Talk:General relativity/Archive 9

From Wikipedia, the free encyclopedia

 This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.
← Archive 8 Archive 9 Archive 10 →

Contents

Question!

I know you guys get a lot of silly technical questions, but I find this one to be at least a little relevant to a little bit of Wikipedia.

Let's say that a massive star is collapsing into a black hole. Would the critical mass for the star to form a black hole be affected by other objects in the vicinity that increase the gravitational potential of that area in space, but do not contribute to the gravitational field? Say a star was surrounded by a Dyson sphere, it is well established that the escape velocity of the combined system is greater than it would be if the mass of the sphere was taken away, but the gravity on the surface of the star is unaffected by the presence of the sphere. The answer would (hopefully) establish in my mind whether the limits for the formation of a black hole is analogous to the gravitational field or to the net exit velocity into flat space, or neither. A critical mass is typically cited as the limit to form a black hole, but that doesn't cut it, I'm not an expert, but in real life many geometric situations exist, even I understand that it's more complicated than that. theanphibian 07:40, 30 May 2007 (UTC)

A static spherical shell of matter around the star would not affect whether it becomes a black hole (via the gravitational potential, it might have an effect if it reflected outgoing matter or radiation back into the star). Of course, if an event horizon forms around the spherical shell, then you have a black hole including the star. But in that case, the shell could not be static. However, the potential is relative, the exponential of a radial integral. That is, everything inside the shell is changed in the same proportions. JRSpriggs 10:25, 30 May 2007 (UTC)
Thanks for your reply. I'm tempted to read this as saying that the creation of an event horizon depends on the magnitude of the gravitational field, this could be wrong and please correct me if it is. Now I have a bit of different questions that stem from this discussion and I would very appreciative if you would entertain them.
A Dyson sphere
A Dyson sphere
Let's say there is a star that has a radius just barely greater than the Schwarzschild radius, and let's also say that this star has a Dyson sphere of considerable mass surrounding it, such that if the Dyson sphere were to collapse on the star, it would push it over the limit and become a black hole. From your previous explanation it would seem that the system would not create a black hole unless such a collapse were to happen. My current curiosity is this: what would be the Gravitational time dilation associated with say, a point on the surface of the star and a point on the inside of the star (I'm mostly concerned with the former) compared to a point that is far away from the system. From the Gravitational time dilation article, we have the formula:
t_0 = t_f \sqrt{1 - \frac{2GM}{rc^2}} = t_f \sqrt{1 - \frac{r_0}{r}}
Will the M in this equation include just the mass of the sun, or the mass of the combined system? If it included the mass of the combined system, that would produce an imaginary number when looking at a point on the surface of the star. However, my understanding is that \frac{2GM}{rc^2} is a statement of gravitational potential, which would mean that the mass of the sphere must be included in M. Please tell me what I have wrong here causing the contradiction. Thanks!! theanphibian 18:49, 30 May 2007 (UTC)
You are taking that equation out of its proper context. It only applies to the Schwarzschild metric, that is, a gravitational potential created by a single mass concentrated at one point (or in a spherically symmetric way within the inner-most radius being considered). JRSpriggs 07:38, 31 May 2007 (UTC)
I know I'm taking the equation out of it's context, we don't have an equation that gives the time dilation for any geometry at all. That's what I want to know (well, just for this geometry). theanphibian 13:22, 31 May 2007 (UTC)

If the Dyson sphere is thin, then I think that we can handle it by assuming that the potential itself is continuous across (inside to outside) the sphere but that its derivatives are discontinuous. So we can use two Schwarzschild metrics: one for the outside and one for the inside, sewing them together on the sphere by matching the potentials there. They will correspond to different masses: one including the sphere and one excluding it. One of the metrics will have to be scaled (multiplied by a proportionality constant everywhere) to allow the matching to work. Then you can apply your equation twice: once to get from the interior to the sphere, and a second time to get from the sphere to the external observer. JRSpriggs 04:00, 1 June 2007 (UTC)

Fascinating! So if I were to take the conventions of the previous equation and introduce Ms, the mass of the Dyson shell, and Rs, the radius of the (comparatively thin) shell, then you could do the problem like this:
t_0 = t_s \sqrt{1 - \frac{2G(M+Ms)}{Rs^2}}
t_s = t_f \sqrt{1 - \frac{2GM}{rc^2}}
t_0 = t_f \sqrt{1 - \frac{2GM}{rc^2}}\sqrt{1 - \frac{2G(M+Ms)}{Rs^2}}
Is this right? I'm not sure :-/ Actually, my understanding of graviational potential is that the gravitational field would be constant throughtout an empty sphere, but it would have a constant potential like a ball with a charge on it. Oh no, I'm don't know if I interpreted all this right or not. theanphibian 05:13, 1 June 2007 (UTC)

Close, but not quite right. I think (I have not checked for a reference, so I could be wrong) that one would get:

\frac{t_0}{t_f} = \frac{t_0}{t_s} \cdot \frac{t_s}{t_f} = \frac{\sqrt{1 - \frac{2GM}{r c^2}}}{\sqrt{1 - \frac{2GM}{Rs c^2}}} \cdot \sqrt{1 - \frac{2GM'}{Rs c^2}}

where M'\! is the combined mass (which is probably a little less than M+Ms\!). JRSpriggs 06:30, 1 June 2007 (UTC)
After thinking some more about it, I believe that:

M' \approx M \sqrt{1 - \frac{2GMs}{Rs c^2}} + Ms

because if we hold the Dyson sphere in place and lower the star into it from infinity (through a "small" hole in the sphere), the mass of the star will effectively be reduced by the amount of gravitational potential energy extracted divided by c^2. The energy remaining is reduced by the same factor as the rate at which proper time passes (due to E = h nu). JRSpriggs 03:35, 2 June 2007 (UTC)

Thanks, this all makes sense. I was about to ask how M' could be different from just the sum of the masses, but I wasn't aware that lowering it into the potential well would change it's mass. I think the conclusion is still mostly the same, which is that time dilation for the sun referenced to a far away point would be just slightly more severe due to the presence of the sphere (I was worried that cases might arise where time goes backwards or strange things like that). And all of those assumptions (such as the sphere being very "thin", or the sun being lowered in through a "small" hole) hold very well because the space between the objects is so comparatively large (93 million miles is VERY large compared to 3 meters). theanphibian 21:17, 2 June 2007 (UTC)
As you know, the mass of an object is just its energy in the frame where it is at rest (divided by c^2 to fix the units). Unfortunately, in general relativity the meaning of energy (the gravitational contribution to it, that is) becomes relative to one's choice of coordinates. Within the Dyson sphere it is natural to define the mass of the star in such a way that it is the same as it would be if the sphere were not there. But its effects outside the sphere are as if it were multiplied by the factor I indicated. I am sorry, if this is confusing. JRSpriggs 09:06, 3 June 2007 (UTC)

SNS fiasco begins here

"space" used a little recklessly in article

I was noticing that in the opening paragraph of the article it mentions that gravity "bends space". If you go to the space article it becomes immediately apparent that there is a philosophical debate about whether space is real or abstract. I think this article should be changed to reflect this obvious uncertainty about the nature of space. Is space something real that you can manipulate or is it simply an abstract coordinate system used to help describe reality? It can not be both things, and if there is so much uncertainty in the space article, this article and others that reference it should reflect that uncertainty. SteakNShake 06:04, 31 May 2007 (UTC)

The fact that the editors of another article are confused (or seem confused to you) is not a reason to corrupt this article. JRSpriggs 07:23, 31 May 2007 (UTC)
I think you misunderstand. First of all, I'm not talking about corrupting this article, I'm talking about fixing it. It is an assumption that space and time can be "bent". Clearly there is a raging debate over whether space is actual or virtual. If it is virtual, then general relativity becomes metaphysical gibberish. If it is actual, general relativity still might be metaphysical gibberish, but isn't necessarily metaphysical gibberish. I don't think the editors of the [space] article are confused, I think they are simply intelligent people who disagree about whether space is something real or just an abstract concept that is tied to nothing real. SteakNShake 14:28, 31 May 2007 (UTC)
General relativity is not metaphysical gibberish as you call it, unless you want to discard a whole host of other scientific theories including many of the most successful theories in history: Newton, Darwin, Heisenberg, et al. The theory itself has been subjected to an enormous number of tests — many of which are mentioned in the article. The fact that it is able to make concrete, testable predictions (which turn out to hold true, most of the time at least) is what distinguishes GR as a physical theory (as in not-at-all metaphysical — see string theory for other possibilities in this direction). You seem to be taking issue with the interpretation of general relativity as a geometrical concept. Not all physicists make this interpretation: for example Steven Weinberg wrote a book which is nearly devoid of the usual geometrical features, regarding the "metric" of space-time as a field much like the electromagnetic field. Nevertheless, the interpretation of GR as a geometrical theory is an inherently useful one for many practitioners and students alike. It gives the field equations of general relativity a greater mathematical context, as well as an intuitive interpretation. You may take issue with the mathematical rigor of such an interpretation, but that too has been thoroughly sorted out in the area of differential geometry. Of course, I'm not saying that GR as a whole is mathematically rigorous. There are still some deep unresolved in the realm of nonlinear partial differential equations. But the basic interpretation is mathematically sound.
From the philosophical standpoint, there are volumes of analysis concerning the "curvature" of space and time to which I could direct you. The Philosophy of space and time article provides somewhat of an overview. For a detailed treatment (before making any more uninformed edits here or elsewhere) see the classic works of Hans Reichenbach and Adolf Gruenbaum, and the more modern work of John Earman. Silly rabbit 15:05, 31 May 2007 (UTC)
It was very nice of you to give your bald assertion that general relativity is not metaphysical gibberish. However, as I pointed out, there is strong contention as to whether space is in fact real or if it is virtual. If it is virtual, then it can not be bent and has no effect on anything real. That is the nature of imaginary things. Perhaps if you have some evidence you can present that space is in fact real and not imaginary then we can accept your changes. All of your other hand-waving is irrelevant. If space is imaginary, an abstract concept, general relativity is necessarily absolute rubbish. If space is real, general relativity may still be rubbish, but need not necessarily be. I urge you to continue your education. And as for all these experiments that it is claimed have been done to support some of the other predictions, it simply isn't true. No experiment has ever shown any gravitational time dilation, frame dragging, space bending, time warping or any of a host of other silly things suggested by the idea that matter bends space and time. SteakNShake 15:15, 31 May 2007 (UTC)
P.S.: The point here is not to accept or abandon hypotheses but to write articles about them. Just because there is contention is no reason to abandon all mention of these erroneous hypotheses. Even if general relativity is metaphysical gibberish, the article should still stand, as well as supporting articles. How else can we learn from our mistakes if we forget (delete) all our mistakes? SteakNShake 15:31, 31 May 2007 (UTC)
there is strong contention as to whether space is in fact real or if it is virtual. Ummm... who is making this contention exactly? Some guy you met at a bar? A philosopher of science? A physicist? One of the basic tenets of writing an encyclopedia article is that you need to cite your sources, so without knowing exactly where this is coming from it really doesn't belong here. Silly rabbit 15:43, 31 May 2007 (UTC)
It would do you well to familiarize yourself with the space article here on wikipedia. Among other things it says: One view of space is that it is part of the fundamental structure of the universe, a set of dimensions in which objects are separated and located, have size and shape, and through which they can move...A contrasting view is that space is part of a fundamental abstract mathematical conceptual framework (together with time and number) within which we compare and quantify the distance between objects, their sizes, their shapes, and their speeds. In this view, space does not refer to any kind of entity that is a "container" that objects "move through". Clearly one of these two views is right and one is wrong and no conclusion is drawn in the space article to distinguish which is more "valid", i.e. which gets more Google hits or more support by wikipedia admins (wonder where the union of those two sets lies haha). If one conclusion is right, then all of general relativity is falsified and mooted. If the other conclusion is right, then all of general relativity may still be metaphysical gibberish, but not necessarily so. In this case we are simply inserting the information so readers of different belief systems can have a common ground explanation for a single phenomenon. We have two cases and two branches for this article: bending of space is real and verifiable; bending of space is an idiotic and nonuseful notion. In either case, general relativity is still a speculative hypothesis, as there is no known way to directly observe this "space" and measure it for bending. Please feel free to contact me privately on this issue if you would like me to educate you further. SteakNShake 17:13, 31 May 2007 (UTC)
I am familiar with the relational notion of space. I find it unusual that the space article doesn't trace this back to Aristotle, since this was really the origin (and the discussion on Kant is a trivialization to say the least). The relational notion of space is closest to that adopted by relativity theory — both special and general, as it happens, although in different degrees depending on the equivalence principle. It's a drastic leap to say that, because of this, any notion of space is meaningless in relativity theory. It would be tantamount to suggesting that Aristotle, Leibniz, Kant, etc., did not believe that relational notions could be ascribed scientific a posteriori meaning.
That, it would seem to me, misses the point entirely. It really boils down to an issue of ontology versus epistemology: How we know things about the world around us as mediated by our experience of the world. This is the significant question Kant tried to answer: how sense-experience attaches to "objective reality." Silly rabbit 17:27, 31 May 2007 (UTC)
Your claims above are simply absurd. In the first place, I never said "any notion os space is meaningless in relativity theory". What I tried to do was point out that not everyone shares your belief that space is something real that can be physically manipulated (such as bending). This assumption that space can be physically manipulated and that it is actually made of something instead of being a complete absence of something is not supported by a single shred of empirical evidence, so its naked inclusion in any article is not warranted. It should always be balanced by the omnipresent and ubiquitous idea that space is an imaginary coordinate system, not something real. SteakNShake 08:07, 2 June 2007 (UTC)
How many red herrings are you going to throw out? Put up or shut up. Let's see the evidence that supports your belief that space is something real that can be physically manipulated (e.g. being bent). SteakNShake 08:07, 2 June 2007 (UTC)
Let it be generally known that I find your behavior Openly Hostile. I have already responded to your challenge that relational ideas of space are not sufficient to conclude that relativity is incoherent. You are suggesting otherwise. I was pointing out that, by the same token, you can also conclude that any sort of physics is incoherent using relational notions of space. Thus reductio ad absurdum. If you find this inadequate, could you please explain in detail what you mean by "space is bent" and how it is incoherent with respect to a relational notion of space. I mean, I live on a sphere (the Earth), and the "bendedness" of that has a very concrete relational meaning. If I travel on a straight line for long enough, then I will wind up in the same position I started in. I don't need any sort of coordinate system to establish this, and I don't need to "imagine" anything. Other (so-called "local") consequences are also available: see the Gauss-Bonnet theorem for example. Anyway, you seem to want me to accept as an axiom that, without some external coordinate system, no a posteriori meaning can be assigned to the "bendedness" of space. I do not accept this as an axiom, and would like to see a detailed account (as, for example, would appear in a philosophical journal, a scholarly book, or other such peer-reviewed resource) indicating why I am mistaken. Silly rabbit 00:17, 4 June 2007 (UTC)
Incidentally, the Lense-Thirring effect has been observed — contrary to your contention — and found consistent with the predictions of GR, although the experimental error involved in the tests were too large for these tests to be viewed as confirmations of the theory. Attempts to gain more precise results are currently underway. Regardless, the fact that such a test can even be performed and seen to confirm or refute the predictions of GR should make it clear that GR is not meaningless. Quite the contrary: it makes definite numerical predictions which can then be tested. That alone establishes the epistemological meaningfullness of the theory. Silly rabbit 19:15, 31 May 2007 (UTC)
Let me just set you straight on something. When your experimental error is larger than the magnitude of your results you have garbage data. You can say it supports whatever you like, but what you have is garbage data that is nonuseful and probably misleading. These kinds of "experiments" are really experiments in self-delusion, and are only going to give you good conclusions by accident, if ever at all. As for the "lense-thirring effect", again, this is something that is going to be gibberish if space is imaginary (which it is). And please explain here or show me to a discussion on the talk pages for the article how exactly you are going to be able to detect "frame dragging" as described by you as the "lense-thirring effect". I'm really excited at the possibility that you can describe an experiment that lies outside the realm of the possible. There is ABSOLUTELY no way to detect "space" or to measure any "bends" or "warps" or "frame dragging" in it. All these are preposterous and fanciful notions, like unicorns.
Let me reply that I find your behavior Openly Hostile. I don't need to be "set straight" by you, and I find the introduction of "unicorns" patronizing. I will simply reiterate (with a reference this time) my assertion that frame dragging has been observed [1] (Bill Steigerwald, Goddard Space Flight Center, FIRST OBSERVATION OF SPACE-TIME DISTORTION BY BLACK HOLES (1997)). Silly rabbit 00:24, 4 June 2007 (UTC)
NASA's assertion that they have observed space-time distortion is as bald as your claims that it's been observed. SteakNShake 16:27, 4 June 2007 (UTC)

To SteakNShake: You said "If [space-time] is virtual, then general relativity becomes metaphysical gibberish.". Well, if you understand what you are talking about, then we are not having this conversation. You are the one who is confused here or else you are a troll. Please go away and leave this article alone. If you continue, I will treat you as a vandal and a troll. JRSpriggs 03:47, 1 June 2007 (UTC)

I'm not confused at all, but you are apparently out of steam in this debate. You have nothing to support your case so you try to call me a troll. This is a weak tactic and does not further the debate. Name-calling is only going to cause animosity and make me want to exact revenge on you by calling you names as well. And what is this tacting you're using? Is your position "stop editing my article or I'll ban you! waaaaaaaaaaaa!" Do you need your diaper changed or what? I suggest you take a break from editing wikipedia for a while until you calm down, can stop calling names and stop threatening people. I'm inclined myself to treat you like a vandal and a troll.
Now, if you don't mind, perhaps you can support your position that space can be bent. Please give me a definition of space that would even allow for the possibility of it being bent. I know of no reasonable definition of the word "space" that would even allow for this possibility or the possibility of it being physicall manipulated in any way, since space is a virtual coordinate system invented by human beings. SteakNShake 08:02, 2 June 2007 (UTC)

You are clearly confusing mathematical and physical notions of space. A mathematical space is an abstract notion, any co-ordinate sytstem imposed on it is arbitary, and so in a sense imaginary. Consider Euclidian 3-space, this is the set of all points belonging to R^3. There are many ways to impose a coordinate system on this which are arbitary, but all share the property that they contain 3 degrees of freedom. But this does not mean the the geometry of the space is arbitary, it has certain properties (such as parrallel lines stay parallel forever) that are fundametal properties of teh geometry and are independant of the co-ordinate system. Thus It is not permissible to think of the space as imaginary, because it has real properties. When talking about GR we use Space time in place of geometry because geometry normally refers only to spatial dimensions, and in general parlance we refer to 4D space-time as space. The coordinate systems we use embody convenient aspects of the properties of space. Using different metrics we incorporate different properties of the 'space', and the properties are real. In minkowski 4-space parallel lines stay parallel, in the robertson walker 4 space they do not. These are real (and not imaginary) properties of the space_-time), and it is philosophically incoherent to think of an imaginary concept having real measurable properties. Flat and curved space refer specifically to whether parallel lines diverge or converge, it has a specific meaning. It is known that real physical 4-space is curved - parallel lines diverge/converge. Micro lensing is a common observation. We try to embody this in our physical theory in a way that explains our observations. Spherical symettry is normally most convenient as self gravitating bodies are (nearly) always spherically symettric, but we could equally well formulate it in polars or cartesient or finkelstein co-ordinates if we think it is helpful to solve a given problem, but none of this affects the properties of the space - parallel lines will diverge in all of them. Phil 20686 15:53, 4 June 2007 (UTC)

You're the one who's confused here, and so is anyone else who thinks that because you can describe motion and think of it as curved space that anything you can describe using such a model (such as black hole) must necessarily translate to reality. This is not the case. Yes, you can IMAGINE space being curved in order to describe the motion of objects, but you can not take what you imagine and force the universe to comply with it. And the notion that space and time can be curved is utterly bereft of utility. There is not one single practical application stemming from this idea. People frequently say "X wouldn't work if not for general relativity" but in each case it winds up being a magic rock that keeps away tigers. SteakNShake 16:27, 4 June 2007 (UTC)

I repeat: Flat and curved space refer specifically to whether parallel lines diverge or converge, it has a specific meaning. It is known that real physical 4-space is curved - parallel lines diverge/converge. In more detail, geodesics converge/diverge, this can be measured by the difference in proper timeflow between orbiting and grounded clocks. These are the accepted terms. There is no ambiguity in meaning. There are many things that do not work without general relativity, the most obvious one is the perihelion advance in mercury. This is a real and observed effect that is not explainable with newtonian ideas of gravity. There is a whole wiki page devoted to the tests of general relativity, all 3 of them depend crucially on the curved properties of space time - i.e having non-zero christoffel symbols. Genneral relativity predicted and explained these 3 puzzling effects - gravitaional lensing by the sun, perihelion advance of mercury, and gravitational redshift. You can look up the derivations of all 3 in any simple GR text. Phil 20686 17:39, 4 June 2007 (UTC)

Also the Geodetic effect - that has its own wiki page too... 129.67.61.142 17:48, 4 June 2007 (UTC)

space, being virtual, can not be bent

Here is some support for the claim that space is virtual, and can not be bent:

from Princeton's wordnet project[2]:

# S: (n) space, infinite (the unlimited expanse in which everything is located) "they tested his ability to locate objects in space"; "the boundless regions of the infinite" # S: (n) space (an empty area (usually bounded in some way between things)) "the architect left space in front of the building"; "they stopped at an open space in the jungle"; "the space between his teeth"

Here we see that space is an expanse (made of what? nothing, apparently) Also note that it says space is empty (as in there is nothing there)

from the University of Minnesota's Geometry Center[3]:

Often the x-axis is imagined to be horizontal and pointing roughly toward the viewer (out of the page), the y-axis also horizontal and pointing more or less to the right, and the z-axis vertical, pointing up. The system is called right-handed if it can be rotated so the three axes are in this position.

Here we see that space is a system and that it is imagined (in other words an imaginary system)

I think you are showing a great deal of confusion between the concept of space in general (which is a word, no less and no more) and the particular mathematical formulation that seems to fit the phenomena we observe.
The sentence "the phenomena we observe related to what we usually call "space" are best described by mathematical equations that resemble the equations we would use to describe the bending of a sheet" is far less easy to parse than "space can be bent", but I believe they are a more accurate formulation of what physicists mean when they say "space can be bent". Pulling in linguistic descriptions and arguing as if they could describe anything precisely is not going to help very much with anything.
Curious fact: In Norwegian, the word used for "space" also means "room" and "rum". Language is malleable. --Alvestrand 11:24, 2 June 2007 (UTC)
I think it's really cute that you think I'm confused. As you can see, I have posted some reliable sources indicating quite strongly that space is virtual. It is a system we invented to describe reality, it is not reality itself and there is nothing tangible to space. Since it is virtual (and I don't see anyone posting any sources stating that space is real, malleable, "touchable", observable, etcetera), it can not be bent. Describing space with math will not make it any more real. That is the crux of the issue. Space is an abstract idea, like time, it is not something you can touch, observe, manipulate, store, collect, paint, rub, tickle, engage, lose, find, have or hold. SPACE IS VIRTUAL, ANY HYPOTHESIS THAT ASSUMES IT IS REAL IS ONLY EVER GOING TO BE RIGHT BY ACCIDENT. SteakNShake 14:30, 2 June 2007 (UTC)
Alvestrand, I agree. Nevertheless I have made a small change to the wording in the intro, in order to make it - well... - less scary to a non-physicist like SteakNShake. DVdm 12:14, 2 June 2007 (UTC)
I was clearly not too scared to edit this article. I have been a physicist for thirty-five years. SteakNShake 14:30, 2 June 2007 (UTC)
==> I clearly did not imply that you are "too scared to edit this article". Before you comment, try to read what people write, please? Rather, you sound like a layman who is scared from concepts like "bended space", although the term does not even appear in the article. So, technically, since this talk page is about the content and the format of the article, you are in conflict with the purpose of this talk page. DVdm 14:58, 2 June 2007 (UTC)
The concept of "bended space" is not frightening, it is stupendously idiotic (as idiotic as curved space or curved time or curved spacetime) and so obviously wrong one wonders how anyone but a troll or a vandal could suggest such a thing. SteakNShake 15:24, 2 June 2007 (UTC)
Please consider that Euclidean space and Riemann space both use the word "space" to describe them. What are you using the word "space" to describe, SteakNShake? --Alvestrand 13:47, 3 June 2007 (UTC)
I'm using space in the context in which it is used in the hypothesis of general relativity, which conjectures that the emptiness between matter can be curved. This is not rocket science, this is simply a case of too many people not understanding that space is virtual. There are no reasonable definitions of space that would even allow for the possibility of it being curved or bent or physically manipulated in any fashion. It is nothingness. Nothingness has no substance and no effects on anything real. SteakNShake 22:15, 3 June 2007 (UTC)
Now you are saying that "space is nothingness" and "nothingness has no effects on anything real". Yet you say that it is "between matter" - that is, by reference to space, the statement "things are separated" has meaning. I'd consider that an effect. You contradict yourself.
Test question: Do you consider Riemann space to be bent, or not? --Alvestrand 06:38, 4 June 2007 (UTC)
Thanks - I was planning to make a similar edit at some point: there are a lot of misconceptions out there about how science works, what a physical theory is, and the distinction between a physical model and the physical world. Anyway, I think the intro needs work for other reasons: it is a looking a bit long and over-edited now, and could do with some renewal. (This is not intended as a criticism, it is just based on my observations on the way Wikipedia works.) Geometry guy 12:37, 2 June 2007 (UTC)
The solution here is to wipe everything off the article and start it over beginning with the statement that "general relativity is a metaphysical notion that relies on space being bendable". Once you have knocked the legs out from under this beast we have no need to debate any of the irrelevant musings about how right or wrong the idea is, we can safely abandon it at that point and call it another pointless, failed hypothesis. SteakNShake 14:30, 2 June 2007 (UTC)
SteakNShake, earlier you stated that you "have been a physicist for thirty-five years". I think others will agree that you sound and behave like an over-enthusiastic sixteen years old school kid with an interest in metaphysics and semantics, and with no idea about how science actually works. I find it very hard to believe that you ever took a significant course in physics. DVdm 14:58, 2 June 2007 (UTC)
So again we are back to safety in numbers. You seem to think that because you can summon more people who think I am wrong that your beliefs should remain present without challenge in the article in question here. What's the point of citing references, if this is the way things work around here, just poll for every change, don't bother asking people to cite references that will simply be ignored. SteakNShake 22:33, 3 June 2007 (UTC)
Let it be generally known that I for one support your last two reverts, should this ever come to an intervention or arbitration. Furthermore, SteakNShake's edit summary suggests that his view of GR is now unchallenged. This is patently false. In fact, it's hard to find any support for his view here at all. Silly rabbit 15:40, 2 June 2007 (UTC)
What the record suggests is that I am the only one who has cited references for the changes I propose, the opposing belief systems were and remain unsupported by any references on this page or in the main article itself. And if you're having trouble finding the sources I cited, it's because of all the chattering noise surrounding them, noise that seems conspicuously absent of any reliable references to back it up. If you like I can cite my sources all throughout this now-convoluted discussion that should have been abrupt and final. SteakNShake 22:33, 3 June 2007 (UTC)
I see only two references here: both are essentially dictionary definitions, and neither of them even mentions relativity theory. A reference in support of your position would necessarily follow the following basic schema:
Doe, J. (2000) General relativity and space: Can space be bent or is relativity rubbish? J. Phil. Sci. 29 pp. 298-322.
Furthermore, the burden of proof is on you. It's fine to point the finger of blame and say that the rest of us aren't providing references for our position, but it's you that is trying to argue a point against a well-established physical theory. References already abound. Here's a short list:
  • Grunbaum, A. (1973) "Philosophical problems of space and time," Reidel. (One of the more comprehensive treatments of the philosophy of relativity theory, covering everything from the meaning of the line element to the equivalence principal and the meaning of curvature. A must-read.)
  • Reichenbach, H. (1957) "Philosophy of space and time", Dover. (A classic book on the subject written by one of the founders of the school of logical positivism. Includes a very detailed discussion of the mathematical and geometrical well-posedness of general relativity, precisely in opposition to the point you are trying to make.)
  • Basically any standard text on general relativity: E.g., Misner, Thorne, and Wheeler (1973) "Gravitation". They don't say anything about a debate as to whether space is "real" or "imaginary", nor do they take the position that space cannot be "bended". In fact, they describe in precise mathematical detail what space is, in terms of observers actually situated within it, as well as the physical and mathematical meaning of curvature as an observable feature of this space.
  • More recent textbooks, e.g., D'Inverno (1992) "Introduction to Einstein's relativity", include detailed discussions of the experimental verifications of general relativity which, according to your position, is impossible. No mention of their impossibility is made.
So that's a short list of references. All of these are from eminent specialists in the philosophy of science and physics. I should think that the weight of such references clearly outweighs a dictionary definition of space taken from wordnet and an elementary-school level discussion of Cartesian coordinates. Silly rabbit 03:45, 4 June 2007 (UTC)
You seem to be misunderstanding or else you are simply ignorant of the edits I tried to make. What I did was put into the GR article the fact that there is an ongoing and irresolvable dispute about the nature of space, many people think it is virtual and in the context of GR virtual space is impotent and does nothing whether it is imagined to be curve or imagined to be straight. It is my opinion that space is virtual, and this opinion is clearly shared by enough users to keep it in the article on space, so it should be pointed out in the GR article that the nature of space is in question (by some people who don't realize it is virtual). SteakNShake 16:53, 4 June 2007 (UTC)
This paper provides no experimental support for the idea that space can be curved and that the curvature of space is anything more than an imaginary construct with no real consequences. SteakNShake 16:53, 4 June 2007 (UTC)
This paper provides no experimental support for the idea that space can be curved and that the curvature of space is anything more than an imaginary construct with no real consequences. SteakNShake 16:53, 4 June 2007 (UTC)
This paper provides no experimental support for the idea that space can be curved and that the curvature of space is anything more than an imaginary construct with no real consequences. SteakNShake 16:53, 4 June 2007 (UTC)
This paper provides no experimental support for the idea that space can be curved and that the curvature of space is anything more than an imaginary construct with no real consequences. SteakNShake 16:53, 4 June 2007 (UTC)
In the case of experimental evidence that you conclude supports GR, not one shred of the evidence addresses the issue of whether space is in fact virtual, it simply proves that by imagining space being curved we can approximate the motion of objects through space reliably. This evidence does NOT support the notion that by imagining space to be curved we can somehow force the universe to obey our imaginations. The upshot of this is that predictions made by GR are only going to be right by accident. Black hole is one of those predictions, many claims have been made that black hole has been found, but in every case the candidates are not only non-black, they are all prodigious producers of electromagnetic radiation. These observations force astronomers to invent new properties of matter on a routine bases. SteakNShake 16:53, 4 June 2007 (UTC)
I think SteakNShake has proved conclusively that he doesn't listen to arguments. Calling a 900-page book a "paper" just shows that he's not even looked at the references before dismissing them as providing "no experimental support" (whatever he means by that - all his arguments so far have been strictly philosophical, not concerned with experimental evidence). --Alvestrand 18:28, 4 June 2007 (UTC)
That is totally correct. GR inherently assumes that spacetime is a real entitity that can be curved, as well as the confirmatory observations. I for one do not understand how SteakNShake can walk from one side of the room to the other and then immediately sit down at this computer and claim the "space is virtual". However, he is correct that these observation do not deal with his concern. However, there is no reliable source that says that this is a valid conern for general relativity, and and claim on the part of SteakNShake that it is a valid concern is a novel synthesis of the facts and therefore original research. --EMS | Talk 19:00, 4 June 2007 (UTC)

It appears to be over for now (thank goodness)--Cronholm144 15:55, 2 June 2007 (UTC)

Kudos to everyone keeping things moving in a reasonable direction. I would mention to SteakNShake that he ought to take a look at the Hubble photographs that demonstrate gravitational lensing, and for which I haven't heard of any alternative (scientific) explanation. Or perhaps I am misunderstanding the nature of his misunderstanding. Uurtamo 21:36, 2 June 2007 (UTC)

Please feel free to post some links to these photographs you say demonstrate gravitational lensing. Then after that you can explain what exactly is being lensed, how its original state is known when it is in deep space far from Earth and what methods were used to eliminate all other possible mechanisms for this supposed lensing? It is firmly-established by laboratory experiment that magnetic fields can and do bend light. No controlled experiment ever done supports this notion of light being bent by "gravity". You can not simply hypothesize an observation then take the observation as proof of your hypothesis. I've seen many supposed "gravitational lensing" images. In every case they show celestial objects in proximity to one another, and in every case the bald assertion is made that what is observed is in fact gravitational lensing. The "einstein cross" comes to mind. In the case of the "einstein cross" it is said that one object in direct alignment with Earth and another object is "gravitationally lensed" so that we see four images of it around the central object supposedly doing the lensing. The only reason the four quasars around that galaxy are ASSUMED to be vastly more distant is because of their spectra. Halton Arp et al have shown that "redshift" and "blueshift" of obejcts in space is an intrinsic property, relating to their age, not their distance or relative velocity. Galaxies eject quasars, and these quasars are routinely "blueshifted" relative to their parent galaxies. The universe is over 99% plasma, plasmas (and thus over 99% of the observable universe) largely ignore gravity, they are dominated by the much stronger electric and magnetic forces, which we can generate on demand for study in the lab. SteakNShake 22:33, 3 June 2007 (UTC)

I just want to add that whatever the space might be, be it an object actually made of something or be it a system that helps determine relative locations of matter, you can create an interpretation of GR that works. As far as GR is concerned, these two possibilities are physically indistinguishable. Temur 19:14, 3 June 2007 (UTC)

Okay, here is a parable to explain. A boy is in love with a girl, but she doesn't love him. So the boy goes to a witchdoctor and the witchdoctor explains that this woman's love is simply curved away from the boy, and that if he sells the boy some magic beans it will curve the girl's love toward him. So the boy buys the beans and invites the girl to his pad. The girl's love doesn't seem to be curving toward the boy so he decided to cook and eat the beans and share them with the girl. After the meal the boy farts and the girl thinks it's cute and falls in love with him. The witchdoctor's hypothesis is correct! The beans were magic and they curved the girl's love! Ridiculous, isn't it? This is essentially what you are trying to palm off here. GR says matter bends space, and anything going through that space is consequently bent. Never mind that objects don't follow the same bent paths as light through the space, there are numerous numerological fudge factors we can insert to explain that. Never mind that gravitation only seems to affect things with mass, light can be simply assumed to have mass for the sake of saving the Blessed Einstein Model. Anyone can make a prediction and guess right. It takes science to distinguish between fact and delusion. For another example, say Ih ave a magic rock that keeps away tigers. I observe all around me and see no tigers, just as my magic rock hypothesis predicts. Never mind that I live in the midwest of the United States where no tigers are ever found. My observation supports my hyothesis, therefore my rock is magic and keeps away tigers. Anyone care to get in a cage with a hungry tiger holding only my magic rock? SteakNShake 22:33, 3 June 2007 (UTC)

Well, you have to consider space and time together. Assuming only gravity, everything moves on a geodesic, and geodesic depends on the initial velocity of the object. Light is faster than other objects and that is why objects don't follow the same bent paths as light through the space. You don't have to assume that light has mass, since everything should follow their geodesics. Guessing that there is no tiger in the midwest is one thing, guessing gravitational laws with incredible precision is another thing. Temur 23:45, 3 June 2007 (UTC)

Question

Resolved.

Sorry, I'm new to this discussion, so could please define for me what the assertion "space can be bent" (or its contrary "space cannot be bent") means, and direct me to places in the article where there is an assertion that "space can be bent" according to your definition? Thanks Geometry guy 11:32, 3 June 2007 (UTC)

Space is virtual, that means imaginary. You can not perform real actions on imaginary things, like bending or curving, you can only imagine doing so. And being able to imagine something is not the same as that something necessarily being real. And these are not my definitions, I didn't invent the English language. SteakNShake 16:29, 4 June 2007 (UTC)
Thanks, but this doesn't answer my question. Where in the article does it say that space can be bent in your literal/dictionary sense? Geometry guy 16:44, 4 June 2007 (UTC)
For some reason SteakNShake seems to be put off by the notion of curvature of space-time, which is used as the set of events to model the world. DVdm 17:59, 4 June 2007 (UTC)
I understand that, but I want SteakNShake to answer the question, so I will repeat it. Geometry guy 18:54, 4 June 2007 (UTC)
Where in the article does it say that space can be bent in your literal/dictionary sense? Geometry guy 16:44, 4 June 2007 (UTC)
I don't think it does mate, that Snake twat was bringing it up for the sake of doubting a generally accepted theory. I'd check out the [Space] or a spacetime article if you want to read up on it. Alex 20 June 2007

Protected Article

I notice that the article is being swung between two differing opinions and in the interest of getting everybody talking without WP:3RR violations I have protected the article. Please remember to assume good faith be civil and dont bite the new comers Gnangarra 15:43, 2 June 2007 (UTC)

Just ban SteakNShake (talk · contribs)! He is clearly a troll. JRSpriggs 05:49, 3 June 2007 (UTC)
Just ban JRSpriggs (talk · contribs)! He is clearly a troll. SteakNShake 22:40, 3 June 2007 (UTC)

After reading this I thought maybe saying this might make it easier for the person who says space "can not be bent". Think of it this way, a area of bent space allows all mass and energy traveling through that area to follow a curved path from an outside observation. But since it is space that is bent, the object is actually going straight through a bent field. The object is not curving, it is just going through bent space on a straight line. So instead of a force changing the path of the object and curving it, the force changes the space it travels through, and the computations of motions on the object still fit the various laws of an object not acted on by an outside force.

Changes the space? Care to explain how you change something that doesn't exist? And I'm still the only one who has posted any support for my position. I posted more than one link to reputable and reliable sources supporting my position that space is virtual, it is imaginary, it is not affected by anything real and has no effect on anything real. SteakNShake 22:43, 3 June 2007 (UTC)
You have still not answered my question. Please do. It might lead us out of this. Thanks. Geometry guy 22:46, 3 June 2007 (UTC)
5 reliable physics textbooks which are taught in educational facilities and contain sourced proven theories > 2 links to internet sites. SteakNshake, you do NOT have better references or support please stop using that argument. If your opinion is provable then please consider adding a section on it somewhere else instead of replacing this page. —Preceding unsigned comment added by 124.176.2.58 (talk • contribs) 10:45, June 12, 2007 (UTC)

Passed Ed Gerck's Wikipedia Test

This article has passed Ed Gerck's Wikipedia Test Count Iblis 16:13, 3 June 2007 (UTC)

I find this revelation puzzling, even disturbing. Could you perhaps elaborate? Are you suggesting that SteakNShake is a sock-puppet of Ederck? Silly rabbit 16:41, 3 June 2007 (UTC)
I was concerned about that too, but I the link seems to be referring instead to EdGerck's contributions to Mass in special relativity. Geometry guy 16:43, 3 June 2007 (UTC)


See my reply here
And let's also see is someone makes edits to this section of the talk page like changing the title or blanking this page  :)
Count Iblis 17:36, 3 June 2007 (UTC)

SteakNShake

On user talk:SteakNShake, this editor wrote:

These changes will stand, come hell or high water, because I have the only sources on the table so far and no others appear to be forthcoming.

This article will soon be unprotected (or so I hope), and this is evidence that the disagreement is unresolable, as there are plenty of sources supporting the article in its current state in the article itself, but apparently SteakNShake feels that their support of the accepted viewpoint only impeaches them as reliable sources.

I suggest that our first line of defense is to soon make a case to an admin that SteakNShake is disruptive and get in blocked for that reason (assuming that SteakNShake continues to attempt to impose his POV on the article). In the meantime, I suggest that a Request for arbitration is in order. Any comments? takers? --EMS | Talk 02:56, 4 June 2007 (UTC)

This dispute mentioned at WP:ANI

I copy the following from Wikipedia:Administrators' noticeboard/Incidents#Taken from WP:AIV. JRSpriggs 06:43, 4 June 2007 (UTC)

Resolved.

Well, I am not sure if this is the right place to post for a troll but here goes. SteakNShake (talk · contribs · deleted contribs · logs · block user · block log) was being disruptive and generally rude at Talk:General_relativity. I posted a message on his talk page User_talk:SteakNShake that asked him to cool his jets and find some sources. He replied and asked me to point out where he was being pejorative. I pointed out those instances, he replied in a fashion that would lead me to believe he is a troll or a crank of some sort. Also User_talk:Ems57fcva contains another instance of his rudeness. Oh and he just started vandalizing again at GR. He just threatened User:DVdm.--Cronholm144 14:47, 2 June 2007 (UTC)

Looking at his contributions, I think there isnt any uncivil remarks, also WP:BITE is worth reading. I would recommend that you ask for page protection to stop the revert waring while the issue is discussed. Gnangarra 15:38, 2 June 2007 (UTC)
This is a clear case of Cronholm144 trying to ban people who disagree with his beliefs. SteakNShake 22:55, 3 June 2007 (UTC)
Follow up protected the article and advised of bite, agf, civil, and 3r Gnangarra 15:48, 2 June 2007 (UTC)

Thanks!--Cronholm144 15:50, 2 June 2007 (UTC)

I'm a big fan of WP:BITE, but in this case it seems to be the newcomer doing the biting. Although too early to make a judgement, this is so far a single purpose account, that purpose being WP:POV-pushing at General relativity, so far in a very disruptive fashion. In terms of WP:CIVIL, although I would not say this is a serious case of taunting, it heads in that direction. I would like to assume good faith, but the description of one form of trolling at WP:UNCIVIL as attempting to "push others to the point of breaching civility, without seeming to commit such a breach themselves" does resonate somewhat in this instance. So I'm not convinced protecting the article is the best way forward here. Geometry guy 16:06, 2 June 2007 (UTC)
This claim above that I am "pushing POV" is bald and without merit. What I am pushing is a necessary change to this one article that seems to be guarded by some self-appointed experts who refuse to allow any changes at all. SteakNShake 22:55, 3 June 2007 (UTC)
Just a note, his username could be summarily blocked as per WP:U... that would be dumping a major amount of gas on the fire, but I thought I'd point that out. EVula // talk // ☯ // 19:32, 2 June 2007 (UTC)

End of copy from WP:ANI. JRSpriggs 06:43, 4 June 2007 (UTC)

proposed change to article

I want the line "General relativity is currently the most successful gravitational theory, being almost universally accepted and well supported by observations." changed to "General relativity is currently the most widely-accepted gravitational theory, and conforms to many observations."

The reason for this change is simple. GR predicts things like black hole. To do so it uses ten (!) coupled hyperbolic-elliptic nonlinear partial differential equations. This type of model can be tinkered with indefinitely to match any observation of anything anywhere any time. What's that, you plug in some data and your formulae spit out an obscenely large mass? It must be so, no reason to appeal to logic at all, if the formulas say infinite density then such a thing must be possible. Do the formulae make predictions already falsified by observation? No problem, just tinker with a few terms and pronounce the fundamental structure of everything to be redefined to include something new we will never observe and can't simulate in the lab. There are no experiments that even remotely come close to proving the notion that space has a tangible substance that is deformed predictably by matter and which in turn has any effect whatsoever on the matter (or passing light) in return.

By way of the above example, black hole, I can explain the errors made along the way.

  1. Karl Schwarzschild uses field equations to describe an spherical static object of infinite density (zero volume with any amount of mass)
  2. professors of physics classes read news blurbs about the solution and conclude that if it can be described mathematically then it must necessarily exist
  3. astronomy students all over the world fall in love with the idea of black hole as taught by their professors and begin looking for them everywhere in space
  4. numerous prodigious producers of electromagnetic radiation discovered are given the label "black hole" despite the fact that they are some of the most energetic displays of electromagnetic radiation we can observe
  5. ad hoc explanations for stark difference between prediction and observation without examination of underlying premise (that space bends and bent space distorts matter and motion) SteakNShake 18:28, 4 June 2007 (UTC)
  • Oppose - This proposed edit is at best misleading as it implies that there are a significant number of observations that are known to contradict GR when compared with the number that confirm GR. That simply is not true. In addition, the detailed reasons given above demonstrate a lack of understand of general relativity, astrophysics, and the scientific method. Only the first complaint (about the singularity of the Schwarzschild black hole) has any validity, and that is noted in the article. I also consider this request to be part of an ongoing campaign of disruption by user:SteakNShake and call for him to be blocked because of it. --EMS | Talk 18:43, 4 June 2007 (UTC)
  • Oppose - the edit is not improving the article, and the arguments given in support are invalid. --Alvestrand 19:00, 4 June 2007 (UTC)
  • Comment - Without commenting one way or the other on the merit of the proposed change, I have a question for SNS: Do you understand how Wikipedia works? From your request above and your previous statements, I would have to guess the answer is no. Let's say the article is unprotected and you make your edit and none of the present editors object. How long do you think it will last? Are you planning on monitoring this article from now on? Don't you understand? Someone will come along and change your edit(s). That's the way Wikipedia works. That's the point you didn't get from my comment on your talk page. Are you really so naive as to think that any of your edits are permanent? Let my copy and paste a phrase that is prominently featured right below this edit box I'm typing in right now:
"If you don't want your writing to be edited mercilessly or redistributed by others, do not submit it "
Perhaps you should take some time to absorb the meaning of this. This 'stand' you are making is just an exercise in futility my friend. Alfred Centauri 19:05, 4 June 2007 (UTC)
  • Oppose - Arguments sound purely emotional rather than factual. DVdm 19:12, 4 June 2007 (UTC)
  • Oppose - Even if the reasons were valid, the edit does not clearly reflect the point, not to mention that the reasons are invalid. Everybody knows any scientific theory can be refuted based on a future experiment, so no need to mention it here to confuse the reader as if it was more so for GR. Temur 19:25, 4 June 2007 (UTC)
  • Oppose - Propose instead that SteakNShake be blocked from editing this or any other scientific article unless he/she can demonstrate an understanding that Wikipedia is not the place for original research or fringe ideas differing from the overwhelming consensus of the scientific community. The appropriate venue for changing the consensus would be a publication in a reputable scientific journal, but not here. Article protection should not be the answer for this type of disruption and this discussion (in addition to the related previous discussion) does nothing to move this page in the direction of 'good article' status. R. Baley 19:48, 4 June 2007 (UTC)
I've disabled the editprotected request. There doesn't seem to be consensus for the proposed changes. Cheers. --MZMcBride 19:45, 4 June 2007 (UTC)

Consensus

I have removed the protection for this article, the above clearly shows that consensus is for the changes not to occur. I also direct editors including SnS(or who the new name will be) to WP:NOT WP:3RR and WP:BLOCK#Disruption. Gnangarra 02:53, 5 June 2007 (UTC)

Question

You seem to be concerned about the ten components of the PDE used in the model. Can you clarify for me why coordinate invariance does not address these concerns? Thanks, Geometry guy 19:19, 4 June 2007 (UTC)

SteakNShake is permablocked.

The issue is the username, which violates WP:USERNAME. So "SteakNShake" is gone, but the person can and probably will choose a new user name and be back. --EMS | Talk 01:23, 5 June 2007 (UTC)

Why general relativity is ridiculous

Discussion inserted by 84.59.139.30 12:03, 16 June 2007 (UTC) redacted. It is archived at [4] (permanent link). Silly rabbit 12:15, 16 June 2007 (UTC)

But there are other reasons, too. General relativity is in fact completely senseless, since not any observation on Earth can be explained by it, which can't be explained without it (at least by special relativity). Or can someone tell me about such an effect ? 84.59.34.8 09:23, 17 June 2007 (UTC)

Sure: GPS.
DVdm 10:27, 17 June 2007 (UTC)
In case satellites in orbit do not meet the user's "on earth" criterion, gravitational time dilation has also been observed in mine shafts and by flying atomic clocks on planes. Geometry guy 10:51, 17 June 2007 (UTC)
Yes, gravitational time dilation can even be observed in an ordinary laboratory Pound-Rebka_experiment. But, this effect can easyly be understood quantitatively correct as energy or frequency shift, due to the mass m=E/c2 of radiation (special relativity) and Isaac Newton's law of gravitation. 84.59.63.85 11:21, 17 June 2007 (UTC)
... and Mercury's perihelion precession is also observed right here on Earth :-) DVdm 11:07, 17 June 2007 (UTC)
Mercury's perihelion precession is a rather small effect mostly explained by perturbations of other planets and Isaac Newton's law of gravitation. A small fraction can also be explained by special realtivity due to the addional mass of mercury caused by its motion. 84.59.63.85 11:28, 17 June 2007 (UTC)
Er, yes, the effects predicted by a more accurate theory are less accurately predicted by less accurate theories. This is not at all surprising!
For a more extreme observation, see Tests of general relativity#Strong field tests. Geometry guy 11:44, 17 June 2007 (UTC)
I don't think we should try to educate this person here. It didn't work on Usenet and I'm sure it won't work here. Getting educated seems not to be on this person's agenda. And after all, this talk page has another purpose. DVdm 12:04, 17 June 2007 (UTC)

I cannot resist pointing out — All true consequences of general relativity can be deduced from the combination of special relativity and Newtonian gravity. This is neither surprising nor helpful since anything at all can be deduced from them, that is, they contradict each other. JRSpriggs 06:23, 18 June 2007 (UTC)

Excellent point! DVdm 09:45, 18 June 2007 (UTC)
If really all true consequences of general relativity can be deduced from the combination of special relativity and Newtonian gravity, it immediately follows that nothing true can be derived from general relativity, that is not possible to derive without it. Moreover it seems, that anything at all can be deduced from general relativity. As an example a steady state universe as well as an expanding universe. That proves: General relativity is just ridiculous. 84.59.141.201 08:37, 19 June 2007 (UTC)
Well thats just fantastic logic. Thanks for the chuckle. --LiamE 10:50, 19 June 2007 (UTC)

Conclusion

Nothing of any importance for (human) live on Earth can be explained by general relativity, which can't be explained without it (at least by special relativity). 84.59.40.134 12:15, 17 June 2007 (UTC)

It is clear by now that you are genuinely convinced of this, and that on your Earth the conclusion is perfectly valid, but this is not the place to ventilate your personal points of view, not even if they were correct or relevant. See Wikipedia:Talk page guidelines:
The purpose of a Wikipedia talk page is to provide space for editors to discuss changes to its associated article or project page. Article talk pages should not be used by editors as platforms for their personal views.
DVdm 13:02, 17 June 2007 (UTC)
84.59.*.* will be singing a different tune when a gamma ray burster cooks us all, I'm sure. Silly rabbit 13:10, 17 June 2007 (UTC)
I don't think that it can be predicted from general relativity that we will be cooked by a gamma ray burster. But, even if, it would not help us much, since we can not prevent it, in contrast to the global warming. 88.68.101.193 17:28, 17 June 2007 (UTC)
Two questions:
  1. Do you have some particular reason for using different IP addresses for every inappropriate edit you make on the talk pages of articles?
  2. Are you aware of the fact that most people find this rather annoying?
DVdm 18:10, 17 June 2007 (UTC)
DVdm - I can answer the IP question. The reason for the different IP addresses is that this user's ISP uses dynamic addressing. So every time he or she logs onto their ISP, a different address is obtained from the ISP's address pool.
As for the being annoying, that seems to be part of trolling. "Don't feed the troll", and we will be much happier. I'm not sure if this person is educatable, but I can tell you that he or she is so far off-base that it will take a substantial effort to ge enable him or her ot see what is really going on with GR. IMO, our time is better spent working on the article itself and keeping the vandals away. --EMS | Talk 20:48, 18 June 2007 (UTC)

Please don't feed the troll. He is well known in the german wikipedia for his trolling in all GRT-related topics. His essays might well be mere translations from german to english... -- 217.232.45.203 08:37, 25 June 2007 (UTC)

Non-trolling part of archive

Manuscript

Resolved. I am going to archive this soon

http://www.alberteinstein.info/db/ViewImage.do?DocumentID=25&Page=1 134.91.200.139 12:57, 11 June 2007 (UTC)

Quick help on theory article please

Resolved.

Hi, I watch the article on Theory just to keep tabs on it, and while I have a science background, physics is not a subject I have authoritative knowledge. A little while back there was some change to this sentence:

"For example, it is a fact that an apple dropped on earth has been observed to fall towards the center of the planet, and a theory which explains why the apple behaves so is the general theory of relativity."

which is in the lead section. This sentence has had a bit of a problem on the exact wording to use (I have made a change or two: one diff here). So I guess I have two questions: (1) seems like this part, '. . .planet, and a theory which. . ." should instead be: ". . .planet, and the theory which. . ." and (2) should the General relativity link be piped to the article Gravitation. I know in general this is discouraged, but current ideas about gravitation are generally described in terms of GR, while there really isn't (technically speaking) a current theory with the name "theory of gravity" which I think is why the confusion began. This will also be posted on the talk page at Talk:Theory. Thanks in advance for any input. R. Baley 21:58, 15 June 2007 (UTC)

Wouldn't Newton's theory of universal gravitation be a much better theory for this particular phenomenon? People don't usually invoke GR to talk about apples after all: unless the apples under consideration are near a black hole, rotating very rapidly about their core, or about to undergo gravitational collapse. Silly rabbit 23:41, 15 June 2007 (UTC)
Forgive my ignorance, but it has been my understanding that Newton's theory describes the 'how', but that GR also describes the how (but more complex) and also is our best current understanding of the 'why' (the sentence in question talks about why the apple falls). It seems that the article we have on gravitation is more comprehensive in that it links to both newton's theory and GR, which is why I think we should link to it. But given a choice between newton's theory or einstein's, I thought GR should be linked because it describes 'why'. R. Baley 02:13, 16 June 2007 (UTC)
I wouldn't say it describes why the apple falls. The apple does not fall because spacetime is curved. We use the model of a curved spacetime to describe how the apple behaves. I don't think that any physical theory provides the ultimate why. With regard to Newton's theory you could ask why two masses attract each other, and you get no answer. In general relativity you can ask why spacetime is curved, and you get no answer either. Both theories just provide convenient and successful means to describe things. DVdm 10:14, 16 June 2007 (UTC)
Think I got it. So the 'why' should be taken out of the sentence altogether. Based on the above discussion, perhaps a better sentence would read like this:
"For example, it is a fact that an apple dropped on earth is observed to fall towards the center of the planet, and the theory commonly used to describe this motion is Newton's theory of universal gravitation (see also gravitation)."
Does everyone agree that this sentence is better than the original? R. Baley 18:46, 16 June 2007 (UTC)
Yes, good point, but since the article is about theories, I have modified the sentence as follows:
"For example, it is a fact that an apple dropped on earth is observed to fall towards the center of the planet, and the theories commonly used to describe and explain this behaviour are Newton's theory of universal gravitation (see also gravitation), and General relativity."
DVdm 11:00, 17 June 2007 (UTC)
I appreciate the help DVdm and Silly rabbit, I'm going to link here and replace the sentence. Already done. Thanks! R. Baley 18:22, 17 June 2007 (UTC)


Regarding section "Spacetime as curved Lorentzian manifold"

Resolved.

This section claims that a ping-pong ball fired "at just the right speed" will orbit the bowling ball in the trampoline. I don't think this is correct, and the analogy with planets is certainly not correct. A planet will orbit the sun at any speed below the escape velocity; the orbit will be elliptical, or in the extreme case, a straight line through the sun (which is still technically an orbit). Similarly, a ping-pong ball fired at the bowling ball will orbit (possibly elliptically) for any (radial?) speed below a threshold. Of course, this doesn't really work if the ping-pong ball hits the bowling ball. -David —Preceding unsigned comment added by 128.135.102.79 (talk • contribs)

You are taking that paragraph too seriously. Remember it says "...can be viewed intuitively...". It is not an exact analogy. JRSpriggs 09:40, 27 June 2007 (UTC)
I agree with David here. Even if the analogy should be taken to be viewed intuitively, then the phrase "at just the right speed" is wrong, and I don't think we should allow a mistake in the description of an analogy. I would replace the phrase with "at some suitable combination of direction and speed". Any objections? DVdm 09:56, 27 June 2007 (UTC)
No objection. Just try not to turn it into an essay that requires us to examine the similarities and differences between gravity bending space-time and a bowling ball bending a trampoline. JRSpriggs 10:58, 27 June 2007 (UTC)