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Author Topic: Is Einstein's general relativity misunderstood?  (Read 21976 times)

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #25 on: 28/01/2010 12:39:50 »
No, it really is your theory because you are making claims about experiments and observations that contradict what every scientist who uses relativity theory claims. For example, you say that relativity theory, if used "correctly", will produce the right rotation curves for galaxies. However, every scientist working in astronomy and astrophysics says that this doesn't happen.
I'm not making claims that contradict relativity. We all know that Einstein missed the expansion of the universe, it's just a trivial matter of looking at what Einstein said about inhomogeneous space and then applying knowledge of the expanding universe. As for "every scientist", you should read Mordehai Milgrom's New Physics at Low Accelerations (MOND): an Alternative to Dark Matter at http://arxiv.org/abs/0912.2678. Note page 4 where he says:

"We see that the modification of GR entailed by MOND does not enter here by modifying the ‘elasticity’ of spacetime
(except perhaps its strength), as is done in f(R) theories and the like."


I've merely stated the obvious. Einstein told us that a gravitational field is a region of inhomogeneous space, and we all know of the raisins-in-the-cake analogy for the expanding universe. Space expands between the galaxies but not within, giving rise to another source of inhomogeneous space. According to Einstein, that's a gravitational field, with no causative matter. I really can't see why you have such a problem with this.

When you say this, you are obviously ignoring what Einstein said about the aether. You even ignore what the author of the page hosting your favourite link to Einstein's address says about that address. This author writes on the page, "This address has been frequently misunderstood as positing that a return of the ether theory." Anyone who reads the address or the page must see that Einstein is clearly rejecting the standard idea of an aether theory in favour of, at best, an idea that bears only one feature of an aether theory, that of being a medium.
I'm not obviously ignoring anything, I'm reporting what Einstein said. He talked about a non-constant guv that causes curvilinear motion, and he talked about the aether of general relativity. See http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm. What more can I say? There it is, in black and white. 
 
We are not talking about mathematical exercises, we are talking of the actual content of the theory. When you say that relativity theory does away with the need for dark matter, you are making a claim about actual values that are measured and actual values that are calculated. You have shown no way to reconcile these values. If you have a way to reconcile these values, you should share it. If you have no way to reconcile these values, you should retract your claims.
No I shouldn't. We have free speech in science, and observations and comments are permitted. 

You need to show exactly how "a non-constant guv that causes curvilinear motion along with the aether" produces the calculations for the rotation curve of a galaxy and how this calculation matches up with the observed rotation curve.
As above.

An astronomer or an astrophysicist who makes a claim about dark matter backs up her or his claim with the relevant observations and calculations.
But even to this day, no astronomer or astrophysicist can provide conclusive proof for the existence of dark matter. It remains the subject of debate. And since it was first proposed by Zwicky seventy three years ago, we are surely free to discuss alternatives. People are discussing them more, and proposing experiments, see for example Testing MOND/TEVES with LISA Pathfinder by Christian Trenkel, Steve Kemble, Neil Bevis, and Joao Magueijo at http://arxiv.org/abs/1001.1303.

I note that you have retracted some of your previous claims. For example, you have removed your two calculations of the size of the universe from your public document version of your theory, two calculations that differed by several orders of magnitude. Many actual scientist retract claims when they have made an error. If your claims about dark matter are in error, it is no shame to retract them.
I haven't retracted anything. I never gave any calculations, I reported two numbers, a contradiction was pointed out, so I removed the contradiction. That was back in January 2008, see "last updates". And please can we stay on topic.
« Last Edit: 28/01/2010 13:57:01 by Farsight »
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #26 on: 28/01/2010 20:53:27 »
As for "every scientist", you should read Mordehai Milgrom's New Physics at Low Accelerations (MOND): an Alternative to Dark Matter at http://arxiv.org/abs/0912.2678. Note page 4 where he says:

"We see that the modification of GR entailed by MOND does not enter here by modifying the ‘elasticity’ of spacetime
(except perhaps its strength), as is done in f(R) theories and the like."
Perhaps you failed to notice that this proposes a modification of GR. Do you propose a modification of GR?
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I've merely stated the obvious. Einstein told us that a gravitational field is a region of inhomogeneous space, and we all know of the raisins-in-the-cake analogy for the expanding universe. Space expands between the galaxies but not within, giving rise to another source of inhomogeneous space. According to Einstein, that's a gravitational field, with no causative matter. I really can't see why you have such a problem with this.
The widely examined and accepted cosmological models are not relevant here. I have a problem with your claims because you are denying the facts. The facts are that the rotation curves of galaxies do not work out unless we include dark matter. Please show us, and the entire scientific community including Milgrom, how standard GR can produce the rotation curves of galaxies without the need for dark matter.
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I'm not obviously ignoring anything, I'm reporting what Einstein said. He talked about a non-constant guv that causes curvilinear motion, and he talked about the aether of general relativity. See http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm. What more can I say? There it is, in black and white. 
Indeed it is. But somehow, you have it in your head that guv isn't exactly what everyone means when they speak of curved spacetime. It's like you are pointing at a picture from Picasso's blue period and telling everyone that the painting is done entirely in red paint.
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We are not talking about mathematical exercises, we are talking of the actual content of the theory. When you say that relativity theory does away with the need for dark matter, you are making a claim about actual values that are measured and actual values that are calculated. You have shown no way to reconcile these values. If you have a way to reconcile these values, you should share it. If you have no way to reconcile these values, you should retract your claims.
No I shouldn't. We have free speech in science, and observations and comments are permitted. 
You aren't entirely correct; we are not in a venue of free speech. For example, I was banned from this forum for saying true things about you that are relevant to understanding your position. At the risk of further banning, I will point out that your refusal to actually acknowledge the data that exists, as you are fee to do, should be taken as a symptom that you really do not understand anything in this field and that your claims are bogus.
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An astronomer or an astrophysicist who makes a claim about dark matter backs up her or his claim with the relevant observations and calculations.
But even to this day, no astronomer or astrophysicist can provide conclusive proof for the existence of dark matter. It remains the subject of debate. And since it was first proposed by Zwicky seventy three years ago, we are surely free to discuss alternatives. People are discussing them more, and proposing experiments, see for example Testing MOND/TEVES with LISA Pathfinder by Christian Trenkel, Steve Kemble, Neil Bevis, and Joao Magueijo at http://arxiv.org/abs/1001.1303.
If we look at that paper, we see attempts to reconcile different theories to the various observations though comparisons of predictions and measurements. This is, again, something you refuse to do. This is what makes it plain that your position is not a scientific one but one not far from fiction.
I note that you have retracted some of your previous claims. For example, you have removed your two calculations of the size of the universe from your public document version of your theory, two calculations that differed by several orders of magnitude. Many actual scientist retract claims when they have made an error. If your claims about dark matter are in error, it is no shame to retract them.
I haven't retracted anything. I never gave any calculations, I reported two numbers, a contradiction was pointed out, so I removed the contradiction. That was back in January 2008, see "last updates". And please can we stay on topic.[/quote]
This is very much on topic, as your refusal to acknowledge the facts here highlights your refusal to engage the science in an honest and open manner. You certainly derived one value, writing, "The universe is larger than the Compton wavelength of a proton by a factor of 10^40. That’s why gravity is weaker by a factor of 10^40." Here you were attempting to use the matching of mathematical results to support your theory, something you refuse to do with your claims about dark matter. When if became obvious that you contradicted yourself by several orders of magnitude, you removed the statement and now you say that you haven't retracted anything. Either you still endorse this derivation or you have retracted this derivation. Either you accept that mathematical results are important in science or you do not.
 

Offline Ron Hughes

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Is Einstein's general relativity misunderstood?
« Reply #27 on: 28/01/2010 21:40:02 »
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The widely examined and accepted cosmological models are not relevant here. I have a problem with your claims because you are denying the facts. The facts are that the rotation curves of galaxies do not work out unless we include dark matter. Please show us, and the entire scientific community including Milgrom, how standard GR can produce the rotation curves of galaxies without the need for dark matter.

There is one way Phys, if the equation F = ma is not the same in all frames of reference.
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #28 on: 28/01/2010 23:54:55 »
Perhaps you failed to notice that this proposes a modification of GR. Do you propose a modification of GR...
Not at all. I report Einstein's statements: a gravitational field is a region of inhomogeneous space caused by a concentration of energy tied up the matter of a planet, which in turn causes the curvilinear motion that is described as curved space-time. I don't deny the facts of general relativity, I report them. They're as described by Einstein, and they are validated by experiment. I'm sorry they're not as you wish them to be, and I'm sorry that the non-uniform expansion of the universe clearly offers another causative agent for inhomogeneous space which dispenses with the need for dark matter. I know it's distressing to you, but after 77 years without validation, dark matter has had its day, and science must progress.

I would urge you to consider Einstein's inhomogeneous space in the light of this statement:

"We see that the modification of GR entailed by MOND does not enter here by modifying the ‘elasticity’ of spacetime (except perhaps its strength), as is done in f(R) theories and the like."

 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #29 on: 29/01/2010 05:18:47 »
I report Einstein's statements: a gravitational field is a region of inhomogeneous space caused by a concentration of energy tied up the matter of a planet, which in turn causes the curvilinear motion that is described as curved space-time.
Einstein did not write or say this anywhere.
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I don't deny the facts of general relativity, I report them.
When you say that GR can account for rotation curves without dark matter, you are denying the facts. Anyone who reads the links about MOND you have provided can easily tell this. You could easily prove that all the authors you cite are incorrect with a few calculations. Your refusal bears on your behaviour in general and the character of the theories you offer.
« Last Edit: 29/01/2010 14:33:37 by PhysBang »
 

Offline litespeed

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Is Einstein's general relativity misunderstood?
« Reply #30 on: 29/01/2010 15:47:28 »
I like this thread and hope no one gets banned from it. As a practicing lay-person myself, I find such exchanges useful, if not always edifying. Can I throw a pebble into the pond and to see if any interference patterns evolve?

Specifically, General Relativity seems to predict infinite singularities in black holes, but infinities do not exist in our universe. I do not see this as all that alarming. After all, the same sort of thing happened to Newton regarding the weird orbit of Mercury. Now we have another weird phenomenon to think about.

Opinion requested: is (are) additional dimensions outside of, but including, space time considered reasonable possibilities for examination? I am thinking of Vehn diagrams. A single dimension is included in two dimension which is included in three dimensions which is included in four dimensions etc.
« Last Edit: 29/01/2010 15:49:52 by litespeed »
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #31 on: 01/02/2010 16:07:28 »
litespeed: general relativity itself doesn't predict the central black hole singularity. Instead the Misner/Thorne/Wheeler "geometrical interpretation" does. See http://www.mathpages.com/rr/s7-02/7-02.htm and note this bit:

Incidentally, I should probably qualify my dismissal of the "frozen star" interpretation, because there's a sense in which it's valid, or at least defensible. Remember that historically the two most common conceptual models for general relativity have been the "geometric interpretation" (as exemplified by Misner/Thorne/Wheeler's "Gravitation") and the "field interpretation" (as in Weinberg's "Gravitation and Cosmology"). These two views are operationally equivalent outside event horizons, but they tend to lead to different conceptions of the limit of gravitational collapse. According to the field interpretation, a clock runs increasingly slowly as it approaches the event horizon (due to the strength of the field), and the natural "limit" of this process is that the clock just asymptotically approaches "full stop" (i.e., running at a rate of zero) as it approaches the horizon. It continues to exist for the rest of time, but it's "frozen" due to the strength of the gravitational field. Within this conceptual framework there's nothing more to be said about the clock's existence. This leads to the "frozen star" conception of gravitational collapse.

I'd say additional dimensions are OK so long as they're dimensions of measure rather than dimensions that offer freedom of motion. For example we have three dimensions of space through which we can move, but we aren't free to move through the time dimension.
 

Physbang: see http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm

"According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν).."

Einstein said this in 1920, and he talked about curvilinear motion in The Foundation of the General Theory of Relativity in 1916. The theory I offer is Einstein's relativity. I'm not denying the facts.
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #32 on: 01/02/2010 19:04:22 »
Physbang: see http://www.zionism-israel.com/Albert_Einstein/Albert_Einstein_Ether_Relativity.htm

"According to this theory the metrical qualities of the continuum of space-time differ in the environment of different points of space-time, and are partly conditioned by the matter existing outside of the territory under consideration. This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that “empty space” in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials gμν).."

Einstein said this in 1920, and he talked about curvilinear motion in The Foundation of the General Theory of Relativity in 1916. The theory I offer is Einstein's relativity. I'm not denying the facts.
This is another example of you cherry-picking quotations. Academics tend to call such behaviour dishonest.

Let's begin with the first sentence of the paragraph, the sentence that you failed to copy:

"Mach’s idea finds its full development in the ether of the general theory of relativity."

This makes it clear that what Einstein is talking about in his paragraph is an idea of Mach, in particular, that that aspect of physics that imparts the properties of inertia to objects is also influenced by these objects.

You are also cherry-picking by ignoring the actual cosmological models designed and endorsed by Einstein throughout his life. You are trying to make the point that it is wrong to ever consider anything to be homogeneous and isotropic in GR, but by ignoring all of Einstein's science and focusing on a single passage from an address out of context, you merely promote ignorance.

If you think that there is a case for GR to account for dark matter, then make the case with the actual observations and calculations of the science, don't cherry-pick statements from Einstein taken from a popular lecture and paste them out of context.
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #33 on: 01/02/2010 23:25:24 »
I'm not cherry picking, PhysBang. You said Einstein didn't say that stuff about inhomogeneous space etc. But he did. I'm not promoting ignorance, I'm promoting knowledge. I've given you the link, and out of context just doesn't wash. He said what he said.
 

Offline demografx

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Is Einstein's general relativity misunderstood?
« Reply #34 on: 01/02/2010 23:58:50 »

PhysBang, let's keep ad hominems out of the forum. Such as accusations of dishonesty and promoting ignorance.

Talk to the facts, and only the facts, such as those on public record. Offer your interpretation, if you wish, be specific, then let the readers decide for themselves if there is any distortion going on.

Thank you.
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #35 on: 02/02/2010 16:02:31 »

PhysBang, let's keep ad hominems out of the forum. Such as accusations of dishonesty and promoting ignorance.
To commit an ad hominem is to perform an ignotario elenchi argument. That is, it is to bring up facts irrelevant to the matter at hand. I have done no such thing. It is relevant to understanding Farsight's claims that one understand that he is presenting a small subset of the available literature, out of context, in such a way that a reader might be mislead. It is also relevant for a reader to know that Farsight has been made aware of the misleading nature of his presentation and that he continues to present his claims in this manner.
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Talk to the facts, and only the facts, such as those on public record. Offer your interpretation, if you wish, be specific, then let the readers decide for themselves if there is any distortion going on.
Part of addressing the facts is to actually show how these facts are presented. In this case, I have to somehow demonstrate that what Farsight is offering is not actually relevant to the points that he wants to make. If Farsight would offer something to work with, namely scientific arguments to back up his scientific claims, then I could engage in an analysis of the facts.
 

Offline demografx

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Is Einstein's general relativity misunderstood?
« Reply #36 on: 03/02/2010 02:16:54 »

By ad hominem, I simply refer to your character attacks, again, such as your referring to his "dishonesty and promoting ignorance", or "you really do not understand anything in this field."

You did a good job of largely avoiding that in your reply directly above, which expresses and re-states your technical objections, but without the mudslinging.
« Last Edit: 03/02/2010 03:06:02 by demografx »
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #37 on: 03/02/2010 09:29:12 »
Physbang: I'm afraid it isn't a small subset of the available literature. In 1911 Einstein wrote a paper "On the Influence of Gravitation on the Propagation of Light" where he said "If we call the velocity of light at the origin of co-ordinates c0, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = c0 (1 + Φ/c˛).". See http://www.relativitybook.com/resources/Einstein_gravity.html for an online version. 

In 1912 he wrote "On the other hand I am of the view that the principle of the constancy of the velocity of light can be maintained only insofar as one restricts oneself to spatio-temporal regions of constant gravitational potential". I’ve got this page as a PDF image, I’ll have to check where it’s from. Similarly in 1913 he wrote "I arrived at the result that the velocity of light is not to be regarded as independent of the gravitational potential".

In 1915 he wrote "However the writer of these lines is of the opinion that the theory of relativity is still in need of generalization, in the sense that the principle of the constancy of the velocity of light is to be abandoned."  This is on page 259 of Doc 21.

I’ve already given information from chapter 22 of Relativity: The Special and General Theory written in 1916 where Einstein refers to the postulate of special relativity. I’ve got a page showing the original German, where Einstein says die Ausbreitungsgeschwindigkeit des Lichtes mit dem Orte variiert. Get a German friend to translate it and he will confirm the google translation the speed of light varies with the locality. It’s backed up by the actual scientific evidence of for example the GPS clock adjustment. A GPS clock employs microwaves. That’s light. The clock runs slower because the light moves slower. There’s also the Shapiro delay. It’s a delay, the light moves slower when it passes the limb of the sun. The wiki article on the Shapiro delay even includes the quote from Chapter 22: 

"In the second place our result shows that, according to the general theory of relativity, the law of the constancy of the velocity of light in vacuo, which constitutes one of the two fundamental assumptions in the special theory of relativity and to which we have already frequently referred, cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity of propagation of light varies with position. Now we might think that as a consequence of this, the special theory of relativity and with it the whole theory of relativity would be laid in the dust. But in reality this is not the case. We can only conclude that the special theory of relativity cannot claim an unlimited domain of validity ; its results hold only so long as we are able to disregard the influences of gravitational fields on the phenomena (e.g. of light)."

All you have to do is look at the original material to understand that the modern interpretation of relativity is different to Einstein’s, and appreciate that this then causes misunderstanding. As an example of this, read Is The Speed of Light Constant? on the Baez website by Gibbs and Carlip, and look at the section on General Relativity. You see the chapter 22 quote again along with the comment “Since Einstein talks of velocity (a vector quantity: speed with direction) rather than speed alone, it is not clear that he meant the speed will change, but the reference to special relativity suggests that he did mean so. This interpretation is perfectly valid and makes good physical sense, but a more modern interpretation is that the speed of light is constant in general relativity.” Lower down the article says “ Finally, we come to the conclusion that the speed of light is not only observed to be constant; in the light of well tested theories of physics, it does not even make any sense to say that it varies.”. Hence the article says Einstein’s variable speed of light makes sense, and doesn’t make sense. 

All of this isn’t out of context, it’s conclusive.

demografx: thank you for your moderation.   
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #38 on: 03/02/2010 13:27:36 »
Physbang: I'm afraid it isn't a small subset of the available literature. In 1911 Einstein wrote a paper "On the Influence of Gravitation on the Propagation of Light" where he said "If we call the velocity of light at the origin of co-ordinates c0, then the velocity of light c at a place with the gravitation potential Φ will be given by the relation c = c0 (1 + Φ/c˛).". See http://www.relativitybook.com/resources/Einstein_gravity.html for an online version. 
Why, if you want to defend a point about general relativity, are you looking at things Einstein wrote before general relativity?

Since you seem to want to use the 1911 theory as representative of Einstein's theory, please show us using this theory where Einstein uses an aether. Additionally, please show us how one can use the 1911 theory to calculate the rotation curves of galaxies. It would be nice if you could also show how this use gets rid of the measurements of the amount of dark matter.
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All you have to do is look at the original material to understand that the modern interpretation of relativity is different to Einstein’s, and appreciate that this then causes misunderstanding.
OK, so please demonstrate how, using the 1911 theory or the later theory, the rotation curve of a galaxy doesn't produce a measurement of dark matter.
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Hence the article says Einstein’s variable speed of light makes sense, and doesn’t make sense. 
A discerning reader should note that the authors write, "In general relativity, the appropriate generalisation is that the speed of light is constant in any freely falling reference frame (in a region small enough that tidal effects can be neglected).  In this passage, Einstein is not talking about a freely falling frame, but rather about a frame at rest relative to a source of gravity.  In such a frame, the speed of light can differ from c, basically because of the effect of gravity (spacetime curvature) on clocks and rulers." Thus one notes that the authors are pointing out that in the particular passage of Einstein that they quote, Einstein is using an improper generalization. What makes one generalization proper and the other improper is that the proper generalization recognizes the role that light has in determining the causal structure of events. AS the authors note, the constant speed of light is fundamental to the way that general relativity determines causal structure. Thus it is conceptually more fundamental than the time it takes for light to cross a certain distance in a certain time in a certain particular system of coordinates. This is particularly true since the correct description of any physical system in any well-formed set of coordinates in general relativity must maintain this causal structure.

The most well known system of coordinates in general relativity with what one might call a variable speed of light is that associated with the Friedmann equations. These equations provide a solution to the Einstein field equation and the form the basis of a family of cosmological models preferred by Einstein after 1929 and survive in a modified version in contemporary cosmology. In these solutions, light can travel faster than light, because over time the distance between where the light left and where the light is received can get larger. However, one should recognize that this is not a way to measure speed that is representative of the causal structure of the universe and when one takes that into account properly, one finds the speed of light as constant. Despite working with, and accepting as approximately correct, the Friedmann models, cosmologists do not run around saying that the speed of light is variable.

All this is clear from not simply cherry-picking particular parts of the document and from looking at the authors' claims in context.
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #39 on: 03/02/2010 15:31:05 »
Why, if you want to defend a point about general relativity, are you looking at things Einstein wrote before general relativity?
To demonstrate that I'm not cherry picking. We see Einstein repeatedly telling us the speed of light is variable.

Since you seem to want to use the 1911 theory as representative of Einstein's theory, please show us using this theory where Einstein uses an aether.
I don't. Plus I've already shown you the 1920 Leyden Address where Einstein talks of the aether of General Relativity.

OK, so please demonstrate how, using the 1911 theory or the later theory, the rotation curve of a galaxy doesn't produce a measurement of dark matter.
I politely decline on the grounds that such a laborious exercise is unnecessary in the light of Einstein's description of a gravitational field as inhomogeneous space, along with our current knowledge of the expansion of the universe. Space expands between the galaxies, not within. The result is inhomogeneous space, and that's a gravitational field with no causative matter. 

...As the authors note, the constant speed of light is fundamental to the way that general relativity determines causal structure.
It is at odds with Einstein, who described the central concentration of energy tied up in as the matter of a planet causing a conditioning of the surrounding space described via a non-constant gμv which causes a variable speed of light that then causes the curvilinear motion that is described as curved spacetime. I've paraphrased, but read the original material, and you will find that I am correct. 

Thus it is conceptually more fundamental than the time it takes for light to cross a certain distance in a certain time in a certain particular system of coordinates. This is particularly true since the correct description of any physical system in any well-formed set of coordinates in general relativity must maintain this causal structure.
No, I'm afraid it isn't. What's conceptually more fundamental relates to what we actually observe. We don't observe time passing, our seconds are defined using the motion of light. Thus when our second changes, it's because the rate of motion of light has changed. 

The most well known system of coordinates in general relativity with what one might call a variable speed of light is that associated with the Friedmann equations. These equations provide a solution to the Einstein field equation and the form the basis of a family of cosmological models preferred by Einstein after 1929 and survive in a modified version in contemporary cosmology.
Noted.
 
In these solutions, light can travel faster than light, because over time the distance between where the light left and where the light is received can get larger. However, one should recognize that this is not a way to measure speed that is representative of the causal structure of the universe...
No, of course not. There are galaxies receding from us at more than c due to the expansion of the universe, but we do not consider them to be actually moving at more than c.   

..and when one takes that into account properly, one finds the speed of light as constant.
I'm afraid one doesn't. One only "finds the speed of light to be constant" when one employs the motion of light to define one's seconds and metres to then measure the speed of light. It isn't constant, Einstein said it, gravitational time dilation is scientific fact, and our best clocks are atomic clocks which count microwave peaks. Those clocks run slower when the light moves slower. The scientific evidence is there, and "when one takes that into account properly" in no way counters it.   

Despite working with, and accepting as approximately correct, the Friedmann models, cosmologists do not run around saying that the speed of light is variable.
But I'm afraid some do. See for example http://en.wikipedia.org/wiki/Variable_speed_of_light and http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.4507v1.pdf where Magueijo and Moffat responded to Ellis. Its constancy has become a tautology.
 

Offline Ron Hughes

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« Reply #40 on: 03/02/2010 17:13:05 »
Phys, does the rotation curve of galaxies guarantee the existence of dark matter? I would think that a logical mind must realize there is the possibility of another explanation even that one of our fundamental tenets may be wrong.
 

Offline Ron Hughes

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« Reply #41 on: 03/02/2010 17:23:17 »
One more question phys and I will explain after your answer. Suppose that the result of the BB was the creation of a single proton and no other particles, how much space would be created for that proton?
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #42 on: 03/02/2010 18:55:12 »
Phys, does the rotation curve of galaxies guarantee the existence of dark matter? I would think that a logical mind must realize there is the possibility of another explanation even that one of our fundamental tenets may be wrong.
The rotation curves of galaxies are one piece of evidence for dark matter among many. If one wants to demonstrate an alternative to dark matter, one has to address the evidence. Traditionally, alternative hypotheses to dark matter have found the galaxy rotation curves the easiest piece of evidence to account for, but have had problems with the rest.

Simply imagining a different possibility is not enough to claim that existing science is wrong. If one wants to say that the work of practising astronomers is incorrect, one should demonstrate this.
One more question phys and I will explain after your answer. Suppose that the result of the BB was the creation of a single proton and no other particles, how much space would be created for that proton?
Well, given the standard model, it looks like there could be any amount of space created for that particle. This depends on other initial conditions, primarily the rate of expansion in the space of the universe. That rate can only be so high in a finite universe. If the universe is finite in size, then it could have a maximum radius and collapse on itself, again depending on the initial condition that sets the rate of expansion.
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #43 on: 03/02/2010 19:14:51 »
To demonstrate that I'm not cherry picking. We see Einstein repeatedly telling us the speed of light is variable.
Picking statements from wildly different theories to say that the speed of light is variable in GR is a perfect example of cherry-picking. You are taking quotations out of their original context and using them to support a point about a significantly different context.
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Since you seem to want to use the 1911 theory as representative of Einstein's theory, please show us using this theory where Einstein uses an aether.
I don't. Plus I've already shown you the 1920 Leyden Address where Einstein talks of the aether of General Relativity.
So you admit that you reject the theory of 1911 in which Einstein says that the speed of light is variable. Good. Now you can simply show us how to properly calculate the rotation curves of galaxies in GR.
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I politely decline on the grounds that such a laborious exercise is unnecessary in the light of Einstein's description of a gravitational field as inhomogeneous space, along with our current knowledge of the expansion of the universe. Space expands between the galaxies, not within. The result is inhomogeneous space, and that's a gravitational field with no causative matter. 
It is not unnecessary, because every astronomer working with dark matter uses GR to calculate rotation curves. You are saying that they are doing this incorrectly. Why do you dismiss their work if you are not willing to point out what they are doing wrong? These people are using gμv like any other scientist. Are you claiming that these astronomers are simply lying about their results?
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It is at odds with Einstein, who described the central concentration of energy tied up in as the matter of a planet causing a conditioning of the surrounding space described via a non-constant gμv which causes a variable speed of light that then causes the curvilinear motion that is described as curved spacetime. I've paraphrased, but read the original material, and you will find that I am correct. 
I have read the original material and I note that you are incorrect. You are incorrect because you are continuing to ignore exactly what the authors of the page you cited explain.
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No, I'm afraid it isn't. What's conceptually more fundamental relates to what we actually observe. We don't observe time passing, our seconds are defined using the motion of light. Thus when our second changes, it's because the rate of motion of light has changed. 
If you can make a theory out of these claims, then demonstrate it with a simple example. For example, using your theory, calculate the rotation curve of a galaxy. Alternately, calculate the perihelion shift of Mercury.
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Despite working with, and accepting as approximately correct, the Friedmann models, cosmologists do not run around saying that the speed of light is variable.
But I'm afraid some do. See for example http://en.wikipedia.org/wiki/Variable_speed_of_light and http://arxiv.org/PS_cache/arxiv/pdf/0705/0705.4507v1.pdf where Magueijo and Moffat responded to Ellis. Its constancy has become a tautology.
This is another example of cherry-picking. Magueijo and Moffat do not support anything like your theory, nor do they use the fact that there is expansion in the Friedmann models as evidence for the variable speed of light. As evidence, we can see that they discuss VSL theories as alternatives to GR, not as interpretations of GR. Additionally, they note "The c in VSL theories is never a
coordinate speed of light. It is the physical speed of light measured by free-falling observers and cannot be undone by a coordinate transformation." (pg. 3) This is a fundamental different in determinations of speeds that was expressed in Gibbs and Carlip's article that you apparently fail to understand: Einstein's variable speed of light in the quotation is a coordinate speed, not that speed measured by free-falling observers. It is this latter speed that one should use as the basis of generalizations, not the speed in a particular coordinate system. It is this latter speed that determines the causal structure of events, not the speed in a coordinate system.

You are welcome to come up with your own theory and test it against the evidence, but you should not try to use Einstein in some kind of ham-fisted argument from authority in lieu of providing evidence.
 

Offline Geezer

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Is Einstein's general relativity misunderstood?
« Reply #44 on: 03/02/2010 19:35:41 »
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Offline Ron Hughes

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Is Einstein's general relativity misunderstood?
« Reply #45 on: 03/02/2010 19:58:10 »
Phys, I would say that space in my single proton Universe, at the instant of the proton's creation, would start expanding at C because the electric field of the proton would start creating space at C.
 

Offline Farsight

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Is Einstein's general relativity misunderstood?
« Reply #46 on: 04/02/2010 11:51:35 »
I've given you ample Einstein quotes PhysBang, enough to demonstrate that I'm clearly not cherry-picking, and the hoary old "out of context" does not undo what Einstein actually said. We all know that the 1911 theory was incomplete, just as we know that not all cosmologists examining gravitational anomalies support the dark matter hypothesis, just as we know that there are cosmologists who do walk around talking about the variable speed of light. This isn't a "my theory" issue, this is Einstein's theory. If you'd really read the original, you'd have read "the principle of the constancy of the velocity of light is to be abandoned." Dismissing Einstein is no substantive argument.

Here's the deal re dark matter, as simply as I can put it: it's energy that causes gravity, not matter. Matter only causes gravity because of the energy content. Einstein told us that a gravitational field has energy, and that a gravitational field is a region of inhomogeneous space. Now take a region of homogeneous space and divide it into cubes. Now decrease the energy-density of all of the cubes bar the one in the centre. The result? An energy-density gradient all around it. A gravitational field. But try as you might, when you look in that central cube, there's not a single speculative WIMP, there's no dark matter there. Because the dark matter you're looking for, is space itself. It's dark, it has energy, it isn't moving with respect to you, and E=mc2.   
 

Offline Ron Hughes

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Is Einstein's general relativity misunderstood?
« Reply #47 on: 04/02/2010 16:28:50 »
My gedanken about the single proton should be enormously important for anyone who thinks about it's meaning. THE EXPANDING ELECTRIC FIELD OF THE PROTON IS THE AETHER OF SPACE . When all the electrons and protons were created their expanding electric fields created space at C.
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #48 on: 04/02/2010 17:52:37 »
I've given you ample Einstein quotes PhysBang, enough to demonstrate that I'm clearly not cherry-picking, and the hoary old "out of context" does not undo what Einstein actually said.
The statement "out of context" is surely old to you because you keep using the same flawed technique to try to make your case. Your continuing behaviour of taking things out of context does nothing to change any of the science that Einstein and others published. If you want to actually address the content of the science, we'll all be waiting.
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Here's the deal re dark matter, as simply as I can put it: it's energy that causes gravity, not matter. Matter only causes gravity because of the energy content. Einstein told us that a gravitational field has energy, and that a gravitational field is a region of inhomogeneous space. Now take a region of homogeneous space and divide it into cubes. Now decrease the energy-density of all of the cubes bar the one in the centre. The result? An energy-density gradient all around it. A gravitational field. But try as you might, when you look in that central cube, there's not a single speculative WIMP, there's no dark matter there. Because the dark matter you're looking for, is space itself. It's dark, it has energy, it isn't moving with respect to you, and E=mc2.   
OK, so, please, do the calculation for just one galaxy that astronomers use as evidence for dark matter and show people wrong based on scientific evidence. You are trying to say that every textbook, and pretty much every equation in every textbook, on this subject is wrong. You can easily prove your point by doing one simple example.

We are all waiting.
 

Offline PhysBang

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Is Einstein's general relativity misunderstood?
« Reply #49 on: 04/02/2010 17:55:52 »
My gedanken about the single proton should be enormously important for anyone who thinks about it's meaning. THE EXPANDING ELECTRIC FIELD OF THE PROTON IS THE AETHER OF SPACE . When all the electrons and protons were created their expanding electric fields created space at C.
What you have written fails to be a gedanken experiment because it fails to elicit gedanken. You make some claims, but I have no idea what they could possibly mean.
 

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Is Einstein's general relativity misunderstood?
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