All physical systems can be thought of as registering and processing information, and how one wishes to define computation will determine your view of what computation consists of.
Seth Lloyd[With quantum computers] you can calculate how many bits are in the universe, how much energy it takes to flip them, how much energy exists, and use that to rule out lots of things about the universe's history. Anything that takes more bit flips couldn't have happened.
Seth LloydIf you wanted to build the most powerful computer you could, you can't do better than including everything in the universe that's potentially available.
Seth LloydI have not proved that the universe is, in fact, a digital computer and that it's capable of performing universal computation, but it's plausible that it is.
Seth Lloyd