Wikipedia:Reference desk/Archives/Science/2011 February 15

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February 15

California power plant's NOx emissions

I have had a good look around and have been unable to find an answer for this. I was wondering if anyone else had anymore luck finding the regulated NOx emissions limit (in ppm or otherwise) for power generating plants in California? Any help would be appreciated. Cheers 150.49.180.199 (talk) 02:50, 15 February 2011 (UTC)

Decompressing the spine

Is there a reason that some people who have had a back injury feel their spine get compressed throughout the day and feel better when they decompress it with an inversion table and people who have not had a back injury do not feel like their spine is getting compressed? —Preceding unsigned comment added by 76.169.33.234 (talk) 06:51, 15 February 2011 (UTC)

The spine gets compressed during the day by standing, in either case, but it may be more of a problem for those with a spinal injury, where the compression may result in pain. StuRat (talk) 08:01, 15 February 2011 (UTC)

That's right: one doesn't need to have had a back injury to feel the results of the compression (OR). Dbfirs 08:15, 15 February 2011 (UTC)

If you don't have a back injury, you probably don't care about it, but the compression reduces your height in about 1 inch along the day. Quest09 (talk) 15:32, 15 February 2011 (UTC)

SPEED OF LIGHT

I am a student of science and want to know that light has a speed of 3*10^8 m/s. Why not greater than it?Mohammad babar (talk) 07:38, 15 February 2011 (UTC)

http://en.wikipedia.org/wiki/Meter#Speed_of_light 157.193.175.207 (talk) 08:13, 15 February 2011 (UTC)

It is what it is because of the way the Second and the Metre are defined. To "increase" the speed of light (which is a universal constant) you would have to either shorten the metre or lengthen the second. Roger (talk) 09:03, 15 February 2011 (UTC)

That (the definition of the meter in terms of the speed of light) is of course a very recent definition, and both the meter and measurements of the speed of light existed before that definition. OP's question makes more sense if turned around: Given the speed of light (and the values of the other constants of nature), why do atoms and people have the sizes that they have? That is a question that can actually be answered. The values of the constants of nature are contingent (at least in the context of our present theories), we do not know of any reason why they are what they are. --Wrongfilter (talk) 09:14, 15 February 2011 (UTC)

This page claims that if the speed of light was higher, nuclear decay would be faster and nuclear reactions in stars would be faster. Therefore the sun might have gone out by now, even if it hadn't the Earth would be much colder (because it gets some of its heat from nuclear decay) and the universe would last a much shorter period of time. Possibly this would be too little time for human beings to evolve - see anthropic principle - but that is just my speculation. --Colapeninsula (talk) 10:13, 15 February 2011 (UTC)

This is a valid argument that the values are such as they are (inferred from the observation that we exist). It is (scientifically) not acceptable as an argument why they are such as they are. --Wrongfilter (talk) 11:26, 15 February 2011 (UTC)

Actually, that is debatable. See anthropic principle. If the constants were significantly different, we wouldn't be here to observe them. Or, in other words, the fact that the universe can sustain life is a precondition for us being able to observe it. --Stephan Schulz (talk) 12:05, 15 February 2011 (UTC)

Which is exactly what I'm saying. From the observation of our existence we can infer what the values are, because if they were different we wouldn't be here. But we cannot claim that our existence is the reason or the cause (in some teleological sense) for their existence. They were not chosen such that we might come into existence. --Wrongfilter (talk) 12:52, 15 February 2011 (UTC)

Is Mohammad actually seeking an explanation of why light has a maximum speed? You may find the article Introduction to special relativity useful, or maybe the Simple English Wikipedia article, which you can read by clicking here. If you tell us a language you prefer, we can show you explanations in that language. 86.164.25.178 (talk) 11:58, 15 February 2011 (UTC)

You can always ask that question though. If the speed of light was 100 mph faster, you could then ask why can't it be faster than that? If the question is, why is the speed of light what it is, I'm not sure we have an explanation of why it goes at that speed. That's just what we observe its speed to be. Obviously, reading about Special Relativity should answer some other questions. We do know that light travels slower through a medium like air or water. Also the speed of light may have been different in the past, maybe someone can expound on that. ScienceApe (talk) 15:09, 15 February 2011 (UTC)

On the latter point, see Variable speed of light. There is not a lot of compelling reasons to go with a VSL theory at this point. As for why the constants are what they are, nobody is really sure. There are different ways to approach the question. The anthropic principle brought up earlier says that if they weren't what they were, we wouldn't be able to observe them, thus we don't have much of a place for suggesting that they could be different. Those who believe in the possibility that this is just one of many universes that pop in and out of existence regularly (see multiverse) see it as something like natural selection (only some universes are going to stay stable, only some produce life, and here we are, in one of those). (On all of these points, see Fine-tuned Universe.) Some suggest that the exact answer why might be revealed by further work in string theory cosmology; that it will simply be logically impossible for it to be any other way. (It's not clear that this will happen, though; a lot of string theory cosmologies say that you could, in fact, have all sorts of different constants.) Personally I think this sort of thing gets well into metaphysics, even when scientists are doing it, and that there isn't a lot of evidence one way or the other at this point. If you want to say, "God did it," as some clearly do, that's an answer, though in the past we've found that it's generally not as satisfying an answer than the naturalistic ones (and we answer a lot fewer questions with "God did it" these days than we used to). --Mr.98 (talk) 20:38, 15 February 2011 (UTC)

Saying "god did it" isn't even an answer, it's an Argument from ignorance. ScienceApe (talk) 02:45, 16 February 2011 (UTC)

Not necessarily. It depends on one's definition of "God". ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:43, 16 February 2011 (UTC)

Yeah, you're the guy who once said atheism is a religion. Saying "god did it" is an argument from ignorance unless your "definition of god" is the scientific theories proposed which explain observed phenomena, in which case I have no idea why you are calling it god. ScienceApe (talk) 14:40, 17 February 2011 (UTC)

But atheism is a religion. Atheists still believe that the universe has laws (not just scientific laws, but also laws without clear scientific basis (for example) explaining whether an unborn fetus or a dog or an earthworm can feel meaningful pain). They still have some cosmogeny in mind, as to how scientific laws came to be as they are, even if it is by accident or anthropic principle. They believe in morals, in things that should be done or shouldn't. They have a conception of self, whether they feel it is limited to a span of spacetime or find some way to envision their atoms or genes or algorithm of consciousness continuing to be relevant in some other setting. All the basics of religion are there, except for the most colorful and allegorical traditions which personify God in a notably visual or tangible way. Wnt (talk) 07:17, 19 February 2011 (UTC)

Rubbish. Looking for rational explanations cannot be described as a religion. HiLo48 (talk) 07:41, 19 February 2011 (UTC)

First thing, A religion can be defined as a set of beliefs, so atheism/agnosticism can be defined as a religion. Second thing, the speed of light is basically an axiom of modern physics, and there's no way to answer a question "Why is it so?". It's like asking "Why is 1+1 2?", or, "Why do an infinity of lines pass through a given point?". The value of the speed of light can be similarly explained (or with the anthropic principle). These problems aren't there only with the speed of light, though. Other constants like Planck energy, Planck time, and Planck length are just formed by combining G, h, and c in various ways, using dimensional analysis. These have a physical meaning, but you can't derive the values from the physical meaning. If you look at the derivation, there's no quantum mechanics involved. They've just found a way of combining the three constants to get a constant with the required dimensions. All these constants sound cobbled-together, but they work. Same thing with the speed of light.

If you want to go into the Standard Model, the speed of light is mathematically derived (not sure on this one). With M-theory, the speed of light is no longer the universal constant, but I'm quite sure it is mathematically derived there, too. ManishEarth^{Talk • Stalk} 16:27, 19 February 2011 (UTC)

Atheism is NOT a religion, it's a stance on a single issue. Atheism just means you don't believe in god. That's not a religion. If I don't believe in unicorns, is that a religion? If I don't believe in the Loch Ness Monster, is that a religion? The proposal that not believing in something, is a religion, is absurd to say the least. ScienceApe (talk) 16:37, 19 February 2011 (UTC)

I do not remember Baseball Bugs ever declared that "atheism is a religion".. I do remember Baseball Bugs declaring that atheism is sometimes thrust with as much intolerant Self-righteousness as a bad religion, and I agree with that. One is on safer ground speaking of anyone's belief system (see disambiguation page) rather than "religion" which is for many a loaded concept. For example, it looks like to ScienceApe, "religion" is inseparable from "the organised acknowledgement of the existence of a single creator-deity about whose modus operandi we need not inquire". (I hope I understand Bugs' and ScienceApe's meanings and will retract with apology if either says I am wrong.) Cuddlyable3 (talk) 22:29, 19 February 2011 (UTC)

I remember him saying that, but if he says that it isn't (meaning if he says that atheism is not a religion), then I'll retract that statement. I'm not saying anything about religion, I'm saying what atheism is NOT. And atheism is not a religion in any way shape or form. How can you "thrust" not believing in something? It's not an ideology, it's not even a belief, it's a rejection of a claim. If you say you have an invisible man in your pocket, and I reject your claim, is that an ideology? How can I "thrust" that rejection? I can understand someone "thrusting" antitheism, but that's a different subject. You're confusing antitheism with atheism. They are not the same. ScienceApe (talk) 22:47, 19 February 2011 (UTC)

We don't know what mechanism might "hold back" the SOL (speed of light) in vacuo, or whether a faster speed can even have meaning in the observable universe, only that the SOL is essentially an observed value that appears to be very constant i.e. if it varies the variation is less than the present measurement uncertainty of 4 parts per billion. In modern physics the SOL is assumed to be a universal constant. The SOL is slightly less than 3*10^8 m/s. The link given by the first responder notes that it is exactly 2.99792458*10^8 m/s by definition.Cuddlyable3 (talk) 22:29, 19 February 2011 (UTC).

somthing about the creation theory of earth

I know that this is not the place to say my own ideas but I ask an opportunity for saying about only this subject that refers to earth. excuse me . I want to know can i do so? Akbar mohammadzade Iran

This is the first time that my own idea is publishing and for the reason of what I think about it is my patent ,may be occure some difficulties in understanding that subject and i have to do so . I am trying to publish my theory .when it happen, I will say what I am thinking about the solar system specially about the earth . According to the data bases collected and the reality observations in astronomy and geology ,it is clear that the earth , mars , venous and mercury which known rock planets created several years after the creation of sun and gas giant planets :Jupiter , Uranus ,Saturn and Neptun. the last bodies of solar system are moons ,Pluto and sates , comas and…. Which has less age than earth . I am trying to upgrade recent astrophysics theories that they are approaching the solution of the paradoxes in theory and practice .--78.38.28.3 (talk) 09:16, 15 February 2011 (UTC)iran feb 2011 mohammadzade

Sooooo what's your question? Someguy1221 (talk) 09:47, 15 February 2011 (UTC)

He asks whether we mind if he tells us his new theory. And I think our advice is probably that he should find an internet forum where people discuss such things, rather than explain it here. Itsmejudith (talk) 16:37, 15 February 2011 (UTC)

Reading Formation and evolution of the Solar System may help you. 92.15.16.146 (talk) 11:22, 19 February 2011 (UTC)

Tidal Force

I'm confused why the moon causes a high tide on the opposite side of the earth. The article 'Tidal Force' shows the tidal forces in figures 2 and 4. Could someone explain what "the residual force after the field of the sphere is deducted" means and why it results in a net outward force on the opposite side of the satelite? Thank you80.168.88.74 (talk) 11:47, 15 February 2011 (UTC)

In short, on the side near to the moon, the moon pulls the water harder than the Earth in total (since it's about 6000 km closer than the center of mass of the Earth). On side opposite the moon, the moon pulls the Earth harder than the water (since the water is about 6000 km farther away than the center of mass). Think about it not as "the water is pulled somewhere", think " the Earth is pulled somewhere, the water remains". --Stephan Schulz (talk) 12:02, 15 February 2011 (UTC)

In effect, the Earth is falling towards the Moon, at a speed that it wants to "on average". The parts of Earth nearest to the Moon want to fall faster than this average, so they're tugged away from Earth towards the Moon. The parts furthest from the Moon want to fall more slowly than this average, so they lag begind. 86.181.174.29 (talk) 12:36, 15 February 2011 (UTC)

And this might be clearly not obvious, as we all should know that when objects fall on Earth, it doesn't matter how massive they are - they always fall with the same acceleration. However, this is only because the effective distances from the center (of mass) of the Earth to the objects that we throw in the air are about the same - as the poster above points out, the oceans on each side of the Earth are about 6000km away from the Earth's center of mass, which ends up making a "big" difference.

I put "big" in quotation marks because remember that relative to the 6000km radius of the Earth, a tide of 1 meter is an utterly-miniscule astrophysical effect, unnoticeable if it were watched from another planet. SamuelRiv (talk) 16:34, 15 February 2011 (UTC)

Quark + Gluon plasma - Evidences

Reading article about matter states I could see reference about quark-gluon plasma that was found in CERN in 2000. From other books I have read that it wasn´t possible until now to detect any quark isolated. The evidence that they exist was taken by electrical effects when electrons travel close to the protons and was detected three concentrated points that have strong effect. It was assumed that they were 02 quarks up and 01 down. So is there more evidence in CERN 2000 experiment that confirms that quarks and gluons really exists ? — Preceding unsigned comment added by Futurengineer (talk • contribs) 11:58, 15 February 2011 (UTC)

The evidence that quarks exist is as strong (at this point) as the evidence that electrons exist. No one has ever seen either one. The evidence comes from the success of the electron/quark picture at predicting the results of all kinds of experiments, and the failure of every alternative model to do the same. It's not especially important to observe the particles "isolated" (though that does tend to rule out alternative theories). The quarks in a quark-gluon plasma are surrounded by other quarks, so they aren't really isolated. For that matter, an isolated electron is undetectable too; they have to interact with surrounding matter to be "seen". -- BenRG (talk) 22:29, 15 February 2011 (UTC)

Schwarzschild Metric

If one sets the angular terms to be zero (by considering a particle travelling on a radial line of the field source) and also sets the spacetime interval to be zero (by considering a photon), the equation for dr/dt does not give c. Why? —Preceding unsigned comment added by 129.67.37.227 (talk) 13:43, 15 February 2011 (UTC)

In general relativity the coordinates are arbitrary and meaningless except as interpreted by the metric. So the t coordinate is not true time, nor is the r coordinate a true distance. They are just numbers that label events in the spacetime, and in order to find distances and times you need to use the metric.

Alternatively, find a local coordinate transformation that makes the metric into the diag(1,1,1,-1) of SR. Then in that frame your photon will move with speed c (tautologically because you selected it to have null worldline). –Henning Makholm (talk) 14:22, 15 February 2011 (UTC)

Discontinuing a vaccine

Isn't it always to risky to stop immunizing your population against a well-known illness? Considering that there are reclusive states which could be, intending or not, a source of a new outbreak. Quest09 (talk) 15:37, 15 February 2011 (UTC)

The risks of the immunization procedure itself must also be taken into consideration and balanced against the risk of an outbreak. Dauto (talk) 15:47, 15 February 2011 (UTC)

In a practical sense, consider the case of smallpox. It is basically eradicated from the wild, however it still exists in laboratories, and could be weaponized by parties with ill intent. If you were a policymaker, you'd have to balance the risk of smallpox being used as an offensive weapon against the risks inherent to the vaccine. Smallpox vaccines have a rate of complications/infections of something like 14-500 per million according to our article. So in a country of 300 million people, that is a fairly large "peacetime" number of people suffering (it would be a justified number compared to that of a smallpox outbreak when it was still "wild"). Whether or not that is a good bet with regards to the threat of smallpox as an agent of war or terrorism is unclear; the US has evidently decided it is not, and does not vaccinate against it generally. Note that in the case of a weaponized threat, you can also say that you might have non-vaccination means of prevention, e.g. a state of deterrence with other nations, or vigorous counter-terrorism strategies. Each of these approaches have their own risk levels and possible numbers of incidental deaths (e.g. you will have a certain number of false positives with your counter-terrorism strategies that may lead to collateral deaths, infringements of liberties, etc.). In all of these situations, people have to make judgments about relative risks and balance accordingly. --Mr.98 (talk) 17:42, 15 February 2011 (UTC)

We need not limit ourselves to the one human disease that's been eradicated either. Take Yellow fever: there exists a vaccine that is largely effective and fairly safe. It's not 100% safe and (1 severe reaction for every 200,000 to 300,000 people, according to the article), perhaps more importantly, it's not free. For the vast majority of people living in the United States and Europe, the chances of contracting yellow fever are slim to none, and the vaccine's not worth it (or at least, the CDC and similar bodies in unaffected areas feel it isn't worth it for most people [1]). Buddy431 (talk) 03:48, 16 February 2011 (UTC)

Yes, see also herd immunity and anti-vaccine conspiracy theories. There has been opposition to vaccines by some, ever since they have been invented. And there have been actual cases of actual problems with vaccines. As a general rule, though, the anti-vaccination crowd is full of nutters, motivation by religion or philosophy, not by the weight of evidence. Friday (talk) 17:03, 15 February 2011 (UTC)

Some opposition may be due to Unethical human experimentation in the United States. Smallman12q (talk) 23:50, 15 February 2011 (UTC)

The practical case of this involves the "endgame" for polio, which has been mostly wiped out. Unfortunately, there are a few reservoirs, and the live vaccine itself has a small chance to mutate and turn wild again. Wnt (talk) 04:18, 16 February 2011 (UTC)

No one has mentioned the more resent example of BCG. This is another vaccine whose wide spread use is being curtailed and focused instead on high risk groups. The main reasons are: First it is no longer cost effective. The number needed to treat are now about 10,000 vaccinations to prevent a single case. “Secondly the harm done in adverse effects from the vaccine, usually abscesses at the sight of injection, outweigh the preventive effect.” Also, it is not very effective in some groups. Here is a fairly clear article about the UK position on BCG. Frequently Asked Questions about BCG. It remains however, a relitivly safe vaccine as you can see from the Complications of bacille Calmette-Guérin (BCG) vaccination and immunotherapy and their management.--Aspro (talk) 10:50, 16 February 2011 (UTC)

Chemical equation

alkyne (CnH2n-2) + Hydrogen sulfide (H2S) = ???????????????????? Rahul^{Text me} 17:19, 15 February 2011 (UTC)

Not knowing if it actually reacts that simply, but our article on alkynes says that the analogous reaction between an alkyne and water yields an enol which tautomerizes to an aldehyde or ketone. <OR> So if it reacts I'd guess that it forms either an aldehyde or ketone (depending on where in the alkyne the triple bond was) in which the oxygen is replaced by a sulfur atom</OR>. 178.26.171.11 (talk) 20:59, 15 February 2011 (UTC)

I can't find any cases of addition to alkynes by the same reaction methodology as for water (reaction begins with alkyne getting protonated to give cationic alkene, then neutral water attacks), but rather I see examples under nucleophilic conditions (looks like sulfur anion attacks alkyne). I see lots of examples using RSH rather than HSH as OP asks, and these give the vinyl thioether (obviously cannot tautomerize to the thioketone). Looking specifically for thioketone products of alkyne reactions though, I'm not seeing many. I do see articles commenting that the ene-thiol is much less unstable than the comparable enol and that the energy barrier to the tautomerization is fairly high...interesting! DMacks (talk) 21:38, 15 February 2011 (UTC)

Hydrogen sulfide seems to be a common contaminant in acetylene, so that suggests that they do not react under pressure at room temperature. However I did find this: https://doi.org/10.1007%2FBF00961927 or http://elibrary.ru/item.asp?id=12690943 "QUANTUM-CHEMICAL INVESTIGATION OF THE MECHANISMS OF REACTIONS INVOLVING NUCLEOPHILIC ADDITION TO ACETYLENE. 3. MECHANISM OF THE FORMATION OF VINYLTHIO ANIONS" by N.M. Vitkovskaya, O.Yu. Dolgunicheva, F.S. Dubnikova, B.A. Trofimov where divinyl sulfide is formed in the presence of KOH in dimethylsulfoxide. Graeme Bartlett (talk) 09:44, 17 February 2011 (UTC)

Immunology and parasites

There's the whole hygiene hypothesis that claims in short that "lack of contact with parasites makes our immune systems nonfunctional." This is usually phrased as the immune system lacks appropriate targets and therefore takes pot shots at things it's not supposed to attack. Has there ever been any serious evaluation of whether the parasites have an immunomodulatory effect, essentially "turning down" the immune system to help their own survival? This would make sense from a coevolution standpoint (i.e. the immune system developed as overreactive because it "assumed" it would be weakened by parasites), but is there any evidence of this? SDY (talk) 20:50, 15 February 2011 (UTC)

There is an article on Helminthic therapy if thats any help.--Aspro (talk) 21:45, 15 February 2011 (UTC)

Of course AIDS turns down the immune system, as its very name implies. There aren't many other parasitic or infectious agents that do, though. See immunodeficiency for more information (but not much).Looie496 (talk) 21:55, 15 February 2011 (UTC)

Well, I don't know about many either, but two common viruses that do, are those responsible for Chicken Pox and Measles. Both have suppressant effects on the immune system and so complications can come in the form of secondary infections. This is why it is important not to vaccinate against these, with live viruses, whilst the immune system is suppressed due to other reasons. --Aspro (talk) 17:35, 16 February 2011 (UTC)

Guadalquivir - second or fifth longest river in Spain?

I've already posted this question in the discussion about the article but nobody has answered...So here it goes again:

In the German article it says the Guadalquivir is the fifth longest river in Spain (after Tagus, Ebro, Douro and Guadiana). I don't know how you would count rivers that also lie in Portugal, but at least for Ebro, which lies entirely in Spain, you just have to compare the lengths in the English articles (Ebro 910 km vs. Guadalquivir 657 km) to see that something is wrong with the statement "The Guadalquivir is the second longest river in Spain (after Tagus)". So which rank does the Guadalquivir actually have? —Preceding unsigned comment added by 77.0.237.4 (talk) 20:57, 15 February 2011 (UTC)

The Spanish WP has quinto río por longitud. Oddly enough, they state the length is 722 km, whilst the en & de WP has 657 km. It must be a consequence of the rain in Spain... --Cookatoo.ergo.ZooM (talk) 21:47, 15 February 2011 (UTC)

Chemical thermodynamics vs. Thermochemistry

Could someone give an explanation of the main difference between Chemical thermodynamics and Thermochemistry, I've read the articles but haven't found a good explanation. /Natox (talk) 21:30, 15 February 2011 (UTC)

The differences are a bit fuzzy, that is the boundaries between the two topics overlap a lot. One textbook I teach from (Brown, LeMay, Bursten The Central Science) roughly considers topics such as calorimetry and specific heat to be squarely in the realm of thermochemistry and free energy and entropy to be firmly in the realm of chemical thermodynamics, but honestly there's not a lot of fundemental difference between the two topics. It would seem that they treat thermochemistry as dealing more with heat transfer between substances, while they treat chemical thermodynamics as energy changes (including enthalpy and entropy and free energy) that occur during chemical reactions. However, one could clearly see how those topics could easily overlap. --Jayron32 01:02, 16 February 2011 (UTC)

Black holes

This may sound like a really stupid question... When a guy approaches the event horizon of a black hole an outside observer will see his clock slowing down, and that he will never actually reach the event horizon (because time stops there). But they also say the guy falling in will reach the center of the hole in finite time, so as he crosses the event horizon he will see time outside speed up infinitely and past eternity!? I wonder what would the universe look like after an infinite amount of time. Money is tight (talk) 22:43, 15 February 2011 (UTC)

We have an article on that. Check out Ultimate fate of the universe. TenOfAllTrades(talk) 22:58, 15 February 2011 (UTC)

Yes, that is correct. The universe would be so distorted by gravitational lensing effects and so blue-shifted that you wouldn't actually be able to see much, though. You would get infinite blue-shift by the time the universe you were viewing was infinitely old, so you wouldn't see anything at all. --Tango (talk) 23:01, 15 February 2011 (UTC)

No, an infalling observer does not get to see the end of the universe. Some of the light he emits immediately before crossing the horizon will take so long to get out that there'll always be some of it left close to the hole, but that does not mean that light from an arbitrary event outside the hole has time to catch up with the observer before he hits the singularity. (The infalling light is subject to the same apparent slowdown as a massive astronaut, so it's hard for it to catch up). –Henning Makholm (talk) 01:48, 16 February 2011 (UTC)

Since there are two contradictory answers above I will weigh in. Makholm is right. The falling observer can only see events inside his past light cone and that does not include the end of the universe. The idea that if A sees B slow down to a halt than B must see A speed up to infinite speed is just wrong. See for instance the situation where two observers are moving relative to each other. They BOTH see the other observer slow down. Dauto (talk) 03:55, 16 February 2011 (UTC)

The infalling observer will also see the Hawking radiation from the event horizon get blue shifted. Just because radiation is blueshifted, does not make it invisible. A thermal blackbody spectrum blue shifted will look like a hotter, and brighter blackboddy spectrum, so the universe will not become invisible to these observers, but should look brighter and brighter over time. The time experienced for this will also get shorter and shorter, so the period for a gamma ray blast may be apparently short, but with an infinite period of light and radiation from the universe outside coming in, the energy should also be infinite, and any infalling object should be expected to be destroyed before meeting the event horizon.Graeme Bartlett (talk) 10:24, 16 February 2011 (UTC)

Actually, you don't see any Hawking radiation if you freefall through the event horizon; you only see it if you accelerate to stay outside. (Yes, that means that some people detect particles where other people detect none—see Unruh radiation.) -- BenRG (talk) 20:09, 16 February 2011 (UTC)

I agree with Henning Makholm and Dauto - the infalling observer does not see the end of the universe, neither are they destroyed by a burst of blue-shifted gamm rays. As Dauto says, these ideas assumes a symmetry between infalling observer and distant observers that simply does not apply. Our event horizon article says "An observer crossing a black hole event horizon can calculate the moment they've crossed it, but will not actually see or feel anything special happen at that moment". As long as they are small and tough enough or the black hole is large enough for them to survive spaghettification for a sufficiently long time, then they can cross the event horizon intact. Gandalf61 (talk) 10:59, 16 February 2011 (UTC)

I agree with Henning Makholm, Dauto and Gandalf61. I think perhaps others are confusing the perspective of an infalling observer with the perspective of an observer that's just barely outside the event horizon, accelerating like crazy in order to remain at a constant Schwarzschild r coordinate. Arbitrarily close to the event horizon, such an observer would indeed in principle see an arbitrarily blue-shifted, arbitrarily sped-up version of the outside universe. Of course, the thrust required to maintain a constant r coordinate also approaches infinity as the distance to the event horizon approaches zero, so there's a practical limit as to how much of the future of the universe you can actually see that way. A human observer could only actually see a negligible amount of speeding up of the outside universe that way at an outward acceleration small enough to keep from turning into a puddle of red goo. Red Act (talk) 12:37, 16 February 2011 (UTC)

In further agreement, let's just remember that seeing "infinitely blueshifted light" means travelling at the speed of light. But even inside a black hole, no one travels faster than light relative to the curved spacetime present there. And if you don't see infinitely blueshifted light, that means that when you look back at a source producing any given frequency of light, you can (at least in concept) count the number of individual wave oscillations that reach you - which means that you're seeing individual ticks of a clock, so infinite time never appears to pass. Wnt (talk) 18:45, 16 February 2011 (UTC)

Would the blueshift be visibly apparent before spaghettification killed the man? Googlemeister (talk) 19:28, 16 February 2011 (UTC)

Whether there's redshifting or blueshifting going on, by the way, depends on which direction the infalling observer looks in. As per Gullstrand–Painlevé coordinates#A rain observer's view of the universe, as of when the infalling observer crosses the event horizon, at least, the stars that are behind the observer are redshifted, and the stars visible around the edge of the black hole are blueshifted.

The answer to your question is that it depends on how big the black hole is. Assuming the infalling observer is freefalling from rest at infinity (or from a matching velocity and position), the amount of redshifting and blueshifting the observer sees at a given time depends purely on how many Schwarzschild radii the observer is from the black hole. But how many Schwarzschild radii you can get from a black hole without getting spagettified depends on the size of the black hole. With a supermassive black hole, you can get well inside the event horizon without getting spaghettified. And the redshifting and blueshifting would be quite noticeable by the time you reach the event horizon, so you would be able to see those effects in that case. But with a smaller black hole, the tidal force on a human as of a given number of Schwarzschild radii is greater, because the ratio of the human's size to the Schwarzschild radius is larger, so you might not be able to notice any redshifting and blueshifting before you get spaghettified if the black hole is too small. Red Act (talk) 22:07, 16 February 2011 (UTC)

Science and Miracles

This is a two parts question. First, can we classify frankly scientific miracles as pseudoscience? I can see here some articles discussing scientific miracles from the cultural point of view but not categorizing them in the pseudoscience area even though they look very similar.

The second part is not directly related to Wikipedia questions, but I am thinking of writing a book or even an article treating this part in details and was wondering if there were some volunteers to share the idea. I can collect enough materials related to Qur'an and miracles subject but I will lack for the miracles believed in other religions and cultures. I believe it would be interesting.--Email4mobile (talk) 23:17, 15 February 2011 (UTC)

We don't have an article on scientific miracles — I see from Googling that it is the practice of trying to find references in scripture to things that would not have been able to be known at the time, which would give credence to the idea that the scripture in question was of divine origins. (E.g. the equivalent of finding a great description of a Boeing 747 in the Bible somewhere.) (Note: our article on this is apparently at Scientific foreknowledge in sacred texts). Those that I have seen, primarily relating to Islam, have been fairly ridiculous — very bizarre interpretations of very vague passages and then trying to claim that these very poetical statements are really evidence of knowledge of very specific scientific theories. This approach also serves to cherry pick quite liberally — things that are apparently scientifically inaccurate (e.g. quite straightforward descriptions of the Sun as a satellite of the Earth) get thrown out or interpreted away. It's definitely not a scientific approach; it's inherently unfalsifiable, and involves utilizing a number of logical fallacies. Whether it is pseudoscience depends on whether the practitioners pretend it is scientific or not. Just because something is being offered as evidence does not mean it has pretensions to being science.

I've not seen Christians or Jews do this myself, but wouldn't be surprised if there was small bit of this out there for them as well. Usually the Christian Creationist approach is to simply try and show that the text is harmonious with the aspects of the scientific account that can be easily verified; it's only in Islam that I've seen that specific argument being made as a positive sign for the strength of the divinity of the text. But this is just my own anecdotal experience. --Mr.98 (talk) 23:48, 15 February 2011 (UTC)

Although we don't have a whole article called scientific miracle, there is at least an article section with that title, so I just now created a redirect for it. Red Act (talk) 00:20, 16 February 2011 (UTC)

I agree with you, and because I'm Muslim, I think I know why such concepts are spreading increasingly in Muslims community. Islam is considered as the final religion and Muslims thus try to make it as consistent as possible with the previous religions but also make it more distinguished by any means. I'm not a judge to assess it but at least I believe that connecting between science and religion is one of the worst tricks used to confuse students in particular. This subject is being studied in some schools and universities in Islamic countries and it was not until I joined University when I started to have a rethink (You can say 99.9% students are brainwashed). I don't like to be emotional but I feel we are somehow responsible if we don't classify this kind of articles. I don't think it is a good idea to make a redirect, because I'm sure other religion have some issues as well but less and hence I'd prefer to generalize the article firstly.--Email4mobile (talk) 00:28, 16 February 2011 (UTC)

Ok then. I think Scientific foreknowledge in sacred texts article would fit better as a redirect.

I redirected to the Islam-specific article because the phrase "scientific miracles" appears to at least quite predominantly be a phrase used by Muslims. Some adherents of some other religions have similar beliefs (but about different religious texts, of course), but they appear to instead prefer to use phrases like "biblical inspiration" or "Vedic science". I did also create a "See also" link at the Scientific miracles section to the Scientific foreknowledge in sacred texts article, in case readers want to examine beliefs like that in a broader context than just within Islam.

The Scientific foreknowledge in sacred texts article, by the way, does already use the word "pseudoscience" multiple times. Red Act (talk) 02:04, 16 February 2011 (UTC)

It's a very interesting topic, thanks for asking it E4M and for your perspective on it.

A friend of mine is a Professor at the Center for Islamic Peace (at American University in DC, though she grew up mostly in Egypt and still spends a lot of time in that region) who has absolutely no scientific background whatsoever and yet insists that Islamic scholars have something to say to scientists about Science! It's been almost very annoying at times, to tell you the truth. But I've wondered how widespread this sentiment might be among Muslims more generally, so found your comments above interesting in that regard.

I do know also that many varieties of fundamentalist Christians put great store in interpreting various translations of various passages in the Christian Bible as prophecies or "miracles" so scientifically sound that even actual scientists would have to admit the absolute Truth of the Word of God if only they weren't such fervent God-haters and -deniers to bother to take the time to scientifically evaluate it (by eg. accepting Jesus as their Lord and Savior and measuring the result).

Personally btw I think Buddhism is the spiritual practice or "belief system" most "compatible" with Science – Buddhism and science.

Good luck with expanding an article on this topic though, I'll enjoy having a look at it as it develops. :) WikiDao ☯ 02:25, 16 February 2011 (UTC)

On Youtube, Thunderf00t just recently did a video on this exact topic in Christianity: [2]. If you don't feel like watching through it or don't have time, here are the two links he gives in the video: one and two, and I also came across these: three and four. This appears to be a relatively minor view in Christianity, but it is not unheard of. TomorrowTime (talk) 08:35, 16 February 2011 (UTC)

Let's say it is not a problem if the Dr. were not specialized in a scientific field, but the serious problem comes into reality when you hear about a scientific degree Dr. or student preparing researches regarding this subject. See here for example, (Sorry, I Googled the translation from Arabic is I couldn't find English similar one). There you will find a Physicist, or Engineer trying to prepare his PhD in refuting Relativity.If you start with the first lines, you expect this researcher using scientific methods; however, when you reach somewhere in the middle of the paragraph and will be surprised that researcher was trying to find logical answers for the story/miracle of the Night Journey.--Email4mobile (talk) 10:17, 16 February 2011 (UTC)

Well, that's pretty much the same problem people have with the so-called "Creation science" - namely that it's not even real science but merely a lot of hot air trying to peddle itself as science to people who can't tell the difference. The creation science proponents will, on the other hand, go to great lengths to try and prove that their "science" is legitimate and that there is some vast conspiracy responsible for keeping them out of universities and research labs. You can watch Expelled: No Intelligence Allowed to get a feel for this. TomorrowTime (talk) 15:43, 16 February 2011 (UTC)

• This Christian theologian and scientist held that a belief in miracles was atheistic. DuncanHill (talk) 15:51, 16 February 2011 (UTC)

I really don't understand Baden Powell's point (granted, I should probably read his book rather than his Wikipedia article). I could understand if he'd said that a belief that God performs miracles was incompatible with Christianity. But how can anyone claim that a belief that God performs miracles is atheistic? An atheist can't claim that God performs miracles and remain an atheist. Marnanel (talk) 17:20, 16 February 2011 (UTC)

I don't know if this is Powell's point, but there's a certain sort of Christianity that treats prayer as a sort of black magic that is supposed to give you what you want, if you wish for it hard enough. The televangelist who, in between ads selling eagle statues to use in prayerful contemplation, tells you about how he can feel someone in West Virginia is praying for little Johnny, and now little Johnny is going to get better. Surely such practices are a mistaken, pagan sort of superstition. (Surely an omniscient God knows of Johnny's pain, and an omnipotent and loving God has a plan to make it so that it never happened, to "wipe away every tear", as they say) Such practices lead inevitably to the belief, antithetical to certain Christian teachings or even the Jewish story of Job, that those who actually do get what they want, who are wealthy and healthy and happy, get these things because they are beloved of God. Now when a person investigates a real miracle, something like the reform against racism in America, a deliverance no less dramatic than the story of Exodus, I think it soon becomes apparent that a miracle is not the achievement of a mundane end by impossible means, but the achievement of an impossible end by mundane means - supplemented only by the intangible, unprovable, but entirely real assistance of God. Wnt (talk) 07:08, 19 February 2011 (UTC)

I have noticed that, too -- that in certain Christian circles (generally the more "fundamentalist" and/or Evangelical "Mega-Church" adherents, but certainly also in the ritualism of many Roman Catholic practices) what they are essentially practicing is various forms of "magick" plain and simple (though not really too often the "black" variety of that afaik...). I used to mention the similarities between those practices to some of the Christians I know who are like that, which tended to make them very upset, so I've stopped doing that but thought it was nevertheless worth mentioning here. WikiDao ☯ 13:53, 19 February 2011 (UTC)