Wei Dai wrote:
Jason, I think there may be some incorrect assumptions behind your argument. Let me state the facts as I understand them and you can check them against your assumptions or correct me if I'm wrong. The only reason we need reversible computation to do an infinite number of computations is that physics is reversible. If we had irreversible physics, then we would be able to do an infinite number of computations with irreversible computations.Also, "reversible" and "irreversible" computation refers to the method of implementing the computation, not the content of the computation. Reversible computation can be used to simulate an irreversible universe, and vice versa.
If that is true then my underlying assumptions were flawed. My argument assumed that a non-reversible universe could not be simulated by a computer with bounded memory and using only reversible computations. The way I arrived at this assumption was imagining a non-reversible universe, such as the John Conway's game of life. If the computer that implements this simulation has limited memory then in order for the simulation to continue forever, prior states cannot be saved in memory and instead old states would have to be overwritten. This destruction of information which cannot be undone would be logically irreversible as I understand it. However if the simulation were one where each state has a 1 to 1 mapping, overwritting old states does not destroy them forever because previous states could always be computed from the current state. Jason --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---
