If we send a particle with mass through the double slits we observe a interference pattern. That is of course if we don't observe which slit the particle goes through. If we do then we get two peaks as if a particle had passed through the slits. But what if we detect what slit the photons pass through when using light. Is this even possible? and if so would we get two peaks (opposite each slit) or an interference pattern?
It's not about disturbing the photon. If you observe it, your detector gets entangled with it. It's possible for the photon going through the left slit and going through the right slit to end up in the same state and interfere, but if you get a detector involved then one of those will set off the detector and the other won't, so they won't be in the same state and they won't interfere.