Quote (Mastersam93 @ Nov 12 2013 05:08am)
I heard the phenomenon compared to a pair of gloves. If you have the right glove then you know the other is always left
that is a decent explanation of what classical entanglement might have been like. However this description fails to describe quantum entanglement (as do all non-mathematical descriptions).
To paraphrase your example:
We take pair of gloves and put them in a box and shake the box up real good.
Then you extract one of the gloves without checking to see if it is the right or left hand, and put it in a new box and well call this box A. You then put the other glove in another box and call it box B. You take box A and go home; I take box B and go home. The next morning I open up my box (b) and find I have the left handed glove, and I call you on the phone and tell you. Now you know you have the right handed glove; you open your box just to check the logic and sure enough you do. Your explanation (above) seems to be something like: "This is not surprising, the right glove was in box A the entire time, and the left handed glove was in box B all the time, we just didn't know it until someone opened their box.
Now the quantum version:
We take a pair of electrons in a total spin 0 state (this means that their spins are opposite, not unlike the gloves). Again we put one in each box and take them home. I measure the spin on mine (along a certain axis) and call you and give you the results. You now can predict what result you will get if you do this same experiment (you will get the opposite of what I found, not unlike the gloves). And again you might be tempted to give the explanation you gave above: that this is not surprising, you always had the "left electron" and I had the "right electron" all along. But now it fails, because we can clearly show with other experiments, that the state (the left/rightness) of my electron was not determined until I measured it. In fact neither electron was in a definite state until I measured mine. And both of them were in a definite state after my measurement. And therein lies the weirdness.
How can the laws of nature be different for electrons and gloves you ask? Especially since gloves are made out of electrons (and other stuff)? Well of course the laws aren't really different. A better version of the story above would include the incredible special care we would need to use to keep those electrons in an indefinite left/rightness state. They would need to be isolated extremely well from their environments. Without these precautions the electrons would almost immediately collide with the walls of the box, interact with molecules of air in the box, perhaps be hit by photons, and other kinds of ugly stuff. These unwanted events are very similar to the measurement process I was planning on doing later, and achieve the same result (they make the left/rightness state definite). So without special care your description would be pretty good, in that the state of those electrons would have been determined immediately after they were put into their boxes, so when you took home box A, you had the "right handed" electron all along (and I had the left).
The punch line is that while it is possible to isolate an electron in this fashion if you use great care, it is essentially impossible to do this with gloves, they are just too big. This is why gloves seem to obey a different set of rules than electrons, but in reality it is the same set of rules.
And I should mention, even the above is a gross over simplification. And if you prod my explanation too much, it will fail, just like yours did.
This post was edited by Azrad on Nov 12 2013 07:11am