Hi
I didn't read all the posts and I don't know how the subject is now the twin paradox, but I have some taught about the original question: When a photon is released, which way does it head?Some photon are realesed by excited atoms. Considering the law of conservation of momentum we can imagine a situation where we can predict the direction of the released photon.
Consider an atom at temperature close to 0K so it can be considered stationary.
Shot a photon from the left on that atom. If the atom absorb that photon , the conservation of momentum tell us that the atom will be moving to the left. After a while the atom is de-exited and emit a photon of the same momentum as the incident one, so the photon will continue in the left direction and the atom will stop.
Is it theoriticaly correct ?
Is it pratically correct ? (I guest that we cannot have a stationary atom because of Heiseinberg uncertanity)
Just a thaught