Re: A paradox?

[Leigh Palmer <palmer@sfu.ca>]

> Sorry, I never learned about the Lenz-Thirring effect, or about the Terrell
> effect. I just recall that object cotract relativistically in the direction
> of motion by the factor of sqrt(1-v/c). Thus a rapidly moving sphere will
> become a flat ellipsoid of revolution in my stationary frame of reference.

That will be true of the instantaneous locus of points on the surface
of the moving sphere when referred to the stationary frame. However,
because of the limit of lightspeed, the appearance of the sphere will
not be the same as its instantaneous shape in that frame. Light coming
to the observer from a greater distance (the parts of the object more
distant from the observer) will seem to come from a place the object
occupies later than that light which comes to the observer from a
lesser distance (the nearer part of the object). The overall effect
for a sphere is that it will appear to be spherical, but rotated on an
axis perpendicular to the observer's line of sight and the sphere's
direction of motion. This is called "Terrell Rotation".

Leigh

Terrell, J., "Invisibility of the Lorentz Contraction",
Phys. Rev. vol 116 no. 4 pp. 1041-1045 (1959)