On 3/23/2019 5:45 AM, agrayson2...@gmail.com wrote:
On Thursday, March 21, 2019 at 12:40:13 AM UTC-6, smitra wrote:
On 21-03-2019 06:21, agrays...@gmail.com <javascript:> wrote:
> On Wednesday, March 20, 2019 at 12:51:18 PM UTC-6, Brent wrote:
>
>> On 3/20/2019 3:07 AM, agrays...@gmail.com 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 <agrays...@gmail.com> 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 <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?
The energy comes from the field that accelerates the charge, i.e. the
gravitational potential. The photons radiated away carry energy, but
not charge.
Brent
Yet I don't believe that is claimed, so the result of the article is
baffling. AG
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