Talk:General relativity

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Rebuttal by Mohamed F. El-Hewie[edit]

The following charges are raised by Stigmatella aurantiaca:

(1) that new section contains original research

(2) self-referencing of a vanity press publication

(3) discredited misinterpretations of experiments

(4) misuse of references

My responses are as follows.

(1) There is no original research on relativity beyond sports fans turning physics in fiction. There has never been a single practical application to relativity beyond mental experiments and unreal theoretical assumption.

(2) Self-referencing and the quality of the publication does not attack the merits of the argument but defame the effort to criticize flawed theories.

(3) The only experiment I stated was Pound-Rebka experiment which was total waste of time and money and which led to nowhere, other than inflating relativity out of its death-bed.

(4) I am not sure what reference was misused and I challenge any physicist who could cite any peer-reviewed publication that could support the use of relativity in tuning the GPS. Mohamed F. El-Hewie (talk) 05:39, 3 May 2013 (UTC)

— Preceding unsigned comment added by Mohamed F. El-Hewie (talkcontribs) 05:33, 3 May 2013 (UTC)

Your five supposed criticisms of general relativity (to the extent that they make sense) do not appear to me to actually show any error in GR. So what is your complaint? You do not like GR merely because you do not like GR. So what? JRSpriggs (talk) 05:54, 3 May 2013 (UTC)
-I assume that this a professional forum, not a casual argument.

Why would your opinion matter when you did not offer any support beside your own subjective feeling? Physics does not work with liking or disliking. Physics must adhere to the tenets of the scientific method of verifiability, reproducibility, and validity. If you lake expertise on such issue, why pick a fight? Mohamed F. El-Hewie (talk) 06:13, 3 May 2013 (UTC)

Regarding #1: Experiments have consistently shown that the speed of light in a vacuum is constant relative to a local inertial frame of reference. The absence of direct measurements at locations many light-years distant is not proof of anything. The burden of proof is upon you to show that there is an exception, not upon the supporters of SR to show that no exception is possible.
Regarding #2: You made an error in the geodesic equation — it should have a plus not a minus on the term containing the Christoffel symbol. Also, the tensor indices on x should be superscripts (contravariant), not subscripts (covariant). You appear to be ignoring the source equations (Einstein field equations). You should see Einstein field equations#The correspondence principle. The (approximate) correspondence between Newton's gravity and Einstein's gravity does not mean that Einstein is merely disguising Newton's. What Einstein and Hilbert did was to find a generally covariant theory which agrees with all available evidence about gravity. Newton's theory is definitely not generally covariant, and is thus inadequate without alteration. JRSpriggs (talk) 10:19, 3 May 2013 (UTC)
Note to Mohamed F. El-Hewie: this is definitely not a professional forum. It is not even a forum to begin with. This is the talk page of an article where we discuss the content and the format of the article. We do not discuss the subject or our opinions about the subject here. See our wp:Talk page guidelines. - DVdm (talk) 10:20, 3 May 2013 (UTC)
If you wish to discuss your ideas, online forums available for you include
General Science Journal forums
The Naked Scientists
Sci Physics Relativity
The Science Forum
Talk pages are not the place for you to rant about your pet misunderstandings. You are hopelessly ignorant of current experiment and of the sorts of experimental controls that completely negate your claims. For instance, if the bending of light around the Sun were an atmospheric phenomenon, then measurements at different wavelengths should show dispersion. They do not. Atomic clocks and matter interferometers have demonstrated general relativistic effects such as gravitational time dilation in tabletop experiments. So stay off these pages.
Stigmatella aurantiaca (talk) 12:21, 3 May 2013 (UTC)


Responses by El-Hewie

(1) The constancy of the speed of light is an experimental finding by Michelson and Morley. That was tamed into mathematics by Hendrik Lorentz. Neither of the two is definitive proof that man will never disprove both. Even though the neutrino experiment in CERN failed, it nevertheless shows that scientists are not content with the constancy of c.

(2) Error in writing the geodesic equation can be corrected and checked. Errors in typing do not support the concept of gravitation bending of spacetime in the absence of motion of mass.

(3) The source equations (Einstein field equations) was simplified to the first degree Newtonian gravitation by Einstein's paper of 1916, cited by me.

(4) Insults by Stigmatella aurantiaca weakens his/her arguments and proves the his/her irrational reaction to scientific facts that displease him/her.

Accusing someone by saying "pet misunderstandings", "hopelessly ignorant", does not advance a scientific argument.

(5) Asking me to "stay off these pages" shows clear intent to deceive and misinform the public by Stigmatella aurantiaca. Why would I stay away while Stigmatella aurantiaca remains to misinform and distort information?

(6) The bending of light around the Sun is a coronal atmospheric phenomenon, and our measurements of different wavelengths of dispersion is impossible because we only receive the narrow bundle of rays that are dispersed in our direction from the dispersing star.

(7) Stigmatella aurantiaca's claim that "Atomic clocks and matter interferometers have demonstrated general relativistic effects such as gravitational time dilation in tabletop experiments." need to be referenced, argued and put into its historic content in order to show the merits of the that claim.

(8) Light cannot bend with gravitational mass, because the theory of General Relativity did not invent any new physical law where photons are influenced by gravity. In contrast, Einstein's 1916 paper used Newton's inverse square law of gravitational attraction in order to quantify the advance of the perihelion of Mercury. Nowhere in physics can Newton's inverse square law of gravitational be applied to photons.

Mohamed F. El-Hewie (talk) 20:57, 3 May 2013 (UTC)

You have a fundamental misunderstanding of the laws of physics. Here is not the place for that: read this and other articles, and the references and other good reference works, to gain a better understanding. If you have questions then the reference desk is the place for them, but clearly erroneous statements like yours above will be refuted there as here. This talk page is for improving the article, but you cannot help with that if you do not understand the topic.--JohnBlackburnewordsdeeds 21:40, 3 May 2013 (UTC)
What are your credentials that give you the authority to tell others how to think or understand?

As long as you fail to render any scientific argument, ignoring you is the only way to go. Mohamed F. El-Hewie 22:36, 3 May 2013 (UTC) — Preceding unsigned comment added by Mohamed F. El-Hewie (talkcontribs)

  • Note to innocent bystanders and involved editors: I have deleted the incredibly malformed Wikipedia:Requests for mediation/ General relativity. El-Hewie had already filled out the answers for his counterparts, and the RfM is nothing but disruptive. Anyone with an admin hat on is free to investigate my deletion, which I performed per WP:IAR, and revert me if they think I am wrong. Drmies (talk) 02:35, 4 May 2013 (UTC)

Our old friend is asking that his block be reviewed. See his talk page: User talk:Mohamed F. El-HewieStigmatella aurantiaca (talk) 03:10, 5 May 2013 (UTC)

  • It seems he won't be sanctioning our products anymore. I wasn't going to propose him for a t-shirt anyway. But do keep an eye on this and other article and drop me a line if necessary--they've socked before. Drmies (talk) 02:03, 6 May 2013 (UTC)
Someone criticizing gen. rel.? Such criticisms, if notable, would perhaps belong in Criticism of the theory of relativity.--Solomonfromfinland (talk) 12:43, 1 November 2013 (UTC)
It would, but they are not. Martin Hogbin (talk) 16:04, 1 November 2013 (UTC)

Black Holes[edit]

These were considered before General Relativity, using Newton's Law. A complete gravitational collapse was possible, although problematic. They didn't call it a " Black Hole", but that statement in an early paragraph is misleading, and implies that gravitational collapse had never occurred to anyone before GR. — Preceding unsigned comment added by 184.147.125.176 (talk) 06:15, 3 December 2013 (UTC) 77Mike77 (talk) 12:17, 3 December 2013 (UTC)

Do you have a reference to gravitational collapse being considered before GR? Martin Hogbin (talk) 09:12, 3 December 2013 (UTC)

I couldn't find what I was looking for, but found this http://www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/cs_michell.html , which has the idea of a "black hole" in all but name. 1783, hypothetical star so massive that the escape velocity exceeds the speed of light, so it is, effectively, black.77Mike77 (talk) 12:17, 3 December 2013 (UTC)

Are you referring to, '...it implies the existence of black holes...'? I do not think that this statement can be taken to imply that Newtonian gravitation could not have had black holes. Do you have any suggestions as to how the text might be made clearer? Martin Hogbin (talk) 09:18, 3 December 2013 (UTC)

Did I suggest that? I thought I was suggesting that BHs are possible with Newtonian gravity. Once the field is stronger than the material's ability to resist, the object has to collapse. The only problem is that of the infinities at the centre point. In GR, time slows to a stop at the event horizon, when viewed from the universe outside, so the singularity at the centre only exists for someone who falls through; for those outside, the BH is hollow, and the central singularity only exists in a hypothetical infinite distance into the future. I'll think about how to make it clearer with minimal change, and get back.77Mike77 (talk) 12:17, 3 December 2013 (UTC)

I'm thinking of replacing these two sentences, "Einstein's theory has important astrophysical implications. For example, it implies the existence of black holes—regions of space in which space and time are distorted in such a way that nothing, not even light, can escape—as an end-state for massive stars."...with this: "Einstein's theory has important astrophysical applications. For example, the mystery of what happens when a star undergoes catastrophic gravitational collapse was explained, leading to the modern concept of black holes—regions of space in which space and time suffer such extreme gravitational distortion that nothing, not even light, can escape—as an end-state for massive stars." Does anybody object to this, or have any suggestions to make it better?77Mike77 (talk) 23:30, 4 December 2013 (UTC)

Your language is perhaps a bit too flowery for my taste, and somewhat inaccurate in what it implies about the historical sequence of events. See Chandrasekhar limit. However, I won't be the person to revert it if you make the change. I suspect somebody else would, however. Stigmatella aurantiaca (talk) 01:27, 5 December 2013 (UTC)

The only "flowery" word I can see is "mystery". Let me know if you can think of a non-flowery synonym. I was trying to keep the flow of the article intact, and not turn it into another edit disaster where a huge paragraph of dull prose replaces a sentence. It's just plain wrong the way it is. If this is like most other articles, someone will revert it back to its current incorrect version once people have spent a few hours straightening it out, so I'll probably just leave it wrong if there is no simple synonym for "mystery".77Mike77 (talk) 22:18, 5 December 2013 (UTC)

How about this? "Einstein's theory has important astrophysical applications. For example, the problems involved in trying to find a Newtonian description of what happens when a star undergoes catastrophic gravitational collapse were resolved, leading to the modern concept of black holes—regions of space in which space and time exhibit such extreme gravitational distortion that nothing, not even light, can escape—as an end-state for massive stars."77Mike77 (talk) 02:22, 6 December 2013 (UTC)

The language is improved, but your statement still has inaccuracies. Please bear in mind that although theorists such as John Michell predicted that massive bodies could exist exhibiting gravitational forces sufficiently great that light would not escape, no physicist working with Newtonian concepts EVER anticipated the possibility of gravitational collapse. The implicit assumption was always that, although a mass might be squeezed down to something incredibly dense, it would nevertheless remain a finite sized body. It was the 19-year-old Chandrasekhar who showed that general relativity predicted a runaway collapse of the mass into a point singularity. Eddington was perfectly aware of older work predicting the possibility of dark stars. But the idea of a mass collapsing into a point singularity was something that he simply could not accept.
Therefore, when you write that the "problems involved in trying to find a Newtonian description of what happens when a star undergoes catastrophic gravitational collapse were resolved", you are writing about things that never occurred. Stigmatella aurantiaca (talk) 03:16, 6 December 2013 (UTC)

I give up then. The original sentence is still wrong, because it gives the false impression that nobody had previously thought of a situation where light could not escape because of gravity, when this clearly had been thought of (Mitchell, and those who commented on Mitchell), and so I guess that the article will simply remain with this serious flaw, since any attempt to correct that error will be rejected. Despite the subtle inaccuracies in my statement, it is still an improvement on the existing mistake. Unfortunately, the mistakes in the article itself do not come under as much scrutiny as attempts to rectify those mistakes. Oh well, another defective Wikipedia article remains defective...what else is new?77Mike77 (talk) 15:27, 6 December 2013 (UTC)

No need to give up. It is extremely difficult to tell the entire story without going into WP:Undue detail. Yes, it is true that certain properties of what we know of as "black holes" could have been, and were, anticipated by theorists working exclusively within a Newtonian framework. But gravitational collapse was not one of them. "Escape velocity greater than the speed of light" is not "gravitational collapse." We need to be careful not to conflate these distinct concepts. Stigmatella aurantiaca (talk) 19:49, 6 December 2013 (UTC)

I was just posting an edit to my comment, but got a posting conflict. I wanted to say that you had a valid point re Mitchell's "Dark Star" not collapsing to a point, and that you are right that the light not escaping is a distinct concept from gravitational collapse. I had somehow got the idea from something I read, that the idea (that a gravitational field could be stronger than the material's ability to resist gravitational collapse) was first thought of in Newtonian terms, where the star would collapse to a point with infinite density and infinite gravitational field strength, and that those infinities were part of the problem. I think what I read must have been hypothetical, i.e. the author was posing a Newtonian "solution" to contrast it with the Relativistic one. I have a B.Sc. with a physics major, and am an "avid amateur" in following physics, so I understand Special Relativity very well, but never took post-grad courses in General Relativity, just a little tensor analysis in final year, and so I am certainly no "expert" on any formal treatment of GR. There is an important role to play in translating the abstract into terms understandable to the average reader, which I think is part of what wikipedia is supposed to do, even thought that goal is too often lost here. Anyway, I'll have another go at it and post it soon. Thanks for your "colourful" comment.77Mike77 (talk) 20:04, 6 December 2013 (UTC)

Okay, this is a new attempt. "For example, the topic of extremely strong gravitational fields, and their effect on light, was clarified. In 1783, John Mitchell hypothesized that light might interact with gravity, and suggested the possible existence of "Dark Stars", which were massive stars with gravitational fields so strong that light could not escape. His analysis was based on the Newtonian view that light consisted of "pellets" traveling at a certain speed, and that if the gravitational field of the star were strong enough, the "escape velocity" would exceed the speed of light, so that the light could not escape. General Relativity generated a completely different analysis of this problem, which took into account the wave nature of light, and the possibility of a catastrophic gravitational collapse in which the massive star would collapse down to a point, leading to the modern concept of black holes—regions of space in which space and time exhibit such extreme gravitational distortion that nothing, not even light, can escape—as an end-state for massive stars." I've tried to keep the "flow" of the original statement, even though I've lengthened this part. There is a wikipedia entry for "Dark Star", which I can link to that phrase. I used the word "point" instead of "singularity", because the lay reader won't know what a singularity is (I could link the word "point" to the article https://en.wikipedia.org/wiki/Gravitational_singularity). What do you think? — Preceding unsigned comment added by 77Mike77 (talkcontribs) 20:32, 6 December 2013 (UTC)

If a black hole is defined as "regions of space in which space and time exhibit such extreme gravitational distortion that nothing, not even light, can escape", then they were hypothesized back in 1783 and general relativity has very little to do with their existence. Relativity sheds some light on properties of black holes, but not existence. So I agree that the sentence is wrong but so are your fixes. Roger (talk) 21:28, 6 December 2013 (UTC)
I think your current attempt is well-reasoned enough to try out in the article. Just be sure to reference this Talk section discussion, remember that John Michell has no "t", and don't take it too hard if somebody immediately objects to something or other and rewords it. Popular articles such as this one are heavily monitored by lots of cooks. Good luck! Stigmatella aurantiaca (talk) 21:42, 6 December 2013 (UTC)

Blacklisted Links Found on the Main Page[edit]

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Why is there a qualitative statement about the Wheeler-DeWitt equation in this article?[edit]

Hello, I've just read in section "Quantum Gravity" the following:

"Another approach starts with the canonical quantization procedures of quantum theory. Using the initial-value-formulation of general relativity (cf. evolution equations above), the result is the Wheeler–DeWitt equation (an analogue of the Schrödinger equation) which, regrettably, turns out to be ill-defined.[177] " The source given is the only one: Kuchař, Karel (1973), "Canonical Quantization of Gravity", in Israel, Werner, Relativity, Astrophysics and Cosmology, D. Reidel, pp. 237–288, ISBN 90-277-0369-8

Wheeler-DeWitt equation is pretty much out there influencing physics research, and it is extremely strange that here it is called "ill-defined" and only one reference dated 1973 is given.

There has been recent experimental research confirming the absence of time for an external observer of a universe: http://arxiv.org/pdf/1310.4691v1.pdf

It's highly ridiculous for a Wikipedia article to have qualitative statements about theories unless they have completely been dismissed by the entire scientific community through numerous failed attempts to verify them. — Preceding unsigned comment added by Whitely3000 (talkcontribs) 17:35, 24 February 2014 (UTC)

Expected domain of validity[edit]

I think there should be a (sub)section on the expected domain of validity of GR in the article. When reading about GR (whether popular or real thing), one is always fed the message that "most physicists expect..." and hence quantization is necessary. (The breakdown is just around the corner...) From the little I know myself, the circumstances are pretty extreme when one can surely expect GR to break down (giving incorrect predictions). Note: This is not something that can be disposed of by saying GR has already broken down because black holes exist and singularities don't. I think it would be interesting for the reader to get "pretty extreme" quantified in terms of, say, distance from the singularity of a really nasty black hole, or anything else suitable.

Also, provided GR is correct (within its expected domain of validity), can we ever expect to experimentally verify a quantum theory of gravity? Sure, such a theory might predict other things that can be detected, but I personally doubt that we will be able to produce graviton showers (instead of gravitational waves or whatever) at CERN. I understand I'm being vague here, but some skilled and knowledgeable editor might have an idea about good stuff to spice up the article with. YohanN7 (talk) 02:58, 4 July 2014 (UTC)