For light rays that originate inside a crystal ball, those that are totally internally refracted will still be totally internally refracted again at the next point they touch the sphere. Part of the ray escapes as the ray is due to particles in circular motion, the orbits of which swing around the apex of a cone, on the surface of the cone, centered at the apex. (From the post "A Bloom Crosses Over" dated 10 Aug 2015.)
Other rays with incident angle at less than the critical angle for total internal refraction will be refracted repeatedly. All such rays will be lost from inside the crystal ball.
A lot of photons collide inside the sphere among the rays that remain inside the crystal ball. This is just like inside a furnace where a lot of photons collide too. Colliding particles generate particles with high energy \(\psi\) and are sent back in time as their \(\psi\)s subsequently collapse.
If a furnace can sent images from a future date back in time, then a crystal ball can do the same. At lower temperature, crystal balls sent images back in time over a shorter period; a few weeks maybe.
(Just cover the other side of the crystal ball, it is not necessary to rotate the ball.)
How much later in time do you need to sign to your crystal ball to receive a message now? Only by experimentation can you tell, given the size, type of material and temperature of your crystal ball.
And you would illuminate the crystal ball such that total internal refraction occurs for most of the rays from the light source. It is the collisions among the photons trapped by total internal refraction inside the crystal ball that produce the time travel phenomenon.
Now that we have a side business reading crystal balls as gypsies, have a nice day.
