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Thursday, May 06, 2010
12:30 PM - 2:00 PM
T-DO Conference Room (TA-3, Bldg 123)

Quantum Lunch

When Quantum Mechanics Meets Time Machines

Graeme Smith

Physicists and science fiction writers have long been interested in time travel, wherein a person or object travels backward in time to interact with a younger version of itself. The many studies of such closed timelike curves have led to the general conclusion that, while conditions for their creation may not arise in typical astrophysical or cosmological settings, in principle there seems to be no barrier to their existence. That said, it is not entirely clear how to do quantum mechanics in the presence of closed timelike curves. In this talk I値l discuss some of the different proposals for quantum mechanics with closed timelike curves. I値l illustrate what the world is like under some of these models, using simple quantum computations as illustrative examples of interaction and change. Because time-travel induces nonlinear evolution in most cases, there are a lot of subtleties that don稚 come up in linear quantum mechanics. This leads to questions about what it means to 田ompute", 電istinguish", and even 田hoose".

Host: Jon Yard