Thursday, May 25, 2017

quantum mechanics - Does photon interference violate causality?


Suppose a hydrogen atom jumps down an energy level and emits a photon and that photon later goes through a double slit and gets absorbed by one atom of a screen making it jump up an energy level. Doesn't the photon have an extreme uncertainty in position and exist as a wave that travels in all directions until it suddenly collapses to have an uncertainty in position of about the diameter of an atom and gets completely absorbed by a single atom in the screen. That seems to violate causality because it's guaranteed that the screen will detect at most one photon from that atom so the detection by one atom sends the information to another atom faster than light to not detect it.


One possible explanation is that the universe follows de Broglie–Bohm theory and despite the fact that information can travel faster than light, it can never be sent in such a way to create a paradox. That in turn might be because those laws are a simulation by the fundamental laws which is that the universe is a Conway's game of life so it could not have simulated a universe with laws that allow for a paradox.


Another possible explanation is that the universe follows a different theory where it was already determined ahead by a hidden variable which atom will absorb the photon before the atom actually absorbs it. Maybe the photon emits a classical wave which stays a classical wave which gets gradually absorbed classically and the probability density of any atom on the screen jumping up an energy level at any time is completely determined by the rate of absorption of the classical wave so the jump down in energy level of the hydrogen atom actually can causing two atoms in the screen to jump up an energy level. Maybe it can actually be determined ahead which atoms will jump up in energy level but it seems random because the universe is chaotic. If that were the case, we would never be able to tell that the universe doesn't follow the accepted theory because we couldn't tell which jump ups in energy level of an atom in the screen came from which jump downs in energy level of a hydrogen atom. Just because a theory is consistent with observations doesn't mean the universe actually follows that theory.




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