On 9/23/2019 12:45 PM, Philip Thrift wrote:
On Monday, September 23, 2019 at 2:32:11 PM UTC-5, Brent wrote:
On 9/23/2019 8:59 AM, Alan Grayson wrote:
> But Laplace was wrong in one very important respect. One can never
> know the exact position and momentum of any particle, let alone the
> entire universe. There are no perfect measurements!
Laplace knew that. His point was that the future (and the past) were
completely determined by the present state of the world. Even
though we
can't measure it perfectly, Laplace assumed that the variables like
position and momentum had definite values. That's what is
fundamentally different about quantum mechanics, they don't have
definite values.
> Further, the situation is further aggravated by the Uncertainty
> Principle. In sum, using classical mechanics the future is NOT
> determined by its present, imprecise configuration.
The uncertainty principle is part of QM not CM. Just because you
can't
measure it precisely, doesn't mean that the present configuration
is not
precise; it means that we are ignorant of the precise values. This
was
Einstein's idea, that QM was incomplete and its randomness was
just an
expression of our ignorance, as in CM.
> Not only is Laplace mistaken, but Carroll as well, who should know
> better. AG
Neither Laplace nor Carroll is mistaken.
Brent
Both were/are superstitious, basically religiously so, in their
fear/rejection of probabilities.
https://en.wikipedia.org/wiki/Laplace%27s_demon#Quantum_mechanical_irreversibility
Did you tell Carroll that?
Brent
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