Re: a paradox?

[LUDWIK KOWALSKI <KOWALSKIL@alpha.montclair.edu>]

> Date: Thu, 26 Feb 1998 10:33:04 -0500 (EST)
> From: "James W. Wheeler" <jwheeler@eagle.lhup.edu>
> Subject: Re: a paradox ?
>
> There will be "drag" forces from flying through a "rainstorm" of light.
> The Terrell rotation will be important.  In effect the net radiation force
> on the "spheres" will certainly change direction as a function of v/c.
> What is your exact prediction?

I have no idea. The "drag" force was ignored in my consideration. I did 
not realize it would be present. The main point was a possibility of 
verifying that the volume shrinking is real. That was the question asked 
by Lowell. My prediction was YES, the experimental verification is, in
principle, possible. Should the presence of the drag force be a good 
reason for the negative answer? I do not know. How does the "drag force" 
depends on v? Is it practically constant when v is close to c? What is
this "drag" force? Is the air resistance analogy applicable?

> > Several spheres (they have same masses and sizes in a rest frame) travel 
> > with relativistic velocities (different v/c) with respect to that frame. 
> > The spheres enter a region near a very massive and very hot star. Two 
> > forces are involved, one is due to gravity (same for each sphere) and
> > one is due to the radiation pressure. [The forces are opposite to each
> > other]. The second force, proportional to the exposed area, is larger 
> > for the spheres whose v/c are smaller. This is due to the relativistic 
> > contraction (photons travel perpendicularly to v toward an observer) in 
> > a fixed frame of reference. 
> >
> > Will an observer [located in a favorable place of our rest frame]
> > record different trajectories for different v/c? If so then a change
> > in volume is "experimentally confirmed". Of course, all this is "just 
> > in principle". We can not see a change of volume with our eyes but we 
> > know it is real.