Hacker News Reader

Comment by jwally | Hacker News Reader

I'm a layman, so I'm not 100% certain on this, but I think this is a quantum version of Laplace's Demon; where if you know all the information about the state of a system, you can calculate what the system will look like at any point in the past, present, or future.

View on HN

Does this imply that if we knew the total state of the universe, we could calculate its future state?

Basically, does this imply the universe is deterministic, or that we're living in a simulation?

The evolution of the wave function is deterministic. However, the observables of the wave function are not deterministic. So if I tell you the state of a photon moving toward your eye, you can determine the probability distribution of what color you will see, but not the actual color, because there's randomness during collapse.

(Alternately, there's indexical uncertainty in timelines, which rouuuughly comes out to the same thing if you handwave about game theory a bit https://plus.maths.org/content/playing-games-part-i )

It implies that the universe is deterministic, with the caveat that what’s deterministic is the universe as a whole, which includes umpteenillion extra “timelines” which we can’t see, in addition to our own.

There’s remains indexical uncertainty, as we can’t predict which timelines we’ll see. The answer is of course all of them.

Unknown: https://physics.stackexchange.com/questions/63811/is-the-uni...

Also, has been argued philosophically for thousands of years https://plato.stanford.edu/entries/freewill/

It's known that the universe is deterministic, just not all people agree.

Reply on news.ycombinator.com