On Thursday, March 21, 2019 at 12:40:13 AM UTC-6, smitra wrote: > > On 21-03-2019 06:21, [email protected] <javascript:> wrote: > > On Wednesday, March 20, 2019 at 12:51:18 PM UTC-6, Brent wrote: > > > >> On 3/20/2019 3:07 AM, [email protected] wrote: > >> > >> On Tuesday, March 19, 2019 at 7:23:29 PM UTC-6, Brent wrote: > >> > >> On 3/19/2019 9:32 AM, John Clark wrote: > >> > >> On Tue, Mar 19, 2019 at 4:50 AM <[email protected]> wrote: > >> > >>> I SUPPOSE EINSTEIN STARTED WITH THE MOTIVATION OF FINDING A > >> GENERAL TRANSFORMATION FROM ONE ACCELERATING FRAME TO ANOTHER, AND > >> LATER GAVE UP ON THIS PROJECT AND SETTLED FOR A THEORY OF GRAVITY. > >> IS THIS TRUE? TIA, AG > >> > >> Einstein's breakthrough, what he called "the happiest thought of my > >> life" was when he realized a man in a falling elevator will not feel > >> gravity but a man in a accelerating elevator will. In other words an > >> accelerating frame and gravity are the same thing, that's why it's > >> called the Equivalence Principle. > > > > I wonder if Einstein ever considered whether a charged particle in > > the falling radiate would radiate? > > > > Brent > > > > Because of your typos, at first I thought you were joking. Well, maybe > > it was a joke, but for me it sounds like a damned good question. I > > surmise that a charged particle accelerating due to gravity does NOT > > radiate energy, but why? AG > > > > Sorry about the typos. Yes, it does seem paradoxical. Here's a > > paper that purports to solve the problem. > > > > THE RADIATION OF A UNIFORMLY ACCELERATED CHARGE IS BEYOND THE HORIZON: > > A SIMPLE DERIVATION > > > > Camila de Almeida [1], Alberto Saa [2] > > (Submitted on 6 Jun 2005 (v1 [3]), last revised 2 Dec 2005 (this > > version, v5)) > > > >> We show, by exploring some elementary consequences of the covariance > >> of Maxwell's equations under general coordinate transformations, > >> that, despite inertial observers can indeed detect electromagnetic > >> radiation emitted from a uniformly accelerated charge, comoving > >> observers will see only a static electric field. This simple > >> analysis can help understanding one of the most celebrated paradoxes > >> of last century. > > > > Comments: > > Revtex, 6 pages, 2 figures. v2: Some small corrections. > v3: > > Citation of a earlier paper included. v4: Some stylistic changes. v5: > > Final version to appear in AJP > > > > Subjects: > > Classical Physics (physics.class-ph); General > Relativity and > > Quantum Cosmology (gr-qc) > > > > Journal reference: > > Am.J.Phys. 74 (2006) 154-158 > > > > DOI: > > 10.1119/1.2162548 [4] > > > > Cite as: > > arXiv:physics/0506049 [5] [physics.class-ph] > > > > (or arXiv:physics/0506049v5 [6] [physics.class-ph] for > this > > version) > > > > And another paper that looks at possible experimental evidence. > > > > ELECTRICAL CHARGES IN GRAVITATIONAL FIELDS, AND EINSTEIN'S > > EQUIVALENCE PRINCIPLE > > > > Gerold Gründler [7] > > (Submitted on 14 Sep 2015 (v1 [8]), last revised 12 Oct 2015 (this > > version, v3)) > > > >> According to Larmor's formula, accelerated electric charges radiate > >> electromagnetic waves. Hence charges should radiate, if they are in > >> free fall in gravitational fields, and they should not radiate if > >> they are supported at rest in gravitational fields. But according to > >> Einstein's equivalence principle, charges in free fall should not > >> radiate, while charges supported at rest in gravitational fields > >> should radiate. In this article we point out indirect experimental > >> evidence, indicating that the equivalence principle is correct, > >> while the traditional interpretation of Larmor's formula must be > >> amended. > > > > Subjects: > > General Physics (physics.gen-ph) > > > > Cite as: > > arXiv:1509.08757 [9] [physics.gen-ph] > > > > (or arXiv:1509.08757v3 [10] [physics.gen-ph] for this > version) > > > > However, I don't find them entirely convincing. We know that double > > stars, which are orbiting one another in free-fall, radiate > > gravitational waves. Are we to suppose that if one or both of them > > had an electrical charge that there would be no EM radiation? > > > > Brent > > > > IF WE GO BACK TO CLASSICAL E&M, WHERE DOES THE EM RADIATION COME FROM > > WHICH IS EMITTED FOR ACCELERATING PARTICLES? IT CAN'T COME FROM > > THE SELF FIELD OF, SAY, AN ELECTRON, SINCE THAT WOULD IMPLY LOSS OF > > MASS OR CHARGE OF THE ELECTRON, WHICH IS NEVER CLAIMED. SO IT MUST > > COME FROM THE EM FIELD CAUSING THE ACCELERATION. NOW IF WE GO TO THE > > CASE OF GRAVITY WITHOUT ANY EM SOURCE FIELDS, AND WE STILL GET EM > > RADIATION DUE TO THE ACCELERATION, WHERE DOES IT COME FROM? AG > > > It comes from the self-force, see here: > > https://arxiv.org/abs/0905.2391 > > Saibal >
In the case of GR, assuming no external EM sources, we still get (according to resident experts) radiation emitted for accelerating charges. So the claim of the article must be true; that the energy comes from the field created by the accelerating charge. But wouldn't that imply the charge of said particle must decrease to account for the reduced self-field? Yet I don't believe that is claimed, so the result of the article is baffling. AG -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
