sci.physics.electromag

On Fri, 7 Sep 2007, rge11x wrote:

> What I do not understand is why from the beginning one must assume
> that the ether, if existed, it be in thermal equilibrium with itself
> and with matter. One might say that only equilibrium thermodynamics,
> better yet thermostatics, is understood fully and not the
> nonequilibrium kind, and because of the former one's obvious utility
> and mathematical simplicity one should try that first and see if it
> worked. It does not: as you pointed it out that if it were in thermal
> equilibrium then it would contradict experience. Very well but now
> assume that it is not in equilibrium and why should be so? It is in
> constant flux, radiation all over is being exchanged with matter
> particles. Does one still get nonsensical and nonphysical infinities
> if the presumed "substrate" is fundamentally in a state of
> nonequilibrium? In other words is the assumption of "ether in
> equilibrium" needed for the ultraviolet catastrophe argument, and if
> not the argument is to fail? Exactly because of Occam's razor one
> should consider this possibility, after all the "state of equilibrium"
> is about as special assumption as one can possible make about the
> nature of something that might completely surround us.

Basically, the usual uniformitarian argument - the past is like the
present and so is the future (to at least some extent, cosmology breaks
this). If the laws of physics are to appear at least approximately
constant, then the universe is in some kind of quasi-steady-state. If
there is an ether, then it must be in some kind of (approximately at
least) steady state.

This suggests that either the ether is in thermodynamic equilibrium, or
there is some energy flux through the ether, from some (unknowable?)
source to some (unknowable?) sink. The latter is not as ludicrous as it
might appear at first. Consider gravitation and the equivalence principle
- if free fall is the true inertial state, then the ether would be
infalling into masses (that's the sink, but where is the source?). But
that's a bulk flow, not the same thing as thermal fluctuations. Consider
fluid dynamics, where one can have local thermodynamic equilibrium and
bulk flows and non-uniform temperature.

In the end, it comes down to that the low frequency end of the interaction
of matter and (EM radiation/the ether) tells us how strongly matter and
EM/ether couple at low frequencies. Either this is frequency dependent
( ., through quantisation of the EM field in QED, or unknown but very
convenient properties of an ether), or we get the ultraviolet catastrophe.
Saying "let ther be photons of E=hf" is the simplest current working
solution.

Assuming E=hf works, but the _why_ of quantisation remains one of the
apparent deep mysteries of physics. But physics has never been good at
"why".

--
Timo Nieminen - Home page: /people/nieminen/
E-prints: /view/person/Nieminen,_Timo_A..html
Shrine to Spirits: /timo_nieminen/