Hey, I was watching this video About the quantum eraser experiment (I suggest you watch too, so we would be speaking in the same terms). As I understand it, The experiment goes such that: first the photon enters through the slits as a superposition, then the photon gets measured to gain which-slit information (via its twin brother, as explained in the video), and then the superposition 'collapses' to a single state (according to the which-slit information), and the photon reaches the screen. The result, after many trials, is no interference. No future-affects-the-past business here. So my question is, what if we run the experiment the following way: Suppose that you could trap the twin brother of the photon that goes through the experiment, for as long as you would like, without measuring it (I have no idea if that's practically possible). So you fire many photons at the screen, get your pattern, and then measure each photon's twin. Are you still going to get a no-interference pattern? If so, I could imagine a way to send signals to the past. Say your measuring device measures the twin photons only if some dice rolls a six. If the dice rolls a six after we get our pattern, the pattern has to be no-interference, and thus we could conclude that the dice rolled a six before it was rolled! So my questions are: 1. What does the theory dictate should happen? 2. Is this experiment actually practically possible? 3. If so, has it been done? Thank you for your time.