Entangled particles?

Question

Can someone explain to me the theory of "entangled particles"?

How can a particle here affect another paired particle on the other side of the universe instantaneously?

It sounds too fantastic to be true, but I know there's been experimental proof of this.

I've read and re-read this theory but too stupid to understand it.

Answer 1

Well actually the experiment didn't involve two particles on opposite sides of teh universe!

As for QM, one of my favorite quotes is: "What we're seeing is not nature, but nature as exposed to our method of questioning."

Which is another way of saying: we're all too stupid to understand it. And anyone who says they do is fulla.

Answer 2

Entanglement arose with quantum mechanics.

One of the fundamentals of quantum mechanics is that you know nothing of a system until it is measured.

So, for instance, if two particles collide and exchance magnetic moments, where the sum of the moments must be 0 before and after the collision. Then we seperate these particles without measuring their moments. These particles moments remain in a superposition defined by a wavefunction which collapses at the point we finally measure them. Then we finally discover that one particle's moment is 2. This instantly implies that the others must be -2 due to conservation laws.

Answer 3

And to add to the weirdness, if somehow we could change the spin of one of the particles, the other would have to change to match instantaneously. These effects come from "Bell's Principle" and have been proposed as a possible way to communicate at faster than the speed of light. However, I believe that this has be proved impossible. Read "The Fabric of the Universe" by Brian Greene.

Edit: It's "The Fabric of the Cosmos"