Actions at a Distance
Quantum entanglement is a strange phenomenon in physics in which spatially separated particles can be correlated in such a way that any measurement performed on one influences the state of the other instantaneously. Attempts to try to explain the phenomenon using a more psychologically satisfying model than the one quantum mechanics provides led to Bell’s inequality, which bounded how large these correlations could be. However, the model in quantum mechanics better predicted the outcome of experiments than Bell’s inequality. Thus, Rule 3 led to the adoption of the new model.
While not instantaneous, communication systems based on classical mechanics have been closing the gap. Despite being on the West Coast, I saw the Agassi-Baghdatis match “live” on my television. After the match, I exchanged an e-mail about it with a friend, who had seen the match in Chicago. Arthur Ashe stadium, where the match was played, is in Queens, New York.
This week, we have been studying results around a communication system in which two transmitters and two receivers are all spatially separated. One subtlety in this setting is that if these terminals timeshare, which synchronizes them through a common random variable, they can communicate at higher rates than any achievable in the convex hull of all unsynchronized strategies. Thanks to MSN Messenger’s conferencing features, we were able to sort out many of these subtleties with my former officemate, who now lives in San Diego.
In our connected world, it’s difficult to imagine events that violate a sequential ordering. During the War of 1812, Andrew Jackson led America to a decisive victory in the Battle of New Orleans on January 8, 1815. The Treaty of Ghent, which ended the War, had been signed in Belgium on December 24, 1814.