"Once you take seriously that all possible universes can (or do) exist then a slippery slope opens up before you. It has long been recognised that technical civilisations, only a little more advanced than ourselves, will have the capability to simulate universes in which self-conscious entities can emerge and communicate with one another. ...if we live in a simulated reality we should expect occasional sudden glitches, small drifts in the supposed constants and laws of Nature over time, and a dawning realisation that the flaws of Nature are as important as the laws of Nature for our understanding of true reality."