He is studying the Einstein-Podolsky-Rosen Paradox. Basically, using spooky action, he wants to be able to use entangled pairs to send messages, not only through space, but also in time.
As the evidence for this has accumulated, several fairly contorted and unsatisfying efforts have been aimed at solving the puzzle. Cramer has proposed an explanation that doesn't violate the speed of light but does kind of mess with the traditional concept of time.
Question: How do you know where to find and "listen" to the right entangled particle to receive a message from the future? Or, in that vast amount of noise, if you don't know someone is sending a message, how do you know its there?"
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