What is the particle pair phenomenon and how does quantum entanglement work?

[macd]

Hi everyone
Thanks for taking the time to read my first post.
I was reading Bill Bryson's A short history of nearly everything (which may be like saying that I was reading cat in the hat in an english literature forum, but i shall see).
Unfortunately I don't have the book here, or i would make specific references, quotes and probably be able to research myself on the net easier.

Anyways he mentions particles (which kinds?) always being in pairs, matching and having opposite spins. That in an experiment in Europe, Germany as I remember, these particles were separated eight miles and when spun in an other direction the other particle spun in the opposite direction.

So sorry for such a vague question, but I'm hoping that the boffins here could shed a bit more light on said experiment, did it really happen, how did they do it, and most importantly where can i read more about this?

Thanks again for your time.
Mac

 

[Hootenanny]

What Bill Bryson is referring to is known as "Quantum Entanglement". You'll find lots more information using Google and there are plenty of threads in this forum devoted to entanglement.

 

[G01]

As Hoot said, this is an example of quantum entanglement.

In a nutshell:

Particles in quantum mechanics are described by mathematical functions called "wave functions."

A system of particles will also be described by a wave function. In your case, the two particles, even though they move miles apart are still described by that same wave function, and that wave function dictates that the spin of each particle must be opposite to each other.

On a side note, I think it's a great idea for you to do some googling on the topic of entanglement, but, as I'm sure many people here agree, there are a lot of websites out there that really cannot be trusted with their usage of quantum mechanics. (I have even seen a website that tries to use quantum mechanics to justify astrology!)

Wikipedia is usually a decent place to start, though you should remember that it is not the best source. It is nowhere near the worst though:

http://en.wikipedia.org/wiki/Quantum_entanglement

Here is another cool article on the entanglement of 5 particles! It also talks about applications of entanglement to quantum computing.

http://physicsworld.com/cws/article/news/19793