Originally posted by Metal Brain
Someone once suggested that massless particles have to travel at the speed of light. Electrons are a little slower than c because they do have mass, but very little.
How slow can a massless particle travel? How slow can an electron travel?
A massless particle can be at zero velocity in the right medium, an infinite refractive index material and it happens. An electron can be trapped to not move at all also since it is controlled by electric fields, if you shape the field right it will fit in an energy valley and not move away from it unless energy is added overcoming the energy valley it currently resides in.
Electrons CAN be a bit slower than c but only with the addition of a lot of energy. It cannot go exactly at c so photons will always outrun electrons in free space.
Both follow the curvature of space, in short, gravity fields, however. Electrons just get accelerated or decelerated by electric fields and deflected by magnetic fields which attempt to force said electron in a curved path and if the electron is going slowly enough
the magnetic field lines can cause said electron to spiral around the field pretty much forever, I think anyway, can't testify to that since it might also give off Cherenkov radiation from the spinning path it takes, if so it will lose energy and I don't know exactly what happens in that case.