The Doppler Effect and the Velocity of Light in Einstein's Theory

[jcsd]

SR doesn’t apply. Its “speed limit of c” is not correct, and its constancy postulate is not correct.

The classical Doppler redshifts indicate that the distant galaxies move much faster than c relative to the Earth and their light takes so long to reach us because it is first moving at an average of c relative to the galaxy that emits the light but at – c relative to the earth. Light gradually slows down the negative speed as it travels through space and it gradually speeds up in the direction of the earth.

So, the D&L paper reveals that the speed of light is not “constant”, the galaxies don’t have any “speed limit” relative to the earth, and some kind of “local ether” regulates the speed of light in space, which is what I’ve been saying all along. GR theory originally said the universe was not “expanding”, so Einstein had to modify GR to make it fit observation. So regarding both SR and GR, Einstein was wrong. He had to change his incorrect theories to match observation.

SR applies locally still, indeed SR always applies locally in GR. Of course in the case of recession velocites we are not dealing with the Minowski metric, so we cannot look at just the special case we have to look at the general case (think of it this analogy: SR is like the generalized form of the equation of a circle and GR is like the generalized form for the equation of an elipse, of which the circle is a special case). The local coordinate velcoity of light is still always c in GR (this should be obvious as the spaces are described are still manifolds), but the remote coordinate velocity isn't always c.

Now we never use the non-relativistic formula for redshift in this situationas we know that it is only an approximation valid when c >> v and doesn't take into account the curvature of spacetim or it's expansion.

GR does say that the universe is expanding, indeed it comes naturally out of the theory, rmemebr that the Friedmann-Lemaitre cosmolocal model was entirley based on GR and this was before any evidence was observed for an expanding universe.

 

[David]

GR does say that the universe is expanding, indeed it comes naturally out of the theory, rmemebr that the Friedmann-Lemaitre cosmolocal model was entirley based on GR and this was before any evidence was observed for an expanding universe.

No, that is not true. If GR said “the universe is expanding,” then Einstein would have said, “the universe is expanding” in 1916. But he specifically said the universe was “fixed”.

GR was specifically designed to keep the universe from either expanding or contracting.

All of this goes back to the question that Newton and others asked, “If the gravity of all astronomical bodies ‘pulls’ on each of the bodies, then why does the universe not collapse in on itself, due to all the gravitational pull?”

Newton suggested four possible solutions to that question: 1) maybe it is collapsing but we just don’t notice it; 2) maybe it is expanding but we just don’t notice it; 3) maybe the universe is infinite and all gravity ‘pulls’ cancel each other out in all directions; 4) maybe the whole universe is rotating.

Turns out that he was right about #2.

Turns out that Einstein was wrong and the universe was not “fixed”. He wrote a paper about this in 1932, in which he retracted his “curved space” idea and his cosmological constant. So, he not only didn’t “predict” the expansion, he was caught off-guard by it and had to change his GR theory to accommodate the expansion. Here are some excerpts from his 1932 paper:

”In a recent note in the Göttinger Nachrichten, Dr. O. Heckmann has pointed out that the non-static solutions of the field equations of the general theory of relativity with constant density do not necessarily imply a positive curvature of three-dimensional space, but that this curvature may also be negative or zero.

There is no direct observational evidence for the curvature, the only directly observed data being the mean density and the expansion, which latter proves that the actual universe corresponds to the non-statical case. It is therefore clear that from the direct data of observation we can derive neither the sign nor the value of the curvature, and the question arises whether it is possible to represent the observed facts without introducing a curvature at all.

Although, therefore, the density corresponding to the assumption of zero curvature and to the coefficient of expansion may perhaps be on the high side, it certainly is of the correct order of magnitude, and we must conclude that at the present time it is possible to represent the facts without assuming a curvature of three-dimensional space. The curvature is, however, essentially determinable, and an increase in the precision of the data derived from observations will enable us in the future to fix its sign and to determine its value.”

Full title of the paper: “On the Relation between the Expansion and the Mean Density of the Universe” Albert Einstein and Wilhelm de Sitter, Proceedings of the National Academy of Sciences 18, 213-214. Reproduced in “A Source Book in Astronomy and Astrophysics, 1900 – 1975”, published by Harvard University Press, Cambridge, MA, and London, England, 1979. Edited by Kenneth R. Lang and Owen Gingerich.

What started the new renewed interest in the possibility that the universe was “expanding” was Sliper’s work early in the 20th Century, and especially his 1917 paper, “A Spectrographic Investigation of Spiral Nebulae,” Proceedings of the American Philosophical Society 56, 403-409 (1917). He said in his paper that his spectrographic evidence revealed that the majority of spiral galaxies he examined were moving away from the Earth at high speeds, at speeds much faster than the speeds of the motions of the stars. So it was his work that told physicists as early as 1917 that the universe certainly was not “fixed” and that it seemed to be expanding. 10 years later Hubble confirmed Sliper’s findings. Five years after Hubble’s announcement, Einstein retracted his “universal curved space” idea and his “cosmological constant”.

You need to go back and read the original papers and original books. You can’t rely on information published in modern books and magazine articles, written by science writers who haven’t conducted the proper historical research. What they often do is merely copy two or three other recent articles they’ve read. I was in the magazine business, and I know how it works. Writers grab urban legends from other recent magazine articles and books, and they pass the legends along without conducting any in-depth research of their own.

 

[jcsd]

No, that is not true. If GR said “the universe is expanding,” then Einstein would have said, “the universe is expanding” in 1916. But he specifically said the universe was “fixed”.

GR was specifically designed to keep the universe from either expanding or contracting.

All of this goes back to the question that Newton and others asked, “If the gravity of all astronomical bodies ‘pulls’ on each of the bodies, then why does the universe not collapse in on itself, due to all the gravitational pull?”

Newton suggested four possible solutions to that question: 1) maybe it is collapsing but we just don’t notice it; 2) maybe it is expanding but we just don’t notice it; 3) maybe the universe is infinite and all gravity ‘pulls’ cancel each other out in all directions; 4) maybe the whole universe is rotating.

Turns out that he was right about #2.

Turns out that Einstein was wrong and the universe was not “fixed”. He wrote a paper about this in 1932, in which he retracted his “curved space” idea and his cosmological constant. So, he not only didn’t “predict” the expansion, he was caught off-guard by it and had to change his GR theory to accommodate the expansion. Here are some excerpts from his 1932 paper:

”In a recent note in the Göttinger Nachrichten, Dr. O. Heckmann has pointed out that the non-static solutions of the field equations of the general theory of relativity with constant density do not necessarily imply a positive curvature of three-dimensional space, but that this curvature may also be negative or zero.

There is no direct observational evidence for the curvature, the only directly observed data being the mean density and the expansion, which latter proves that the actual universe corresponds to the non-statical case. It is therefore clear that from the direct data of observation we can derive neither the sign nor the value of the curvature, and the question arises whether it is possible to represent the observed facts without introducing a curvature at all.

Although, therefore, the density corresponding to the assumption of zero curvature and to the coefficient of expansion may perhaps be on the high side, it certainly is of the correct order of magnitude, and we must conclude that at the present time it is possible to represent the facts without assuming a curvature of three-dimensional space. The curvature is, however, essentially determinable, and an increase in the precision of the data derived from observations will enable us in the future to fix its sign and to determine its value.”

Full title of the paper: “On the Relation between the Expansion and the Mean Density of the Universe” Albert Einstein and Wilhelm de Sitter, Proceedings of the National Academy of Sciences 18, 213-214. Reproduced in “A Source Book in Astronomy and Astrophysics, 1900 – 1975”, published by Harvard University Press, Cambridge, MA, and London, England, 1979. Edited by Kenneth R. Lang and Owen Gingerich.

What started the new renewed interest in the possibility that the universe was “expanding” was Sliper’s work early in the 20th Century, and especially his 1917 paper, “A Spectrographic Investigation of Spiral Nebulae,” Proceedings of the American Philosophical Society 56, 403-409 (1917). He said in his paper that his spectrographic evidence revealed that the majority of spiral galaxies he examined were moving away from the Earth at high speeds, at speeds much faster than the speeds of the motions of the stars. So it was his work that told physicists as early as 1917 that the universe certainly was not “fixed” and that it seemed to be expanding. 10 years later Hubble confirmed Sliper’s findings. Five years after Hubble’s announcement, Einstein retracted his “universal curved space” idea and his “cosmological constant”.

You need to go back and read the original papers and original books. You can’t rely on information published in modern books and magazine articles, written by science writers who haven’t conducted the proper historical research. What they often do is merely copy two or three other recent articles they’ve read. I was in the magazine business, and I know how it works. Writers grab urban legends from other recent magazine articles and books, and they pass the legends along without conducting any in-depth research of their own.

As I saidn expansion comes naturally out of GR, but if you assume a certain value for the cosmological constant then you get a steady state. this is all Einstein did.

 

[Hurkyl]

One should recall that when Einstein was deriving his field equations, he was distressed to find that they predicted an expanding universe.

So he went back to a previous step where he had performed integration. His original derivation had assumed the constant of integration was zero, so he removed that assumption. That constant of integration is what we now call the cosmological constant, and can yield a steady state model when set to the right value. Einstein was happy.

Later, when it was shown the universe is expanding, Einstein said that dismissing GR's prediction of said fact was the greatest blunder of his life.

 

[David]

As I saidn expansion comes naturally out of GR, but if you assume a certain value for the cosmological constant then you get a steady state. this is all Einstein did.

No, “collapse” comes naturally out of any gravity theory. That’s why he added the cosmological constant, to keep the universe from collapsing. The constant served his purposes to keep the universe from contracting or expanding. This was due to an ideological belief of his, which you can read about in chapter 30 of his 1916 book:

http://www.marxists.org/reference/archive/einstein/works/1910s/relative/ch30.htm

He didn’t want the universe to be either contracting or expanding. It’s unfortunate when scientists allow their ideological beliefs to interfere with their science research.

 

[David]

Later, when it was shown the universe is expanding, Einstein said that dismissing GR's prediction of said fact was the greatest blunder of his life.

LOL, show me the original Einstein document that quote is in! Your version is new. That’s not what I’ve been reading in books and magazine articles for the past 20 years.

He was embarrassed for not in any way predicting the expansion, and he was embarrassed because Newton did predict it 235 years earlier.

Here’s what Einstein actually said in his 1917 paper, “Cosmological Considerations on the General Theory of Relativity”:

“From this it follows in the first place that the radiation emitted by the heavenly bodies will, in part, leave the Newtonian system of the universe, passing radially outwards, to become ineffective and lost in the infinite. May not entire heavenly bodies fare likewise? It is hardly possible to give a negative answer to this question. For it follows from the assumption of a finite limit for Φ at spatial infinity that a heavenly body with finite kinetic energy is able to reach spatial infinity by overcoming the Newtonian forces of attraction. By statistical mechanics this case must occur from time to time, as long as the total energy of the stellar system – transferred to one single star – is great enough to send that star on its journey to infinity, which it never can return.”

Here he is merely speculating that “from time to time” some stars might escape a spherical Newtonian universe, and he is certainly indicating here that he has no idea that a mass “expansion” of stars and galaxies was taking place.

He went on to say,

“These differences must really be of so low an order of magnitude that the stellar velocities generated by them do not exceed the velocities actually observed.”

He is talking here about the very low speeds of stars, which is all he knew about at that time. He didn’t even know then, in 1917, that galaxies were collections of stars outside our own galaxy, and he was not yet aware of Sliper’s work regarding the high-speed motion of the galaxies.

 

[Hurkyl]

It is attributed to Einstein by George Gamow in "My World Line". I find it difficult to believe that you have spent 20 years researching the topic without ever having encountered the phrase; it appears in just about every non-technical article about the cosmological constant.

 

[Hurkyl]

I find it curious that the only two references I could find to "projectile impulse" in reference to an expanding universe was http://www.metaresearch.org/msgboard/topic.asp?TOPIC_ID=481 by, well, you.

 

[Hurkyl]

But in any case, I just don't see the point of your post, David. Democritus believed matter was made up of atoms, but we can hardly attribute to him the atomic theory of matter. Supposing Newton did consider the idea that all mass did originally have a "projectile impulse" that has not yet been overcome by gravitational attraction, such a theory bears no resemblence to big bang theory. (Though it is somewhat similar to the popular misconceptions of BBT)

 

[russ_watters]

It is attributed to Einstein by George Gamow in "My World Line". I find it difficult to believe that you have spent 20 years researching the topic without ever having encountered the phrase; it appears in just about every non-technical article about the cosmological constant.

Here are 3,570 references... http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=cosmological+constant+einstein+blunder (here's one):

Einstein's original cosmological model was a static, homogeneous model with spherical geometry. The gravitational effect of matter caused an acceleration in this model which Einstein did not want, since at the time the Universe was not known to be expanding. Thus Einstein introduced a cosmological constant into his equations for General Relativity. This term acts to counteract the gravitational pull of matter, and so it has been described as an anti-gravity effect.

In addition to this flaw of instability, the static model's premise of a static Universe was shown by Hubble to be incorrect. This led Einstein to refer to the cosmological constant as his greatest blunder, and to drop it from his equations.

 

[David]

The gravitational effect of matter caused an acceleration in this model which Einstein did not want, since at the time the Universe was not known to be expanding.

Uhh, excuse me, but the “gravitational effect” doesn’t cause masses to fly apart. It causes them to collapse in on each other.

 

[David]

I find it curious that the only two references I could find to "projectile impulse" in reference to an expanding universe was http://www.metaresearch.org/msgboard/topic.asp?TOPIC_ID=481 by, well, you.

Oh, you’ve searched all the books of the world?

You’ve searched through all my books?

Or did you just do a quick Google?

Quick Googles are bringing ignorance to the world of science.

Here, try this search engine and go find yourself some real books:

http://www.trussel.com/f_books.htm

 

[David]

It is attributed to Einstein by George Gamow in "My World Line". I find it difficult to believe that you have spent 20 years researching the topic without ever having encountered the phrase; it appears in just about every non-technical article about the cosmological constant.

The most published phrase has been, “the cosmological constant was my worst mistake”. It had absolutely nothing to do with Einstein’s equations claiming the universe was “expanding”. His equations did not show that, and he did not believe that.

Just like with any gravity theory, a spherical universe will collapse, not expand, unless someone adds something like the “cosmological constant” or hypothesizes a “projectile impulse” at the beginning. Neither Einstein nor his equations “predicted” the Big Bang.

 

[David]

Do you understand? Gravity attracts. He thought the universe would collapse if he didn’t add the “cosmological constant”. It didn’t occur to him that it might be “expanding”. The combined gravity fields of the universe would have had a natural “collapsing” effect, not an “expansion” effect. So he added the constant to keep it from collapsing and also to keep it from having a center.

What you said here was wrong:

One should recall that when Einstein was deriving his field equations, he was distressed to find that they predicted an expanding universe.



Later, when it was shown the universe is expanding, Einstein said that dismissing GR's prediction of said fact was the greatest blunder of his life.

His equations DID NOT predict an expanding universe, and that’s not why he added the “cosmological constant”.

 

[Hurkyl]

Quick Googles are bringing ignorance to the world of science.

You're right, I suppose I should've consulted the vast collection of books on the history of science that I have on my bookshelf. How silly of me.

(allow me to point out that there is a lot of good information available on the internet if one knows how to look and how to sort the good from the bad)

(And, for the record, "projectile impulse" did appear in a Google search, but aside from your post, the term is not in reference to an expanding universe)

(And, incidentally, I did a bit more than a quick search)

Anyways, it would tend to be customary in this situation for you to provide a specific reference, rather than deride others for not finding it.

I've since come across the text of four of Newton's letters to Bentley. Nowhere in them appears the word "projectile", let alone "projectile impulse", nor do they seem to contain any content resembling what you ascribe to Newton. (Though I will admit it's past midnight and I'm sleepy, so I may not have been 100% thorough in browsing them, so if you still stand by your assertion, maybe you could point out just where it appears)

Just like with any gravity theory, a spherical universe will collapse, not expand, unless someone adds something like the ?cosmological constant? or hypothesizes a ?projectile impulse? at the beginning.

I did some checking, and every reference I encountered confirms what I remember. Solutions with Λ = 0 all have decreasing rates of expansion (negative expansion = contraction). Among possibilities are (this list may be exhaustive, given reasonable constraints on matter): an ever contracting universe, an ever expanding universe, and a universe that starts off expanding but eventually contracts.

In any case, Λ = 0 cannot yield a static universe, thus Einstein introduced it (said it was nonzero) to enable a static universe.


For the record, references I did find to "projectile impulse" suggest the idea of some object physically imparting momentum to the other object to propel it (or parts of it) into an interesting trajectory. (e.g. Godwin's "Essay XXI of Astronomy") This is unsatisfactory for the concept of an expanding universe since there was no external object to impart said momentum. Furthermore, I even think it's nonsensical to suggest that the net expansion of space-time could be caused by any sort of collision. (But, alas, I don't know enough about GR to be sure of this last claim)

 

[David]

You're right, I suppose I should've consulted the vast collection of books on the history of science that I have on my bookshelf. How silly of me.

(allow me to point out that there is a lot of good information available on the internet if one knows how to look and how to sort the good from the bad)

I agree with that, Hurkyl, and I use Google all the time, but I’ve never told anyone that such and such is not true because I couldn’t find it on Google. That’s the danger of Google and the internet. There are things in books that are not on the internet and not indexed by Google.

I’m older than you. We didn’t have Google most of my life. We had “books”. Things made out of ink and paper, cardboard and leather.

Here is a quote from an 1803 book that I have in my library. This information comes from Newton’s letters to Bentley. I don’t have time to type up all my books and put all their text on the internet.

“Natural Theology”, by William Paley, 1803, page 276:

“But many of the heavenly bodies, as the sun and fixed stars are stationary. Their rest must be the effect of an absence or of an equilibrium of attractions. It proves also that a projectile impulse was originally given to some of the heavenly bodies, and not to others. But further; if attraction act at all distances, there can be only one quiescent center of gravity in the universe: and all bodies whatever must be approaching this center, or revolving around it. According to the first of these suppositions, if the duration of the world had been long enough to allow it, all its parts, all the great bodies of which it is composed, must have been gathered together in a heap round this point.”

Here are a few comments by Newton about the “big bang”, which he simply attributes to a “Deity”, since he couldn’t figure out how all the stars got distributed around space. As he points out, gravity should have been pulling all the stars inward, and there was no physics mechanism to account for the projectile motion of all the stars. In fact, today there is STILL no physics mechanism that can account for the projectile force that started the Big Bang.

“I would now add, that the Hypothesis of Matter’s being at first evenly spread through the Heavens, is, in my Opinion, inconsistent with the Hypothesis of innate Gravity, without a supernatural Power to reconcile them, and therefore infers a Deity. For if there be innate Gravity, it is impossible now for the Matter of the Earth and all the Planets and Stars to fly up from them, and become evenly spread throughout all the Heavens, without a supernatural Power; and certainly that which can never be hereafter without a supernatural power, could never be heretofore without the same Power.”

Here he is basically saying that God must have been responsible for the expansion of the universe and the even distribution of matter. This was written in one of his letters to Bentley, dated Feb. 11, 1693. His personal opinions about theological causes were generally restricted to his letters to Bentley, since Bentley was a preacher. Also keep in mind that in the old days the term “supernatural power” also meant a “natural power” that was “super” but “unknown.” In other words, not “magic”, but just an unknown natural power that was not understood yet. That was sort of like Einstein’s term, “God does not play dice with the universe.” In other words, God designed nature to work by “laws”, even if we don’t know yet what all those laws are. This excerpt is from the book “Isaac Newton Papers and Letters on Natural Philosophy,” edited by Bernard Cohen and published in 1958. You won’t find this stuff on Google. You have to get it from books. You can order a copy of this book from AbeBooks for as little as $15.

 

[David]

I did some checking, and every reference I encountered confirms what I remember. Solutions with Λ = 0 all have decreasing rates of expansion (negative expansion = contraction). Among possibilities are (this list may be exhaustive, given reasonable constraints on matter): an ever contracting universe, an ever expanding universe, and a universe that starts off expanding but eventually contracts.

In any case, Λ = 0 cannot yield a static universe, thus Einstein introduced it (said it was nonzero) to enable a static universe.

I know that. That’s what I said. You said he introduced it to keep the universe from expanding, but I told you that he introduced it to keep the universe from contracting.

With gravity, the universe should contract, not expand, and since he didn’t know of any evidence of the radial motion of the galaxies, he added the constant to explain why it was not contracting.

But a myth has grown up in recent years that says he added it to keep the universe from “expanding”. That is silly and it is just one of the many Einstein urban legends that have grown up in the past 30 years.

And as I said, Newton went over all of this very same stuff with Bentley and others 300 years ago.

 

[jcsd]

I know that. That’s what I said. You said he introduced it to keep the universe from expanding, but I told you that he introduced it to keep the universe from contracting.

With gravity, the universe should contract, not expand, and since he didn’t know of any evidence of the radial motion of the galaxies, he added the constant to explain why it was not contracting.

But a myth has grown up in recent years that says he added it to keep the universe from “expanding”. That is silly and it is just one of the many Einstein urban legends that have grown up in the past 30 years.

And as I said, Newton went over all of this very same stuff with Bentley and others 300 years ago.

David, it depends on the parameters whether or not the unieverse will exopand in general relativity, but an expansion phase is a feature of realistic models.

 

[David]

David, it depends on the parameters whether or not the unieverse will exopand in general relativity, but an expansion phase is a feature of realistic models.

This is nothing new. With all the gravity in the universe, the only thing the universe can naturally do is “contract”, unless we add some kind of “cosmological constant” to keep it steady, or imagine some kind of “projectile force” to cause it to expand fast enough so that the expansion counter-acts the gravity. This has been known for hundreds of years. Einstein studied Newton’s stuff. He knew this. His personal preference was for a “static” universe because all the astronomy books he had read at the time said the universe looked “static”, so he designed the GR theory around that concept.

If he had preferred a “collapse”, he would have left out the constant. If he had preferred an expansion, he would have added an initial “projectile force” to his theory.

 

[jcsd]

You need a 'projectile force' in GR as spacetime containing energy expands naturally (countered by gravity). Of cousre for ceratin densities to achieve certain rates of exapnsion some sort of force is needed (i.e. dark energy)

 

[DrChinese]

... This is explained by a moving medium in classical Doppler theory, 1842. There is no “relativity” involved with this phenomenon.

Einstein’s own incorrect relativity ideas kept him blind to this phenomenon and the expansion of the universe. He had to alter his theories after Hubble made his announcement.

It was Newton who first proposed the BB theory, and he turned out to be right.

David, your abuse of history is even worse than your abuse of physics. All physicists consider many ideas and concepts during their liketime. To say that Newton invented or was a strong proponent of the BB is ridiculuous. It is just as absurd to say that Einstein created GR to justify a static universe, or that he was opposed to the BB.

And if you know of somewhere an observer can measure the speed of light to be different than c, well, please enlighten us. If you know of a way to accelerate an object above c, please enlighten us on that as well. Your Nobel awaits.

P.S. How could I have overlooked Doppler's contributions to photon theory, seeing instead Einstein's undeserved contributions? I guess it is that scientific conspiracy thing. Einstein would be amused to find that he was the beneficiary of that conspiracy.

 

[russ_watters]

Uhh, excuse me, but the “gravitational effect” doesn’t cause masses to fly apart. It causes them to collapse in on each other.

?? It doesn't say anything in that quote about masses flying apart. What are you talking about?

Just like with any gravity theory, a spherical universe will collapse, not expand, unless someone adds something like the “cosmological constant” or hypothesizes a “projectile impulse” at the beginning. Neither Einstein nor his equations “predicted” the Big Bang.

So you're saying that its natural to assume that the universe is infinitely old and has been collapsing for an infinite amount of time, but has a finite amount of life left before collapsing completely? Doesn't that seem a little absurd to you (there are a large number of reasons why that is absurd)? Your intuition is pretty much opposite of what physicists have theorized, and for good reason: it leads to an absurd conclusion.

At one time, it was believed that the unvierse was eternal and static. But throwing gravity into that universe would indeed cause contraction: therefore the universe cannot be static. It must either be expanding or contracting. Gravity causes an acceleration that either slows expansion or causes contraction after an expansion phase (or both).

Since the universe cannot be infinitely old, contraction must have been preceded by expansion. And as it turns out, we're still in the expansion phase and we aren't yet sure if it will ever contract again (though its looking like no).

And, for the record, "projectile impulse" did appear in a Google search, but aside from your post, the term is not in reference to an expanding universe

My guess would be you didn't find it because "projectile impulse" implies to me an explosion, the usual misunderstanding/mischaracterization of the Big Bang

David, it appears I gave you too much credit before in assuming you were just arging points you knew to be wrong for fun: you appear now to have some major gaps in your knowledge/understanding and a simple unwillingness to learn. Though it may be more pathological: you abuse/distort/misrepresent/mischaracterize to cover your unwillingness to learn. Disappointing, actually.

 

[russ_watters]

And if you know of somewhere an observer can measure the speed of light to be different than c, well, please enlighten us. If you know of a way to accelerate an object above c, please enlighten us on that as well. Your Nobel awaits.

He has quite a lot actually - all based on the same type of abuses (or, to be fair, common misconceptions). A good one is the "acceleration" of light around a star through gravitational lensing and gravitational doppler shift being a variable C phenomenon.

The most common though I guess is his abuse of frames of reference such as in his statements about >C expansion of the universe.

 

[russ_watters]

Among possibilities are (this list may be exhaustive, given reasonable constraints on matter): an ever contracting universe, an ever expanding universe, and a universe that starts off expanding but eventually contracts.

For my own personal enlightenment, is that a reasonable possibility? I know it doesn't fit with what we observer our own universe to be doing, but hypothetically, could a universe be eternally contracting? It doesn't seem to me that it would be.

 

[DrChinese]

He has quite a lot actually - all based on the same type of abuses (or, to be fair, common misconceptions). A good one is the "acceleration" of light around a star through gravitational lensing and gravitational doppler shift being a variable C phenomenon.

The most common though I guess is his abuse of frames of reference such as in his statements about >C expansion of the universe.

What I meant was:

SR is a theory. All theories have a scope of applicability. So trying to apply it outside of that scope may provide non-sensical results.

SR does say that an observer cannot create an experiment in which the speed of light is measured as other than c. SR does say that you cannot accelerate a galaxy faster than c. However, SR does not say that galaxies cannot be measured to recede from each other faster than c. That is in fact an application of SR outside of its scope.

That is why I said "if you know of somewhere an observer can measure the speed of light to be different than c, well, please enlighten us." This is in response to David's comment against SR: "Its 'speed limit of c' is not correct, and its constancy postulate is not correct." Even if the value of c changed over time, SR would still be correct. Because it is not a postulate of SR that the value of c has always been the same throughout the history of the universe. Just as it is not a postulate of SR than space cannot expand.

 

[Hurkyl]

Here are a few comments by Newton about the ?big bang?, which he simply attributes to a ?Deity?,

http://vms.cc.wmich.edu/~mcgrew/Bent3.htm (Just so others have a reference; you want the other 3 letters, just change that '3' to a '1', '2', or '4')

Here he is basically saying that God must have been responsible for the expansion of the universe and the even distribution of matter.

I can see how the letter could be interpreted as expansion, though it seems a big stretch. In particular, because this phrase appears to be elucidating the statement "... the Hypothesis of Matter?s being at first evenly spread through the Heavens ..." (boldface mine)

But I cannot see how this could be reasonably described as projectile impulse because not only does the deity have to be responsible for the "flying up", but responsible for keeping them falling back down.

I don?t have time to type up all my books and put all their text on the internet.

I'm not asking you to do so; I do have access to a library that might have these things, should I know for what I'm looking. (though I admit it is awfully nice to quote passages; one reason why I strongly prefer internet resources in these debates is so that everyone has access to the references)

With gravity, the universe should contract, not expand

No; you're mixing up first and second derivatives. The rate of growth is what is required, by gravity (and Λ=0), to be decreasing.

Even Newtonian gravity has examples of eternal universal expansion.

But a myth has grown up in recent years that says he added it to keep the universe from ?expanding?. That is silly and it is just one of the many Einstein urban legends that have grown up in the past 30 years.

The focus is on the expansion because, of the cases with Λ=0, that is the one that turned out to be right.

I will note that you do need Λ>0 in order for expansion to be accelerating, a key ingredient of BBT.

but hypothetically, could a universe be eternally contracting?

Einstein's field equations are symmetric under time reversal, aren't they? If they admit an eternally expanding solution, they must also admit an eternally contracting solution. (Of course, this doesn't suggest that there aren't other reasons why an eternally contracting universe is unreasonable. Boy, lots of negatives in that statement )

 

[jcsd]

Yes they are time symmetric, but I don't think it necessarily follows from time symmetry that if in one model there has a certain state at t = 0 and and anothe rat t =infinity then there exists another model that has the same state that the first one had at t = infinity at t' = 0 and the same state as the first one had at t = 0 at t' = infinity because basically the first universe will never be in state t = infinity. In fact I think you find that at t' = 0 you have a universe that is in equilibrium, neither contracting nor expanding,

 

[pallidin]

For the record, references I did find to "projectile impulse" suggest the idea of some object physically imparting momentum to the other object to propel it (or parts of it) into an interesting trajectory. (e.g. Godwin's "Essay XXI of Astronomy")

(Emphasis mine) Hurkyl, perhaps this is not relevant to this discussion, but you statement prompted me to offer this info.
Impulse force propagation does not behave in the same way as non-impulse.
It is very curious that this is the case, and it is not well understood by those researching it(NYU, NASA and others)
Apparently, constant force applied on object contact effects a generally linear propagation(we all know that), whereas the same force, segmented as an impulse, does not do this, rather exhibiting a non-linear contact propagation characteristic.
In general, an object hit by an quick impulse will experience a non-linear, spherical wave propagation of the force imparted to it.
This can lead to somewhat bizarre effects, especially if other "objects" of differring dimensions are involved in the contact scenario.
How this might relate to cosmological influence is unknown(to my knowledge), but certainly worthy of further inquiry.

 

[russ_watters]

What I meant was...

We're on the same page.

 

[Michael F. Dmitriyev]

The velocity of light is unique, absolute and SINGLE speed existing in the nature.