User talk:JimJast/Discussion of speed of light with Pdn

Discussion of GR with Pdn

Sorry but I changed a lot of stuff you put into GR. I am willing to discuss more if it is not clear [Pdn].

It isn't clear and the main point is the principle of conservation of energy. If you can demonstrate in a straightforward fashion that energy is still conserved when c=const then I might agree with you.

So the problem we should discuss is a simple non inertial coordinate frame attached to the surface of the earth in which a brick is in free fall. The energy of the brick is seemingly increasing (by its kinetic energy) but where is the source of this kinetic energy?

My answer is that when brick falls into space in which time runs slower and therefore c is smaller accordingly there is in fact drop of internal energy of the brick therefore the kinetic energy is the part of internal energy converted into kinetic energy (I did the necessary calculations and they agree with this result). What's your answer to question about the origin of kinetic energy of a falling brick? (We may deal with the rest of your text later when we are through with questio of conservation of energy). Jim 08:16, 3 September 2005 (UTC)

The rest of the problems (partly discussed)

• The basic problem with the varying-c varying-mass approach is that it is useful mostly in weak field cases admitting a rigid reference frame. I mean, like the Schwarzschild metric has spatial reference points that remain at constant distance from each other. Note that all of these points have a nonzero acceleration! In more complicated cases, like near an emitter of gravitational waves, or in cosmology, it's much harder, and, in the end confusing, to let c vary.

• By the way, your main page has "Art Institut of Boston" on it but I think there is probably an "e" after "tut". Pdn 00:58, 2 September 2005 (UTC)

I fixed this one. Thank you. At the next edit session you may remove this whole item. Jim 11:45, 4 September 2005 (UTC)

• Thanks for your reply - sorry I offended you. I am not sure what you meant about discussing the stuff - when I engage in dialogues often the other party does not make any change, even when his/her material is wrong.

(i) I'm not offended. (ii) By "discussing the stuf" I mean showing that the material is wrong and securing an agreement of the other party. I know that sometimes it isn't possible but it should be tried first because the other party may have valid arguments.

All contemporary cosmology is most likely wrong because it is based on an assumption of non conservation of energy in general relativity that isn't yet accepted by physicists. Actually the contemporary GR is constructed with an assumption of expanding universe in it so (i) it is automaticaly wrong if the universe is not expanding and (ii) it prevents verifying within this "new general relativity" (as distinguished from original "Einstein's general relativity", most likely with at least implicit conservation of energy in it) whether the universe is expanding. Bad physics.

IMHO the reason for this "bad physics" is that it is done by mathematicians instead of physicists and I noticed that mathematicians tend to ignore "physical reality" and are satisfied with a set of non contradictory assumptions that for them all are created equal. So dropping the conservation of energy from their assumptions because it doesn't fit Riemannian geometry is a right thing to do. Physicists on the other hand don't care at all about consistent set of assumptions, but care a lot about "physical reality" that does not even exist for mathematicians. For physicists the egreement with observation is all what counts. For a mathematician if observations don't fit the equations it disqualifies the observation (they can't dump their theory every time the nature doesn't like it). Facts of life noticed at discussions between astrophysicists and theorists at my school. That's why we have a conflict here (IMHO). It seems to me that you tend to believe theorists who don't have a single right prediction since 1927. And the famous SN experiment that was designed to provide first such successful prediction ended in spectacular failure: just opposite result (the expansion of the universe accelerating!) to the predicted, and interestingly enough the result consistent with Einstein's theory with conservation of energy (in which the expansion is just an illusion caused by "general time dilation", a phenomenon overlooked in his original theory by Einstein himself, luckily rescued by truly yours). Jim 11:45, 4 September 2005 (UTC)

Reply

What you have written above and in the on-line paper you cite [1] does not make any sense to me. The stuff above on this page mainly seems to express irritation with all or most physicists and mathematicians, which does not illuminate the topic. The stuff in your web paper seemd off the mark to me for many reasons, among them being that it is really another tired light theory. You say the redshift is due to scattering off dust (galaxies).

Do I really? Could you quote the offensive phrase that gave you this impression? I surely didn't mean it so if you have such an impression I have to fix it. The reason is only Einsteinian (general) time dilation, no scattering, since the universe is treated as sufficiently homogeneous universe and in such a model there can't be any scattering (vanishing average deflection). Jim

But scattering diffuses the light, so the appearances would be blurred, so much so that high redshift objects would have their images obliterated. Also by your idea we'd find that redshifts (for equal type or intrinsic brightness) were bigger for galaxies seen through others, or maybe through clusters of galaxies, which does not hold, I believe. I do not have time to study this stuff much more - if you still think it's good you could try to publish it in a journal. Your main page says you are an astronomy student, so maybe you could discuss your ideas with some professors there in physics and astronomy.

I talked to physics professors and astronomy professors and none is seeing a formal problem with this approach. Some believe it is a right approach. I'm looking for critical opinions though. Jim

I do not know what "IMHO" means.

"IMHO" is internet slang word meaning "in my humble opinion". Jim

Good luck Pdn 04:11, 5 September 2005 (UTC)

The question was not about my paper but about speed of light. Do you know any reason why coordinate velocity of light has to be c? And if you do then what is it and how do you explain bending of light in vicinity of the Sun? Jim 15:59, 5 September 2005 (UTC)

The coordinate velocity of light does not have to be c.

So we agree on this point. Jim

The bending of light near the Sun is calculated in many papers. Some of them use a post-Newtonian or weak-field approximation, in which you can indeed deal with the whole problem using a varying coordinate-velocity of light! So you could fix up part or all of your additions by using the term coordinate-velocity, explaining that you are using a weak-field approximation, and, hopefully giving a reference from which your equations came. You might even work up a discussion of relativistically varying mass there. Nowadays, it has been more customary to introduce the full theory and downplay the weak field approximation, precisely because it leads away from understanding the theory for strong fields and time varying gravitational fields.

The problem with present "full theory" is that it is wrong since it does not conserve energy. So in practical terms we don't have yet a "full physical theory" but only weak field approximations. Neither we observe any "strong fields" to verify the theory. So you are not talking about physics just about (wrong) mathematical theory based on wrong geometry of spacetime (since symmetric metric does not allow conservation of energy neither in stationary nor in expanding space - correct me if I'm wrong). Jim

But Chandrasekhar made a lot of progress extending the "Post Newtonian" theory to more interesting cases (see many papers by him, sometimes with John L. Friedman, Norman Lebovitz or others). Also most of your discussion that I called insulting is so obviously so that a thirteen year old child would recognize it, and I do not intent to pick up phrases in detail. Mathematicians "don't care about" or ignore this and that, physicists are in the same boat - only Jim Jast, it seems, knows "what's up." You are just trying to clue in all those Philistines, but maybe insulting them in Wikipedia is not an expedient way to do it. Seems your "IMHO" (thanks for the explanation)is not very humble.

I thought that I'm just explaining facts (why mathematicians ignore conservation of energy) and it didn't occur to me that it might be offensive to someone if it is true. What to do if truth offends someone? We are supposed to explain the world and it has to involve saying truth even if it offends someone, am I wrong? I'm baffled when someone like Prof. John Baez is trying to convince me that energy is not conserved in the real world and only in Newtonian approximation. That it is an established fact and he won't allow the issue to be discussed in sci.physics.research. Which he can do being a moderator there. I'm trying to find a rational explanation for Prof. Baez action which IMHO is that he isn't a physicists. Why it would be offensive? It just says that I believe that all physicists believe in conservation of energy. Is it really offensive? Jim

Oh, about the falling brick. Once again it is the weak field, static approximation. Fine within its scope, but leading readers away from understanding GR. In a more general GR context, the observers who see the brick fall are accelerated upwards by the Earth beneath (this is discussed later on the same page, not by me). The brick mass is constant and it is not accelerated. That may seem strange, but that is the more accurate GR approach. I think that if you count kinetic and potential energy...

There is no "potential energy" in GR since there is no field of force. It's all geometry of spacetime. Jim

...in the brick mass in the weak-field approximation, though, you will also find its mass is constant.

Not the "inertial mass" since at least it would violate the principle of equivalence. But we don't need to discuss it since I did all the necessary calculations and result is as observed in the real world, and also energy is conserved. So if you agree there is nothing to discuss. Jim

Other things

I read someplace in all the acrimonious debates one sees in Wikipedia that you are not supposed to remove messages people have put on your talk page - that is why it is so long. If you think it is OK to shorten it maybe I will do that. I just printed out of PROLA (Phys Rev on Line) the original paper by Shapiro, and I do not see the velocity of light varying in it. Perhaps you would indicate the place where he says that. The constancy of the velocity of light is at the core of special and general relativity, and in fact it is constant by definition nowadays. That doesn't mean you could not measure a speed of light different from the defined value, but it means you would perforce be measuring that one of your clocks was not running as it was supposed to according to standard fabrication of the clock, or that the yardstick by which you measured the distance traversed had been altered somehow from standard construction.

The velocity of light that has to be constant (or you are into a BIG TIME discovery) is in a freely falling or inertial frame. I believe you are talking about the coordinate velocity of light. That depends on the coordinates that you are using. In the case of static spacetimes (basically ones that admit a rigid transformation along the timelike axis) you can split space and time in such a way that you have a world time. If you do things just right you can get a coordinate velocity of light that varies the way you claim. I hinted at that before. If you want to put in a discussion that explains you are dealing with the coordinate velocity of light and a definition of mass energy that is defined in a certain way (that you have expressed) so that mc^2 is not the rest-energy any more, OK, so long as you explain the approximation you are using. Again, proper clocks do not run slower deep in a gravitational potential well. This result is obtained by comparing clocks at a distance from each other in a static spacetime and using signals that effectively establish a world-time. For example, a world-time for the Earth is defined in a practical fashion by TAI. If you transport a standard clock to the top of a mountain and compare its ticks to TAI you will find it seems to run fast. But that is an artifact of your protocol for comparison. You are using a world-time to compare, but that is an artifact of the coordinate system you are using. It is OK in a sense - but in a more general spacetime that is nonstatic (technically nonstationary) you can't define a world-time and there's no way to tell if clocks that are compared at a distance and found to disagree are in different gravitational potentials, moving at different velocities, or a combination. If you want to define the quantities in your statement "dc/dx=g/(2c), where dx is in direction perpendicular to the light ray, g is acceleration at the location of the light ray. If you have a result of dc/dx=0" and/or give a reference I can easily access (e.g. on-line, or in Phys Rev D, Phys Rev Letters, Science, Monthly Notices of the Royal Astronomical Society, any IOP publication ([2] ) or some book that's in most libraries or that I own. I own relativity books by Moller, Misner Thorne and Wheeler, Roberston and Noonan, P. G. Bergmann (an oldie with a foreward by Einstein), Pauli, R. H. Dicke, Clifford Will, Landau and Lifshitz, and a few more - perhaps one of these contains the material you say is well known. Best re[gards, and sorry if I seemed to be too hard on your additions. Pdn 03:47, 3 September 2005 (UTC)