It is possible to run a person on Conways Game of Life. This would be a person as real as you or me, and wouldn't be able to tell he's in a virtual world because it looks exactly like ours.

I don't see why you call this a "crackpot belief". The ( extended ) Church-Turing Thesis has near-universal acceptance and implies that humans can be simulated by turing machines. Similarly, it is widely accepted that Conways Game of Life can run turing machines . Physicists who don't believe this are widely regarded as controversial.