It's a word given to an experimental result for which there is absolutely no understanding. That happens quite often is science.

The experiment can be done with any particle pair production, most readily with photons or electron-positrons. Take photons. At a point in space, in a number of different ways, physicists can produce aphoton pair that fly off in opposite directions. Presumably they have opposite polarization as well as direction. But according to quantum mechanics the polarization can be anything until it is measured.

Then some distance from the source, one photons polarization is measured. It turns out that the other photon instantly, so they say, has the opposite polarization.

Einstein, Podalsky and Rosen originally proposed this as a thought experiment to prove that quantum mechanics had to be wrong and General Relativity right, as the polarization information would have to travel faster than the speed of light.

The question lay dormant for a number of years until Bell worked out themath to make experimental comfirmation possible. Aspect did the first experiment in France and the result proved that General Relativity was wrong and quantum mechanics right. However, no one knows how one photon knows about the other. So they gave it the name entanglement.

• Thanks - stormcrow - April 28, 2001 - 12:07 UTC
  • Whoops - stormcrow - April 28, 2001 - 12:07 UTC
    • What does NT mean - yanniru - April 28, 2001 - 20:54 UTC
      • "No Text." (oh, NT, btw) :) - stormcrow - April 28, 2001 - 22:56 UTC
• re: Aspect's inequality experiments - harvey1 - April 28, 2001 - 15:19 UTC
  • E & P & R have passed away - yanniru - April 28, 2001 - 20:56 UTC
• Entanglement is no puzzle! - doctordick - April 30, 2001 - 14:07 UTC