Re: EP and Unruh - effect (Layman)

we_pretty@xxxxxxxxx wrote:
>
> Uncle Al wrote:
>
> [snip]
>
> >That the EP does not hold for charged bodies is unsupportable hogwash
>
> If it didn't that would have been trumpeted all over ?
>
> Wikipedia (http://en.wikipedia.org/wiki/Unruh_effect) says:
> "From the viewpoint of the accelerating observer, the vacuum
> of the inertial observer will look like a state containing
> many particles in thermal equilibrium -- a warm gas."
> Does not this mean that when a very cold body is in constant
> acceleration it will warm up until in thermal equilibrium with
> the gas ? In contrast a body in an inertial frame will cool
> down to arbitrarily low temperatures (minus background radiation).
>
> Uncle Al wote:
>
> [snip]
>
> >Locally there is no phenomenon to observe. Globally there
> >is no basis for the observation to the required accuracy.
> >As with the relativistic ten-foot broomstick fitting within
> >the eight-foot barn, the contradiction you imply does not
> >obtain within the maths.
>
> In general relativity space-time is locally Lorentzian except
> at singularities. A(n) (strong ?) equivalence principle postulates
> that locally it is not possible to distinguish between an
> accelerating frame on a planet or in a space ship. I don't
> understand "Locallly there is not phenomenon to observe".
> In a cube not containing a singularity of an arbitrarily small
> size space-time is as flat as neccessary. Does not this cube
> get Unruh-radiation ? Is this not a local phenomena ?
>
> Wikipedia (http://en.wikipedia.org/wiki/Unruh_effect) says:
> "So the temperature seen by a particle accelerated by the
> Earth's gravitational acceleration of g=3D9.81 m/s=B2 is only 4*10-20K.
> For an experimental test of the Unruh effect it is planned to use
> accelerations up to 1026m/s=B2, which would give a temperature of
> about 400,000K."
>
> That probably is the temperature I meant. Because the Unruh -
> radiation is thermal does not this mean that for any energy e,
> the probability that an accelerating body will be hit by a photon
> with energy e, is non-zero. Because some conservation laws
> no photon can smash up a proton. Does the radiation contain
> energetic antiprotons that could do the smashing ?
> My question should perhaps have been what effects low temperature
> thermal radiation has on matter. Answer is something like: Not much.
>
> If I may spew one more question, when a cold body and a warm body
> of same masses are accelerated in special relativity, using the
> same force, does the warm body go faster after acceleration because
> the cold body has got more energy during the acceleration from the
> radiation ? (This may not make sense, I vaguely remember reading
> somewhere about confusions with Unruh - radiation and the neccessity of
> rigorous definitions but cannot recall where)
>
> It would be nice to have this Unruh in FAQ.

10^26 m/sec^2 = 10^25 gees. The surface of a neutron star pulls
10^11-10^13 gees (a gravitational red shift of about z=0.35). There
is NO Unruh effect within the Equivalence Principle any more than the
Scharnhorst effect allows superluminal light propagation in the lab,

http://arXiv.org/abs/gr-qc/0107091
http://arXiv.org/abs/quant-ph/0010055
Phys. Lett. B236 354 (1990)
Phys. Lett. B250 133 (1990)
J Phys A26 2037 (1993)

You can spin the numbers all you want, but there is no real world
measurable effect obtainable even in principle. Example: Given a
body with a surface gravitational acceleration of 10^26 m/sec^2,
calculate its escape velocity and compare that to lightspeed.

Similarly, the Equivalence Principle *cannot* be true in the Earth's
gravitational field because it is divergent and will show quadrupole
(tidal) components, as opposed to purely linear and uniform inertial
acceleration. Tha is piffle disposed of by assuming/imposing locality
in any experiment. Gravitomagnetic effects must occur near a massive
spinning body (e.g., Gravity Probe B) so the EP again will not
obtain. The magnitude of that correction is many decimal places to
the right of EP considerations.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

.

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