Re: A maximum acceleration ?

[brian whatcott <inet@intellisys.net>]

At 00:46 11/30/97 -0400, Ludwik wrote:

 [brian]
> >  It is easy to discount the kinds of electric field which motivate
> >  mechanical force, because at some point a macroscopic object will be
> >  squashed if the acceleration is too great; the force needing to spread 
> >  over a wider area of application until a rather thin layer, perhaps 
> >  a monatomic layer is the limit.
>
> You are referring to contact forces in real materials. In my mind the
> ULTIMATE limit is something which is valid even in the idealized world.

If my humble effort which attempts to represent reality is of some
value in an idealized universe, I shall not complain.

> Please correct me if it is wrong to think that 
> in a perfect vacuum electric breaking down is not possible. [By the way,
> what is the mean free path of hydrogen atoms between galaxies?]

You are indeed wrong to think that electric breakdown does not occur in the
vacuum. It is intuitively plausible but in fact, the breakdown voltage
is smaller for a given vacuum gap than for an air gap. This was a matter of
considerable practical importance when high power radars were carried to
great heights, where they proceeded to misbehave until their waveguides
were pressurized.

I will refer you to the standard Physics texts for mean free path estimates
for the common deep space species.

 [Brian]
> > So then I consider the force that impels particles in an accelerator.
> > In a one-pass arrangement, there is some limiting value of electric 
> > field which can be arranged; the vacuum breaking down (or permitting
> > ionization or plasma production ) in the limit.

> I am assuming the term "hole" is used 
> as a reference to a region where the V=-G*M/r potential is extremely large. 
> Do we think that the M/r ratio can be as large as we want? This would 
> mean that any acceleration is possible.

The idea of massive black-holes is now so fashionable and pervasive, that I
can hardly cite one reference among so many! They seem to agree that the
M/r ratio may be arbitrarily high - even though it may be unobservable -
and hence a metaphysical rather than physical question at that point.

> > And so I am finally left with the force of gravity, which it appears 
> > may be multiplied without limit and which would provide an arbitrarily 
> > large acceleration to a particle approaching a hole of sufficient mass.

I should mention that it is quite easy to accelerate electrons to rather
high fractions of c in an electron tube. Only a modest distance is needed
to impel electrons this fast with an electric field.

 But I fancy the attainable force due to gravity may be stronger in
the region of collapsed matter. 
Sincerely,

brian whatcott <inet@intellisys.net>
Altus OK