goombah99 writes "Nick Bostrom discusses the computational requirements needed to simulate human existence. He offers a proof based on the anthropic principle, that you are almost certainly a computer simulation and not "real". The idea is that given that humans don't go extinct in geologically short time then eventually computer capability will allow complete simulation of the human cortex. Consequently, there must be far more simulations running in future millennia than seconds since you were born. Thus its astronomically more likely you are a simulation than real ... if humans don't go extinct shortly. Recalling the 13th floor, Robin Hanson discusses how one should try to live in a simulation. David Wolpert also weighs in on the physical limits of Turing machines for simulation of the universe. This also may explain why time travel seems impossible: we dont meet visitors from the future since only the present is being simulated."