To apply quantum theory to the entire universe... is tricky... particles of matter fired at a screen with two slits in it... exhibit interference patterns just as water waves do.

Feynman showed that this arises because a particle does not have a unique history.

That is, as it moves from its starting point A to some endpoint B, it doesn’t take one definite path, but rather simultaneously takes every possible path connecting the two points.

From this point of view, interference is no surprise because, for instance, the particle can travel through both slits at the same time and interfere with itself.

In this view, the universe appeared spontaneously, starting off in every possible way.

In his eyes shone the reflection of the most beautiful planet in the Universe — -a planet that is not too hot and not too cold; that has liquid water on the surface and where the gravity is just right for human beings and the atmosphere is perfect for them to breathe; where there are mountains and deserts and oceans and islands and forests and trees and birds and plants and animals and insects and people — -lots and lots of people. Where there is life. Some of it, possibly, intelligent.

It is hard to imagine how free will can operate if our behavior is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.