tag:blogger.com,1999:blog-480555353132580100.post4731136191602777904..comments2020-05-02T08:28:34.499+01:00Comments on ErkDemon: The Moon, considered as a Flat DiscErkDemon (Eric Baird)http://www.blogger.com/profile/00430413494529535159noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-480555353132580100.post-61228846445111271912009-09-16T06:23:29.459+01:002009-09-16T06:23:29.459+01:00continued from previous post
4. Your comment here...continued from previous post<br /><br />4. Your comment here makes no sense, because you allude to “all the problems with the present system” being due to special relativity, which you think should be replaced by a fictitious version of general relativity which does not satisfy the equivalence principle (i.e., the principle that we can choose coordinates at any event so that the metric at that event is Minkowskian). In addition to being a contradiction in terms (and completely insane), we’ve just seen that exactly the opposite is the case. Special relativity as embodied fully in quantum field theory is what gets Hawking radiation “right”. The part of relativity that we haven’t been able to reconcile with quantum field theory (which gets Hawking radiation “right”, remember) is precisely the part that you tout as correct, namely, the representation of the universal coupling of gravitational interaction as curvature. THIS is intractable problem with the present system. As to “all the other problerms”, you can’t actually cite any. Look, let’s be honest. When you wrote about “those whose first exposure to special relativity prompted an immediate instinctive loathing”, you were obviously among those people. Your loathing of special relativity dates back to your youth, and is based on simple lack of understanding. All this stuff about acoustic metrics and Hawking radiation came along much later, and really has nothing to do with the source of your loathing for special relativity.<br /><br />5. Your comment here is a total non-sequitur. Anti-matter is not a general result. It exists only on the context of Minkowski spacetime. See above. Your comment about how pre-relativistic optics gives the wrong redshift in some circumstances is obviously not relevant.<br /><br />6. You missed the point. No one has said that special relativity (or general relativity) must be correct physics. What has been said is that the only logically self-consistent metrical representation of an attractive effect with redshift near gravitating bodies in terms of curved spacetime must be locally Minkowskian. This is a mathematical fact about the mathematical relationship between two mathematical theories, constrained to be consistent with a small set of fairly evident empirical facts. The very foundation and essence of general relativity is the equivalence principle, which is nothing other than the assertion that spacetime is locally Minkowskian. To suggest that general relativity could be reformulated in a way that is not locally Minkowskian is literally a contradiction in terms, and simply reveals that the person claiming it has not the slightest idea what he is talking about. Of course, Lorentz invariance is among the most thoroughly verified properties of all physical phenomena, but that’s separate from the mathematical fact that nothing remotely resembling general relativity is consistent with the denial of local Lorentz invariance. So, as noted previously, both from a rational and from an empirical standpoint, your claims are absurd.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-480555353132580100.post-17526352379718096712009-09-16T06:22:36.040+01:002009-09-16T06:22:36.040+01:001. Your reply doesn’t address the point at all. Y...1. Your reply doesn’t address the point at all. You argued that the equations of special relativity were arrived at based on aesthetic criteria of mathematical beauty. I corrected your misconception by reminding you that the Lorentz transformation was not developed or adopted based on mathematical beauty, it was painstakingly derived, step by grudging and somewhat incredulous step, from empirical results and purely physical considerations. Hence your premise is false.<br /><br />2. Please stop and think for just one minute: You say “crappy old Newtonian dark stars can successfully predict Hawking radiation classically… Newtonian theory, incomplete as it was, still manages to get this part right”. What do you mean “right”? Think for a minute. Hawking radiation has obviously never been observed, so we’re not talking about an empirical fact. The reason Hawking radiation is considered to be “right” is because of Hawking’s derivation of it from a combination of quantum field theory – based crucially on special relativity for anti-particles, etc. – and the curved spacetime of general relativity – based crucially on special relativity for the equivalence principle, etc. Do you understand how insane it is to cite the prediction of Hawking radiation as evidence of a failure of special relativity? Only if you could somehow prove that there is no such thing as Hawking radiation would you be in a position to impugn special relativity. As always, your reasoning is completely backwards. Needless to say, the banal fact that analogs of Hawking radiation (not true Hawking radiation) can be found in other physical contexts, like the water in your bathtub, does nothing at all to lessen the silliness of your beliefs.<br /><br />3. Your answer here makes no sense. The point is that anti-particles make sense only in the context of a spacetime with negative metric signature, i.e., locally Minkowski spacetime. Are you now claiming that anti-particles (or some analog of anti-particles) occur in the context of acoustic analogs of event horizons? I find no reference to “anti-particles” in any paper on that subject. Furthermore, you are basing your claim on “crappy old Newtonian dark stars”, so are you saying that anti-particles are operative in the dark star version of black hole radiation? And still further-more, even if you could find analogs of anti-particles in these models (which you can’t), it still would not be a defense of your original claim, because (again) genuine Hawking radiation is believed to be “right” only because it arises as a consequence of special relativity, so it is utterly silly to cite Hawking radiation as an example of the failure of special relativity. If anything, you might argue that it shows a deficiency in classical GENERAL relativity, which doesn’t mesh perfectly with quantum field theory, but quantum field theory is founded firmly and inextricably on SPECIAL relativity. The part of general relativity that doesn’t mesh with quantum field theory is curvature, the very thing you claim as a secure basis. As always, your reasoning is completely backwards.<br /><br />continued next postAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-480555353132580100.post-2868104442972088942009-09-15T01:51:00.207+01:002009-09-15T01:51:00.207+01:001. The Lorentz transformation was proposed by Geor...1. The Lorentz transformation was proposed by George Fitzgerald as an ad-hoc fix for aether theory, and developed independently as a more abstract logical system by Poincare. Most math/physics people I've talked to seem to reckon that the relationship is so "deep" that a theory based on it pretty much has to be right. I don't think they're seeing the bigger picture.<br /> <br />2. I agree that it's not news that SR fails to "do" gravity. That's what GR is for. What I'm saying is that when it comes to gravitational horizons, the embedded SR component causes models like GR1915 to "fail" gravity too. That's why crappy old Newtonian dark stars can successfully predict Hawking radiation classically but the more advanced GR1915 can't handle the effect at all. Newtonian theory, incomplete as it was, still manages to get this part right, because it has the advantage of not having to reduce to SR physics over small regions. <br /><br />3. Just because pair-production was originally developed in the context of SR doesn't mean that SR "owns" the effect. Historical association is not the same as unique mathematical dependency.<br /><br />4. I often refer to "GR1915", because I'd like to see Einstein's general theory replaced by an more purist implementation of a general theory that that loses the (IMO troublesome) SR layer, which I think is the root of nearly all the problems with the current system. So when I'm critical of current gravitational theory, I try to be specific and refer to "current GR" or "textbook GR" or "GR1915". "GR1915" is shorter. I used to refer to "GR1916", but someone complained that the essence of GR was published the previous calendar year and that I was being unfair by using a date as late as '16, so I backed up a year. <br /><br />5. The matter-antimatter thing isn't a great triumph for SR if it's a general result (remember, N.O. has a Lorentz-squared redshift/contraction component in place of SR's single Lorentz component)<br /><br />6. If nobody competent would say that mathematics always corresponds to physics – then I'd refer you to the anonymous poster here who keeps insisting that the /mathematical/ reduction of curved spacetime to flat-spacetime over sufficiently-small regions means tthat SR has to be correct physics :) <br /><br />I've pointed out that this mathematical reduction isn't guaranteed to yield a physical result, but they don't seem to understand how it couldn't. Of course, they might not be a mathematician or a physicist, so perhaps they don't count … but the "reduction" argument is also in GR textbooks, which are presumably written by folk who are somewhat representative of the "mathematical physics" community. :)ErkDemon (Eric Baird)https://www.blogger.com/profile/00430413494529535159noreply@blogger.comtag:blogger.com,1999:blog-480555353132580100.post-44896037194316352932009-09-13T00:10:56.947+01:002009-09-13T00:10:56.947+01:00Your blog posting is based on several mis-understa...Your blog posting is based on several mis-understandings. First, the Lorentz transformation was not developed or adopted based on mathematical beauty, it was painstakingly derived, step by step, from empirical results and purely physical considerations. Second, it is exceedingly well known that special relativity fails because it does not account for the curvature of spacetime associated with any mass or energy, so when you confide to your readers the suspicion that perhaps special relativity doesn’t take the curvature of spacetime into account, you are not exactly making news. Third, the whole concept of anti-particles and hence “pair production” was derived by Dirac as a direct and unavoidable consequence of (wait for it) special relativity. In other words, the very phenomenon that you seem to think undermines special relativity was actually derived FROM special relativity, i.e., from reconciling quantum mechanics with special relativity, the result of which was quantum field theory. Fourth, your appending of “1915” to general relativity is misguided, because the field equations of general relativity are the same today as they were at the end of 1915, and of course flat Minkowski spacetime is still a trivial solution of those equations, and every solution approaches the Minkowski metric over sufficiently small regions. (Have you given any thought to how you are going to change this fact?) Fifth, you claim, on the basis of a patently specious staw analogy, that special relativity is “bad physics” because it leads to wrong results, and yet the result you cite is Hawking radiation, which is a direct consequence of the pair production phenomena involving anti-particles derived from (wait for it) special relativity. So, far from being an example of a failure, the phenomena of anti-matter and pair production are among the greatest triumphs of special relativity. Sixth, when you say the statement that “mathematics doesn’t always translate directly into physics” might sound odd to a mathematician, you are (again) dealing in staw. No mathematician would say that mathematics always translates directly into physics… in fact, I doubt that any mathematician would even know what you mean by that staw assertion. Seventh… well, enough of this…Anonymousnoreply@blogger.com