X-Message-Number: 15054 Date: Wed, 29 Nov 2000 23:28:52 -0700 From: Mike Perry <> Subject: More on Turing Emulations Robert Ettinger, #15045, says >A Turing machine (finite but >unlimited sequential digital computer) is classical in its construction and >behavior, even though it can calculate quantum mechanics. Since its >capabilities are finite, it cannot generate a full set of Many Worlds future >histories of any system, let alone an emulated person. A "full set" of future histories might require infinite time. However, from an appropriate starting point, bounded (finite) in energy and spatial extent, the TM could patiently enumerate the possible outcomes for successively increasing but always finite times. Over finite time there will only be finitely many possible different states for such a system. So over infinite time our TM would generate all the infinite possibilities. It would, of course, be grossly inefficient since the number of possibilities it would have to consider would grow exponentially with the time step. > ... It [the TM again] can only, at best, generate >successive internal computer states corresponding to successive most-probable >quantum states of the emulated system. Again (I posted on this yesterday) the TM could change its states probabilistically and thus pick the less probable states sometimes. (Indeed, I've seen a chess machine that did this very thing. If you tried to play the same game twice by repeating your moves it would vary its moves thus producing a different game.) Such a device, then, should be able to model quantum state changes with the expected frequencies so that emulating a complex system like a human being is not ruled out. Note that this idea is a different one from the many-worlds emulation where all possible future histories are emulated (though again with great inefficiency). In the probabilistic case, only one timeline is considered, which seems far more reasonable from a practical standpoint. But it is also fascinating that the quantum computer could overturn this judgment, so that maybe some form of many-worlds emulation is what will actually be done. Mike Perry Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=15054