Thanks. However the uncertainty principle doesn't solve this. In the case that the atom is as far away as Alpha Centauri, then it will have recoiled hundreds of thousands of kilometres before the photon reaches Earth. I think that a committed QM expert would be reduced to saying that the atom...
Sorry that my explanation was so incomplete. In the photon-as-a-particle (standard) model there is no problem. Momentum and energy are conserved. I was referring to the problem that the photon behaves as a widely dispersed wavefront while the atom recooils in a very precise direction. It's...
Thanks v much. The standard model produces the EPR paradox, photon entanglement and other quantum weirdness. The issue of photon momentum that I mentioned is just another problem with the standard model. We build our physics ever higher but should be ready to accept it may be built on ideas...
Errr... Thanks for the respectful response. A hydrogen atom in a nebula emits Lyman alpha. It recoils at 3 m/s. The photon travels through space for 5 years say, before being absorbed into an observer;s retina. In the meantime the hydrogen atom has recoiled hundreds of thousands of...
I am interested in what the recoil velocity of an initially stationary hydrogen atom in free space would be when it emits a Lyman alpha photon. I tried to do the calc and got about 3 metres per second which seems rather high.