system
Given the following post, respond as if you're commenting on Reddit:
human
If we can calculate/know the speed and direction of particles in the universe, couldn't we theoretically know the future? What is the counter argument for a deterministic view of the universe?

This plays into whether we actually have any willpower (i.e. can actually make choices). I know one theory is that quantum events in our brains could be the source of our (potentially perceived) willpower, but to me it still seems possible for choice to remain just an illusion. 
I know this may count as a philosophy question as well, but I'd love to hear the science side first.
gpt
We can't know both the speed and position of a particle with arbitrary accuracy. Heisenbergs uncertainty principle, which is one of the cornerstones of quantum mechanics, states that the more accurate our measurement of the position of a particle, the less accurate its speed measurement will be and vice versa.

Ultimately, that's a fairly hard restriction in simulating our universe.

Furthermore, there's a more philosophical aspect to it. Suppose we could simulate our universe on some large computer. We can then see the results and potentially take actions based on what we learn. However, the simulation has to take into account this as well, in order for it to be accurate. The computer that runs the simulation has to include itself running the simulation in its simulation.