Today, let’s kick off our shoes and relax our standards for what counts as a reasonable spacetime. Let’s talk about spacetimes allowing for a certain kind of time travel, called…
Ice water on closed timelike curves
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Hyper-intelligent fish and black hole thermodynamics
Bill Unruh’s recent collection on black hole analogues begins, Deep beneath the great encircling seas of the Discworld lived a species of hyper-intelligent fish. (Unruh 2007, p.1) Unusual, but inspiring:…