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Old 7th May 2014, 08:02 AM   #2521
Perpetual Student
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Originally Posted by dasmiller View Post
Instead of 'skill,' how about 'respect?' Crackpots often seem to view the math as merely a trivial elaboration of the 'real' truth. From that perspective, the fact that they don't understand the math is like, say, a racecar driver not knowing what kind of paint is on the car.

Those who lack the skills but respect the math would be more likely to admit that they simply don't understand the physics well enough to dispute it.
Yes.
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Old 30th July 2014, 01:05 PM   #2522
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I'm not certain that this has been mentioned before.
A hallmark characteristic of crackpots seems to be their total unwillingness or incapability to recognize and understand even the the most simple and stark demonstration that any facet of their dogma is false. This inability to yield on even the most trivial detail regarding their fantasies is quite remarkable.
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Old 30th July 2014, 01:32 PM   #2523
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It's true. The problem is that they will not accept that their fantasies are just that. If somebody shows them Einstein saying space is inhomogeneous or the speed of light varies with position, the crackpot will utterly reject it, and comfort themselves by calling the other guy a crackpot. Even though what Einstein said is there in black and white and a matter of public record, with professional endorsement. It is truly bizarre.
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Old 30th July 2014, 02:58 PM   #2524
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Originally Posted by Farsight View Post
It's true. The problem is that they will not accept that their fantasies are just that. If somebody shows them Einstein saying space is inhomogeneous or the speed of light varies with position, the crackpot will utterly reject it, and comfort themselves by calling the other guy a crackpot. Even though what Einstein said is there in black and white and a matter of public record, with professional endorsement. It is truly bizarre.
The funny thing is, I don't believe in GR just because Einstein said it. I believe in GR because it's been carefully tested, by people (a) checking its equations for internal consistency and (b) devising experimental measurements and comparing them to GR calculations.

The thing I strongly believe to be true is that actual GR calculations, using Einstein's GR equations, are internally consistent and have passed extraordinarily-stringent experimental tests. The equations, in the form used to make the predictions, are widely taught, researched, explained in standard textbooks, and the meaning thus conveyed is uncontroversial. This is what I mean when I say "I believe GR is true" or "I know/understand GR". I know the same version everyone else knows, the version that's passed experimental tests.

I furthermore believe that Einstein was talking about the same GR that I believe in, and that his words have a reasonably clear meaning to people other than yourself, you being a hostile witness who's actively mining for things to misunderstanding.

However, my belief in the latter is much weaker than my belief in the former.

The standard version of GR, the equationy version, the Misner Thorne and Wheeler version, has been tested, and I'm happy to have learned it and to understand it well and to be confident in its reliability (within the domains in which such confidence is warranted), and everyone who claims to know GR will say the same thing. If it were true that Einstein's popular writings describe something else---some equationless theory that's not the one MTW picked up on---well, this "something else" theory would be untested, undeveloped, cannot be called "General Relativity", and would not inherit the intellectual heritage of the known/tested/taught version of GR. (I reiterate that you have not identified a "something else" in Einstein's writings, only familiar things that you personally misunderstood.)

Can you take your interpretation of Einstein's words and make your prediction for, say, the inspiral of the Hulse-Taylor binary pulsar? Go ahead.

Last edited by ben m; 30th July 2014 at 03:00 PM.
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Old 30th July 2014, 03:58 PM   #2525
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Originally Posted by ben m View Post
The funny thing is, I don't believe in GR just because Einstein said it. I believe in GR because it's been carefully tested, by people (a) checking its equations for internal consistency and (b) devising experimental measurements and comparing them to GR calculations.
Me too. I've said repeatedly that GR is one of the best-tested theories we've got, and that the evidence is actually more important than what Einstein said.

Originally Posted by ben m View Post
The thing I strongly believe to be true is that actual GR calculations, using Einstein's GR equations, are internally consistent and have passed extraordinarily-stringent experimental tests.
Me too. I've referred to Clifford Will's Confrontation between General Relativity and Experiment on many occasions.

Originally Posted by ben m View Post
The equations, in the form used to make the predictions, are widely taught, researched, explained in standard textbooks, and the meaning thus conveyed is uncontroversial.
That isn't true. The meaning is controversial. And one thing at the heart of that controversy is the speed of light.

Originally Posted by ben m View Post
This is what I mean when I say "I believe GR is true" or "I know/understand GR". I know the same version everyone else knows, the version that's passed experimental tests. I furthermore believe that Einstein was talking about the same GR that I believe in, and that his words have a reasonably clear meaning to people other than yourself, you being a hostile witness who's actively mining for things to misunderstanding.
Only I'm not the hostile witness, and I don't misunderstand. I point to what Einstein actually said about the speed of light varying with position, and I point to Magueijo and Moffat and Ned Wright and the Baez website and the NIST optical clocks and more to back up what I'm saying. You know, this kind of thing:

"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... 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 [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers."

Originally Posted by ben m
Can you take your interpretation of Einstein's words and make your prediction for, say, the inspiral of the Hulse-Taylor binary pulsar? Go ahead.
No. I've never said the maths is wrong, I've said some aspects of the modern interpretation is wrong. The understanding is wrong.

Originally Posted by ben m
...I reiterate that you have not identified a "something else" in Einstein's writings, only familiar things that you personally misunderstood...
I haven't misunderstood it. The bottom line is this: Wheeler misunderstood it. Yes. That's the size of it. Some aspects of MTW, the "bible", are just wrong.
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Old 30th July 2014, 04:31 PM   #2526
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Originally Posted by Farsight View Post
Me too. I've said repeatedly that GR is one of the best-tested theories we've got, and that the evidence is actually more important than what Einstein said.
This is clearly the opposite of what you have repeatedly said. You routinely repudiate contemporary physics, indeed any physics since 1920, and any use of GR out of the hands of Einstein. This means that you reject the theory as it is tested.
Quote:
Me too. I've referred to Clifford Will's Confrontation between General Relativity and Experiment on many occasions.
This, too, goes against most of your previous statements, since you regularly insult posters for using mathematics rather than the textual analysis that you provide.
Quote:
That isn't true. The meaning is controversial. And one thing at the heart of that controversy is the speed of light.
You have yet to demonstrate that anyone who has studied relativity theory believes that there is something to be debated about the speed of light in the theory.
Quote:
Only I'm not the hostile witness, and I don't misunderstand. I point to what Einstein actually said about the speed of light varying with position, and I point to...
Case in point: you insult those who attempt to discuss the mathematical details of the theory and point yourself to textual analysis.
Quote:
No. I've never said the maths is wrong, I've said some aspects of the modern interpretation is wrong. The understanding is wrong.
So far, you have never attempted to show anyone how to coincide the mathematics with your interpretation. Everyone who has studies relativity theory doubts that it is possible. You either have a means to reconcile the two or you dogmatically believe that there is such a reconciliation.

Quote:
I haven't misunderstood it. The bottom line is this: Wheeler misunderstood it. Yes. That's the size of it. Some aspects of MTW, the "bible", are just wrong.
Yet another example of insulting without serious evidence.

I think that it might be nice to adopt a slogan from another realm: Cranks believe their theory works because it seems right, scientists believe their theory is right because it seems to work.
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Old 30th July 2014, 06:46 PM   #2527
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Originally Posted by ben m View Post
The funny thing is, I don't believe in GR just because Einstein said it. I believe in GR because it's been carefully tested, by people (a) checking its equations for internal consistency and (b) devising experimental measurements and comparing them to GR calculations.

The thing I strongly believe to be true is that actual GR calculations, using Einstein's GR equations, are internally consistent and have passed extraordinarily-stringent experimental tests. The equations, in the form used to make the predictions, are widely taught, researched, explained in standard textbooks, and the meaning thus conveyed is uncontroversial. This is what I mean when I say "I believe GR is true" or "I know/understand GR". I know the same version everyone else knows, the version that's passed experimental tests.

I furthermore believe that Einstein was talking about the same GR that I believe in, and that his words have a reasonably clear meaning to people other than yourself, you being a hostile witness who's actively mining for things to misunderstanding.

However, my belief in the latter is much weaker than my belief in the former.

The standard version of GR, the equationy version, the Misner Thorne and Wheeler version, has been tested, and I'm happy to have learned it and to understand it well and to be confident in its reliability (within the domains in which such confidence is warranted), and everyone who claims to know GR will say the same thing. If it were true that Einstein's popular writings describe something else---some equationless theory that's not the one MTW picked up on---well, this "something else" theory would be untested, undeveloped, cannot be called "General Relativity", and would not inherit the intellectual heritage of the known/tested/taught version of GR. (I reiterate that you have not identified a "something else" in Einstein's writings, only familiar things that you personally misunderstood.)

Can you take your interpretation of Einstein's words and make your prediction for, say, the inspiral of the Hulse-Taylor binary pulsar? Go ahead.
I have spent a good deal of my time over the last three years studying physics (call it a hobby). The dozens of lectures, texts and papers I have studied from around the world include physics concepts and principles defined by mathematical equations and mathematical descriptions of physical phenomena. Never do the authors and professors say, "Newton wrote this," "Einstein said this" or "Maxwell believed that."
The physical systems are described and analyzed mathematically. It does not matter if the subject is statistical mechanics, relativity, quantum field theory, etc.; it's the mathematics that defines and describes the physical systems.
It seems that using and depending on the words of the "masters" is exclusively a crackpot indulgence.
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Old 30th July 2014, 07:00 PM   #2528
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I have sat in on many academic lectures and seminars where people did discuss what Newton believed and what Maxwell believed. The evidence for the discussion was, for the majority of claims, a rigourous analysis of the mathematics presented in their works.
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Old 30th July 2014, 07:01 PM   #2529
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An important part of Farsight's method is what may be called scriptural exegesis, sacred-book interpretation, or in more blunt terms, book-thumping. Complete with saying how wrong it is to deny the authors of the thumped books. If my experience is any guide, it is *very* rare in physics crackpottery, and indeed most forms of crackpottery, though it is common in creationism.

Physics crackpots usually argue more like their mainstream counterparts, addressing theories without considering their favorite theorists to be inspired prophets of revealed truth whom it would be wrong to question. However, they may also make lots of ad hominem arguments, like what orthodox oxen mainstream physicists are.
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Old 30th July 2014, 07:43 PM   #2530
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Originally Posted by Farsight View Post
"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... 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 [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers."
Funny that you fail to quote the following paragraph (by bold)

Quote:
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 not-quite-well-defined "speed" of light can differ from c, basically because of the effect of gravity (spacetime curvature) on clocks and rulers.
So, you quoted some bog-standard relativity. An accelerating observer thinks light behaves differently than an inertial one does. But you placed your cursor very carefully in order to imply both (a) "here's something that you Wheelerites failed to understand about Einstein, I know better" and also (b) "Baez is on my side on this". Nope. Your quote has Baez and Einstein (and Wheeler and, a long way down, me) agreeing on standard mainstream GR. Did you have something to add?
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Old 30th July 2014, 09:36 PM   #2531
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Originally Posted by edd View Post
Originally Posted by farsight
The front portion of a photon is a little like a partial positron, the back is a little like a partial electron. But the main point is that photons interact with photons, and QED doesn't cover it.
Wow. I expect some things from Farsight but I didn't expect anything like that.
So then there must be anti-photons with reverse charge. Can you tell us about these anti-photons farsight?
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Old 31st July 2014, 12:52 AM   #2532
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Originally Posted by ben m View Post
...and also (b) "Baez is on my side on this". Nope. Your quote has Baez and Einstein (and Wheeler and, a long way down, me) agreeing on standard mainstream GR. Did you have something to add?
Yes. The Baez website has been referred to here because it includes a crackpot index. Only when it comes to what Einstein said and the speed of light varying in the room you're in, the Baez website agrees with me. The irony is delicious. It means I'm not the crackpot. So if I'm not the crackpot, who is?

Originally Posted by Perpetual Student
It seems that using and depending on the words of the "masters" is exclusively a crackpot indulgence.
No, saying Einstein was wrong is the crackpot indulgence. And I'm on the right side of that fence.

Originally Posted by Kwalish Kid
The evidence for the discussion was, for the majority of claims, a rigourous analysis of the mathematics presented in their works.
Evidence consists of experimental results and observations, not a "rigorous analysis of the mathematics".

Originally Posted by Kwalish Kid
This is clearly the opposite of what you have repeatedly said.
No it isn't. Enough of your false assertions.

Originally Posted by lpetrich
An important part of Farsight's method is what may be called scriptural exegesis, sacred-book interpretation, or in more blunt terms, book-thumping
I'm not the book thumper, people like ben m are the book thumpers. He treats MTW like a bible. I point out what Einstein said, and he dismisses it because it proves his bible wrong.


Originally Posted by Russ Dill
So then there must be anti-photons with reverse charge. Can you tell us about these anti-photons farsight?
There aren't any. What you found related to gamma gamma pair production where the Wikipedia article used to say this:

"From quantum electrodynamics it can be found that photons cannot couple directly to each other, since they carry no charge, but half wavelength is a positive charge and the next half wavelength is a negative charge".

The issue we were discussing was that the QED given explanation says pair production occurs because pair production occurs, spontaneously like worms from mud. There's an obviously tautology with that. It's crackpot, it's cargo-cult science. What actually happens is that one photon interacts with the other.

PS: this forum is very slow.
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Old 31st July 2014, 02:06 AM   #2533
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Is The Speed of Light Everywhere the Same? stated "Given this situation, in the presence of more complicated frames and/or gravity, relativity generally relinquishes the whole concept of a distant object having a well-defined speed." Farsight, however, seems to think that the variation of the speed of light in general relativity is well-defined. He ought to stop thumping his heroes' writings and work out how to calculate this variation. He won't get taken seriously by anyone working on general relativity unless he does so.

Originally Posted by Farsight View Post
Evidence consists of experimental results and observations, not a "rigorous analysis of the mathematics".
Disdain for math again. If math is an important part of a theory, then a rigorous analysis of it is a Good Thing.
Quote:
I'm not the book thumper, people like ben m are the book thumpers. He treats MTW like a bible. I point out what Einstein said, and he dismisses it because it proves his bible wrong.
Pure projection. After calling ben m a book thumper, Farsight then acts like a book thumper, making an issue out of "what Einstein said".

Quote:
The issue we were discussing was that the QED given explanation says pair production occurs because pair production occurs, spontaneously like worms from mud. There's an obviously tautology with that. It's crackpot, it's cargo-cult science. What actually happens is that one photon interacts with the other.
Something firmly denied by those who have worked on Quantum-Electrodynamics processes at a professional level, like Richard Feynman. In pair production, the two photons do NOT directly interact, but instead make virtual electrons between them.
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Old 31st July 2014, 05:30 AM   #2534
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Farsight has expressed a curious set of opinions on what constitutes physics crackpottery. He has described supersymmetry, magnetic monopoles, string theory, multiverses, etc. as crackpottery, because there is no evidence for them, or at least so he claims.

That is strange, because that would consign *any* untested prediction of a theory to crackpottery status, and because that would imply that theorizing is not allowed to get ahead of observation and experiment. I've seen some criticisms of string theory that it's too far ahead of observation and experiment, but what Farsight seems to propose goes too far in the opposite direction.

So would these hypotheses be crackpottery?
  • 1869. Dmitri Mendeleev predicts some then-unknown chemical elements.
  • 1920. Ernest Rutherford predicts the "neutral proton" (neutron).
  • 1930. Wolfgang Pauli predicts the "neutron" (neutrino).
  • 1935. Hideki Yukawa predicts a strong-interaction carrier (pion).
  • 1962. Murray Gell-mann and Yuval Ne'eman predict the omega baryon.
  • 1964. Robert Brout, François Englert, Peter Higgs, Gerald Guralnik, Carl Hagen, and Tom Kibble predict the Higgs particle.
  • 1964. Moo-Young Han and Yoichiro Nambu predict the gluon.
  • 1968. Sheldon Glashow, Steven Weinberg, and Abdus Salam predict the W and Z particles.
  • 1970. Sheldon Glashow, John Iliopoulos, and Luciano Maiani predict the charm quark.
  • 1973. Makoto Kobayashi and Toshihide Maskawa predict the bottom and top quarks.
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Old 31st July 2014, 05:41 AM   #2535
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Originally Posted by lpetrich View Post
Is The Speed of Light Everywhere the Same? stated "Given this situation, in the presence of more complicated frames and/or gravity, relativity generally relinquishes the whole concept of a distant object having a well-defined speed." Farsight, however, seems to think that the variation of the speed of light in general relativity is well-defined.
The point is that Einstein "talked about the speed of light changing". And that this doesn't just apply to distant objects, it applies to the room you're in. Hence "this difference in speeds is precisely that referred to above by ceiling and floor observers". The Baez article backs me up. Not Perpetual Student.

I wouldn't consign *any* untested prediction of a theory to crackpottery status.
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Old 31st July 2014, 07:05 AM   #2536
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Originally Posted by Farsight View Post
No, saying Einstein was wrong is the crackpot indulgence.
Then Einstein was a crackpot, since he many times pointed out where he was wrong.
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Evidence consists of experimental results and observations, not a "rigorous analysis of the mathematics".
Not when you are looking at the way that somebody used mathematics.
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Old 31st July 2014, 07:28 AM   #2537
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Originally Posted by Farsight View Post
The point is that Einstein "talked about the speed of light changing". And that this doesn't just apply to distant objects, it applies to the room you're in. Hence "this difference in speeds is precisely that referred to above by ceiling and floor observers". The Baez article backs me up. Not Perpetual Student.
Excuse me! I have never rendered any opinion on the speed of light in GR, simply because it is not a question I have studied. However, I do see that the authors of the article you linked do say this:


Quote:
Given this situation, in the presence of more complicated frames and/or gravity, relativity generally relinquishes the whole concept of a distant object having a well-defined speed. As a result, it's often said in relativity that light always has speed c, because only when light is right next to an observer can he measure its speed—— which will then be c. When light is far away, its speed becomes ill-defined.
and this:
Quote:
In general relativity, the constancy of the speed of light in inertial frames is built in to the idea of spacetime being a geometric entity. The causal structure of the universe is determined by the geometry of "null vectors". Travelling at the speed c means following world-lines tangent to these null vectors. The use of c as a conversion between units of metres and seconds, as in the SI definition of the metre, is fully justified on theoretical grounds as well as practical terms, because c is not merely the vacuum-inertial speed of light, it is a fundamental feature of spacetime geometry.
So, I think you are a bit confused about what the authors of the article you linked are actually saying.
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Old 31st July 2014, 08:28 AM   #2538
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I'm not at all confused, and I reiterate this: yes, "relativity generally relinquishes the whole concept of a distant object having a well-defined speed". But we aren't talking about distant objects. We're talking about light in the room you're in. The light at the ceiling goes faster than the light at the floor. If it didn't light wouldn't curve, your pencil wouldn't fall down, and the NIST optical clocks would stay synchronised. Remember you said "A hallmark characteristic of crackpots seems to be their total unwillingness or incapability to recognize and understand even the most simple and stark demonstration"? The parallel-mirror gif is the simple stark demonstration.
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Old 31st July 2014, 08:40 AM   #2539
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Originally Posted by Farsight View Post
I'm not at all confused, and I reiterate this: yes, "relativity generally relinquishes the whole concept of a distant object having a well-defined speed". But we aren't talking about distant objects. We're talking about light in the room you're in.
That passage is a canonical example of Farsight confusion: you are talking about distances, yet you claim that you are not talking about distances.

In order to study physics, one has to study how physics problems are presented and solved and how physics applications are considered and implemented. If one has never done this, as Farsight seems not to have done, then one misses the very basic elements of physics. Of course, many physicists also miss the fundamental operations of their own discipline when asked to consciously consider it, but they at least have the opportunity and the basic knowledge to be lead to a proper consideration.

Quote:
The light at the ceiling goes faster than the light at the floor. If it didn't light wouldn't curve, your pencil wouldn't fall down, and the NIST optical clocks would stay synchronised.
It seems for many crackpots that they pursue a grand unified theory. Farsight's grand unified theory seems to be that light slows at different locations. As we have seen in the proper thread for its discussion, Farsight has no reason to believe this, since he has no means of turning different speeds of light into, using his example, the forces governing the trajectory of a pencil.

Quote:
Remember you said "A hallmark characteristic of crackpots seems to be their total unwillingness or incapability to recognize and understand even the most simple and stark demonstration"? The parallel-mirror gif is the simple stark demonstration.
I have seen a number of crackpots present pictures that they felt communicated a lot of information that present absolutely nothing, perhaps worse than nothing. When asked for the details, they ultimately fail to produce.
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Old 31st July 2014, 08:51 AM   #2540
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Originally Posted by Kwalish Kid View Post
I have sat in on many academic lectures and seminars where people did discuss what Newton believed and what Maxwell believed. The evidence for the discussion was, for the majority of claims, a rigourous analysis of the mathematics presented in their works.
Since I'm only an amateur studying textbooks, lectures and papers that I can find online, my experience is limited. It's true that Newton, Einstein, Maxwell, Heisenberg, etc. may be discussed in passing when the equations describing the physics are developed and discussed, but the real physics is based on the equations and experiments, not the words of the "Masters."
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Old 31st July 2014, 09:11 AM   #2541
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Originally Posted by Perpetual Student View Post
Since I'm only an amateur studying textbooks, lectures and papers that I can find online, my experience is limited. It's true that Newton, Einstein, Maxwell, Heisenberg, etc. may be discussed in passing when the equations describing the physics are developed and discussed, but the real physics is based on the equations and experiments, not the words of the "Masters."
I thought what you wrote was clear and insightful: if one is studying physics, then you study the theory and its relationship to observations. Who came up with the theory is interesting, but not necessary for comprehension and use. It is not merely in amateur study of physics that one experiences things as you described.

As the philosophers say, you are describing the study of physics qua physics (i.e., physics as itself), where as I was trying to add to the discussion by describing the study of physics as a conceptual, rhetorical, historical or sociological subject or a study of physicists themselves. I am perhaps biased to a certain type of study that takes physics seriously as a means of generating reliable knowledge rather than a study of it as a means of producing text, but given what I have seen the majority of scholars studying physics in these secondary manners share my bias.

What I sought to point out was that when one is studying physicists, then one studies their statements and their statements as expressed in the structure of their theories. Sometimes there are aspects to the structure of their theories that they miss, but the "masters" were pretty good about understanding the structures of their theories.

I can't remember the reference, but Einstein noted a debt to Maxwell in pointing out where relativity theory made its conceptual advances and one can indeed find places in Maxwell (early in Matter and Motion, for example) where he points out necessary assumptions in the structure of classical physics, assumptions that were later replaced by Einstein.

If we are interested in studying Einstein, then we should look carefully at what he had to say and how he commented on and personally used relativity theory. If we want to study relativity theory, we should look carefully at an accepted presentation of the theory (one isomorphic to, or that otherwise preserves the content of, other presentations) and its relationship to observations, regardless of whether or not it matches Einstein's peculiar commentary. Einstein's comments might produce an effective teaching tool (though the more I read, the less I find Einstein's conceptual choices helpful), but they can at best be an aid to understanding the structure and the empirical evidence.
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Old 31st July 2014, 10:00 AM   #2542
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Originally Posted by Farsight View Post
I'm not at all confused, and I reiterate this: yes, "relativity generally relinquishes the whole concept of a distant object having a well-defined speed". But we aren't talking about distant objects. We're talking about light in the room you're in. The light at the ceiling goes faster than the light at the floor. If it didn't light wouldn't curve, your pencil wouldn't fall down, and the NIST optical clocks would stay synchronised. Remember you said "A hallmark characteristic of crackpots seems to be their total unwillingness or incapability to recognize and understand even the most simple and stark demonstration"? The parallel-mirror gif is the simple stark demonstration.
The question seems to come down to this:
In my own frame of reference, whether in an inertial frame, accelerating, rotating or in a gravitational field, will I measure any source of light from any direction traveling by me at anything other than c?
I admit that I have not really studied this question, however I believe, based on what I've read, that no source of light from any direction would be measured at anything other then c. Is that not correct?
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Old 31st July 2014, 12:18 PM   #2543
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Originally Posted by Farsight View Post
There aren't any. What you found related to gamma gamma pair production where the Wikipedia article used to say this:

"From quantum electrodynamics it can be found that photons cannot couple directly to each other, since they carry no charge, but half wavelength is a positive charge and the next half wavelength is a negative charge".
Please explain how you have applied this quote to the "front" and "back" of a photon and how you chose front-positive back-negative.

ETA: Also, why are you referring to a specific revision of a WP page with an edit that has been removed. I'm not able to find any substance to what the WP editor added which was later removed. Can you link to an actual source?

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Old 31st July 2014, 01:01 PM   #2544
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Still a very simple answer for a very easy question: there are plenty of incompetents who sew words together that were never sewn up that way by real scientists. But because they have seen some words and have a vague knowledge of what the words mean out in the normal not very scientific world, they go on to misuse those words (use them in non-scientific ways /with non-scientific meanings to explain how they think real things and real science works). They have no clue as to how to develop and test hypotheses, a high school regular class knowledge of testing a hypothesis and no idea of the complexity involved in truly doing the research to verify that a hypothesis is verified or not verified. How can they, they are trying to mix writings with each other, not trying to actually perform the necessary experiments. They are doing nothing more than science by text borrowing and rearranging. Not science, just old fashioned and completely irrelevant word games. OR: Q: Why is there so much crackpot science? A: Because there are so many crackpots.
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Old 31st July 2014, 03:26 PM   #2545
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Originally Posted by RussDill View Post
ETA: Also, why are you referring to a specific revision of a WP page with an edit that has been removed. I'm not able to find any substance to what the WP editor added which was later removed. Can you link to an actual source?
Yep, it's really bizarre. An anonymous Spanish IP address adds one sentence of nonsense to a stub of a Wikipedia page. Four edits later someone removes it. For the year it was up there it was practically a case study of why Wikipedia is a complicated reference source for the unwary. But to mine this of the past-versions log and treat it as a citation ... well, if you go looking for nonsense you can find it.

It's particularly amusing to see anonymous deleted wikicruft quoted as a source, given that Farsight's usual weapon is "argument from authority"; he acts as though any Einstein quotation automatically defeats any subsequent research result. I'm sure we can find a deleted Wikipedia edit that states clearly that Einstein was a reptoid. Irrefutable, really.

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Old 31st July 2014, 08:14 PM   #2546
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Originally Posted by Kwalish Kid View Post
I can't remember the reference, but Einstein noted a debt to Maxwell in pointing out where relativity theory made its conceptual advances and one can indeed find places in Maxwell (early in Matter and Motion, for example) where he points out necessary assumptions in the structure of classical physics, assumptions that were later replaced by Einstein.
Here's an example from one of Einstein's pop-science lectures that Farsight cited earlier today:
Originally Posted by Einstein
The first stage, the special theory of relativity, owes its origin principally to Maxwell's theory of the electro-magnetic field. From this, combined with the empirical fact that there does not exist any physically distinguishable state of motion which may be called "absolute rest", arose a new theory of space and time.


Originally Posted by Kwalish Kid View Post
If we are interested in studying Einstein, then we should look carefully at what he had to say and how he commented on and personally used relativity theory. If we want to study relativity theory, we should look carefully at an accepted presentation of the theory (one isomorphic to, or that otherwise preserves the content of, other presentations) and its relationship to observations, regardless of whether or not it matches Einstein's peculiar commentary. Einstein's comments might produce an effective teaching tool (though the more I read, the less I find Einstein's conceptual choices helpful), but they can at best be an aid to understanding the structure and the empirical evidence.
I'm interested in both (studying Einstein and studying relativity theory). My interest in Einstein was rekindled by Farsight's dogmatic insistence that Einstein's general theory of relativity is quite different from what is taught by modern textbooks. Farsight's wrong about that, but seeing the equivalence between Einstein's presentations and that of (for example) Misner, Thorne, and Wheeler (MTW) does require some mathematical sophistication.

Einstein's early papers on general relativity were fairly rough, and a few of his earliest contain outright errors. Einstein had fixed most of these errors by 1916, in Die Grundlage der allgemeinen Relativitätstheorie, but some notations of that paper are so different from modern notation that reconciling its equations with those of MTW isn't always obvious. Five years later, Einstein delivered the lectures collected in The Meaning of Relativity. Those lectures mostly follow the structure of Die Grundlage der allgemeinen Relativitätstheorie, but Einstein had modernized his notation to such an extent that the correspondence between his 1921 equations and those of MTW or Weinberg is far easier to see.

I agree that Einstein's prose is often more confusing than his equations, partly because Einstein wasn't consistent. Consider, for example, the question of what Einstein meant by "the gravitational field". In one paper he refers to Christoffel symbols as "the components of the gravitational field". In another lecture he refers to components of the pseudometric tensor as "the gravitational potentials". In 1916, Einstein uses the word "curvature" only when talking about the curvature of light within a gravitational field. By 1921, Einstein uses the word "curvature" only when talking about the Riemann curvature tensor and its contractions. I think it's fair to say that Einstein's notation and terminology changed as much in those five years as those notations and terminologies would change in the next fifty (after which, MTW's Gravitation devoted two red pages of front matter to summarizing 37 notational conventions).

It's easy to understand how crackpots are confused by all this.
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Old 31st July 2014, 08:49 PM   #2547
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Originally Posted by Kwalish Kid View Post
You have yet to demonstrate that anyone who has studied relativity theory believes that there is something to be debated about the speed of light in the theory.
No debate known by this person who studied relativity theory many many years ago!
And can read Wikipedia: Propagation of light in non-inertial reference frames
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Old 31st July 2014, 09:04 PM   #2548
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Originally Posted by Farsight View Post
No, saying Einstein was wrong is the crackpot indulgence. And I'm on the right side of that fence.
Sorry, Farsight, but:
Being wrong about what Einstein in a speech puts you on the crackpot side of the fence.
Relying on Einstein quotes rather then modern textbooks puts you on the crackpot side of the fence.
Displaying the inability to get past the third equation in an Einstein paper and thinking that you know about GR puts you on the crackpot side of the fence.
Then there are the many other indictors of which side of the fence you are in the Relativity+ thread (e.g. the cartoon of the EM field around a particle that just adds up the E field from a particle + the B field from a current!)

Evidence for a position consists of experimental results and observations and citations of "rigorous analysis of the mathematics". IOW: Evidence for a position consists of citations to both the experimental and theoretical scientific literature.

Russ Dill is talking about a strange new idea from you: "The front portion of a photon is a little like a partial positron, the back is a little like a partial electron" and the lie about "But the main point is that photons interact with photons, and QED doesn't cover it". The point is that QED does cover photon-photon interactions and says that photons do interact as you cited
Two-photon physics
Quote:
From quantum electrodynamics it can be found that photons cannot couple directly to each other, since they carry no charge, but they can interact through higher-order processes.

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Old 1st August 2014, 03:59 AM   #2549
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Originally Posted by Reality Check View Post
No debate known by this person who studied relativity theory many many years ago!
And can read Wikipedia: Propagation of light in non-inertial reference frames
I think I'd prefer it if you reference an older edit of wikipedia.
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Old 1st August 2014, 06:19 AM   #2550
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Originally Posted by Perpetual Student View Post
In my own frame of reference, whether in an inertial frame, accelerating, rotating or in a gravitational field, will I measure any source of light from any direction traveling by me at anything other than c?
No, because of the tautology described by Magueijo and Moffat in http://arxiv.org/abs/0705.4507 . Imagine you get down near the floor, then you define your second as the duration of 9192631770 periods of radiation going past you. Then you define your metre as the length travelled by this radiation in 1/299,792,458th of a second. You've used the motion of light to define your second and your metre. Then you use them to measure the motion of light. Hence the tautology, wherein you always measure the local speed of light to be 299,792,458 m/s.

You get up near the ceiling and repeat. Again you're using the second and the metre defined using the motion of light, to measure the motion of light. Again you measure the local speed of light to be 299,792,458 m/s. But one 299,792,458 m/s isn't the same as the other. The speed of light at floor level is slower than up at the ceiling, hence the second is bigger down there. The metre is the same because the slower light and the bigger second cancel each other out.

Originally Posted by Perpetual Student View Post
I admit that I have not really studied this question, however I believe, based on what I've read, that no source of light from any direction would be measured at anything other then c. Is that not correct?
Yes. See the Wikipedia article on gravitational time dilation.

"The speed of light in a locale is always equal to c according to the observer who is there. The stationary observer's perspective corresponds to the local proper time. Every infinitesimal region of space time may have its own proper time that corresponds to the gravitational time dilation there, where electromagnetic radiation and matter may be equally affected, since they are made of the same essence[5] (as shown in many tests involving the famous equation E=mc²)".

The points to note are the infinitesimal region and the same essence. The room you're in is not an infinitesimal region. The same essence means you're affected just like light. When light goes slower so do you, so you don't notice it.

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Old 1st August 2014, 06:58 AM   #2551
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Originally Posted by RussDill View Post
Please explain how you have applied this quote to the "front" and "back" of a photon and how you chose front-positive back-negative.
No. It's just something that came up in the conversation. We were talking about gamma-gamma pair production, and some Wikipedia guy had said something about half wavelength is a positive charge and the next half wavelength is a negative charge. I don't go round saying a photon is half a positron followed by half an electron.

Originally Posted by W.D.Ciinger
I'm interested in both (studying Einstein and studying relativity theory). My interest in Einstein was rekindled by Farsight's dogmatic insistence that Einstein's general theory of relativity is quite different from what is taught by modern textbooks. Farsight's wrong about that...
I'm not. Einstein really did say the speed of light varies with position. He really did describe a gravitational field as inhomogeneous space. But many physicists today will tell you that the speed of light is absolutely constant, And they will confuse space and spacetime. Then they'll wax lyrical about curved space. Or moving through spacetime. Or how the principle of equivalence is sacrosanct, forgetting that it applies to an infinitesimal region. A region of zero extent.

Originally Posted by Reality Check
Sorry, Farsight, but: Being wrong about what Einstein in a speech puts you on the crackpot side of the fence.
I'm not wrong. I'm on the right side of the fence. The same side as this Baez article:

"Einstein talked about the speed of light changing in his new theory. In his 1920 book "Relativity: the special and general theory" he wrote: "... 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 [...] cannot claim any unlimited validity. A curvature of rays of light can only take place when the velocity [Einstein means speed here] of propagation of light varies with position." This difference in speeds is precisely that referred to above by ceiling and floor observers.".

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Old 1st August 2014, 11:05 AM   #2552
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Originally Posted by Farsight View Post
No. It's just something that came up in the conversation. We were talking about gamma-gamma pair production, and some Wikipedia guy had said something about half wavelength is a positive charge and the next half wavelength is a negative charge. I don't go round saying a photon is half a positron followed by half an electron.
I didn't say anything about positrons or electrons. You said that 'The front portion of a photon is a little like a partial positron, the back is a little like a partial electron.' I'm trying to find out why you assigned "a little like a partial positron" to the front and "a little like a partial electron" to the back. It would seem that this would be arbitrary and if it were true, there should be an anti-photon that is "a little like a partial positron" in the back and "a little like a partial electron" in the front.
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Old 1st August 2014, 11:51 AM   #2553
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It is hard to respond with anything but "lol". The complete rejection of using mathematics to support/refute arguments is stunning (on a certain nay-sayer's part).
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Old 1st August 2014, 12:55 PM   #2554
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Originally Posted by RussDill View Post
I didn't say anything about positrons or electrons. You said that 'The front portion of a photon is a little like a partial positron, the back is a little like a partial electron.' I'm trying to find out why you assigned "a little like a partial positron" to the front and "a little like a partial electron" to the back. It would seem that this would be arbitrary and if it were true, there should be an anti-photon that is "a little like a partial positron" in the back and "a little like a partial electron" in the front.
As a wave packet passes a particular point where there is no non-zero background field, the magnitude of the field briefly increases and then returns to zero. If I had to guess, I'd say that someone mistakenly conflated the idea of a negative rate of change with that of a negative charge.
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Old 1st August 2014, 01:23 PM   #2555
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Originally Posted by ctamblyn View Post
As a wave packet passes a particular point where there is no non-zero background field, the magnitude of the field briefly increases and then returns to zero. If I had to guess, I'd say that someone mistakenly conflated the idea of a negative rate of change with that of a negative charge.
Actually, my guess was that someone saw a cartoon illustration of a wavepacket --- a little snippet of sine wave, maybe made of little arrows representing field vectors --- and saw that (in this particular cartoon) on one end of the packet the arrows were pointing up, and on the other end they were pointing down. The person says "OK, positive arrows on this end and negative arrows on this end" and thinks that means positive charge and negative charge.

Farsight himself has made cartoon-wave-interpretation mistakes---I forget the details and won't go hunting for the link. IIRC, he linked to a cartoon showing several sine waves at different frequencies; in the cartoon, the waves were all drawn at the same amplitude. He mistakenly thought this was evidence for some sort of constant-amplitude-vs-frequency effect in Nature and made some nonsensical claim for which that was the premise.
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Old 1st August 2014, 01:31 PM   #2556
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Originally Posted by ben m View Post
Actually, my guess was that someone saw a cartoon illustration of a wavepacket --- a little snippet of sine wave, maybe made of little arrows representing field vectors --- and saw that (in this particular cartoon) on one end of the packet the arrows were pointing up, and on the other end they were pointing down. The person says "OK, positive arrows on this end and negative arrows on this end" and thinks that means positive charge and negative charge.

Farsight himself has made cartoon-wave-interpretation mistakes---I forget the details and won't go hunting for the link. IIRC, he linked to a cartoon showing several sine waves at different frequencies; in the cartoon, the waves were all drawn at the same amplitude. He mistakenly thought this was evidence for some sort of constant-amplitude-vs-frequency effect in Nature and made some nonsensical claim for which that was the premise.
Oh yes, the "common amplitude" debacle. This was one of those posts. Unfortunately the link to the original image is now dead, but it was something like this.
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Old 1st August 2014, 01:54 PM   #2557
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Originally Posted by Farsight View Post
No, because of the tautology described by Magueijo and Moffat in http://arxiv.org/abs/0705.4507 . Imagine you get down near the floor, then you define your second as the duration of 9192631770 periods of radiation going past you. Then you define your metre as the length travelled by this radiation in 1/299,792,458th of a second. You've used the motion of light to define your second and your metre. Then you use them to measure the motion of light. Hence the tautology, wherein you always measure the local speed of light to be 299,792,458 m/s.

You get up near the ceiling and repeat. Again you're using the second and the metre defined using the motion of light, to measure the motion of light. Again you measure the local speed of light to be 299,792,458 m/s. But one 299,792,458 m/s isn't the same as the other. The speed of light at floor level is slower than up at the ceiling, hence the second is bigger down there. The metre is the same because the slower light and the bigger second cancel each other out.

Yes. See the Wikipedia article on gravitational time dilation.

"The speed of light in a locale is always equal to c according to the observer who is there. The stationary observer's perspective corresponds to the local proper time. Every infinitesimal region of space time may have its own proper time that corresponds to the gravitational time dilation there, where electromagnetic radiation and matter may be equally affected, since they are made of the same essence[5] (as shown in many tests involving the famous equation E=mc²)".

The points to note are the infinitesimal region and the same essence. The room you're in is not an infinitesimal region. The same essence means you're affected just like light. When light goes slower so do you, so you don't notice it.
It seems that this effect happens in a gravitational field:

Quote:
Gravitational Space Dilation

Richard J. Cook

We point out that, if one accepts the view that the standard second on an atomic clock is dilated at low gravitational potential (ordinary gravitational time dilation), then the standard meter must also be dilated at low gravitational potential and by the same factor (gravitational space dilation). These effects may be viewed as distortions of the time and length standards by the gravitational field, and measurements made with these distorted standards can be "corrected" by means of a conformal transformation applied to the usual spacetime metric of general relativity.
LINK

The above would hold even if the meter were still based on some length of platinum in Paris. So, it seems that there is no tautology: the velocity of light is constant in all frames in GR (just as in SR) as both time and space are transformed by the influence of gravity.
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Old 1st August 2014, 04:00 PM   #2558
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Originally Posted by Perpetual Student View Post
The above would hold even if the meter were still based on some length of platinum in Paris. So, it seems that there is no tautology: the velocity of light is constant in all frames in GR (just as in SR) as both time and space are transformed by the influence of gravity.
I think the "all frames in GR" part is a misleading generalization of what your cited paper claims:

Originally Posted by Richard J Cook
The notion of gravitational space dilation derives from a single observer’s view that, when a distant observer’s standard time interval is dilated by a gravitational field, his standard length must be dilated as well and by the same factor. If this were not so, the distant observer could not understand how the local observer obtains the invariant value c for the locally measured light speed.
That's true enough, but the fact remains that the frame chosen by the single observer is probably showing a coordinate velocity of light other than c at the distant observer. So I don't think you should say the velocity of light is constant within the frame.

In SR, we speak only of inertial frames, and fall into the habit of dropping the "inertial" qualifier. In GR, inertial frames are rare. In GR, a frame is highly arbitrary. A GR frame (aka coordinate patch, map) can be any smooth mapping from an open subset of spacetime to R4. The coordinate velocities of light within a GR frame are therefore equally arbitrary.

Your cited paper points out that a GR frame plus knowledge of the pseudometric tensor field's components throughout that frame allows the local velocity of light to be computed at any point of spacetime within the domain of the frame, and that this (often daunting) computation will result in the standard value c. In my opinion, that's not quite the same as saying the velocity of light is constant in all GR frames.

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Old 1st August 2014, 05:07 PM   #2559
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Originally Posted by W.D.Clinger View Post
I think the "all frames in GR" part is a misleading generalization of what your cited paper claims:


That's true enough, but the fact remains that the frame chosen by the single observer is probably showing a coordinate velocity of light other than c at the distant observer. So I don't think you should say the velocity of light is constant within the frame.
I have assumed the phrase "the velocity of light is constant in all frames in GR" implies that c is being measured by someone in each frame. Is not the "distant observer" you refer to in some other frame? By frame in this context do we not mean some infinitesimal patch of spacetime? Perhaps I'm missing something.

Quote:
In SR, we speak only of inertial frames, and fall into the habit of dropping the "inertial" qualifier. In GR, inertial frames are rare. In GR, a frame is highly arbitrary. A GR frame (aka coordinate patch, map) can be any smooth mapping from an open subset of spacetime to R4. The coordinate velocities of light within a GR frame are therefore equally arbitrary.

Your cited paper points out that a GR frame plus knowledge of the pseudometric tensor field's components throughout that frame allows the local velocity of light to be computed at any point of spacetime within the domain of the frame, and that this (often daunting) computation will result in the standard value c. In my opinion, that's not quite the same as saying the velocity of light is constant in all GR frames.
So, if an observer at any point in spacetime will compute the standard value of c, what else might we mean by saying "the velocity of light is constant in all GR frames."? Is this merely a semantic question? Again, I may be missing something (or lots of things).
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Old 1st August 2014, 06:16 PM   #2560
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Originally Posted by Perpetual Student View Post
I have assumed the phrase "the velocity of light is constant in all frames in GR" implies that c is being measured by someone in each frame. Is not the "distant observer" you refer to in some other frame? By frame in this context do we not mean some infinitesimal patch of spacetime? Perhaps I'm missing something.
The highlighted question is key. The paper you cited uses the word "frame" three times, and I do think it's possible the author of that paper tends to think of frames as infinitesimal patches of spacetime. If so, then he's probably thinking of what MTW refer to as a "moving, infinitesimal reference frame, or tetrad" in sections 6.4 and 6.5. MTW section 6.3 introduces those sections by talking about the difficulty of understanding what might be meant by "the coordinate system of an accelerated observer".

It took me a few years to figure out that some physicists' habit of talking about "the reference frame of an observer" as if it were well-defined was an artifact of the historical progression from SR to GR, and that the concept of an "infinitesimal reference frame" is mostly an artifact of (mostly futile) attempts to come up with a well-defined notion of an arbitrary observer's reference frame. See, for example, MTW section 13.6 on "The Proper Reference Frame of an Accelerated Observer". That section tells how to construct an extended (non-infinitesimal) "proper reference frame" but warns:

Originally Posted by Misner, Thorne, and Wheeler
Only a foolish observer would try to use his own proper reference frame far from his world line, where its grid ceases to be orthonormal and its geodesic grid lines may even cross!
Consider, for example, a Schwarzschild coordinate patch. That's the proper reference frame for an observer observing a spherically symmetric, non-rotating and uncharged star or black hole from infinitely far away, and serves as an excellent approximation to the proper reference frame for observers observing from a great distance. Thanks to some of the crackpot physics we've discussed in this thread, we are familiar with the folly of trying to use that reference frame to reason about physics near the event horizon of a black hole.

Note, however, that a Schwarzschild coordinate patch is far from infinitesimal. Although it does not and cannot cover all of spacetime (despite crackpot claims that it does), a Schwarzschild coordinate patch does cover all of the (idealized) spacetime outside of a hypothetical black hole's event horizon except for those points that lie on the coordinate singularities of the space-like spherical coordinates. (We are also familiar with the crackpot consequences of failing to understand that the coordinate singularities at the event horizon are no more meaningful than coordinate singularities of spherical coordinates.)

As I say, it took years for me to figure out that the notion of a reference frame in general relativity is best identified with the notion of a coordinate patch (aka map) in differential geometry. That's the notion of reference frame assumed by the FLRW metrics and by all of the standard metrics that generalize the Schwarzschild metric. That notion is not infinitesimal; for the spacetime manifolds of general relativity, a coordinate patch is defined on an open subset of spacetime. In practice, that open set is (implicitly) taken to be the largest connected open set that avoids the coordinate singularities of the pseudometric form.

Originally Posted by Perpetual Student View Post
So, if an observer at any point in spacetime will compute the standard value of c, what else might we mean by saying "the velocity of light is constant in all GR frames."? Is this merely a semantic question? Again, I may be missing something (or lots of things).
I think it's mostly a semantic question, and I think it's a dangerous question to try to answer because (1) there's more than one possible interpretation of "all GR frames" and (2) there's more than one possible interpretation of what is meant by "the velocity of light is constant" in a frame.

For someone like me, who takes "all GR frames" to mean all possible maps of all complete atlases of all possible spacetimes and takes "the velocity of light is constant" within a frame to mean the coordinate velocity is constant throughout the frame, then "the velocity of light is constant in all GR frames" is trivially false.
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