tag:blogger.com,1999:blog-5418994588621362010.post5293069258787883619..comments2023-11-15T10:08:56.796-08:00Comments on the blog formerly known as The Statistical Mechanic: memoriesWolfganghttp://www.blogger.com/profile/07086991199438418163noreply@blogger.comBlogger3125tag:blogger.com,1999:blog-5418994588621362010.post-51055975802596245322009-08-24T12:06:55.658-07:002009-08-24T12:06:55.658-07:00>> the universe could be doing them all the ...>> the universe could be doing them all the time. But if this is true, then computationally all hell breaks lose<br><br>again, I agree with you. In this model there could be computational processes which run 'backwards in time' but we would not be aware of them. <br>But then, we would not be able to read out the results of such computations. So everything is fine there...<br><br>>> so far they have either given me models with an extremely large amount of computational power<br><br>I would think this could still be fine, as long as you can explain why we have no access to the results of such computations 8-)wolfganghttp://tsm2.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-5418994588621362010.post-57375687772891482742009-08-24T12:01:46.873-07:002009-08-24T12:01:46.873-07:00Dave,>> we can't even "predict"...Dave,<br><br>>> we can't even "predict" our past<br>I agree, the paper suggests that we would only remember the entropy increasing but the world could be indeed time-symmetric. If this is so we would be unable to 'predict' the past. (By the way this is imho not as crazy as it sounds, because somebody who believes in the MWI must believe in the reality of the wave function of the universe, which [following Hartle & Hawking] would not be evolving in the usual sense)wolfganghttp://tsm2.blogspot.comnoreply@blogger.comtag:blogger.com,1999:blog-5418994588621362010.post-53177443617139495392009-08-24T10:30:01.627-07:002009-08-24T10:30:01.627-07:00This reminds me of a corollary to the idea that we...This reminds me of a corollary to the idea that we've discussed before that one cannot predict the future...we can't even "predict" our past<br><br>More relevant to this paper. If one cannot distinguish entropy constant evolutions from those where entropy increases, then this would seem to imply that entropy constant evolutions don't "cost" anything and the universe could be doing them all the time. But if this is true, then computationally all hell breaks lose, since the universe could reversibly compute some crazy computation without time advancing. <br><br>I've tried to play around with classical models like this but so far they have either given me models with an extremely large amount of computational power, or the same as classical complexity.Dave Baconhttp://www.blogger.com/profile/03506030153326411733noreply@blogger.com