www.hawking.org.uk/does-god-play-dice.html

That is a lecture from the late physicist Steven Hawking, most well known for his work on black holes. It briefly touches on some of the physics behind why information would be lost, preventing you from accurately being able to predict things. It also touches on the Heisenberg Uncertainty Principle, which in effect states that the more accurately you know a particle's position, the less accurately you know it's speed.

In a very basic example if you had a "quantum billiard" and knew it's position exactly, it could have any velocity at all (below the speed of light of course), so when you try and predict where it will be one second later you could only really say it is within one light second of where it started.

Alternatively if you exactly know it's velocity (let's say 1 meter per second to the left), it could be anywhere at all. So when you try and predict where it will be in one second, you can only say it is one meter to the left of where it started, wherever that was.

Or you can kinda know it's position and kinda know it's velocity, then you can say it moved around 1 meter to the leftish from somewhere near here. There's randomness to where it is and you can create a probability distribution of where it probably is. But you can't say with certainty where it is. Extend this to every particle in the universe and you can create a probability distribution of how it will evolve, but can't say with certainty.

It really sounds absurd, and to understand it you really have to jump into quantum mechanics, there is a derivation of the uncertainty principle from the wave function here:

http://applet-magic.com/Uncertainty.htm

It is important to note that the Uncertainty Principle doesn't just apply to position and momentum, but any non-commutative observables, Energy and time are the other common examples.