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 -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/e0d4366d-33a3-92ea-57c2-4965f11f2564%40verizon.net.
