Wikipedia:Reference desk/Archives/Science/2017 March 2

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March 2

Have there been any recent attempts at this?

According to here, Many-worlds interpretation#Weak coupling, it's possible for communication to take place between two different worlds with the right technology. Have any attempts been made to communicate with other worlds so far, or is still purely hypothetical?Uncle dan is home (talk) 07:07, 2 March 2017 (UTC)

There are no published papers regarding attempts to actually create the experiments hypothesized in that section. So I'll go with "still purely hypothetical". Someguy1221 (talk) 10:19, 2 March 2017 (UTC)

Science fiction stories involving weak coupling

Are there any stories involving what I described above? — Preceding unsigned comment added by Uncle dan is home (talk • contribs) 07:08, 2 March 2017 (UTC)

None that really hinge on particularly realistic science, or even anything particularly approximating the specific mechanics you are looking for, but there are a few that present something similar. This is a main conceit of Bioshock Infinite (spoiler!). Which is an excellently told story, wonky science or not. Snow ^{let's rap} 09:45, 2 March 2017 (UTC)

Oh, Fringe did something similar too, but also with a de-emphasis on actual physics. Snow ^{let's rap} 09:54, 2 March 2017 (UTC)

The story The Gods Themselves has elements of this, namely that a machine which allows the exchange of matter between two parallel universes with different physical laws allows the generation of (seemingly) limitless energy.208.90.213.186 (talk) 21:59, 2 March 2017 (UTC)

Is there a means of communication through it, though? I think that might be the more specific kind of plot point Dan is inquiring about. Specifically the mechanism here would be set up during a common origin for the split universes. I'm not aware of any narrative that uses exactly that device. But depending on how generous you want to be about a broader category of "communication between parallel worlds (often through a device with a minimalist interface/simple experimental design)", a few come immediately to mind. The closest I've ever seen in any medium is the story of the Lutece "twins", from the afore-mentioned BioShock Infinite, who found a way to communicate to eachother in code, through some physical method that is never really expounded upon. Of course, the science fiction gets a little less sciency and a bit more fictiony from there. ;) Before they end up a part of a trans-dimensional epic tragedy story, though, I seem to recall that it's "output" was a very simple device. There's a very similar device in Fringe, a show with a story that is largely centered around the concept of two alternate Earths, and the dangers and opportunities of communication and interaction between them. The veil between the two worlds is pierced in various science-fictiony ways throughout the series, but one of the little thematic standouts was a room which to the uninformed would look like a room with nothing but a desk, a typewriter and a mirror, but the mirror is actually a one way viewing device and the typewriter able to print out coded messages to agents who have already been sent from "the other side", a system that allows for both brief reports and any changes in orders. Snow ^{let's rap} 14:05, 3 March 2017 (UTC)

Yes there is, one of the characters learns that the pump is dangerous by exchanging messages between the universes with his counterpart who has come to the conclusion as he has that exchanging matter between the universes is leading to the collapse of the physical laws that govern each universe.208.90.213.186 (talk) 18:33, 3 March 2017 (UTC)

Of course Asimov got there first. ♥ Snow ^{let's rap} 19:37, 3 March 2017 (UTC)

Robert A. Heinlein, in his novel The Number of the Beast, has his "mad scientist" character Jacob Burroughs invoke Wheeler–Feynman absorber theory (although not by name) to explain how travel between different parallel Many-worlds interpretation universes is possible - that not only is symmetry in propagation of quantum electrodynamical interactions along the time axis theoretically possible, but that there ought to actually be three axes of time symmetrical with the three Cartesian coordinate system axes of space, each axis traversable by means of his invention. (I know, big can of squirmy worms opened by Heinlein over privileged frames of reference - which he does address in the novel to my satisfaction - and temporospatial phenomena such as Woodward effect which by consideration of Mach effects allows for reactionless drives of at least two types in which some sort of exchange between mass and inertia and spatial displacement exists and can't be easily modelled in a three planar axis system. But it was a good novel.)

Ingeniously, Heinlein's character Dr. Burroughs harnesses gyroscopes in three axes which are mechanically fixed to his device (and any vehicle secured to it) to allow a craft to translate between points on the three axes of time (he considers these to be quantum states) and move between different many-worlds interpretation universes. It's not instantantaneous communication between points in each of two such universes, and I'm not sure anyone's ever tackled even the theoretical physics behind such a phenomenon. loupgarous (talk) 22:33, 4 March 2017 (UTC)

Physicist and science fiction author Gregory Benford wrote Timescape in which weak coupling seems to be the medium through which tachyonic communication happens between a future Earth whose people are dying from contamination by toxic organisms contaminating all food sources, and a California physicist in 1963 (not long before the assassination of John F. Kennedy). The tachyon beam moves faster than light to the Earth's location in space in 1963 (far away from its location in the future, because the Earth, Solar System and galaxy are all moving constantly and their position in space changes accordingly) and interferes with an experiment measuring spontaneous resonance in indium antimonide. Presumably (it's been years since I read the novel) the tachyon stream is a T-symmetrical advanced wave, so that it also goes backward along the quantum-electrodynamical time axis to 1963, early enough for Earth to be warned against using the pesticides which change the algae in the oceans into the strain creating the lethal poison which is killing off all life on Earth.

This, again, is Wheeler–Feynman absorber theory in action, along, perhaps, with the Hoyle–Narlikar theory of gravity and to this point in the story all happening in a single Many-worlds interpretation universe. But when the 1963 physicist shares his findings with an unscrupulous churnalistic popular-science journalist to see confidentially how this might be possible, the journalist publishes the message and the story of how it came to the year 1963, and starts a chain of events leading to a hulking Texas high-school boy (sent up to the book depository on Dealey Plaza in Dallas to get a copy of an article on the message from the future) stopping Lee Harvey Oswald from killing John F. Kennedy.

All along this chain of events, new many-worlds interpretation universes are being spawned. The future Earth dies anyway - the equivalent of a Schrodinger's cat-type quantum wave function collapse preserves causality in the original universe, and the changes occur in other new universes in which Earth is not menaced. That seems to be the most plausible case of "communication between alternate universes" - creation of such universes, whether by conventional activity in our current understanding of quantum electrodynamics or by exotic transactions backward in time which spawn new universes which hadn't yet existed. loupgarous (talk) 23:39, 4 March 2017 (UTC)

Plant-based diet

If a diet is 60% fungi and 40% plants and algae, then is it still plant-based? 107.77.195.150 (talk) 14:23, 2 March 2017 (UTC)

Definitions do not necessarily translate between domains. What I mean by that is that what a botanist considers a plant, a nutritionist may hold different definitions. For analogy, concepts like fruit are different; a botanist would consider a cucumber a fruit, but a nutritionist would not; that is usually classified as a vegetable. So, merely because the fungus kingdom is different from the plant kingdom according to biologists does not necessarily mean that a nutritionist would consider a mushroom to be of a different category than a cucumber or lettuce. Being comfortable with flexible definitions is a useful trait to have. This page by the way discusses the difference in definitions. Some consider edible fungi like mushrooms to be vegetables, even though they aren't strictly "plants". For example, many vegans consider mushrooms acceptable for their diet, also noted here Vegetarian societies around the world do not classify mushrooms as unsuitable for vegetarians. For example, the North American Vegetarian Society defines a vegetarian as someone who eats no animal flesh, including meat, fish, chicken and other sea creatures. The Vegetarian Society of the U.K. uses a similar definition, stating that vegetarians eat no meat, fish, game, poultry, shellfish or by-products of the slaughter of animals. If we knew for what purpose you were trying to classify dietary fungus we could help you with deciding what particular classification to use. There are no universal rules that apply to everything here, it depends for what purpose you are trying to decide if fungi should count as "plants" or whatever. --Jayron32 14:37, 2 March 2017 (UTC)

Also note that "plant-based" doesn't necessarily mean all plants, fungi, etc. While, vegans are strict about this, other vegetarians allow milk and/or eggs, and semi-vegetarians even allow fish and sometimes chicken in their diet. Their diets are still plant-based, though, in that the majority of food is not from animal sources. See Vegetarianism#Varieties. StuRat (talk) 16:05, 2 March 2017 (UTC)

• Most vegetarians or vegans would also eat salt, a mineral, yet have no problem with describing their diet as "plant-based". It's not useful to define mushrooms as outside this.

The "by-products of the slaughter of animals" issue is often one issue that does divide vegetarians: some are far stricter than others over this. A common issue is rennet. Andy Dingley (talk) 17:59, 2 March 2017 (UTC)

So veganians (or vegans, or veganists?) picked the wrong term. Should have called themselves botanists (tho i think some group already picked that for the treehuggers, toplantsspeakers and gardeners) or Botanians :p --Kharon (talk) 23:11, 2 March 2017 (UTC)

Shared DNA

My sisters and parents: 50% with each one. Bananas: 50%. Is my family bananas? --Llaanngg (talk) 19:14, 2 March 2017 (UTC)

No. If you have 6 cards in your hand, lets say A-2-3-4-5-6 and a banana has six cards, 4-5-6-7-8-9, then you and the banana have 50% of your cards in common. That's what the second stat means. Now, lets say that you have A-2-3-4-5-6 and your mate has A-2-3-4-5-7. Your children get half of your cards and half of your mate's cards to make their own hands. That's the meaning of the first 50%. Your mate, you, and your child ALL have more DNA in common with each other than any of you do to the banana. It's important to recognize that math is contextual, and you need to understand what 50% means. 50% of what, or compared to what is important. Without context, 50% is meaningless. You share 50% of your DNA with a banana, but you share 99.9% of your DNA with every other human on the planet. --Jayron32 19:24, 2 March 2017 (UTC)

(EC)This I think is a problem arising from conflating allele with gene. They are two different things. The gene is the place and the function, the allele is the "spelling" or the thing that occurs at that place. These "You have X% same genes as Y animal" are often about the locus, the gross functional unit (when they are meaningful at all) . In that sense, you have (roughly) 100% in common with your parents, and with me. As humans we share (virtually) all the same "slots" - that's what genes really are: places. However, in addition to that you share 50% of alleles with each parent, that's what is filled in those slots. Does that help? I'm of course simplifying a bit, but I think this (very common) conflation is the root of your confusion. Even professional scientists are guilty of saying "gene" when they really mean "allele", and if you search through the history here enough, you'll find me harping on this issue repeatedly over the years: your question is a great example of why we should be careful :) (Nb. one caveat is things like sex-linked genes, meaning a male cannot literally share all loci with a female, as there is a whole chunk of chromosome they do not share.) SemanticMantis (talk) 19:28, 2 March 2017 (UTC)

Also note there are only four "letters" to pick in DNA, so any two random strings of the same length would be expected to have 25% of their single nucleotides in common at each single position. For any "% DNA in common" comparison, the claim needs to specify if it is the Nucleic_acid_sequence that is being compared, the genome, the genotype, or whatever specific thing is being compared. For example, when NASA [1] talks about why the send fruit flies to space, they clearly say "50% of fly protein sequences have mammalian analogues." (emphasis mine)SemanticMantis (talk) 20:31, 2 March 2017 (UTC)

We're not allowed to give medical advice. If you think you're bananas, see your doctor! ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:47, 2 March 2017 (UTC)

There's a general problem with comparing "DNA comparisons', as different authors use totally different meanings of "in common". In the case of Humans and Bananas, we do not share 50% of our DNA sequence by any meaningful way of defining that. Rather, 50% of human genes have a homologous gene in the Banana genome. But even those individual genes will have many differences, and the intergenic spaces between them will have many more. As mentioned, you share about 99.9% of your genome on average with any other given human on the planet. Here the comparison works a lot better. Since all humans have broadly the same genomic structure (that is, how the genes are arranged on chromosomes, and how the genes themselves are structured) you can actually directly compare sequences to measure similarity on a genome-wide scale. In the case of your parents, if your two parents are 99.9% identical to each other, then you will be 99.95% identical to each of your parents, and 99.925% identical to each of your siblings, on average. You could also say that you inherited 50% of the genetic polymorphisms from each of you parents, and share 25% of your own genetic polymorphisms with each of your siblings. Someguy1221 (talk) 00:06, 3 March 2017 (UTC)

To correct your last sentence, full sibs have a genetic relatedness of 50% (the same as between a mother and child); half sibs have a genetic relatedness of 25%, identical twins 100%. "Genetic polymorphisms" is not quite the right concept here either. Some relevant key terms are identical by descent and identical by state. Jmchutchinson (talk) 13:19, 3 March 2017 (UTC)

Again, we're using the misleading terms here. You, your twin, your mother, and every human on the planet shares 99.9% of the same DNA. You got half of your DNA from your mom and half from your father, but the half you got from each was already mostly identical. You can say "you got 50% of your DNA from your mom and 50% from your dad" and that is correct. To say "You share 50% of your DNA with your sibling" is wrong. You share about 99.9% of your DNA with your sibling, the differences are minuscule. Precise language matters here. --Jayron32 13:33, 3 March 2017 (UTC)

Actually I was careful to give my correction only in terms of genetic relatedness: see coefficient of relationship. You are of course right that I share a very high percentage of my DNA with my family and other humans. But if you want to understand evolution (especially the evolution of parental care and altruism), this is not the important quantity, but rather the probability that two individuals share alleles identical by descent (i.e. that they have inherited mutations occurring in a recent common ancestor). It is not trivial to prove rigorously that this is the parameter that determines whether or not evolution will favour altruism, but this is what comes out of the population dynamics models (given various simplifying assumptions) and indeed it fits our intuition. Jmchutchinson (talk) 14:04, 3 March 2017 (UTC) [Added later: to read more see Kin selection and in particular the section on Hamilton's rule. Jmchutchinson (talk) 16:01, 3 March 2017 (UTC)]

All of that is true, and also entirely unrelated to the OP's misconception that is leading to the initial question. You're discussing Shakespeare, the OP is having problems understanding Sesame Street. Being true and correct isn't always useful to helping correct a specific misconception in context. --Jayron32 16:20, 3 March 2017 (UTC)

What are these turkeys doing?

In this video you can see a flock of turkeys walking in a circle around a dead cat. Is this known turkey behavior and if so what are they doing? 24.255.17.182 (talk) 21:55, 2 March 2017 (UTC)

I suspect a mix of fear and curiosity, and in this circumstance the object of interest is in the center. Birds can of course follow other birds in a line (i.e. a common scenario is chicks following parents), which appears to also occur here... But I don't have a good reference to link. PaleoNeonate (talk) 00:37, 3 March 2017 (UTC)

Yes, and you can get ants to form a walking circle, too, by starting them out with a scent trail shaped like that. In animals with simple logic, like "follow the one in front", things like this can happen (whale beachings may have a similar explanation,despite their much greater intelligence). As to why the circle formed in the first place, curiosity balanced with fear seems like one explanation for keeping a constant distance, but another is if they want to keep an eye on the cat while walking by, and don't want to turn their back on it. StuRat (talk) 22:46, 3 March 2017 (UTC)

The Twitter discussion now includes a link to this story [2] which includes a possible explaination. Nil Einne (talk) 12:00, 3 March 2017 (UTC)

Using a canal as a source of drinking water?

I own a 400 sq ft boat house that is on a canal and I was wondering if it'd be feasible to use the canal as a source of clean water with a filtration system and a sump pump? The canal is near a city and is pretty filthy, I wouldn't want to drink it without proper filtration.

I am not too familiar with filtration technology/systems but are there any that may be adaptable to a canal house? Would it have to filter into a separate container that is pressurized or would it be better to have the sump pump just turn on whenever i needed pressure.

I found things like this online http://www.aquasana.com/whole-house-water-filters but I am not sure they are suitable to turn dirty canal water into safe drinking water... 2601:406:4C01:5480:6D79:989:F2AE:F68 (talk) 22:18, 2 March 2017 (UTC)

There are allot of filter solutions for a huge worldwide market, serving governements, communities and citizens of developing countries but also tourists, campers and backpackers ofcourse. There is a difference tho because in developing countries often any filter is an improvement and a traveling individual usually uses common filter sets only for a limited time. I would not recommend selfmade or cheap solutions for everyday use over a long time, unless you know what you are doing in terms of crafting and you have the scientifical knownledge to know what you have to make shure to filter out. Your (very bad) product choice already left me with little hope about your knownledge. But hey you can read - there are certainly good books on this - so there is hope and a good chance you can get what you want, maybe even cheaper then you thought. You have to make some seriouse efford tho. Many filtering methodes are (see tourists sollutions)but as a longterm project/installation its not that simple. Clearly, for your good health and the good health of everyone "living under your roof", you want to make shure you do/buy the right thing. Go find and read multiple good books about this should be your next step. --Kharon (talk) 23:44, 2 March 2017 (UTC)

British (taking a guess) urban canals are full of dead dogs, oil,bicycle frames, two hundred years of industrial waste, heavy metals, sewage etc etc. I think unless someone has designed built and taken responsibility for a filtration unit specifically to handle that you would be borderline suicidal to drink canal water in the UK. Greglocock (talk) 01:42, 3 March 2017 (UTC)

A still may be more effective with unlimited filthy water. The idea is that you boil the water, then condense the water vapor and collect it. This gives you distilled water. It's not quite perfect, as some other volatile components in the filthy water might also become vapor and condense, but it's better than just a filter. Also, distilled water lacks many of the minerals you expect in water, so tastes rather boring by itself. But it's good when mixed with anything, like soup mix. StuRat (talk) 04:11, 3 March 2017 (UTC)

You will probably want to look into whether doing so is even legal, as most developed countries tend to have laws governing water rights. --47.138.163.230 (talk) 04:16, 3 March 2017 (UTC)

If you are using a significant amount of water (such as for general household use), then you will need to apply for a water extraction licence (see here for UK). For small quantities (a few pints), StuRat's still, or a simple filter and boil system might suffice, but I think I would prefer to carry water to the boathouse just to be sure that it is safe to drink. Dbfirs 08:19, 3 March 2017 (UTC)

Canal water quality varies enormously depending on many factors. In the UK there are numerous forums such as www.rboa.org.uk and www.narrowboatworld.com where there are people who will be better placed to suggest a safe solution.--Shantavira|^{feed me} 09:45, 3 March 2017 (UTC)

• This is doable, for UK canals and water filtration technology - but it's something like an RO system, with extensive pre-filtering. The price of doing so would be at the same sort of level as having Amazon fly you in supplies of Evian by drone. Given that UK waterways have decent water supply, modest demands for water (we don't need to hydrate at desert levels) and that a static mooring away from water is becoming a problem to achieve for UK canals, then I can't see it. Andy Dingley (talk) 12:29, 3 March 2017 (UTC)

• A side note on distilled water: I read (maybe here in Wikipedia) about a commercial late 19th century distiller to produce potable water on passenger ships. It was steam powered, but a system could operate on various heat sources. The thing was, the newly distilled water lacked dissolved gasses, so they were quick to aerate it and dissolve some oxygen. If that was not done, it would be virtually undrinkable because it would taste of other ambient smells such as paint, exhaust fumes,grease and oil, fish (or seamen). Edison (talk) 20:43, 3 March 2017 (UTC)

See Evaporator (marine). Andy Dingley (talk) 22:38, 3 March 2017 (UTC)

Yep, you need a fresh supply of oxygen or air to bubble through it. StuRat (talk) 22:49, 3 March 2017 (UTC)

Could a rocky planet naturally experience a nuclear fusion explosion?

For example, if the planet had a large amount of uranium that eventually migrated to a high concentration in the deepest core, so that runaway fission reaction occurred under extreme pressure, could hydrogen atoms fuse in a natural fusion bomb? (In this particular scenario, I'm not proposing that denizens on the planet's surface would necessarily notice the bomb, although I do wonder if they would. Also, I'm not proposing ongoing fusion, like in a star.)Rich (talk) 23:48, 2 March 2017 (UTC)

To my surprise we have the article Natural nuclear fission reactor. Im not shure tho if this article is correct because from my limited knownledge of nuclear physics this is exclusively to sun like enviroment (aka a sun or a sun like bomb or reactor) to enable a fusion of atoms to build new (higher) elements. --Kharon (talk) 00:07, 3 March 2017 (UTC)

Nothing inconsistent there, Kharon, as the article is about natural fission, while the sun is undergoing fusion. As to the original question, probably not, and for several reasons. Firstly, look at the power output involved. From our article, the power of the natural fission reactions was estimated in the realm of 10⁵ watts. The fission primary in a hydrogen bomb puts out in the realm of 10¹⁴ joules in a fraction of a second. The pressure the fusion secondary is put under is estimated at around 10¹⁴ pascals, which is 100,000 times higher than the pressure in the Earth's core. So even if you just tried to use one of these natural fission reactions as the trigger for a hydrogen bomb, you wouldn't get close in either temperature or pressure to set it off. And that's not to even mention that most hydrogen is just garbage for fusion reactions. Hydrogen bombs use highly nuclear-reactive fuel such as lithium deuteride, which converts into a hot soup of tritium and deuterium when bathed in neutrons, and fuses very energetically. As our article Nuclear fusion gets into, the reaction between two protons (two ionized hydrogen atoms) releases only a millionth the energy of the fusion between a deuterium nucleus and a tritium nucleus. Now, this may sound weird, "but the sun is so hot? Fusion must be an awesome power source!" Well, the sun actually produces a surprisingly small amount of power per unit volume of core material [3]. Someguy1221 (talk) 01:13, 3 March 2017 (UTC)

Isn't there a fusion reaction where the probability of a collision causing fusion increases by Kelvin to the 36th power? I can't remember which isotope(s). Sagittarian Milky Way (talk) 01:50, 3 March 2017 (UTC)

Are you referring to the Widom-Larsen theory? --Guy Macon (talk) 05:12, 3 March 2017 (UTC)

I would guess he is thinking of the triple-alpha process. As our articles says, the reaction rate is approximately proportional to the 40th power of temperature. Dragons flight (talk) 08:16, 3 March 2017 (UTC)

Yes, that's likely it. So if you don't like the Sun's energy density just wait till it gets hot enough for the K⁴⁰ thing to start biting and it'll reach 100,000,000,000 sunpower within minutes. Sagittarian Milky Way (talk) 18:13, 3 March 2017 (UTC)

In contrast, the energy production in the proton–proton chain reaction and the CNO cycle (which both happen in the Sun)are proportional to "only" the 4th and the 17th powers of the temperature respectively. Double sharp (talk) 17:03, 3 March 2017 (UTC)

No. Uranium doesn't mesh well with rock, and gets squeezed out. And water is needed as well.32ieww (talk) 17:27, 11 March 2017 (UTC)