The Unruh effect is the fact that an accelerated observer doesn't see vacuum, but a thermal bath of particles with an effective temperature proportional the proper acceleration. The explanations that I've seen for this effect seem very mysterious to me. It seems to involve the fact that the generator for boosts in the Rindler coordinate systems looks just like the Boltzmann factor for thermal physics, once you identify the acceleration with the temperature. But that just seems like slight of hand. I don't understand intuitively the connection between temperature and acceleration. Can somebody describe in more detail than Wikipedia, why this makes sense?