Ian Mallett wrote:
Of course, there is a paradox in all this, that the ball can
retain kinetic energy, yet have no mass. It could be viewed that, by
Physics, it could not impart energy with no mass, because energy
transfer is proportional to the mass and speed of an object.
That's only the case in Newtonian physics. It's true that Newtonian physics doesn't include the concept of an object with zero mass, but things are different in relativity. One of the differences is the meaning of the word "mass". Nowadays it's used to mean "rest energy", i.e. the energy an object has even when it's not moving. When it is moving, it has additional energy as well, calculated from its rest energy and its speed. But a photon is never at rest, so the concept of rest energy doesn't really apply. Its energy is calculated a different way, based on its frequency.
But photons accelerate, at least, so ???
No, they don't. They're born moving at c, and they do so until they die. -- Greg