On 3/20/2019 3:07 AM, agrayson2...@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
<javascript:>> 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
<https://arxiv.org/search/physics?searchtype=author&query=de+Almeida%2C+C>,Alberto
Saa <https://arxiv.org/search/physics?searchtype=author&query=Saa%2C+A>
(Submitted on 6 Jun 2005 (v1 <https://arxiv.org/abs/physics/0506049v1>),
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
<https://arxiv.org/ct?url=https%3A%2F%2Fdx.doi.org%2F10.1119%252F1.2162548&v=623983a0>
Cite as: arXiv:physics/0506049
<https://arxiv.org/abs/physics/0506049>[physics.class-ph]
(orarXiv:physics/0506049v5
<https://arxiv.org/abs/physics/0506049v5>[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
<https://arxiv.org/search/physics?searchtype=author&query=Gr%C3%BCndler%2C+G>
(Submitted on 14 Sep 2015 (v1 <https://arxiv.org/abs/1509.08757v1>),
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
<https://arxiv.org/abs/1509.08757>[physics.gen-ph]
(orarXiv:1509.08757v3
<https://arxiv.org/abs/1509.08757v3>[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
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