I've always found the idea of the universe being a simulation rather silly. There are estimated to be 10^80 particles in the observable universe.<p>Assuming our universe is being simulated on an earth sized computer (this is mind bogglingly ridiculous to me) <i>and</i> that the simulation meets Bremermann's limit (also ridiculous, since we're 40 orders of magnitude away according to this <a href="http://arxiv.org/pdf/quant-ph/9908043v3.pdf" rel="nofollow">http://arxiv.org/pdf/quant-ph/9908043v3.pdf</a>), then it would take on the order of <i>a whole earth day</i> to simulate a single time step.<p>Of course, perhaps the host universe doesn't have the same limitations. Such speculation seems pointless. Maybe solipsism is true. Maybe the simulation runs on magical fairy dust.