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From: minsky@media.mit.edu (Marvin Minsky)
Subject: Re: GREAT Pynchon AI.Life Quote!
Message-ID: <1995Jan12.215835.10754@news.media.mit.edu>
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Cc: minsky
Organization: MIT Media Laboratory
References: <D27J7C.26w@undergrad.math.uwaterloo.ca> <3evkij$2p3@crl5.crl.com> <D2AG1B.4D7@topazio.dcc.ufmg.br>
Date: Thu, 12 Jan 1995 21:58:35 GMT
Lines: 25

In article <D2AG1B.4D7@topazio.dcc.ufmg.br> omni@topazio.dcc.ufmg.br (Lucio de Souza Coelho) writes:

>Otherwise, talking about Laplace... He believed that past and future
states of the Universe could be calculated from present since a
sufficiently precise measurement of present state was obtained. But
Heisenberg's Uncertainty Principle, discovered after Laplace's time,
proof that arbitrarialy precise measurements >are impossible (and so
arbitrarialy precise predictions).

Laplace was saying that *if* you knew all initial conditions, then
newtownian mechanics would prdict the future.  In other words, he
wasn't saying that practical predicitons are feasible, but that the
world is deterministic.  You should know that the modern Shrodinger
theory has the same implication: *if* you know the entire wave
function now, then you can predict it in the future.

In any case, even newtonian orbits can be chaotic, in the sense that
future states can be exponentially sensitive to initial conditions.
In fact, Liebniz knew this in Newton's time, so I'm sure that Laplace
was aware of it.

