Re: A maximum acceleration ?

[brian whatcott <inet@intellisys.net>]

At 12:00 11/30/97 -0800, John M wrote:
> > > Clearly, to the extent that "electric breakdown" requires the presence of
> > > a gas, it simply cannot happen in a vacuum.
>
> To which brian wrote:
>
> > 1) provide two adjacent point electrodes of "molecular"
> > sharpness.
> > 2) Increase the electric field between the points,
> > taking care that the vacuum is maintained at the highest 
> > obtainable levels by positioning in space or by means of 
> > getters.
> > 3) High field emission of electrons will soon create a 
> > plasma discharge at a vacuum so high that it passes
> > Ludwik's standard of idealisation.
>
> Of course you are right, but I wouldn't like to confuse field emission
> with the more common phenomenon of "electric breakdown." I was responding
> only to the clear and incorrect implication in your statement (quoted
> above) that the kind of electrical discharges that are often observed in
> moderately low pressure situations are somehow to be associated with "the
> vacuum."  Your statement that "the breakdown voltage is smaller for a
> given vacuum gap than for an air gap," is simply not true in general even
> *if* you expand the definition of "electric breakdown" to include field
> emission.
>
> John

It just amazes me sometimes how wrong I can be when I am right!

 Still, if we now can reasonably admit that there is a limit to the 
strength of macroscopic electric fields in the real and maybe even 
the ideal universe, I expect I have said enough! 

Of course, there IS the renormalization issue which is said to be
needed to evade the idealist's difficulty with the infinite electric field 
strength of the point electric charge, but perhaps we had better 
keep that one swept under the carpet?      :-)

Respectfully,