Seth Lloyd, a quantum-mechanical engineer at MIT, estimated the number of “computer operations” our universe has performed since the Big Bang — basically, every event that has ever happened. To repeat them, and generate a perfect facsimile of reality down to the last atom, would take more energy than the universe has. - Discover
Well, in order to find Answer to the Ultimate Question of Life, the Universe, and Everything, all we need is some mice and the planet earth.. So he's about right I'd guess.