Yes, I agree. But it could be that information loss is a bit ambiguous. E.g. 't Hooft has shown that you can start with a deterministic model exhibiting information loss and end up with quantum mechanics.
Saibal ----- Original Message ----- From: "Jesse Mazer" <[EMAIL PROTECTED]> To: <email@example.com> Sent: Monday, April 10, 2006 03:22 AM Subject: Re: why can't we erase information? > > Saibal Mitra wrote: > > > > > > >How would an observer know he is living in a universe in which information > >is lost? Information loss means that time evolution can map two different > >initial states to the same final state. The observer in the final state > >thus > >cannot know that information really has been lost. > > If he is able to figure out the fundamental laws of physics of his universe, > then he could see whether or not they have this property of it being > possible to deduce past states from present ones (I think the name for this > property might be 'reversible', although I can't remember the difference > between 'reversible' and 'invertible' laws). For example, the rules of > Conway's "Game of Life" cellular automaton are not reversible, but if it > were possible for such a world to support intelligent beings I don't see why > it wouldn't be in principle possible for them to deduce the underlying > rules. > > As for the question of why we live in a universe that apparently has this > property, I don't think there's an anthropic explanation for it, I'd see it > as part of the larger question of why we live in a universe whose > fundamental laws seem to be so elegant and posess so many symmetries, one of > which is time-symmetry (or to be more accurate, CPT-symmetry, which means > the laws of physics are unchanged if you switch particles with antiparticles > and flip the 'parity' along with reversing which direction of time is > labeled 'the future' and which is labeled 'the past'). Some TOEs that have > been bandied about here say that we should expect to live in a universe > whose laws are very compressible, so maybe this would be one possible way of > answering the question. > > Jesse > > > > > ------------------------------------------------- Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to firstname.lastname@example.org To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list -~----------~----~----~----~------~----~------~--~---