Wikipedia:Reference desk/Archives/Science/2009 June 21

Science desk
< June 20	<< May | June | Jul >>	June 22 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 21

Cockatoos: are they more likely than other birds to go crazy?

It seems as though 3/4 of the cockatoos I see in people's pet videos on Youtube have some sort of psychological problem, whether it's pulling out their own feathers, gnawing strips off of their own flesh or doing that 'rocking around and making repetative noises because I've gone insane' thing. I know that the same thing can happen to most species of parrot but it seems way more prevalent in cockatoos. Is there any particular (known) reason for this? --90.240.20.62 (talk) 00:02, 21 June 2009 (UTC)

There is an article on Feather-plucking but it lacks sources. Sifaka ^talk 00:23, 21 June 2009 (UTC)

Maybe just nobody videos "sane" birds to put onto YouTube? - KoolerStill (talk) 10:32, 21 June 2009 (UTC)

"Enamel strengthening" toothpaste

I see many ads for new toothpaste that proclaim new "enamel strengthening", re-mineralizing, enamel hardening, and other similar claims. Is it me, or is this just new marketing approaches to old fashioned flouride? Are there any new discoveries better than flouride? --70.167.58.6 (talk) 01:14, 21 June 2009 (UTC)

There are other compounds, more recent compounds for that matter, which have been proven to at least a small extent to either strengthen enamel or increase deposits of enamel on your teeth. An example is xylitol. Regards, --—Cyclonenim | Chat  23:21, 23 June 2009 (UTC)

"Waveguide" ultrasonic toothbrushes

Another product I see advertised as being new and different are "waveguide" ultrasonic toothbrushes. Aren't all ultrasonic toothbrushes waveguide -- with the waveguide being the brushing head? A non-waveguide ultrasonic toothbrush could not exist, could it? --70.167.58.6 (talk) 01:23, 21 June 2009 (UTC)

If it's anything like the one described in U.S. patent 7,296,318, then the waveguide is an extra blob of rubber stuck to the brushing head. This is meant to couple more energy into the liquid than you can do by relying on the bristles alone. --Heron (talk) 12:30, 21 June 2009 (UTC)

Interesting. It sounds like a marketing gimmick. At any rate, the company went out of business. [1] --70.167.58.6 (talk) 13:45, 22 June 2009 (UTC)

Range data for Lockheed Electra 10-E?

Hello everyone, sorry to bother y'all about Amelia's plane again, but I seem to be involved in a bit of a dispute about its maximum range (one other editor claims she had barely enough fuel to reach Howland Island, while I'm trying to prove that she had plenty to spare). So I've crunched the numbers a while ago and came up with the following: --Economical cruise speed of ~140 kts. at ~40% power; --Fuel flow rate of ~40 gal./hr. at this speed, giving a maximum range of ~3,850 miles with 1,100 gal. of fuel on board (I know she had exactly 1,100 gallons on board, as it is on the official record).

These figures are pretty close to the range of 3,600 miles that one other source gives, but I'm not sure if they're correct, because (1) I actually calculated the 40% power setting for the Lockheed Lodestar and applied it to the Lockheed L-10 Electra, and (2) I did all the calcs in my head, so I probably introduced quite a bit of rounding error too. So could someone be so kind as to double-check these figures to see if they're correct or not? Thanks!

76.21.37.87 (talk) 06:10, 21 June 2009 (UTC)

I have nothing to say about anything except the calculation: 140 knots X (1100 gallons / 40 gallons/hour) is 3,850 nautical miles. If you were implicitly assuming that "miles" would mean nautical miles in this context, fine. --Anon, 07:21 UTC, June 21, 2009.

Was there a headwind? Remember - your calculations relate to AIRspeed - not GROUNDspeed. There is a huge difference! Also, you use a lot of fuel during takeoff - much more than at cruising speed - particularly if the aircraft is overloaded. Weight is everything here! You also use a lot more fuel if you are changing altitude a lot - eg to get above bad weather or to get low enough to navigate using maps. The amount of power (and hence the fuel consumption) required to maintain level altitude depends on the weight of the plane - so initially, the fuel economy at 140kts would have been much worse than your data suggests. This question (and the previous ones you asked) are extremely bothersome to me. The degree of oversimplification is very worrying. Her plane was not even a standard Electra - and it was not being flown within the manufacturer's original weight restrictions. She'd modified the heck out of the thing...there is no way to know what it's fuel efficiency was - you certainly can't use the data sheets for the standard plane. So IMHO, all bets are off. The answer is "We don't know"...and even..."We will never know". All answers that are other than that are wild-assed guesses and should be treated accordingly. Neither you - nor the person you are disputing with - can possibly have the slightest clue about what you're arguing about! Some mysteries are just mysteries. SteveBaker (talk) 14:15, 21 June 2009 (UTC)

Hey SteveBaker -- good point. Perhaps I should have made it more clear that all the range data that I either calculated myself or quoted from other sources are just ballpark estimates and no more than that. In case you're wondering, this has to do with that whole Gardner Island controversy, I was just trying to see if she would have had the range to reach the island. FWIW, I have tried to model the fuel consumption again, using exact numbers, taking account of the overload, and assuming a 25-knot headwind (which is a worst-case estimate), and got an estimated maximum range of ~2,900 nautical miles (once again, a worst-case estimate that assumes she did not adjust her cruising speed for the overload and the headwind, which she would certainly have done, being the experienced pilot that she was). So, based on these calculations (which, I want to make clear, are only a ballpark estimate), the answer to my original question would be "probably yes". Well, thanks for the info, and clear skies to you! 76.21.37.87 (talk) 04:15, 26 June 2009 (UTC)

Four towers around rocket gantry

What is the purpose of the four towers shown here: http://en.wikipedia.org/wiki/File:LRO-LCROSS_Atlas_V-Centaur_launching_from_Launch_Complex_41.jpg And do the wires that connect them have any non-structural purpose? 89.242.100.210 (talk) 09:29, 21 June 2009 (UTC)

As it says in the description on the image file, they are lightning towers built to reduce the risk of lightning strikes on the launch vehicle or associated equipment prior to launch. The wires are all part of the system, see this animation [2]. Mikenorton (talk) 10:25, 21 June 2009 (UTC)

should we scale down the internet?

Looking scientifically ....

1) Is there enough future energy to power the servers? [assuming no energy breakthrough]

2) Are we being unbelievably selfish to future generations by depleting energy on websites which are lets face it 99% pointless data?

3) Could a way to remedy this is have a vast archive (like the wayback machine) and delete old pages after a few years?

—Preceding unsigned comment added by 84.13.124.167 (talk • contribs) 11:42, 21 June 2009

Those are interesting questions, but I'm not going to attempt to answer them except to say that I suspect the Internet saves energy in terms of visits to libraries, bookshops, and video rental and other shops, as well as saving on postage and fax costs. Perhaps someone knows of a study into this aspect of the Internet.--Shantavira|^{feed me} 12:11, 21 June 2009 (UTC)

Yes, I agree. The Internet uses a really tiny amount of energy compared to all other human activities - and it certainly saves energy in many ways. Sure - it's possible that in future we'll have insufficient energy to power the thing - but I rather doubt that. Computers don't need much power - and it would be perfectly possible to power the servers using solar panels - particularly because solar panels are getting more efficient and computers are needing less and less power as time goes by. The problems for humanity are in things like cars, trucks, planes and ships which (being mobile) can't take advantage of things like solar power and wind energy - and for large scale industrial activities that need so much power that the amount of area they'd need to be powered from renewable sources becomes a huge issue. But the Internet is far, FAR down the list of things that are problematic.

Another thing - the amount of data on a server has little or nothing to do with the energy it takes to run it. Data exists as little magnetic zones on a hard drive. If you power down the hard drive when nobody is accessing it - you can have as much data on the server as you want and it costs zero energy to maintain it. The only cost is when somebody ACCESSES that data and the drive has to spin up to speed, copy the data into main memory and ship it off down the wires. So the fact that 99% of it is "pointless" is not relevent. If you need something to complain about - it should be the number of people who are accessing that "pointless" stuff. However, most of us would argue that if someone feels the need to access it, it's probably not pointless at all.

Deleting pages is actually a wasteful activity because you have to power up the hard drive to do it - and that takes energy. (I should explain a small caveat here: It does take energy to manufacture a hard drive - so I guess there is an initial cost to storing "pointless" data - but very, very few websites need more than one hard drive to store everything - so the cost is the same whether the drive is empty or full.) SteveBaker (talk) 14:03, 21 June 2009 (UTC)

Also, even if the wasted enery came anywhere near that of, for example, cars - i think many people would already prefer to lose the car than the internet. Pointless car journeys (or 5-7 people-carrying cars with only one occupant) far out-number those we need, so eliminating those would be a higher priority in an energy shortage. Why target the internet, but not older industries?YobMod 14:13, 21 June 2009 (UTC)

The free market is capable of working these things out. We would leave fossil fuels in the ground if there weren't better investments, so we're safe in saying that we're not being selfish by using too much energy (though we may be selfish in having too high a prevailing interest rate). As for if we should scale down the internet, the cost of power is part of the maintenance costs. The higher the costs, the fewer webpages will be made. The whole "scaling down the internet" will happen continuously. — DanielLC 17:21, 21 June 2009 (UTC)

"The free market" only works properly if all costs are internalized. See tragedy of the commons. --Stephan Schulz (talk) 00:08, 22 June 2009 (UTC)

They are. There's no way to get energy that doesn't involve owning whatever you're getting the energy from. Or are you referring to environmental costs? — DanielLC 15:07, 22 June 2009 (UTC)

Environmental cost, of course, and political cost - arguably the price of oil is kept artificially kept low by political pressuring and operations like the war in Iraq. For a long time coal-mining has received massive subsidies in Germany (and I'd bet other places). Nuclear power has received not only massive research funding, but so far is not paying market price for safe waste disposal and insurance against possible environmental risks. --Stephan Schulz (talk) 15:14, 22 June 2009 (UTC)

NOTHING

I was just having a discussion with a friend about NOTHING - meaning try to explain nothing in refrence to the univers is expanding into nothing; the idea you can go to the end of the univers and then it stops but whats on the other side. Is there just a quantum theory for this or a mathamaticle one? or is there anybody that could offer a no nonsense explanation for Nothing...a bit about face the question but i am sure you will get my meaningChromagnum (talk) 12:56, 21 June 2009 (UTC)

The word "universe" means "everything". If it had an "edge" and there was something on the other side - then the something on the other side would just be a part of the universe and the "edge" would be some unusual feature running through the universe - not the end of it. But I think you misunderstand how the expansion of the universe works. Space itself is expanding. It's not like there is a bunch of solid objects moving outwards into otherwise empty space...it is the space itself that's growing. Either space is (and always was) infinite - or it curves back around on itself in some fourth spatial dimension - or a couple of other variations on that. But there isn't going to be an "edge". It's best to think of the two-dimensional rubber sheet analogy. Imagine 2D beings living in 2D space...for them, there is no third dimension. Their universe could be a super-stretchy rubber sheet with a grid of lines drawn on it. If space is infinite - then they live on an infinitely large flat sheet...but even though it's already infinite - it's still stretching outwards. If you watch closely, the grid lines around your position on the grid are gradually getting further and further apart. Off in the far distance - the grid lines are moving away from you really quickly - but nearby, the movement is so slow, you can hardly see it happening. That's a valid 2D analogy for what we're seeing happening in 3D. However, there is another possibility. These 2D beings might be living on the surface of a 3D balloon that's slowly being inflated. They can walk around on the surface of the balloon - and the grid-lines on the surface of the balloon will gradually be moving apart - but their universe is still 2D. It has no edge - and it's expanding. In theory, they could travel off in one direction around the balloon in what seems like (for them) a dead straight line - and they'd arrive back at the starting point. However, because the balloon is expanding faster than the speed of light - they could never actually do that in practice - so the universe is larger than they'll ever be able to see.

But in neither case did their rubber sheet universe have an "edge"...and neither does ours. So there is no "nothing" out there that the universe is expanding "into"...space itself is stretching. It's a hard thing to get your head around...but that's how it is. SteveBaker (talk) 13:52, 21 June 2009 (UTC)

I think it is simpler to say we don't understand. If we can't get our heads around something perhaps we should admit that we are stymied by a question. I accept neither that the universe is finite or infinite. I don't understand. That is simpler to say. And I think the same is true of time. I cannot contemplate how time can be infinite, and I cannot contemplate how time can be finite. I'm not trying to stall debate and questioning and contemplation of possibilities. For myself though, I just want to say that I find this unanswerable at this time. Bus stop (talk) 14:21, 21 June 2009 (UTC)

Steve isn't saying he knows the answer, he is just reporting very well-known conjectures that appear in journals. The Flatland comparison is in some UK A-level curriculum - there is no need to deny these theories exist, all becasue we cannot know their validity.YobMod 14:33, 21 June 2009 (UTC)

I don't think it's a good idea to talk about the universe being curved in a "fourth spacial dimension". While things like String Theory and Kaluza-Klein theory posit extra spacial dimensions, that is very different to General Relativity's description of the universe as curved. In mathematics there are two distinct concepts of curvature - extrinsic curvature which describes how a space is embedded in a higher dimensional space, and intrinsic curvature which describes how the space is curved from the point of view of the space itself (eg. what the angles in a triangle in that space add up to). When we talk about the universe being curved we mean the latter, there is no need to consider it being embedded in a higher dimensional space. --Tango (talk) 15:05, 21 June 2009 (UTC)

I'm not denying that any theories exist. I didn't think I was denying anything. On the contrary I am affirming something. I am affirming my own ignorance. I am asserting my inability to cope with such a question as to whether space and/or time is infinite and/or finite. I personally find the questions unanswerable, and even un-addressable. But I don't mean to prevent or discourage others from addressing such questions. Bus stop (talk) 15:04, 21 June 2009 (UTC)

So why the heck are you posting? If there is a question who's answer you don't know or don't understand, the best strategy is to sit quietly in a corner and read the answers. It's pointless to post your own failure to understand. It may be simpler to say "we don't understand" - but we can do much better than that. SteveBaker (talk) 21:03, 21 June 2009 (UTC)

To some extent, it is not exactly correct to call these questions "unanswerable". There are observable consequences to many of the hypotheses about the universe and its shape and curvature. You can read a bit about them here. The effect of having a closed universe, as opposed to an open universe, shows up in many advanced cosmological observations. The math is very hard and I don't pretend to follow all of it, but simply put, there are falsifiable consequences to any hypothesis we make about the nature of the universe. It may show up as a doppler shift on the cosmic microwave background, or a certain flavor of gravitational lensing, or some other subtle effect. This is the point of modern cosmology. It's insufficient just to "think about the unanswerable" - cosmologically inclined physicists must mathematically demonstrate an observable consequence of some theory; or, observe some evidence of somebody else's theory. This is what separates cosmology physics from "wild speculation" or "philosophy." Nimur (talk) 15:11, 21 June 2009 (UTC)

You said "we" not "I". While you may not have the training necessary to truly comprehend these matters there are experts that do. --Tango (talk) 15:16, 21 June 2009 (UTC)

Granted, I said "we," not "I." But I have an expectation of an explanation that I can grasp, on some level, and that has not been forthcoming. It may be a function of the seeming simplicity of the question posed that makes me think someone ought to be able to explain it to an untrained person such as myself. Bus stop (talk) 15:37, 21 June 2009 (UTC)

I think Steve's answer is pretty understandable to the layman. Perhaps you could explain what it is about it you don't understand? --Tango (talk) 15:46, 21 June 2009 (UTC)

It is a non-answering of the question. It is the diverting of a question concerning 3 dimensionality into a 2 dimensional realm. Two-dimensionality is an abstract construct. Three-dimensionality applies best to our understanding of the world, and it is what the original question inquires about. I have to admit, I don't even understand the explanation posed. I only accept analogies so far. And then I want further explanations. The so-called 2 dimensional beings are inconceivable. And even the comparison to a rubber sheet is merely conceptual, because such a rubber sheet would have thickness. I find the question to persist, at the end of the explanation. I still find myself asking if a 3 dimensional universe is finite or infinite. I don't think analogies to 2 dimensionality are answers to problems concerning 3 dimensionality. And again, the same problem, as I see it, applies to time. Is time infinite, or is time finite? I am not trained in these things. I will not rule out that answers are known, concerning these questions, by those more knowledgeable than myself. But I have not seen any that seem realistic. That is all I'm saying. I know I'm repeating myself. Sorry. Bus stop (talk) 16:44, 21 June 2009 (UTC)

It's not a non-answering. It's a means to try to explain a tricky concept by analogy. I don't, personally, have a problem imagining the 3D version of an infinite of a finite-but-wrapped-around universe. But you are kinda stuck with the word "universe" meaning "absolutely everything" - so if there is an "edge" and something "beyond the edge" then it's a part of the universe by definition. If you want to talk about something smaller than everything (like a galaxy or a galactic cluster) then we can - but if we're talking about "everything" then you can't go around asking "what's beyond the edge of everything" - because whatever that is would be a part of everything. Hence, if we are discussing "the shape of absolutely everything" - we have to start to accept infinities and wrapping-around-ness. SteveBaker (talk) 21:03, 21 June 2009 (UTC)

So, you are saying the universe is infinite? And you are saying that we have different understandings of what infinite means? And that "wrapping-around-ness" is an aspect of your understanding of an infinite universe? Bus stop (talk) 22:01, 21 June 2009 (UTC)

I'm pretty sure that was a typo on Steve's part - he means "infinite or a finite-but-wrapped-around universe". As far as I'm aware, modern science hasn't been able to determine which of those options is the correct one (I think we have some lower bounds on the size of the universe, but that's all). --Tango (talk) 22:05, 21 June 2009 (UTC)

What is the scientific definition of "nothing" and in what form can it or has it been found? ~ R.T.G 15:25, 21 June 2009 (UTC)

I don't think there is one. There is vacuum, if that is any help. --Tango (talk) 15:46, 21 June 2009 (UTC)

The problem is that a vacuum is proving to be anything but nothing - quantum foam and virtual particles and the concept of false vacuum. There are a lot of interesting things going on in this supposed nothingness. Also, even if vacuum somehow fitted your definition of nothingness - there is no such thing as a sizeable volume of hard vacuum - even in deep intergalactic space - there are measurable number of hydrogen and helium atoms. Worst still, even the hardest of hard vacuums still has photons and neutrinos and all manner of other exotic things flying through it - so do describe it as "nothing" is a tough sell. SteveBaker (talk) 21:03, 21 June 2009 (UTC)

(Intrinsic curvature has not yet been written.) ~ R.T.G 15:26, 21 June 2009 (UTC)

Try Curvature of Riemannian manifolds, then. It's rather technical, though. --Tango (talk) 15:46, 21 June 2009 (UTC)

To agree with you, Tango, I quote : "In mathematics, specifically differential geometry, the infinitesimal geometry of Riemannian manifolds with dimension at least 3 is too complicated..." :o~ R.T.G 15:49, 21 June 2009 (UTC)

RTG - please stop answering questions...you have no clue about the things you're talking about. Quoting that half-sentence out of context is EXCEEDINGLY misleading. SteveBaker (talk) 22:23, 21 June 2009 (UTC)

You can easily get into trouble talking about "nothing", as in the old syllogism "Nothing is better than eternal happiness; a ham sandwich is better than nothing; therefore a ham sandwich is better than eternal happiness." When you say the universe is "expanding into nothing", you may be making a similar error, treating "nothing" as a concept on the same footing as "empty space" or "green cheese". That will get you into trouble. If space does end, then it just means there's no more space beyond that point. If you ask what's beyond that point, you're implicitly imagining that there's space beyond that point that something could be in. What would happen at the edge? Well, there would be a set of two-dimensional physical laws governing the boundary. It's impossible to know what those laws would be without a better understanding of space than physicists have now, although we have some ideas from studying two-dimensional quantum systems theoretically and in the lab. (This turns out to be a surprisingly deep and interesting subject. Topological quantum computers are one example of new physics that exists only in two dimensions.) Or maybe the edge would be like a black hole event horizon, in which case you wouldn't necessarily need a separate set of laws. Either way, you have physics in space (called the "bulk"), and physics on the boundary, and that's all.

That said, the universe that we see could be expanding into a preexisting vacuum or preexisting cheese. Neither hypothesis seems very likely to me, but they are mathematical possibilities and they're consistent with what we observe. We simply don't know what's out there beyond the limited distance that we can see. -- BenRG (talk) 21:06, 21 June 2009 (UTC)

Gents/Ladies thank you very much for the answers given, a difficult concept for me to understand; however i think i now have a better understandingChromagnum (talk) 05:25, 25 June 2009 (UTC)

The non-entity "nothing" is incapable of having, doing or being anything. Semantically the questions What has nothing, What does nothing and What is nothing are all ill-posed questions that defeat proper answers. However to a Zen buddhist "What is nothing" is a productive Kōan question. The problem posed by a koan is to be taken quite seriously, and to be approached as literally a matter of life and death. The student will realize that even in the vacuum of space the answer is not to be found physically because there is no volume anywhere where intermolecular forces are absent. Even if they could be eliminated forces of attraction remain, and the strongest attractive force is the student's own spiritual clinging desire and repulsion. When the student gains the insight that the Kōan can only be answered after letting go of all clinging, the Zen teacher can observe that "the place and the time and the event where truth reveals itself" is near. Cuddlyable3 (talk) 23:42, 6 July 2011 (UTC)

Pakistan

Does that country of pakistan have any indigeneous missile technology ???I heard it has stacked up the missiles thrown away by N.Korea and China!!! —Preceding unsigned comment added by 121.246.174.130 (talk) 14:48, 21 June 2009 (UTC)

Are you talking about nuclear missiles or missiles in general? Pakistan has had superior weapons technology to N. Korea for some time, I believe, so I doubt they are using N. Korean weapons. It is possible they have bough Chinese weapons, though. --Tango (talk) 14:58, 21 June 2009 (UTC)

This 1999 Unclassified CIA Report discusses Pakistan in particular. According to this report, Pakistan has a well-developed internal nuclear program but their missile infrastructure seems to be largely imported from China and North Korea. Specifically, the CIA claims that the North Korean Rodong-1 inspired (or is) the Pakistani Ghauri_(missile). From a cursory survey, it would seem that missile technology is imported while warhead technology is indigenous to Pakistan. Nimur (talk) 15:17, 21 June 2009 (UTC)

By the time of this 2003 report, Pakistan is no longer considered "developing" a program, and is classified as having a "well-established" program. Nimur (talk) 15:20, 21 June 2009 (UTC)

Well what about the war head technology???Is it superior to it's neighbour India??? —Preceding unsigned comment added by 121.246.174.130 (talk) 17:44, 21 June 2009 (UTC)

It's unclear, but the fact that they have been cooperating with the Chinese on their warhead development suggests that they possibly could be (as China is far more advanced from a nuclear standpoint than India). --98.217.14.211 (talk) 16:29, 22 June 2009 (UTC)

One notices that the anonymous OP refers asymetrically to "that country of pakistan" (not capitalised) and India (properly capitalised). Does the hearsay that N.Korea and China throw away missiles for another country to collect come from a credible source, perhaps overheard in a Calcutta bar ? Cuddlyable3 (talk) 19:20, 22 June 2009 (UTC)

Seems to be from Mumbai. NotAHen (talk) 22:41, 22 June 2009 (UTC)

With a wide range of interests. NotAHen (talk) 22:43, 22 June 2009 (UTC)

You can, of course, deliver nuclear weapons via aircraft - and Pakistan has 700 aircraft in their fleet. Against an enemy with really modern anti-aircraft defences, that's not much use - but when you consider who it is that Pakistan wishes to impress with their nuclear arsenal - that may not be an issue. SteveBaker (talk) 03:37, 23 June 2009 (UTC)

Race and brain size/characteristics.

This might be a bit controversial, but here it goes. I'm looking for information regarding correlations, or lack thereof, between race and brain size/characteristics. For example, do blacks have smaller brains than whites? If true, would that affect their intelligence? Is it true that the brains of whites and blacks are "wired" differently? Links such as this one would be helpful too. Thanks in advance, ― Ann _{( user | talk )} 15:25, 21 June 2009 (UTC)

File:Ele-brain.png

Human, dolphin and elephant brains up to scale

As a start, why don't you read about Intelligence and brain structure in normal individuals, and then you can develop a baseline for comparison? This is a really complicated issue, and it sounds like you want to boil it down to an "IQ vs. mass" plot, or a "race vs. brain size." This is too simplistic and will not possibly capture any meaningful scientific conclusion. Brain structure is very vaguely correlated to mental acuity. Race and ethnicity is only vaguely correlated to brain structure, if at all. Different definitions of "race" will skewer any sort of meaningful comparison studies. Nimur (talk) 15:48, 21 June 2009 (UTC)

See Race and intelligence. WP:WHAAOE! --Tango (talk) 15:56, 21 June 2009 (UTC)

We also have several other articles relating to this topic, including Neuroscience and intelligence, Brain size and intelligence, and Heritability of IQ. Before plunging too deeply into this topic, though, here is a question you should think about: suppose when you look up the data you find that black people have larger brains than white people. What conclusion would you draw? Looie496 (talk) 18:13, 21 June 2009 (UTC)

That you've got the "wrong answer" so your methodology must be flawed, of course! --Tango (talk) 18:26, 21 June 2009 (UTC)

...What to speak of elephants and dolphins.--Shantavira|^{feed me} 07:21, 22 June 2009 (UTC)

Though to be more clear nobody actually asserts it is just large size but large brain size relative to overall body mass. So elephants do better than some animals but are not nearly in league with humans. --98.217.14.211 (talk) 16:27, 22 June 2009 (UTC)

The conclusions that the OP seeks are much more than "a bit" controversial. Measuring comparative intelligence is fraught with controversies, such as what different IQ test results really mean, and whether it is even defensible to postulate black and white as different human races. It seems everyone has a vested interest here, for example I don't think I am alone in viewing favourably the idea that I belong to an excellent race with impressive intelligence. The OP must expect accusations of bias connected with any answers to the questions asked, that can be defended only by very conservative labelling of whatever evidence exists. Cuddlyable3 (talk) 19:08, 22 June 2009 (UTC)

Brain size/exercise

Can anyone correlate brain size to exercise? Bruce Lee (see Bruce_lee#Death) died of a swollen brain which various doctors said was caused by either trace amounts of cannabis or normal painkillers but the urban legend is that he trained so hard his brain swelled inside his head (the painkillers and cannabis were both disputed as causes of death). ~ R.T.G 16:05, 21 June 2009 (UTC)

Brain size is primarily determined by skull size, I think. What you want to look for is a correlation between intracranial pressure and exercise. --Tango (talk) 16:24, 21 June 2009 (UTC)

It's hard to do the experiments properly, damn ethics committees, if some people need to be sacrificed it would be for the greater good ;-) From Dance and health "A study in New York in 2003 has shown that cognitive activities like crosswords help ward off dementia but, except for ballroom dancing, most physical activities do not". It seems you need to use your brain to exercise it, raising weights in the gym won't make you any smarter. Dmcq (talk) 16:38, 21 June 2009 (UTC)

I had heard that physical exercise did increase your IQ, by increasing the blood flow through your brain. My non-scientific personal experience supports that idea. 78.146.242.171 (talk) 12:58, 22 June 2009 (UTC)

To my knowledge, there is no correlation between brain size and intelligence, so whether or not it makes you smarter doesn't answer the question. — DanielLC 17:09, 21 June 2009 (UTC)

I expect there is a correlation within humans between adult brain size and intelligence, if you do not exclude persons with Microcephaly. Also in animals and humans, other genetic causes or trauma can cause stunted brain size with diminished mental ability. Additionally, with extreme age or with many diseases or conditions, the brain often shrinks and mental ability decreases. Also across primate species, there is likely a correlation between brain size and intelligence [3]. "Encephalization" normalizes brain size compared to body size, and thus primates have about twice the relative brain size as other mammals [4]. Sternberg says the brain size, after adjusting for body size, is a measure of information processing ability and thus a measure of intelligence. Scholars debate how to normalize brain size versus body size to make a fair comparison. The relative brain size of higher primates, our ancestors as well as dead end higher primates, have shown higher encephalization over the past several million years [5] page 769. Only if you restrict the range to "normal adult humans" will the correlation disappear, as is usually the case when only the center part of an x-y distribution is used in a correlation calculation. Some research indicates that mental activity can decrease the loss of cognitive ability with age. So it is probably true that whatever "intelligence" is, it does not correlate with absolute brain size in normal humans. As for exercise affecting the structure of the brain, many animal studies have shown that experience and environmental richness affects the brain structure in terms of microscopic structure complexity, as well as cortical size [6] page 47. Edison (talk) 17:35, 21 June 2009 (UTC)

A "swollen brain" such as supposedly killed Bruce Lee is not caused by growth of the brain, but by a build-up of fluids as a result of damage. It happens for the same reason your skin or muscles swell when you get a bruise. There is some evidence that exercise or other types of experience can affect brain structure, making certain parts of the brain slightly larger, but that wouldn't come into play here. We have an article, brain fitness, that deals with some of these factors, but unfortunately it isn't a very good article at the moment. Looie496 (talk) 18:04, 21 June 2009 (UTC)

It's a bit unfair because Bruce Lees life was given to philosophy and to suggest that he stretched his physique more than his mind is unfair at least. Could you fault a man if he stretched that muscle? Well its fair due to say that. ~ R.T.G 12:47, 22 June 2009 (UTC)

Low doses of radiation protecting against cancer?

I have read people saying that low doses of radiation provides a measure of protection against cancer. Is that the case? Unomi (talk) 17:40, 21 June 2009 (UTC)

See radiation hormesis. -- BenRG (talk) 17:50, 21 June 2009 (UTC)

We do not give medical advice. But taking the question as just a request for referenced information, a recent publication from the National Research Council (US) says (p 89[7]) that "low dose radiation acts primarily as a tumor-initiating agent." It says there is no expectation of a low dose threshold below which it does not initiate tumors. On page 10 they conclude that there is a linear relationship between radiation dose and cancer risk down to the lowest doses, with no threshold below which the added risk is zero. Edison (talk) 17:59, 21 June 2009 (UTC)

Thank you, it was not meant as soliciting medical advice, merely a query regarding a statement here: http://news.bbc.co.uk/2/hi/health/3554422.stm that I found 'curious'. I found http://www.radscihealth.org/rsh/Papers/FrenchAcadsFinal07_04_05.pdf to be pretty interesting reading regarding their opinion on low levels of radiation. Unomi (talk) 20:10, 21 June 2009 (UTC)

I think that that paper quoted by Edison doesn't really reflect the best understanding about the action of low radiation doses. This[8] paper, for instance, shows a different point of view. Figure 3 suggests that doses as high as 10000 mGy/year may be considered be considered beneficial. Dauto (talk) 21:47, 21 June 2009 (UTC)

I strongly disagree. The paper is recent and authoritative. "Radiation in low doses is good for you" sounds like rank bullshit. 02:37, 23 June 2009 (UTC)Edison (talk)

I tend to agree with the paper that Dauto linked. The Linear-No-Threshold model seems almost unscientific; I'm not sure if I believe in a benefit of low-doses, but extrapolation of risk by linear model to low-dose seems sloppy in the absence of strong data. Nimur (talk) 23:14, 21 June 2009 (UTC)

It reads as though the posited mechanism of hormesis is by causing enough damage to encourage apoptosis and/or stimulating DNA self repair mechanisms? Also, for general purposes is 1 sievert equivalent to 1 gray for EM radiation ?

no, a sivert is not a unit of EM radiation... its a unit of biological damange... 1 sv = 1 J/kg = 100 Rem... 1 Gray = 100 Rads... a dosage in rems = dosage in rads * QF... the QF depends on the type of radiation (Gamma, Beta, Alpha)... for gamma QF = 1, but alpha has a higher linear energy transfer and QF = 20... 70.71.22.45 (talk) 00:54, 22 June 2009 (UTC)

Ok, but from Sievert it says (as far as I can tell) Sv * Q * N = gray and that a 'human' has an N of 1 and that EMR has a Q of 1, is that a correct interpretation? Unomi (talk) 01:35, 22 June 2009 (UTC)

There are huge differences between saying "low level radiation is tolerable", "low level radiation may be good for you" AND ""Low levels of radiation are probably essential for life itself." The BBC reports Professor Zbigniew Jaworowski stating the latter. Without evidence that sounds like the unscientific adage "The blow that doesn't break my back makes it stronger." I suspect the BBC may have misunderstood the professor if he actually meant that some level of radiation was historically essential to the evolution of life. Cuddlyable3 (talk) 18:18, 22 June 2009 (UTC)

It's apparently the same Zbigniew Jaworowski as this one, with whom I am somewhat familiar. Given his past pronouncements on various topics it wouldn't be at all surprising if he really did say "radiation is good for you." Short Brigade Harvester Boris (talk) 00:24, 23 June 2009 (UTC)

Phone sound

Why is sound quality from phone speakers so poor compared to anything else I've ever heard? Vimescarrot (talk) 19:05, 21 June 2009 (UTC)

Probably for several reasons. First, they are commodity devices and are designed to reduce cost before all other requirements. Next, the telephone system (whether it is POTS or a modern digital wireless system) does not even use high fidelity signal - it is usually found that about 1.5kHz to 3 kHz is sufficient to understand voice and conversations with minimal distortion. So, because the sound played over the speaker is rarely "hi-fi", there is no reason to use a hi-fi speaker. The form-factor of a telephone makes it difficult to have a nice resonant cavity, so the result is a poor signal, poor transducer, and poor acoustic properties - cumulatively, a less than top-notch audio quality. Nimur (talk) 20:02, 21 June 2009 (UTC)

And the reason none of these systems is improved is because of cost? Vimescarrot (talk) 20:12, 21 June 2009 (UTC)

Yeah, pretty much. However, that's a fairly trivial conclusion. Most anything could be further improved if you were willing to spend more for it. — Lomn 20:26, 21 June 2009 (UTC)

Most people who are using their phones as music players are using headphones - it would be hard to justify the size/power/cost of a decent speaker in a phone. SteveBaker (talk) 20:38, 21 June 2009 (UTC)

Just in case you were thinking otherwise, I was specifically thinking of conversation, not music. Vimescarrot (talk) 21:05, 21 June 2009 (UTC)

Well, as others have pointed out, speech is quite comprehensible with just a few kHz of bandwidth. Providing better speakers would help very little because the data simply isn't there. The higher frequencies are chopped off by the microphone - then by any line filtering, then again by the telephone exchange...voice transmitted via phone would sound pretty much like it does even if you had really high quality reproduction. SteveBaker (talk) 22:06, 21 June 2009 (UTC)

Because the frequency range is limited I sometimes find it hard to understand people with accent I am not used to, but understand them much better on VOIP (e.g. Skype). My guess is that VOIP supports a wider range of frequencies. NotAHen (talk) 22:39, 22 June 2009 (UTC)

They could send the signal encoded in MP3 and fit a relatively power-hungry speaker but the batteries wouldn't last very long. My own phone is roughly twice the size of most ordinary phones and yet, the one I had ten years ago was roughly 3 times the size again but the battery size is only about one quarter or less even though it lasts much longer. The Sony Walkman is probably the first well known example of the miniaturisation craze but certainly, your computer is as powerful as one that would have filled a whole building half a century ago. ~ R.T.G 13:01, 22 June 2009 (UTC)

Landlines wouldn't have to worry about power consumption so much, would they? Vimescarrot (talk) 13:16, 22 June 2009 (UTC)

Sure they would. Imagine a million phone calls per day on a companys lines. Power would be one of the main factors in cost and as folks are saying, even a top class speaker system (which you can hook up to your phone) would only recieve a certain quality of signal. (you could hook up as decent a signal as you like over the internet if that is what you are looking for) ~ R.T.G 13:38, 22 June 2009 (UTC)

No - I used to design telephone exchanges - the land lines don't consume much power. The reason relates to bandwidth - and compatability with a trillion phones out there. You can't use MP3 encoding because it's a compressed format - you'd end up with a second or more of latency between speaker and listener. The computer inside a cellphone is considerably more powerful than even the largest computer from 1959. The IBM 7080, for example - released in 1960 - only had 160kbytes of RAM. SteveBaker (talk) 16:52, 22 June 2009 (UTC)

The primary goal of telephone design is intelligibility. Good intelligibility is obtained by restricting the sound bandwidth to, say, 300 - 3200 Hz. However minimal distortion is not necessarily a goal. It is common in avionic and amateur radio communication to limit (clip) the voice waveform. This is a deliberate distortion that actually improves voice intelligibility especially over background noise. It is also a crude way of reducing the dynamic range of the voice signal amplitude that varies with different speakers and mouth-to-microphone distances.

Modern mobile telephones use a variety of voice digitising methods, such as the CELP coding used in GSM networks, that provide data compression while introducing acceptably small delay for natural conversation. MP3 encoding is popular for music i.e. wide bandwidth sound at relatively high data rate; however it uses a masking algorithm that gives poor results for voice bandwith at low data rate, as well as the long latency that SteveBaker mentioned. Cuddlyable3 (talk) 17:56, 22 June 2009 (UTC)

And finally; is sound quality for conversations in phones likely to improve in the future? Vimescarrot (talk) 18:03, 22 June 2009 (UTC)

The technology to improve telephone conversation sound fidelity could be used tomorrow but there is little motivation to make that happen. Most telephony is mobile these days. Mobile networks represent large investments in particular data- and sound bandwidths and codecs while the telephones themselves are overweighted with the features that users are willing to pay for. Examples of these features are music storage, inbuilt camera, GPS, SMS, handheld computing, e-mail, Internet access... But hi-fi voice is not on the investment horizon. Cuddlyable3 (talk) 18:31, 22 June 2009 (UTC)

I think widespread VOIP could solve the hardware problem of telephone lines restricting bandwidth. There could be HiFi VOIP, yes? Multichannel, high-fidelity telephone calls. --Navstar (talk) 00:49, 23 June 2009 (UTC)

Speaking of "land" lines, for over 50 years, long distance phone conversations have been sent in a multiplexed way via coax cable or microwave link. The narrower the bandwidth, the more conversations the communication channel can carry at the same time. A narrow bandwidth is adequate for normal conversation. The same is true , I would expect, for cell phones. When a higher fidelity channel is desired, more bandwidth can be purchased, as for a link between a radio station remote and the transmitter. Even back in the 1920's and 1930's phone company engineers could provide audio channels with much higher fidelity (wider bandwidth and more even frequency response) than normal voice communications required. Edison (talk) 02:34, 23 June 2009 (UTC)

Thanks very much, guys. Best answer(s) yet, keep up the good work. <3 Vimescarrot (talk) 10:00, 23 June 2009 (UTC)

A bit late, but of course there already exist high quality telephone links - ISDN - broadcasters, for example, use (or used) ISDN links between studios. --Polysylabic Pseudonym (talk) 03:01, 25 June 2009 (UTC)

Bacteria-based stain remover

This product and others like it say that they use "nonpathogenic bacteria" and "natural enzymes" to destroy stains and odors. I notice the ingredients list also includes isopropyl alcohol, though, which I'd think would kill all the bacteria. Does anyone know how this solution works? What bacteria are being used to magically destroy the sources of the bad odors? Tempshill (talk) 20:25, 21 June 2009 (UTC)

It probably works the same way as any biological detergent does. Detergents contain enzymes, not live cultures. However, there are bacteria that help remove odors, too. A freshwater aquarium nitrogen cycle is a good example. --Dr Dima (talk) 21:27, 21 June 2009 (UTC)

Oh, and regarding your question on isopropyl alcohol, it really depends on concentration and on duration of contact which bacteria are killed and which survive. --Dr Dima (talk) 21:33, 21 June 2009 (UTC)