people to places of clarity and information. Flying Jazz 04:25, 14 March 2006 (UTC)

SA...I suspect that at the heart of what we've been discussing may be a matter of what different subfields assume as "given starting material". Someone deep in optics might say "Given light with properties of such-and-such, we can find so-and-so." Then someone deep in particle physics says "But in order to obtain light with properties of such-and-such, there must be scattering, so it is ultimately a scattering effect." The person in optics might reply, "Yes, maybe, but I'm just not very interested in original physical cause. I'm interested in what light can do." The optics fan saying this might even be talking about one of the other things besides Wolf effect that people have wanted in this article. These things might also ultimately boil down to scattering if one looks at the initial physical cause. But there is no reason to only consider initial cause when deciding what get mentioned and kept out of an encyclopedia. A reader who is interested in what light can do to increase wavelength should be able to see those interests satisfied as completely as possible by this article without going overboard. Some mention of coherence or interference or, ideally, both, is warranted if the Wolf effect is to be kept out. Flying Jazz 11:22, 14 March 2006 (UTC)

I just don't see it your way, Flying Jazz. Someone that "deep into" optics won't see a problem with a page which relegates reddening to a section on scattering as it generally assumed that this is the way light reddens. Coherence as an effect is really not relevant to this article -- the nature of the source of light has little to do with the actual reddening mechanisms and indeed is only an issue when talking about how the Wolf Effect's resonance is manifested. Likewise, associating interference with reddening runs into the problems of really flying in the face of the way interference is classically treated in optics. These issues are just too removed from the actual content of this page to warrant detailed discussion here. --ScienceApologist 12:29, 14 March 2006 (UTC)

I am not advocating a detailed discussion here in the talk space or in the Redshift article space. We are having this discussion as a consequence of your three rapid reversions. I am advocating mentioning either a specific effect (Wolf) or a class of effects (partially coherent interference) that are represented in the literature as increasing wavelengths in a vacuum in order to inform the reader that these effects are not classical redshift mechanisms. The idea that an increase of wavelength in a vacuum is too far removed from redshift content to merit discussion or mention is indicative that Ian's advocacy of ridiculous positions has impacted your judgement about rational ones. Flying Jazz 12:48, 14 March 2006 (UTC)

That the article on redshift features "classical mechanisms" is an important, though an artificial selection, based on (a) historical reason (b) based on a selection by astronomers. What is most important, is that people can find information that is directly related to the redshift observations.

Scattering has a section of its own because scattering does not produce frequency-independent Doppler-like redshifts.

The Wolf effect is different (a) because it does produce a Doppler-like frequency-independent redshift that has been confirmed in the laboratory (b) that it not only falls into the scattering section, but also falls into a DIFFERENT section on radiative phenomenon (c) that the Wolf effect is discussed in relation to cosmology. (d) That optics people considers this a "new mechanism".

This is not an article titled "Classic redshifts" or "Doppler-like redshifts". This is an article titled "Redshift", which should include anything that is relevant to "redshift": The Wolf effect, "Intrinsic redshifts", "Non-cosmological redshifts", "Redshift quantization"; or at the very least, include links to these subjects. --Iantresman 08:18, 14 March 2006 (UTC)

Not a reasonable request per undue weight. --ScienceApologist 12:34, 14 March 2006 (UTC)

This is your point of view, it is unsubstantiated, and unverifiable. As I have shown on more than one occassion, there have been "more than 100 papers on this subject, both theoretical and experimental, have been published" PDF", that is verifiable, and a neutral discription of the facts. --Iantresman 13:40, 14 March 2006 (UTC)

Move to the Wolf effect page

There is a lot (too much!) of discussion here about the physics of the Wolf effect. No one really understands it, and the partial understandings do not overlap. I propose sorting this out first in the Wolf effect article, ideally with the participation of Wolf himself, now that Ian has made contact. I further propose, as a compromise for this page, putting in a minimal "See also: Wolf effect", with the explicit understanding that it will later be removed or (in moderation) expanded once we sort out the physics. --Art Carlson 09:13, 14 March 2006 (UTC)

Alas I don't see Emil Wolf fully participating. I have one more question awaiting answer from him, but he's over 80 years old now. But if he replies, I'll post it.

As Flying Jazz mentioned ".. this article is about redshift, an observable. Causes of redshift are secondary."[34]; And the references say that the Wolf effect as a redshift is an observable phenomenon, that conforms to the definition given in this article, and is considered a forth mechanism (all this is verifiable). That's why it should be mentioned along side the classicical definition, with the text describing its characteristics.

Perhaps ScienceApologist can clarify whether a spectrum showing a Doppler redshift of starlight is derived from a radiative, scattering, or other source? --Iantresman 10:45, 14 March 2006 (UTC)

Ian, "radiative processes" are usually associated with radiative transfer which takes into account four basic effects emission, absorption, reflection, and transmission. Reflection and transmission with refraction are the forms of radiative transfer traditionally called "scattering" though there is a whole formalism which treats scattering with the appropriate potential formalism which sidesteps the issue, when it gets right down to it every radiative process is either associated with an emission of a photon, an absorption of a photon, or the free streaming of a photon. Mix and match in various combinations to get all other radiative phenomena. --ScienceApologist 12:34, 14 March 2006 (UTC)

I think moving the discussion to Wolf Effect would be a mistake because the matter under discussion is what should be mentioned and not mentioned in the redshift article. The archives on this talk page are already full of partial understandings and lengthy rants. Better to create yet another archive here than to stink up another article's talk page. Flying Jazz 11:22, 14 March 2006 (UTC)

I'm not arguing for them, but could someone summarise why we removed scatting processes? I thought it was because they either (a) producing a reddening, rather than a line shift (b) where they do produce a line shift, it is distorted in some way. In otherwords, they produce a non-Doppler like redshift. --Iantresman 13:37, 14 March 2006 (UTC)

That's part of the issue. The other issue is that they are generally called "reddening" rather than "redshifting" amongst those who use the terms. An article on interstellar reddening has been stubbed to funnel people interested in that phenomenon over there. However, there are only a limited number of scattering phenomena which occur in the rarefied gases and plasmas of space. For example, the Wolf Effect does not occur in material densities like that seen in the ISM. --ScienceApologist 18:36, 14 March 2006 (UTC)

I agree with most of that regarding scattering, and I can see why we would exclude it. So presumably we'd include any other redshift phenomenon that is (a) not reddening (b) frequency independent (c) distortion free. ie. Doppler like, regardless of the cause/mechanism. --Iantresman 21:01, 14 March 2006 (UTC)

The second sentence of Emil Wolf's email to Ian is very concise and relevant.

"It seems, that the term "the Wolf effect" has now been adopted for the phenomena of changes in the spectrum of either a radiated or a scattered field, caused either by source correlations, or by correlations in the physical properties (e.g. the refractive index) of a scattering medium."

The only option that is relevant to my argument for inclusion is that of a change in the spectrum of a radiated field caused by source correlations. Anything else is a scattering effect. ScienceApologist's argument that those source correlations must be DUE to scattering effects is well-taken and probably valid. Taken as a whole, the (1) cause of the radiative Wolf effect and the (2) effect itself may always be due to scattering. SA seems to view #1 and #2 together as the Wolf effect and #2 alone as "how the Wolf effect's resonance is manifested." Wolf himself seems to see #2 as the Wolf effect and #1 as its cause. This may all be semantics, of course, and not worth much argument in terms of the physics (especially since most of us don't understand the mathematical details), but it is at the heart of the issue under debate for inclusion as an effect that is or is not scattering. Flying Jazz 13:42, 15 March 2006 (UTC)

Options for resolution

1) No mention of Wolf effect in the article (advocated by ScienceApologist)

2) Include "See also: Wolf effect" in the "Reddening" section with the understanding that it may be changed later when a consensus is built. (advocated by ArtCarlson)

3) Include in the "Reddening" section "An optical phenomenon known as the Wolf effect may cause a spectral line to shift in a vacuum due to phase coupling with another source, but the change in wavelength cannot be larger than the width of the line itself unless scattering effects are also present." (advocated by Flying Jazz. I think I can find a verifiable reference that uses these words.)

4) Include a descriprion of the Wolf effect as a fourth cause of redshift of equal importance in the article as Doppler, expansion, and relativistic effects. (advocated by Iantresman)

5) A version that mentions partial coherence effects but does not single out Wolf effect by name, per Flying Jazz's comments below.

6) A version that makes it clear the "classical redshift mechanisms" are due to reference frame considerations, reddening is due to light-matter interactions, and mentions coherence effects as a means to obtain such reddening. This satisfies the conditions of undue weight, conforms to summary style and doesn't bog down the prose with needless tangential phenomena, instead directing the reader to the appropriate pages.

If anyone other than us has bothered reading the discussion up there and has formulated an opinion among the four or other suggestions, please let us know. Flying Jazz 02:38, 15 March 2006 (UTC)

• Support 4, 3, 2 (in that order) on the grounds that (a) references say that the Wolf effect is a redshift mechanism consistent with the definition in this article (b) adherents discuss the Wolf effect in a cosmological context (c) We have an obligation to lead readers to information on the redshift. I am reluctant to have it in a section on "reddening" when it is not a reddening phenomenon. I am reluctant to have it in a section on scattering when it is primarily a radiative phenomenon, and scattering may produce a frequency-independent distortion free redshifts (ie Doppler-like redshifts of any magntitude). Including the Wolf effect is "inclusive", does no harm, allows the reader to find out and decide its importance and relevance themselves, is verifiable. and acknowledges over 100 papers on the subject. --Iantresman 08:25, 15 March 2006 (UTC)

• Support 1, 2, 3, 5, or 6 (in any order). It is way out of line to call the radiative Wolf effect equal in importance to the three classical mechanisms. --Art Carlson 08:32, 15 March 2006 (UTC) I like Joshua's new version, though I think it is wrong to refer to the shift in the central frequencies of spectral lines as "reddening" rather than "redshift". I don't know how Ian would include the Wolf effect as an independent fourth mechansim (4, modified) without giving it undue weight. --Art Carlson 21:25, 15 March 2006 (UTC)

• Support 3, 2 3, 5, 2 (in that order). I would also support a version that mentions partial coherence effects but does not single out Wolf effect by name. Flying Jazz 12:59, 15 March 2006 (UTC)

I'd like to accomodate your option of mentioning partial coherence effects -- it seems to me that this is just a conspiratorial version of traditional radiative effects and could be mentioned in the Reddening section with a simple statement that said "there are observed optical effects of coherent radiation that may mimic frequency independent shifts". Would a statement like this satisfy you? --ScienceApologist 14:47, 15 March 2006 (UTC)

No. (a) we've not mentioned partially coherent light sources until now, and I can't see what the relevance is to (b) frequency-independent redshifts (c) the Wolf effect. So make your selection from (1) (2) (3) and (4). --Iantresman 14:56, 15 March 2006 (UTC)

Ian...When Wolf kindly emailed you saying the effect was "due to phase coupling," he almost certainly meant partial optical coherence. Saying that one isn't relevant to the other is silly. The coherence (physics) page might be improved in the future to include the Wolf effect. Flying Jazz 16:52, 15 March 2006 (UTC)

Stop being a stick-in-the-mud. There are more than 4 ways to resolve this conflict. --ScienceApologist 15:12, 15 March 2006 (UTC)

I've added a fifth option, that will enable people to add it to their vote if they wish. --Iantresman 16:25, 15 March 2006 (UTC)

SA...You may be right that a conspiracy is afoot to call a version of traditional radiative effects by a different name, but it could simply be a conspiracy to honor a great scientist by naming a subset of radiative effects after him because he contributed greatly to understanding their optics mathematically and completely. If a link to coherence is included, I would support #5. Flying Jazz 16:53, 15 March 2006 (UTC)

Surely it's not being suggested that there is a conspiracy in naming something after Wolf? Wolf never called the Wolf effect the Wolf effect; his paper predicting the effect is called "Non-cosmological redshifts". And Wolf's email to me (above) seems to suggest that he is resigned to the use of the term, which was so-named by his collegues in the field, probably because (and I'm speculating), "Wolf effect" is easy to write and say than "coherence-induced spectral shift". But that is what it is called (or Wolf shift). I'm sure that there was no conspiracy in "Hubble's Law", Hartle-Hawking state, Kaluza-Klein theory, Planck epoch, Sachs-Wolfe effect, Friedmann-Lemaitre universes, Robertson-Walker coordinates and many other so-name theories and phenomena. --Iantresman 17:26, 15 March 2006 (UTC)

If someone named something after me, I might view it as a friendly and honorable conspiracy being afoot. SA's words about "a conspirational version of traditional radiative effects" were intended in that sense, I hope. Ian, in a talk page, anyone can type anything anywhere, but it might be nice if you at least wait until SA answers a post addressed to him before you engage in another listing event. Flying Jazz 18:22, 15 March 2006 (UTC)

Sorry, didn't note the question. --Iantresman 18:28, 15 March 2006 (UTC)

Additional Comments

I would just mention to Art that I don't think there is any argument that the Wolf effect isn't equal in importance to the other redshifts. Only that it is one of four known mechanisms (so is at least significance), and I would be happy for its context in option (4) to be qualified that way. --Iantresman 09:15, 15 March 2006 (UTC)

Comment on Flying Jazz, does "partial coherence" produce Doppler-like redshifts, I couldn't find many references in the ADS database? --Iantresman 13:57, 15 March 2006 (UTC)

I'm not interested in that topic or in an additional comments subsection. The entire talk page for several months has had too many of those. I am interested in consensus and resolution now, but...in an effort to aid in that cause, I will say, from my limited understanding, no. Maybe from one perspective, the redshifts may appear Doppler-like when viewed from the perfect location with respect to the sources. When viewed from a different location, they would look different or look like a blueshift in a way that is not Doppler-like. Your behavior on this talk page has been consistently baiting, mind-numbingly excessive, repetitive, and obsessive. Please stop. Flying Jazz 14:37, 15 March 2006 (UTC)

I respond to statements with the best verifiable statements I can. How else do I respond, for example, to ScienceApologist's claim for the umpteenth time, regarding "Undue weight", when even mind-numbingly excessive verifiable statements are dismissed? Do I ignore them and make it look like I don't have an answer, or repeat what I've mention several times before? --Iantresman 18:45, 15 March 2006 (UTC)

I have been following this discussion for some time now. Several times it has gone around in circles. I have been also following the literature of the wolf effect. This is a classic example of problems with having an encyclopedia, no matter how open – knowledge is perspective, and thus is always subject to debate. In general this discussion reminds me of Kuhn’s structure of Scientific Revolutions, where in the face of overwhelming evidence, adherents of an old school of thought are unable to come to grips with a new science. Kuhn was a physicist, and a historian of science. I am a physicist and think that the wolf effect is interesting and significant. Not everyone agrees. This is ok, however a long, complete discussion of the wolf effect as a red shift clearly needs to be included (both why is and why not a red shift) in this page, and I encourage Ian to start his article. However, I think that it is incredibly important to include a section on dissenting opinions, WITH citations, and quotes. Personally I am convinced that this is a widely accepted red shift because of the quality of the researchers who have verified it and theorized it, the complete with the phenomenon with the page’s definition. Line width is not a criteria for red shift, if it is (a joke here) we should mention the minimum limit for what is considered a red shift. --PhysicsDude 15:57, 15 March 2006 (UTC)

Do you know enough about the Wolf effect to answer some questions that we might all have, it may help us to decided the (in)significance of the phenomenon. --Iantresman 16:25, 15 March 2006 (UTC)

I agree that there is no minimum limit for what is considered a red shift. However, whether there is a minimum limit for what is considered a "Classical redshift" is for us to determine as encyclopedia editors and the focus should always be on the reader. This means a balance between new science and what people in most fields right now mean when they use a term. If you have been following the wolf effect literature, please (oh, please) improve the Wolf effect article and mention the effect with a diagram if possible in the coherence (physics) article. Once we understand what it is, we'll have the tools to make a better judgement to include it in this article or not. If you are informed, please stop the talk-space madness and ambiguity and improve the articles here. Citations and quotes in other articles about what the effect is should precede citations and quotes here about whether it rises to the level of being included as a redshift mechanism of the same weight as the other three. Flying Jazz 17:10, 15 March 2006 (UTC)

The article is titled "Redshift", not "Classic redshifts". Is there a term "Classic redshift"? If the word "Classic" is being used in a certain sense, then the Wolf effect is "Classic" (ie mechanical), and the "Relativistic effects" are not?

The section used to be called "Causes of redshift", which is what you would expect in an article on redshift. Then it was changed to "Doppler-like redshift" (presumably because it was thought that the Wolf effect was not Doppler like), and then it was changed again to "Shifts in vacuum", presumably because when it was found that the Wolf effect was Doppler-like, it was assumed it did not take place in vacuum... and now we have "Classic redshift" which presumably can mean anything we want, in this case, Redshifts that don't have the word "Wolf" in the title. OK, a bit of a slanted view, but how else does one see the progress? --Iantresman 17:26, 15 March 2006 (UTC)

Email Wolf Clarification II

Emil Wolf has just replied to my last query as follows:

To: Emil Wolf From: Ian Tresman Date: 13 Mar 2006 Can you just comment on whether (a) a "radiated field" is considered a type of "scattering"? (b) Presumably the former may occur in a vacuum (free space), whereas scattering requires a medium?

And his response:

To: Ian Tresman From: Emil Wolf Date: 15 Mar 2006 Here is my response to your question contained in your e-mail of March 13th. The processes of radiation and of scattering are rather similar, but they are distinct. Radiation is generated by atoms and molecules in some region of space (the source). The process may be "spontaneous" or "stimulated", depending on the nature of the source and on the environment in which it is located. On the other hand scattering is always generated by an external field which interacts with the atoms in the medium and makes them radiate. Mathematically the two processes are very similar but physically they are different.

--Iantresman 17:26, 15 March 2006 (UTC)

I could have told you this response, but it doesn't help us understand how to change the article. --ScienceApologist 18:51, 15 March 2006 (UTC)

Explanation of the conflict up until now

Ian wants to see the Wolf Effect included as a "fourth" source of redshifts. I believe that this is an inappropriate gesture because there is a very limited amount of literature that calls observations associated with the Wolf Effect "redshift" and there are some differences between the three types of redshifts currently listed on the page and the "redshift" assocaited with the Wolf Effect. In particular, the Wolf Effect is related to some rather specificradiative transfer points about coherent sources and resonance. The relationship between the Wolf Effect and reddening is much clearer as the term "reddening" is usually associated with frequency shifts in radiative transfer. In fact, the effect is so specific that its inclusion runs the risk of undue weight as the cause of the frequency shifts which may be related to unique forms of wave mechanics and emission/absorption physics.

I think part of the issue is that Ian sees a distinction between the Wolf Effect and scattering. Fine. What there isn't a distinction between is the Wolf Effect and radiative transfer. As such, I'm going to change the section on reddening to be about the interaction between light and matter. This way the Wolf Effect is unambiguously included and will not need to be mentioned.

I think coherence is a level of specificity too great for inclusion in this article. Let me know what the editors think.

--ScienceApologist 19:00, 15 March 2006 (UTC)

OK Flying Jazz, what do I do now that you've mentioned that I'm excessive, repetitive, and obsessive? I've already provided verifiable citations answering every single one of these, whereas ScienceApologist has provided not ONE verifiable citation beyond several chapters of a book we're supposed to read, but can't pick out a statement verifying his position.

"Wikipedia is verifiability, not truth."[35]. No-one has to know WHAT the Wolf effect is, it could be magic for all I care, but we can verify that the literature says that it produces a Doppler-like frequency-independent redshift, and there is no doubt that this article is about redshift.

Who do you go with? Over 100 citations by experts in optics, or ScienceApologist. --Iantresman 19:13, 15 March 2006 (UTC)

Resolved?

At this point I have made it abundantly clear what the differences are between redshifts in general and other effects. At this point, it seems reasonable to even include the Wolf Effect because it doesn't lead readers to believe that it is somehow unique, but I'm still not exactly satisfied with the wording as this is such a "contrived" effect that it probably doesn't belong in the general article. I'm going to continue tweaking, but does this satisify? --ScienceApologist 19:18, 15 March 2006 (UTC)

You lost that effect in the process of rephrasing; I reinserted your version at the corresponding place - looks OK to me. Harald88 19:39, 15 March 2006 (UTC)

I don't think discussing the Wolf Effect in detail makes sense on this page. Let people look up coherence effects. If it makes you more comfortable we can change the coherence effect link to coherence effects. How's that? --ScienceApologist 20:03, 15 March 2006 (UTC)

I have modified the entry slightly. Please comment. I think this makes the above discussion moot. --ScienceApologist 19:30, 15 March 2006 (UTC)

As you said just three days ago to Harald "please let's settle this on talk rather than engaging in pointless edit wars."[36]

Flying Jazz has initiated an "Options for Resolution", which as far as I can see, is still ongoing.

I would suggest that you remove whatever changes you have made, follow your own advice to "settle this on talk", wait at least until the "Options for resolution" has resolved or completed, and then if the opportunity arises, put forward some proposals. --Iantresman 19:44, 15 March 2006 (UTC)

Do you have any specific criticisms of my changes? Because all this above seems like needless handwringing. If I have created a version that works and will avoid all this yammering on the talkpage, then we're done. If not, let me know what I can do to get at a compromise. --ScienceApologist 20:03, 15 March 2006 (UTC)

My specific criticism is that they are not in keeping with Flying Jazz's efforts, in which all the other editors were fully participating. In other words, you making a unilaterial editorial contribution, which I am sure if I had made wouldn't have last a few minutes... as Harald found with his efforts. --Iantresman 20:16, 15 March 2006 (UTC)

So no criticism on the content? --ScienceApologist 20:21, 15 March 2006 (UTC)

SA has instituted option 5 (no wait...now there's a 6 of course). It would have been nicer to have waited a while so more people (ArtCarlson in particular) could comment about it before making the change. The content seems like an improvement to me, and I think a good article would separate redshifts the way this article does now. But it says under Reddening These effects are generally not considered to be "redshifts" and then later such phenomena are sometimes referred to as "redshifts". The first statement of the two is unnecessarily POV and confrontational. It should be deleted. The second statement reflects the truth of the matter that they are called redshifts sometimes even though this article places them under the category of Reddening for valid semantic reasons. Whether they are or not considered to be redshifts should be left entirely to the reader. A futher improvement in my opinion would be to include "(see Wolf effect)" after the link to coherence. As far as I know, nobody has argued that there is a coherence effect that does this other than the one called Wolf effect, so this will add specificity without opening the floodgates to a barrage of other phenomena. Flying Jazz 21:05, 15 March 2006 (UTC)

I think all of your suggestions are good ones. I have changed the wording accordingly and added a distinction between reddening and redshifting. I understand people's desire to "wait", but one of the prime directives of Wikipedia is to be bold. I saw an opportunity to write for the enemy and I thought it would result in resolution so I jumped at it. Of course, if someone wants to revert, that's within their Wikipedian rights. --ScienceApologist 21:24, 15 March 2006 (UTC)

The current version looks good to me when dealing with this subject. An expert on scattering, Wolf shift, and "classical" redshift might be able to improve it, but this seems fine for now. Flying Jazz 00:54, 16 March 2006 (UTC)

... bold, and nicer to have waited... it's bloody hypocritical and disrespectful to the other editors and sets an undesirable prescedence. Criticism of the the text:

• As far as I know, the Wolf effect does not produce a "reddening" like scattering can. If this is considered to be the case, a reference please.
• While the scattering analogue of the Wolf effect may be considered a light-matter interaction, the radiative phenomenon of the Wolf effect is not a light-matter interaction. It is the "name given to several closely related phenomena in radiation physics" [37] (my emphasis). This is clarified by Emil Wolf (above).
• If a radiation is considered a light-matter interaction, then so are spectra from stars, galaxies, etc,. and hence so are the Doppler, cosmological and gravitationa redshifts.
• While scattering may "not [be] considered to be "redshifts"", the Wolf effect IS, and I have provided verifiable references showing that it is. If it is felt that the Wolf effect is not a redshift, references please.
• "These shifts can be due to coherence effects...", (a) What shifts? (b) Not the Wolf effect because it is not one of those that is "not considered to be "redshifts"".
• "the electromagnetic interaction of the photons with intervening matter distinguishes these phenomena from the reference-frame effects discussed above."... which rules out the Wolf effect which may occurs in a vacuum and without intervening matter.
• To summarise, the text does not accurately describe the Wolf effect which MANY references say causes a frequency-independent Doppler-like redshift without the need for intervening matter.

I must have been sleeping. I was and am under the impression, as I have told you repeatedly, that that the radiative Wolf effect is not capable of producing a frequency-independent redshift. Which references would those be? --Art Carlson 21:59, 15 March 2006 (UTC)

I might be mixing up the radiative with the scattering forms. I'll double check and get back when I have confirmation. --Iantresman 23:29, 15 March 2006 (UTC)--Iantresman 21:47, 15 March 2006 (UTC)

I stand corrected, here is the latest clarification from Emil Wolf:

To: Emil Wolf From: Ian Tresman Date: 15 Mar 2006 While I have found many references in your paper indicating that the scattering analogues of the Wolf effect will produce frequency-independent Doppler-like redshifts, will a non-scattering radiative source?

From: Emil Wolf To: Ian Tresman Date: 18 Mar 2006 Here are my answers to your email of March 15. A radiating source will generally produce a shift which depends on the frequency. I say, “generally” because there may be some exceptions, but that would need an investigation. A source which does not obey the scaling law will produce a far-zone spectrum whose relative shift depends on the frequency, i.e. the spectrum will not be Doppler-like.

So indeed, that just leaves the scattering analogue of the Wolf effect that will produce a frequency-independent Doppler-like redshift of any magnitude. --Iantresman 17:24, 18 March 2006 (UTC)

Radiative transfer

ScienceApologist speculated: "there are some differences between the three types of redshifts currently listed on the page and the "redshift" assocaited with the Wolf Effect. In particular, the Wolf Effect is related to some rather specific radiative transfer points about coherent sources and resonance" [38]

James et al wrote: "We have shown that frequency shifts of spectral lines which mimic the Doppler effect can be generated by scattering from a random medium which has a physically plausible correlation function for the dielectric fluctuations. We emphasize that this mechanism cannot be explained either by naive considerations involving photon fluxes or by radiative transfer or coherent wave propagation." (my emphasis). Verifiable reference: "Shifts of Spectral Lines Caused by Scattering From Random Media"

• You also said that the Wolf effect does not produce a Doppler-like redshift. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided
• You said that the Wolf effect does not produce a frequency-independent redshift. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided.
• You said that the Wolf effect does not produce a redshift that is consistent with the definition on this page. You were wrong as is clear from the literature, and is verifiable from the several citations that I have provided.
• You said that the Wolf effect is a scattering mechanism, which effectively the same as a radiative one, but have been unable to prvoide a verifiable quote supporting this view, and Wolf says above that "they are distinct".

--Iantresman 22:11, 15 March 2006 (UTC)

"Vacuum redshifts"

• The article mentions redshifts that occur in a vacuum. Since ScienceApologist is so insistant on the literature confirming the definition of redshift, can he provide a quote and reference in which a vacuum is required in the definition?
• The article mentions in the section on Relativistic effects, "a third class of vacuum redshifts,..."; I think that "vacuum redshifts" is no such class, and a mythical ScienceApologism; again, can you provide any reference that talks about "vacuum redshifts".
• Are we all agreed that no observed redshifts, in space or in the laboratory, take place in/through a vacuum?
• Consequently, are we all agreed that whether there is a vacuum or not, is irrelevant to redshifts.

--Iantresman 23:29, 15 March 2006 (UTC)

The article is greatly improved I think by emphasizing frame-of-reference more and vacuum less, and a few more minor edits might be called for to eliminate the previous emphasis on a vacuum that appears here and there. The specific points you are making and questions you are asking seem to be designed more to score points in some argument than to improve the article. Flying Jazz 01:09, 16 March 2006 (UTC)

This is about accuracy, and as far as I can tell, a "vacuum" has little to do with redshifts, and its importance has been suggested in order to discount the Wolf effect. If I am wrong, then others will have no problem in finding some references as I have asked. But as I see, redshift is not measured in a vacuum, the maths does not require a vacuum, the definitions says nothing of a vacuum, space is not vacuum... so I am left wondering why there is mention of a vacuum. Indeed, I see NO EVIDENCE whatsoever that redshift will occur, or even may occur, in a vacuum. --Iantresman 07:56, 16 March 2006 (UTC)

Reference to the vacuum is now completely removed except for one place where it is totally verifiable as a means to defining reference frames (free space). Also, there is no longer any ambiguity as to whether physical optics (Wolf effect) is part of radiative transfer since there are extremely boring technical issues as to whether it can appropriately be described as such. --ScienceApologist 13:34, 16 March 2006 (UTC)

Thanks, makes better sense --Iantresman 14:06, 16 March 2006 (UTC)

Having said that, the text reads "A single photon traveling through a vacuum can redshift in three distinct ways".

• Space is not a vacuum. Does this mean (a) that this does not apply to space (b) A photon may redshift in a non-vacuum too?
• Isn't the Doppler redshift a source effect? A photon travelling through a vacuum (having left its source) will not subsequently be Doppler shifted?

--Iantresman 14:19, 16 March 2006 (UTC)

• Whether space is a vacuum or not is irrelevant. Since the redshift is a reference frame shift, it also applies not in a vacuum. However, as other effects can occur when there isn't a vacuum, this theoretical treatment prevents naysaying.
• A photon can be Doppler shifted by motion of the source or observer.

--ScienceApologist 14:32, 16 March 2006 (UTC)

But the shift does not occur while the photon is "traveling through a vacuum". Many moons ago I also questioned whether the gravitational redshift occurs at the source or in the intervening vacuum. --Art Carlson 14:45, 16 March 2006 (UTC)

• So since "Whether space is a vacuum or not is irrelevant", I suggest that either we don't mention it, or we clarify that it doesn't matter whether space is a vacuum or not.
• And since a photon can be Doppler shifted by motion of the source or observer, as Art suggests, that implies that it does not occur while it is travelling through a vacuum (or non vacuum)?
• I would think that a "gravitational well" can occur in free space?

--Iantresman 15:13, 16 March 2006 (UTC)

• It's important we keep in the vacuum in order to set-up the scenario where these redshifts appear but other kinds of frequency shifts don't. It does matter if it is a vacuum for other sorts of frequency shifts. This allows for the theoretical description to be comprehensive as well as accurate.
• The redshifts mentioned are all frame dependent in that they are all arbitrary. They don't "occur" anywhere but are rather the physical manifestation of mathematical transformations. The question of what happens to photons in route is a meaningless one.
• You are correct, a gravitational well can occur in free space. It is associated with a curvature tensor which makes no reference to anything but metrics.

--ScienceApologist 19:21, 16 March 2006 (UTC)

Since space is not a vacuum, then it seems to me important to emphasize that a vacuum is not required. Do we have a reference indicating that a vacuum is important to redshift mechanisms?

Does the Doppler redshift occur in free space, or is it a source or observer effect?

--Iantresman 19:44, 16 March 2006 (UTC)

We never state that a vacuum is important to redshift mechanisms. It is clear, though that you get frequency shifts only due to reference frame changes when a single photon is transmitted through a vacuum. Thus, we introduce the construct in order to illustrate the idealization of the conditions.

The Doppler Redshift occurs when a coordinate transformation occurs that is physically meaningful. To measure such an effect you of course need a source and an observer and they need to be in different reference frames. The only way to do this is to have space between the source and observer and additional conditions on the character of the two reference frames in question.

--ScienceApologist 15:52, 17 March 2006 (UTC)

• So we mention a vacuum to characterise the redshift?
• So can a photon redshift if it travelling through a non-vacumm, which is a realistic, rather than idealistic conditions? Bearing in mind that we NEVER see idealistic condition in space, it would make more sense to at least describe the realistic condition?
• So a Doppler redshift does not occur in free space without a source or observational interaction?

--Iantresman 16:33, 17 March 2006 (UTC)

• No, we mention the vacuum to contextualize the discussion. In a vacuum there cannot be any shifts due to photon-matter interactions.
• Since the mechanism section is just setting up the physical arguments, the models used can be approximate. This is similar to someone describing mechanics and setting up the scenarios for consideration while ignoring friction and non-conservative forces. Realistic? No. Useful? Yes.
• A Doppler redshift can occur in free space independent of source or observer. If a photon exists in free space and you perform the appropriate coordinate transform the result is a redshift.

--ScienceApologist 17:03, 17 March 2006 (UTC)

So we should mention a non-vacuum, to put redshifts into the context of the real universe, rather than the mathematical universe. At the moment, the text implies that a photon may redshift (only) in a vacuum, when as you say, this is (a) irrelevant (b) not what is observed in the real universe. --Iantresman 17:25, 17 March 2006 (UTC)

I disagree that "the text implies that a photon may redshift (only) in a vacuum". Just because the theoretical treatment ignores external variables doesn't mean that when those external variables are applied the theoretical treatment no longer applies. That's like saying that the statement "a hammer and a feather fall at the same rate of speed in a vacuum" doesn't have any utility in explaining falling in an atmosphere when it's clear that the constant acceleration due to gravity is still applicable. --ScienceApologist 17:45, 17 March 2006 (UTC)

While I understand what you mean, I think it results in misleading (or theoretical) statement; can you provide a reference which defines redshift in terms of photons moving through a vacuum? --Iantresman 19:39, 17 March 2006 (UTC)

Don't need to. All we need is to establish that a photon is a form of electromagnetic radiation, that electromagnetic radiation propagates through a vacuum, and that a redshift can be obtained from a coordinate transformation. All of these facts are verifiable. --ScienceApologist 20:13, 17 March 2006 (UTC)

• A coordinate transformation describes a redshift, it does not provide the cause.
• The Doppler effect will not work without a physical source or physical observer. Consequently a photon moving in a vacuum cannont be further redshifted unless it meets a physical observer.
  • No one said it provided the cause.
  • The Doppler effect does work without a physical source since you don't need to know the source to witness the Doppler effect. More than that, the observer is just a placeholder for the transformation.

--ScienceApologist 22:10, 17 March 2006 (UTC)

• So why do we mention transformations in the section on causes?
• So what CAUSES a Doppler redshift of a photon moving in a vacuum, in the real universe?

--Iantresman 22:43, 17 March 2006 (UTC)

• • • • We mention transformations because that's what the mechanisms have in common.
      • Physical situations where a coordinate transform is necessary to specify observations.

--ScienceApologist 23:15, 17 March 2006 (UTC)

An example please. What physical situation would CAUSE a coordinate transformation that results in a Doppler redshift, that excludes a source and observer. It can't include matter because we're in a vacuum, and it can't be another photon, because there is only one of them. So in REALITY, a Doppler redshift can not occur without a moving physical source of moving physical observer? --Iantresman 23:26, 17 March 2006 (UTC)

Example: A photon is transmitted through curved space. At one point, the metric will indicate a photon of a certain frequency. At another point, the metric will indicate a photon of a different frequency. This is a redshift due to a coordinate transformation. --ScienceApologist 23:31, 17 March 2006 (UTC)

Isn't this a redshift in which the source and the observer are not moving, or, their movement is irrelevant? According to the definition, this is not a Doppler redshift. Indeed, if redshift can be changed merely by a photon moving through curved space, how do we measure the relative velocity of the source? --Iantresman 00:00, 18 March 2006 (UTC)

I've already addressed the issue of observer and source. This conversation is going nowhere and is not helping improve the article. There is nothing wrong with the current wording. It is verifiable, referenced, and factual. --ScienceApologist 00:30, 18 March 2006 (UTC)

Sorry, I must have missed that verifiable reference. You haven't provided ANY since we started this discussion, and I discount YOU as a verifiable reference.

We are going around in circles be cause you haven't, or can't address the questions.

The Doppler effect is DEFINED as being caused a moving source or observer effect. Now you say that it can occur in a vacuum via curved space without a source of observer. Which is correct, please provide a quote and reference --Iantresman 09:56, 18 March 2006 (UTC)

The references are included in the article itself. I cannot be held accountable for Ian's inability to understand simple statements of fact. If Ian has a suggestion for improving the article let him state it at this point, but right now there is no reason to continue this conversation. --ScienceApologist 10:09, 18 March 2006 (UTC)

For the umpteenth time, I can't find a relevant reference. The onus is on you, as described by Wiki policy, to provide me with a VERIFIABLE citation. Vaguely pointing to "an article" is not good enough. The Doppler effect is defined as moving source or observer effect. Now you claim it can occur in a vacuum by curved space WITHOUT a source or observer. They are mutually exclusive, unless you can verify. --Iantresman 10:58, 18 March 2006 (UTC)

Single photon redshift

The text says "A single photon .. can redshift"; while a single photon can redshift, scattering can also redshift a single photon such that it would be indistinguishable from a single photon that has been redshifted in any other way? Perhaps that needs clarification, or written in a less ambiguous way? --Iantresman 19:39, 17 March 2006 (UTC)

Since this is a single photon in a vacuum, there can be no scattering. There is no ambiguity. --ScienceApologist 20:13, 17 March 2006 (UTC)

The radiative Wolf effect (which is not scattering, and will take place in an idealistic vacuum), will redshift a single photon, and is INDISTINGUISHABLE from any other redshifted photon. --Iantresman 21:37, 17 March 2006 (UTC)

No, the radiative Wolf effect is a coherence effect and needs to have more than one photon as per the very references you cite. --ScienceApologist 22:10, 17 March 2006 (UTC)

"Classical redshift"

I can't find any references to "Classical redshifts". This might be causing some confusion with "Classical physics", which is incompatible with Relativistic causes of redshift. A general ADS search [39] found just 4 references, but I think it's in a slightly different context. It certainly doesn't appear to be a "standard" term. --Iantresman 14:06, 16 March 2006 (UTC)

I never liked it anyway. Removed. --ScienceApologist 14:35, 16 March 2006 (UTC)

CREIL

Well, I'm pleased to see mention of CREIL. I note that it's been included in a section on Coherent interactions, which seems similar to the Wolf effect. I'd like to see:

• Since the Wolf effect is not a reddening, and does not involve radiative transfer, that we create the following section:

• Other Optical effects (Main heading)

• Coherence-related effects (Subsection) (Wolf, CREIL)
• Reddending and scattering effects (Subection)

And we reduce the CREIL section to a summary, together with the necessary references

--Iantresman 11:08, 19 March 2006 (UTC)

A description or even a sentence on CREIL is not appropriate for inclusion in this article based on the current article structure. A different redshift article in an encylopedia for people who want to learn countless alternative explanations for widely accepted phenomena would include lengthy discussions of CREIL and many other things as part of its POV. Wikipedia is not that encylopedia. The redshift article here emphasizes changes of reference frame because Wikipedia was not designed to be an "alternative" encyclopedia but a real one for people who want to find out about how terms are nearly always used in the real world. Nevertheless, there must be balance, and this article appropriately refers readers to scattering and coherence. I hope a link to CREIL is included in those articles if it is warranted. Also, because there is no "vacuum CREIL" effect as there is for Wolf, it does not deserve special mention in this article as a "coherence-only" effect. Flying Jazz 11:30, 19 March 2006 (UTC)

Interesting this CREIL effect, I didn't know about it! Google delivered the following article: http://jean.moretbailly.free.fr/JacquesMB/31tps06-moretbailly-pt1-proof.pdf .

From what I saw on Google, I take Flying Jazz's suggestion that "CREIL" is not used in this real world as alternative explanation for "redshift" as his own and unsustainable POV: NPOV requires to include everything that is notable, so that people can make up their own mind ("the presentation of many competing theories on a wide variety of subjects suggests that we, the creators of Wikipedia, trust readers' competence to form their own opinions themselves"). Nevertheless I agree that, for reason of space, this article refers to the scattering article for all redshifts that are due to scattering. As CREIL is included there, I think htat it suffices if the commentary text in this article does not make claims or suggestions that are contrary to the information in articles on CREIL. Harald88 11:50, 19 March 2006 (UTC)

Surely one sentence each mentioning CREIL, or Wolf effect, or Intrinsic redshifts, or Non-cosmological redshifts, will have little effect on space. If you want to reduce space, delete sentences such "The expanding Universe is a central prediction of the Big Bang theory..." which has NOTHING to do with redshifts.

How do we "trust readers' competence to form their own opinions themselves" when we don't provide any information? (Good policy, must rememeber that) --Iantresman 12:35, 19 March 2006 (UTC)

I agree with your first sentence. The solution is simple. Change the arbitrary structure of the article. Wikipedia is very much an "alternative" encyclopedia. Wiki policy STATES that:

• "NPOV (Neutral Point Of View) is a fundamental Wikipedia principle which states that all articles must be written from a neutral point of view, representing views fairly and without bias" (my emphasis).[40]

Wikipedia does not exclude views because someone is of the OPINION that a view is alternative. The Wolf effect may be "alternative" to you, but it's not for me, nor for Emil Wolf, Dan James, and the DOZENs of other authors who have written on the subject.

Wikipedia is quite clear about what gets into an article:

• "The threshold for inclusion in Wikipedia is verifiability, not truth" [41] and the Wolf effect meets that criteria, as I have provided MANY verifiable citations.
• "A viewpoint is held by a significant minority, then it should be easy to name prominent adherents;", and the Wolf effect meets that criteria too.[42]
• "A common source of obstinacy in NPOV disputes is the belief that one group "owns" a word and has sole authority to define it:"[43]

Note the last policy. Scattering effects, redshifts in a vacuum, and changes of reference, ALL CHARACTERISES redshifts, THEY ARE NOT ARBITRARY GROUND FOR THEIR INCLUSION OR SUPRESSION. Indeed, this is the VERY REASON for including them, describing them, and differentiating them. --Iantresman 12:25, 19 March 2006 (UTC)

It amazes me, Ian, after my successful efforts to include a mention of the Wolf effect in this article, that my position on CREIL, plasma-redshifts, and the dozens of other shifts you have supported in the last year is portrayed by you in such black-and-white, me-versus-them terms. The structure of the article is not arbitrary. It was the result of countless debates that are all archived. I'm disappointed with your obsessiveness and misrepresentations over the last year on this article. I can document your behavior very easily using the archives, and if you do not stop this behavior on the talk pages at once, that is precisely what I intend to do. I have never complained about anyone before at Wikipedia and noone has complained about me. Refamiliarize yourself with the entire archives, and reread every post you have typed. Read every word and imagine you are in the position of someone who cares about keeping obsessive behavior out of Wikipedia. I am asking you now to resolve this by leaving this article and talk space alone for a persiod of time without me having to take those steps to complain against you. Flying Jazz 17:21, 19 March 2006 (UTC)

I am delighted that the Wolf effect is mentioned, and thank you for your support.

• It is mentioned in a section on reddening, yet the Wolf effect does not producing reddening.
• It is mentioned shortly after a statement on radiative transfer. The Wolf effect is not a radiative transfer effect.
• In the past week, we have managed to removed "Vacuum redshifts" and "Classical redshifts" as essentially bogus neolgisms. We still have statements on "single photons in a vacuum" and "frames of reference" that appear designed to marginally the Wolf effect, rather than characterise it alongside OTHER REDSHIFTs.
• The Wolf effect is consistent in every way, with the definition of redshift in this article, and reaches all the criteria set in Wiki policy. If my behaviour to correct misleading statements, and uphold Wiki policy seems obsessive, then yes, this is obsessive behaviour.
• PLEASE PLEASE PLEASE refer this article, or ME personally to arbitration, or ANY OTHER INDPENDENT form mediation. I have more than enough evidence in the way of VERIFIABLE citations, and references to Wiki policy, to back up my contention that other forms of redshift are unfairly marginalised.
• I can't get ONE quote/reference from ScienceApologist to backup his opinions, only allegations that I "take a course or two in physics or physical science".

--Iantresman 18:22, 19 March 2006 (UTC)

My complaints are not about the article content or about your views on article content. My complaints are about your behavior on this talk space. I don't want to do the arbitration thing unless we have to. I just want this talk page to be more article-focused and less full of repetitive lists and rants so that more editors will contribute here and talk to each other above the din. I thought maybe you understood this after my previous try Talk:Redshift#Please_reestablish_the_focus_of_this_talk_page, and your absence contributed to rapid and relatively painless resolution of one dispute Talk:Redshift#Why_I_removed_the_link_to_tired_light, but now the same problems are happening again with your return. Anyone who has been following this, please discuss the specific issues addressed, not the content of the article itself, at: Wikipedia:Mediation_Cabal/Cases/2006-03-19_Talk_at_Redshift. Flying Jazz 20:10, 19 March 2006 (UTC)

The debate about inclusion of CREIL is contained in a running dialog in Archive 5 and 6. It is also mentioned in Archive 3. Flying Jazz 17:23, 19 March 2006 (UTC)

I agree with Ian about undue weight: the choice between redshift effects and ""The expanding Universe is a central prediction of the Big Bang theory" is easy. That last part is actually "soapbox", and doesn't really belong here; it belongs in the big bang article. Harald88 17:43, 19 March 2006 (UTC)

What exact change do you want to make to the article? Do you want a redshift article that does not mention the expanding universe? A redshift article that does not mention the big bang? Or a redshift article that does not connect an expanding universe to the big bang? The Big Bang article and the non-standard cosmology article together link to the redshift article for a sum of about ten times taken together. Eliminating the details of how redshift supports the standard model would be a glaring omission. Is your argument that every non-standard model deserves equal weight here to the standard model or that no models deserve any mention at all? And, most importantly, HAVE YOU READ THE ARCHIVES? Flying Jazz 18:01, 19 March 2006 (UTC)

I have not read the archives; but I have been following some of the discussions. Independent of what may have been said, it's absolutely anti-NPOV to suggest that there was one theory that was called "Big Bang" and that predicted the observed redshift... Your remark "how redshift supports the standard model" is strikingly misleading, as of course all models are supported by this important fact with which all theorie must reckon. It's therefore necessary that such theories link to this article. A NPOV phrasing would be that "Observed cosmological redshifts have led to numerous hypotheses about causes, of which that of cosmological expansion is most popular. Other notable hypotheses are ..., ... and ..." Harald88 23:43, 19 March 2006 (UTC)

The current version of the Non-standard cosmology article makes it very clear that not all models are supported by observed redshifts. All theories must reckon with it in order to gain acceptance. Some do a better job than others. That's part of the reason why they are not widely accepted. Mislabeling the standard model as the "most popular" model would be misleading and POV. Including a list of non-standard cosmologies in the redshift article is too far distant from the subject of the article and will lead to uncertainty and tangential disputes about which non-standard hypotheses are sufficiently "notable" for inclusion and which are not. The same reasoning applies to optical redshifting phenomena that are not related to shifts in reference frame. One can argue for the inclusion of 5 examples or 50 examples. Better to categorize them under coherence and scattering (and the bathochromic diambig) and leave it up to the reader to investigate those broad categories for examples. Flying Jazz 05:27, 20 March 2006 (UTC)

Of course we all agree that mislabeling would be misleading (do you actually realise how POV your writing is?). I can go along with writing that "cosmological expansion is by far the most popular hypothesis" (eventhough I know no way to prove that assumption; and no need to specifically mention any theory).

Other suggestions are welcome. Harald88 16:06, 20 March 2006 (UTC)

• No-one has ever said that the Wolf effect, CREIL, etc deserve equal weight. But NO weight or a single mention by phrase is derisory. When we create a table of the periodic table, we don't exclude the trans-Uranium elements because (a) they are insignficant in comparison with the other elements (b) don't exist in nature. We include them, because they are elements, and because they fall into the definition of the periodic table / elements.
• No one has ever said that we don't include mention of the Big Bang and cosmology, it is VERY important to astronomers' view of redshift.
• But everyone seems to be saying that those who do optics, or research into intrinsic redsifts, etc, their view is not significant COMPARED TO THAT OF THE ASTROMOMERS.
• Astronomer DO NOT OWN THE DEFINITION of redshift, nor is the "astronomical redshift" THE benchmark for what goes into the article. If you want an article to focus on redshift and standard cosmology, then you need another article with a more specific title, such as "Redshift and cosmology".
• But since the article is titled "Redshift" (a very general title), verifiable citations determine what's significant, not you, and no me.

--Iantresman 18:41, 19 March 2006 (UTC)

Partly agree: an article on "Standard Cosmology" is allowed, but it should have the POV designation ("Standard") in the title. Harald88 23:43, 19 March 2006 (UTC)

Your use of the word "etc" in the list "Wolf Effect, CREIL, etc" is of critical importance. By "etc" do you mean that you intend to include the word "etc" in the article? Or that you haven't given up yet on the idea that this article should contain a laundry list of redshift mechanisms? Flying Jazz 07:32, 20 March 2006 (UTC)

Attempting (again) to focus the discussion and bring sanity to the talk page

Ian has used verifiable citations, NPOV arguments, undue weight arguments, and word-definition arguments to advocate the following positions:

• There should be 8 additional redshifts in the article Talk:Redshift/Archive_4#500_Peer-reviewed_references.
• There should be 6 additional redshifts and 3 additional categories of redshift Talk:Redshift/Archive_5#RfC:_Request_for_Comments
• There should be 4 scattering redshifts, 2 other types, and 4 theoretical redshifts Talk:Redshift/Archive_5#Proposal_part_(b)
• There should be 17 additional classes of redshift and 19 additional classes of theories Talk:Redshift/Archive_5#750_Peer-reviewed_.22Untrivial_Redshifts.22
• There should be "Wolf, CREIL, etc" with no mention of what is included in "etc" (above)

1) It is important to note that this one editor can use the literature to come up with so many different and mutually exclusive possibilities for what should be contained in this article. If one editor cannot reach consensus with himself about such a list of what is sufficiently notable then obviously a community of editors will not be able to achieve this task. This is why a list is a bad idea.

2) Instead of saying "Look at what google says! I want CREIL in because it's notable!" or "Look at what this paper says! I want Neutrino redshifts in because it's notable!" or "Don't you people know what Arp says? It's a significant minority position! I want intrinsic redshifts in!" I hope ALL editors pay closer attention to the article archives and to the previous discussions that have occured. With about 50 possibilities for inclusion/exclusion, there are 50! (that's a factorial) possible sets of effects that could be included in this article. (This is a bald-faced lie inaccurate. There are only 2⁵⁰ possibilities, 50 orders of magnitude less! ;-> --Art Carlson 15:08, 20 March 2006 (UTC)) Inaccurate. If he were aware of the error, the motivation to correct it would be much stronger than the motivation to exaggerate an already enormous figure. Art LaPella 17:48, 20 March 2006 (UTC) You are both neglecting the arguments that have already taken place here about the order in which effects are presented. The actual value would be a hypergeometric represented most simply (according to mathematica) by an incomplete gamma function resulting in a value that is actually greater than 50! by a (relatively small) multiplicative factor of (roughly) e. Serves you right for assuming I meant sets presented in any order. Who's off by 50 orders of magnitude now, eh? Flying Jazz 02:34, 21 March 2006 (UTC) Hmmm...well, OK. My wording did say there would only be an inclusion/exclusion choice involved, but the editors here simply don't have the restraint for only 2^50 arguments. Flying Jazz 02:45, 21 March 2006 (UTC) And by the same reasoning, the 100+ permutations of elements in the periodic table means we would never decide which ones to include :-) --Iantresman 10:45, 21 March 2006 (UTC) This applies to observations, categories, explanations, causes, and cosmologies that are verifiable (whether correct or not) because they have been discussed in the literature. If someone devoted one second to ponder each possible set for only including the notable, the task would take over 10^50 years.

3) A good editor will not just say "I want this in because it's verifiable and notable!" without also thinking "Why does my change create an article that is better than what's there right now?" and "Why do I think my change will be better than the 50!-2 other possibilities that might also be argued to be verifiable and notable?"

4) I don't think it's enough any more to imagine an article that says "other notable examples are ...." without explaining EXACTLY what you want to be included in the "..." and why others should be excluded. It's not enough to imagine an article that includes what you're arguing about today and then include an "etc" in your argument so you can argue about something new and different tomorrow. Make up your mind about what you want to include AND what you don't want to include and why. It's just plain selfish to present this debate as if some people want to suppress certain views while others want to include them and it's equally selfish to present the debate as if some people want crazy stuff in while others want to exclude it.

With all of that in mind, there was consensus that Wolf merited mention because the radiative Wolf effect seems to be the only coherence effect that does not (directly) include scattering. CREIL is a scattering effect that involves coherence. Why is CREIL more special and unique than Brillion or Raman or Rayleigh or all the other scattering effects that Ian previously advocated including in the article? Please do not answer with a reference or a list of references or a complaint about policy or a matter of notability. Do that and it's an indication that you are more interested in a talk page archive that's 50! pages long than a good article. If you want to include CREIL, talk about CREIL. Flying Jazz 07:32, 20 March 2006 (UTC)

Thank you for your efforts, and sorry to be wordy. I disagree with your point (3); the number of redshift types, or length of the article, does not determine whether the article is better or worse than it is now. We could write anb excellent one paragraph definition of redshift, and then argue whether adding more sections improves the article. It is our job as editors to make the article decent, no matter what facts are included.

I think that one of the reasons why the article may not seem to be improved by additional types of redshift, is because the current article is not about redshifts. It's about redshifts and cosmology.

I belive that one of the best points you made, Flying Jazz, is that you reminded us some time ago, was that redshift is primarily an observation. Astronomers observe it. Optics people observe it. But we give very little wordage to observed redshift. The very first sentence is not bad: "In physics and astronomy, redshift is an observed increase in the wavelength of electromagnetic radiation received by a detector compared to that emitted by the source." Then we dedicate the article to the relevence in astronomy, and pretty much ignore that in physics (optics), unless it is just meant that we are treating the physics of redshift in astronomy.

I still don't know what an observed redshift looks like. We have an idealised illustration (top right). Is this how a redshift comes out of the machine? What is the name of the machine that produces an observed redshift? Is it the same in an observatory, as in a laboratory. Does the observed redshift cover the entire spectrum (which may be important)? Will the observed redshift be distortion free? Can I demonstrate a Doppler redshift in the lab? How? What objects may produce an observable redshift? A fast moving plane? The Sun? The planets, stars, galaxies? How do these observed redshift differ? How do observed scattering, or coherence-related redshift differ from those in astronomy? How does the observed Doppler-redshift differ from an observed gravitational redshift? Does the blurring of observed redshift due to "thermal or mechanical motion of the source" tell us anything?

And then we come to redshift theories. What is it about the observations that leads astronomy to consider three major theories. But for completeness, there are other theories, and this is how they are different and characterised.

And finally, redshift and cosmology.

I know that we have been through much discussion in the past. While I was pleased to see the Wolf effect finally mentioned, I believe it was in the wrong place (for the reasons I gave presviously), and felt that since no-one was really picking up on this, it was being buried. And then picking up on "Classical redshifts", "Vacuum redshifts", and the insistance of discussing "Photons in vacuum" when it was acknowledged to be irrelevant, again I felt there was a deliberate marginalisation.

To summarise. I think this article is about "redshift and cosmology", and not about the title, "redshift". --Iantresman 13:07, 20 March 2006 (UTC)

I asked for self-control in the talk space and a focus on improving the article by a discussion of why CREIL should or should not be mentioned on its own merits when it seems to be incorporated into other categories that the article mentions. In your reply, you posted a laundry list of questions and ScienceApologist felt required to reply to each one. This is not self-control in the talk space from either of you. I believe that self-control would have been if you had addressed my specific concerns regarding CREIL, which was the topic under discussion most recently. Making the article decent is not our only job. Our other job is to make the discourse as decent as we can so others are encouraged to participate their efforts into making the article decent. Flying Jazz 12:55, 21 March 2006 (UTC)

Answers to Ian's off-topic questions

While I consider these questions to be ignoring FlyingJazz's request, I still think responses are in order if for no other reason that to indicate total completeness:

I still don't know what an observed redshift looks like. We have an idealised illustration (top right). Is this how a redshift comes out of the machine? --> You mean the computer program that matches the spectral signals of well-known elements? Yes.

What is the name of the machine that produces an observed redshift? Today it's a computer. In years past it was a human eye watching a photographic plate.

Is it the same in an observatory, as in a laboratory. -- Yes in as much as flame spectroscopy is the same as the spectra from astronomical objects.

Does the observed redshift cover the entire spectrum (which may be important)? -- Yes.

Will the observed redshift be distortion free? -- Yes (especially compared to reddened spectra).

Can I demonstrate a Doppler redshift in the lab? Yes.

How? Move the object the fraction of the speed of light that is your wavelength resolution.

What objects may produce an observable redshift? -- any object at all.

A fast moving plane? If your spectral resolution is great enough.

The Sun? Ibid.

The planets, stars, galaxies? Ibid.

How do these observed redshift differ? They don't differ. They are the same as other redshifts.

How do observed scattering, or coherence-related redshift differ from those in astronomy? -- Ones in astronomy are broadband and distortion free. Except for very contrived circumstances, the scattering and coherence effects are neither of those.

How does the observed Doppler-redshift differ from an observed gravitational redshift? -- It doesn't differ.

Does the blurring of observed redshift due to "thermal or mechanical motion of the source" tell us anything? -- Yes, it tells us the temperature of the object given a good profile fit.

All of these questions are addressed in the article to various degrees. As with any article, we can't possibly lay out every single scenario-driven question that a reader may or may not come up with. We are confined by summary style to make the articles as succinct and to-the-point as possible. Every question you had was answered in some fashion by the article. We cannot possibly engage in artificial intelligence specificity (i.e. "When Abraham Lincoln was in Washington his right foot was also in Washington.") lest our article tailspin out of control. --ScienceApologist 13:34, 20 March 2006 (UTC)

Excuse me for repying to Flying Jazz, and providing some example queries SPECIFICALLY ABOUT REDSHIFTS! Rather than the computer that processes the redshift, I was thinking of (presumably) the spectrometer, which I assume these days is computer-controlled, and you just select your frequency band and press a button. And then does the compter screen show me a chart like this, or like this, or this (or all these)? Does the computer tell me the redshift of a specific frequency, an average for the whole chart, or what?

And although it's said that the observed redshift are distortion free, is this not the same as blurring, which provides temperature information?

And certainly, we can't provide an answer to every question from readers. This is where we must decide whether it is more important providing information on redshifts, their observation, and theory, compared to several paragraphs concerning the expanding universe, whether it is slowing down or not, and stuff about quantum gravity. --Iantresman 14:03, 20 March 2006 (UTC)

What, are 'several paragraphs of the article off-topic (even on topics that are discussed elsewhere)?! I thought just a few phrases. Time to do a fresh reading of the whole article... Harald88 15:57, 20 March 2006 (UTC)

I feel like I am being baited by IanTresman. What do Ian and the other editors think?

On March 12, I wrote:

"I was recently part of a Group number of lanthanides and actinides debate that resulted in Wikipedia providing a more comprehensive summary of the reasons behind different periodic tables than any summary (to the best of my knowledge) that has ever been published anywhere previously."

This may have been egotistical or off-topic, but I wrote it with the goal of convincing ScienceApologist that just because something isn't in other summaries, that doesn't mean it shouldn't be included in a Wikipedia article. On March 19, Iantresman wrote:

"No-one has ever said that the Wolf effect, CREIL, etc deserve equal weight. But NO weight or a single mention by phrase is derisory. When we create a table of the periodic table, we don't exclude the trans-Uranium elements because (a) they are insignficant in comparison with the other elements (b) don't exist in nature. We include them, because they are elements, and because they fall into the definition of the periodic table / elements."

and in the small-print combinatorial silliness on March 21, he wrote:

" by the same reasoning, the 100+ permutations of elements in the periodic table means we would never decide which ones to include :-)"

Do the other editors think I should assume that Ian is acting in good faith? I feel like I am being baited and that Ian is not asking these questions in good faith to make a better article, but I could be wrong. Should I take the time to write and others time to read a reply in this talk space about the difference between including elements in the periodic table and including redshift mechanisms in an encylopedia article? Should I ignore it? Help. Flying Jazz 12:09, 21 March 2006 (UTC)

I took your calculation as a good faith (though not entirely accurate) point of view. And the "small print" comments to be slightly off-topic, comments on the figures. Even though the figures are not entirely accurate, I accept your point being made. But I also wanted to emphasise that whatever the exactly odds, that is not entirely the issue, and left it in the small print as an acknowledgement that the comment was also slightly off-topic (and I did end it with a smiley face). If I wanted to bait, I would have made a bigger deal of it, and indeed, I had more to say about the figures, but chose not to. But even if my comments came across a baiting, I apologise. --Iantresman 12:58, 21 March 2006 (UTC)

I accept your apology and it was gracious of you to offer it. However, I really am still confused about your March 19 post. Do you think there is a valid analogy between the inclusion of elements in the periodic table and the inclusion of redshift mechanisms in an encyclopedia article, and do you and the other editors think I should reply by writing about the difference between the two in the talk page? Flying Jazz 13:13, 21 March 2006 (UTC)

I believe there is an analogy, though I accept you may consider it weak, possibly because the definition of "element" is easier than that for "redshift". If you were to tell me that the redshift article is about "redshift and cosmology", then I would agree that many redshifts are not significant, and do not belong. If this article was going into an encyclopedia of astronomy/cosmology, or a peer-reviewed astronomical journal, then I have no problem with your point of view.

However, from my perspective, this is an article about "redshift" (as defined by the title), which implies I consider redshifts that are relevent to cosmology, AND redshifts that are relevant to optics, and ANY OTHER SUBJECT. So if it's a redshift, it goes into the article, in exactly the same way that if it's an element, it goes into the periodic table. I suppose it's a weak analogy because there is no contention over what goes into the periodic table... although I recall a time when post-Lawrencium, and "stable island(?)" elements with quite large atomic numbers were in, then out... and element 117 for example has yet to be discovered, as has 119, yet one is in, and one is out.

But the point is that there are ways of including long lists of anything in any article... and it is our job as editors to find the best way of doing so. We wouldn't exclude a couple of rows or groups of the periodic tables on grounds of space --Iantresman 13:58, 21 March 2006 (UTC)

Thanks for answering this question Ian. I've decided it would be a waste of talk page space to engage you on the periodic table issue. Flying Jazz 02:40, 22 March 2006 (UTC)

If you're asking me, I don't know. Months ago, I understood the point about how a red-light district can cause a redshift. But pages of debate about whether or not it's a scattering effect pretty much go in one ear and out the other. Art LaPella 19:53, 21 March 2006 (UTC)

Thanks for reminding me! I enjoyed making the point about the Roxanne-putting-out-the-red-light redshift and the sneaky-postdoc effect redshift. If Ian advocates that all redshifts that are relevant to any subject should be included in this article then those two should definitely be in there because they are relevant to the subjects of rock music and sneaky postdocs (even though both are due to absorption by rhodopsin, a form of scattering. Oops. Now I've done it.) . Now to find a list of verifiable sources... Flying Jazz 02:40, 22 March 2006 (UTC)

Apparently Ian wants to throw in a redshift overview table: I vaguely recall that he has been in mind to do so for a long time. I don't know how useful it is; perhaps such an overview with clickable keywords will be handy for thisn encyclopdia. It may be worth starting a new article called "redshift mechanisms", linked from this article, and which mainly consists of such a table - of course, only including redshifts of physics! Harald88 11:41, 22 March 2006 (UTC)

That's one possibility which compares the different kinds of redshift. Another is to add a couple of extra paragraphs of text, which is hardly excessive. The best solution is to have both. How useful would this be? Readers decide their usefulness of a table and text if they are included; they can't, if they are not. --Iantresman 11:50, 22 March 2006 (UTC)

I once supported the idea of a table in this article (Talk:Redshift/Archive 5#Proposal part (b)). After I saw such a table presented in the talk page, I began to change my mind about many issues because it became even more clear to me that "the redshifts of physics" mentioned by Harald is a set that (unlike the periodic table, and yes, I am actually explaining this explicitly now) contains an indeterminate number of set elements that some place at three and that Ian and the articles he has cited place somewhere between 8 and 50. These set elements may be included/excluded and may be arranged in an very large number of categories in a very number of ways (and then there's the order in which they are mentioned!). The number of set elements, categories, arrangements, and orderings in the literature is entirely based on semantics and are chosen completely based on the goal of the writer. There is not a "redshift with two protons" and a "redshift with three protons." The physics of redshift do not categorize themselves and assign an order to themselves. However, the table presented previously by Ian in the talk page did add clarity to his position, to future discussions, and probably helped to result in the current, much-improved article where redshifts due to scattering and due the Wolf effect are explicitly mentioned after bathochromic shifts are separated out. If Ian and/or Harald88 believes a similar table might result in further improvements to the categories presented in the article right now, I hope they present it here in the talk page again so we can (or will be forced to) continue to discuss categories or subcategories or individual cases of redshifts which may improve the article with the goal of educating the reader. A paragraph with a list based on one person's semantics (Ian) is not striving for consensus and neither are knee-jerk reversions (ScienceApologist). After all these months, I thought that would be clear by now. Flying Jazz 13:54, 22 March 2006 (UTC)

As I don't know how it would look like, and I hate to see this article be messed up, I proposed a separate page; if it's No Good, it will probably be deleted at a time, and anyway it will not disturb this article. OTOH, if it becomes really nice, it may one day be merged with this article. I like to see it! Harald88 20:27, 22 March 2006 (UTC)

I accept that the period table is poor example. So let me suggest the Wiki article on planets as an analogy where we find that the IAC who is the authority on what constitutes a planet. There's a subjective definition "a relatively large mass of accreted matter in orbit around a star". And yet we find so much more. There's already a note on "2003 UB313", technically not an official planet as of today (22 Mar 2006), with relatively few peer-reviewed references [44], but it's already being talked about as the tenth planet [45], and I have no doubt it will eventually be decreed a planet.

By ScienceApologists' criteria, "2003 UB313" (temporarily nicknamed "Xena") is a neologism, constituting undue weight; but we somehow "know" the astronomical community wouldn't be against it being classified a planet, although others are being more cautious in calling it a Trans-neptunian object [46].

So how do we "know" to include "2003 UB313" as an annex to the Nine Planets? How can we decide? -- We don't. The facts are provided (a) It's not an official IAC planets (b) But it's bigger than the planet Pluto (c) There is some discussion over whether it, and Pluto are actually planets. But the important matter, is that we have conveyed this to the reader.

I also note in the planets article a "laundry list" of "candidate planets" (heck! not even real planets), discussion on "Extra solar planets" (we can hardly see these), semantics on "Brown dwarf 'planets'", followed by two more sections on definitions.

I'm sure that if I were to add a table summarising "Characteristics of planets and candidates", and even included (a) candidate planets, extra solar planets, and even the "Brown dwarf planet" for comparison, it would hardly get a criticism. I think it would be useful... we'd note that candidate planets are smaller than the Nine Planets, extra-solar planets are larger, and the Brown dward planet a bit of an oddity.

The same kind of analysis of redshift "types" is not possible, because the decision has been made for people. I don't know whether the Wolf effect is a "true" redshift; I know that astronomers don't count it as a Cosmological-like redshift, and optics people consider it a Doppler-like redshift... but heck, we barely mention it. And as for "Intrinsic redshift", or "Redshift quantisiation", don't even ask!

We don't need to list any of the 50-odd redshift theories from Henri Reboul's paper [47], a reference is sufficient. As for other theories for which there is relatively current research, that's another matter --Iantresman 17:18, 22 March 2006 (UTC)

As per intrinsic redshift or redshift quantization, if you want to create articles on these subjects indepedent of this article, that would be the most appropriate. They don't warrant mentioning here as they are specific points brought up by a very small minority of people who deal with these subjects and they do not represent a major component of the understanding regarding the subject. As it now stands, any frequency shift you can possibly imagine is discussed on this page. --ScienceApologist 18:29, 22 March 2006 (UTC)

What proportion of astronomers do you think are familiar with the terms "intrinsic redshift" and "redshift quantization"? --Iantresman 18:54, 22 March 2006 (UTC)

Off the top of my head? Less than 5%. --ScienceApologist 18:56, 22 March 2006 (UTC)

What percentage would you require to make their mention tenable? --Iantresman 20:07, 22 March 2006 (UTC)

I think that the percentage of astronomers aware of these subjects is beside the point. Editorially, we are bound by the undue weight clause of NPOV. The article's current way of including "alternative suggestions" in my opinion constitutes a fairly good and comprehensive mention of such "redshift controversies" per how obscure the arguments regarding this subject are. --ScienceApologist 20:44, 22 March 2006 (UTC)

What does Wiki (and presumably yourself) define as exceeding "Minority view"? --Iantresman 20:54, 22 March 2006 (UTC)

My point about Reboul's paper is that it is verifiable, so someone wishing to have all of Reboul's categories included in this article would have just as much of a claim to that position as Ian has for his multiple contradictory positions. If Ian is able to write a good paragraph about the redshifts that he wants "in" that explains how and why they are distinct from the classes of redshift currently in the article, then maybe the editors here will agree that the paragraph should be in because it improves the article. If Ian is able to categorize classes of redshift using semantic distinctions that are an improvement over the categories currently in the article, then maybe the editors here will agree that they should be in for the same reason. I think policy is only important once there is some possible content dispute to consider. Endless talk pages of "I think THIS and THAT and THIS and THAT should all be in!" is not a dispute over content, really. It is not building a better encylcopedia. It's disrupting wikipedia to make a point. It's only a talk page disruption, but it is a disruption nonetheless when it goes on for so long. Flying Jazz 23:02, 22 March 2006 (UTC)

OK, I see where you're coming from. I wouldn't expect all (probably any) of Reboul's references to be included in this Redshift article. The main difference between these theories, and others such as the Wolf effect, perhaps scattering, perhaps "intrinsic redshift" is as follows:

• The Wolf Effect/Scattering (a) Produce observed redshifts (b) are ongoing/current with dozens of authors referencing the papers
• Reboul's references, as far as I know, are theoretical, and although a couple of authors have several papers, are generally not ongoing/current.
• Since Reboul's paper is (a) peer-reviewed/verifiable (b) contains such a wealth of information, I would at the very least, reference it. I would do so in the context of mentioning that there have been numerous redshift theories over the years, which sometimes refer to redshift as (a) Intrinsic redshift [48] (b) Non-cosmological redshift [49] (c) Non-Doppler redshift [50].

Ideally, I would like to see the following:

• I would sub-divide the section on "Redshift mechanisms" into FOUR subsection (1) Frequency independent, non-distorted redshifts (the big three) (2) Frequency independent, possibly non distorted (eg. Wolf effect) (3) Frequency dependent, distorted, with various characteristics (eg. scattering) (4) Theoretically (ie. probably not observed) redshifts, with reference to Reboul's paper containing 600+ references, a mention of "Instrinsic redshifts", and perhaps Arp/Narlikar (on the grounds that it is current, and nearly everyone has heard of Arp) etc.
• The current information on scattering would be included in the new sub-section above, plus a summary of how specific types of scattering are differentiated from Doppler-like redshift, (eg Brillouin triplet), and the new sections on the Wolf effect and theoretical redshifts would take up a couple of paragraphs at most.
• The big advantage of all this, is that it (a) characterises the different types of redshift (b) adds relatively little text (c) acknowledges that there are 600+ other redshift theories --Iantresman 17:09, 23 March 2006 (UTC)

Need I say it? I object to each of Ian's suggestions as discussed to death above and in the archives. I reject Ian's novel classification scheme (which is found nowhere but in Ian's own mind) and I dispute the implicit suggestion that the article as it is currently written doesn't provide the information that should be found when someone looks for "redshift" at Wikipedia. --ScienceApologist 18:56, 23 March 2006 (UTC)

So what does Wiki (and presumably yourself) define as exceeding "Tiny minority view"? --Iantresman 19:12, 23 March 2006 (UTC)

That's everyone's guess. Here my 2 cts: A view may be so peculiar that it might be vaguely mentioned in a peer reviewed paper, while no peer reviewed paper can be found that discusses that view in detail. Thus, if it's not elaborated on in any peer reviewed article, it is debatable if it should be mentioned at all in Wikipedia. Harald88 21:58, 23 March 2006 (UTC)

The chances seem slim to me that one peer-reviewed paper would mention a view unless a different peer-reviewed paper in the past had discussed the same view in more detail. The beauty of science is that a huge variety of possibilities, some a little goofy, some which are later proven to be wrong in the view of most scientists, and some which are extremely speculative, may all be published in peer-reviewed papers and so they are all "verifiable". But should they all be in an encyclopedia entry? Even if you think the answer to that is yes, good luck tracking them all down. And if you don't track them all down, you must pick and choose which get in and which don't. And if you are going to do that, then the best way of categorizing how you pick and choose is what we've been discussing. If this were a chapter in a PhD dissertation titled "The History and Diversity of Speculative and Theoretical Redshifts" then mentioning them all individually might be a priority. Fortunately, this is an encylcopedia article, not a dissertation, so an exhaustive list of peculiar beliefs through time does not merit inclusion. Flying Jazz 04:45, 24 March 2006 (UTC)

The key word in Ian's proposal is, once again, "etc". This time the list includes "a mention of "Instrinsic redshifts", and perhaps Arp/Narlikar (on the grounds that it is current, and nearly everyone has heard of Arp) etc." The idea that "nearly everyone has heard of Arp" is just plain wrong. Before posting in this talk page I'd never heard of the guy, but I still knew most of what actual redshift was about. Most people aren't scientists, most scientists aren't physicists, and most physicists aren't cosmologists. This article should be for people, and discussing Arp here would be a mistake. As for the supposed advantages, (a) the current article characterizes the different types of redshift in the exact same way except the current article avoids redshifts which have not been shown to exist (with the exception of "tired light"). (b) the current article also adds relatively little text. (c) the number of redshifts has increased from 50 to 600+? Do you think that is a reason to talk about them all in an encylopedia article? The "etc" must be clarified. In my opinion, the current article talks about the mechanisms of redshift. There are three, and then there are other reddenings due to scattering etc. And in that last sentence, "etc" means exactly "Wolf effect due to coherence" and no more. What does the "etc" in Ian's proposal mean exactly? Flying Jazz 04:45, 24 March 2006 (UTC)

I provided what I considered an "ideal" set of stuff to include. The "etc" was an acknowledgement that there could be a few other examples. So let's forget about any more "etc's". I should have clarified that I think that most astronomers have heard of Arp; I think more that 5% of astronomers have heard of "intrinsic redshift".

There are more that three redshift mechanisms. Some of these produce complex (distorted spectra) such as Brillouin, Raman, scattering; some of them are theoretic (eg. Compton scattering has been proposed as a cause of redshift); some of these are not redshift (eg. those that produce reddening, such as Thompson scattering)

Some peope only want to read a Disneyeque view of the three main causes of redshift. But I think others who read about all this, will have a far better awareness of redshift, and will at least be able to decide for themeselves. --Iantresman 08:37, 24 March 2006 (UTC)

ScienceApologist, for the third time, so what does Wiki (and presumably yourself) define as exceeding "Tiny minority view"? --Iantresman 19:12, 23 March 2006 (UTC)

Undue weight

Would any of the other editors (in addition to ScienceApologist), please clarify what Wikipedia means as exceeding "Undue weight", and thus reach the criteria for including in this article. --Iantresman 20:16, 1 April 2006 (UTC)

Cabal Mediation

Well I have been assigned as your mediator. Let's start by trying to find places where we can agree. I would propose that:

• we agree to have civil discourse on this page
• we agree to avoid arguments about semantics
• we agree to be responsive to each other
• we agree that the purpose of the talk page is to work together to improve the article
• we agree that the purpose of the article is to represent factually the state of science in this field
• we agree that this is not the place to determine the correct theory
• we agree that our personal viewpoint is irrelevant
• we agree that not all theories are equally accepted
• we agree that each theory should be represented proportionally to its prevalence and acceptance within the scientific community
• we agree that any single citation is not definitive
• we agree that there are some theories that are not sufficiently prevalent to warrant inclusion
• we agree that there is room to present alternative theories of sufficeint merit (as alternative theories)

Let me see if we can agree on these principles before we proceed. I would very much appreciate your cooperation. I would hope that we would all end up satisfied with the eventual results. Let's start a new era of consensus building.

--Nick Y. 19:24, 13 April 2006 (UTC)

I agree with every statement made above. --ScienceApologist 20:41, 13 April 2006 (UTC)

Waiting for others to respond. I would however ask that no changes be made to the current article, as is, while I mediate. I do not see any major problems with it as is. The larger problem seems to be here on the talk page anyway. Rather than lock it let us agree to not change it (except to revert it to its current state). Thanks --Nick Y. 22:26, 13 April 2006 (UTC)

Sounds good to me. Will you (Nick) take the lead, presumably on the Wikipedia:Mediation_Cabal/Cases/2006-03-19_Talk_at_Redshift page. --Iantresman 22:53, 13 April 2006 (UTC)

Good to hear that you are agreeable to mediation, Ian. Do you agree with my proposed list of intial agreements before we start with the nitty gritty (reply on mediation page)? Since you and SA are the most involved if we agree on these principles I think we can get started. Others, Flying Jazz, etc. may join as they happen on this. Since Flying Jazz requested mediation I assume he will be along and agreeable to mediation.

This discussion continues on Wikipedia:Mediation_Cabal/Cases/2006-03-19_Talk_at_Redshift. Please do not engage in arguments here on the talk page if you consider yourself a party to the mediation.