  We study classical radiation and quantum bremsstrahlung effect of a moving
point scalar source. Our classical analysis provides another example of
resolving a well-known apparent paradox, that of whether a constantly
accelerating source radiates or not. Quantum mechanically, we show that for a
scalar source with arbitrary motion, the tree level emission rate of scalar
particles in the inertial frame equals the sum of emission and absorption rates
of zero-energy Rindler particles in the Rindler frame. We then explicitly
verify this result for a source undergoing constant proper acceleration.
