Most quantum things come in pairs. For example, electrons have “spin” (no-one really knows what it is – we just call it that – but whatever it is we can measure whether the spin is +1 or -1). And in a pair, one will have one spin, and the other will have the opposite.
Now the really hard thing about quantum mechanics is if you haven’t actually “looked” then you don’t know. But when you look at one and measure its spin, the other one automatically get the opposite valeu.

@misseden: this is not my area of science, so I went directly to simple wikipedia which says:

When we look at particles, we usually say that each particle has its own quantum state. Sometimes, two particles can act on one another and become an entangled system. When a pair or group of particles can only be described with one big quantum state for the lot, and not as a bunch of little quantum states put together, we say the particles are “entangled”.

Quantum entanglement is just what was already described: when you have two particles that are related (say, they came from the same source), you can tell information about one by looking at the other. What is really crazy is that you can take the two particles and separate them by a large distance, and measure their properties at exactly the same time, and you always get the right answer for each of them based on their “entanglement” — as if they communicated with each other faster than the speed of light! The trick, of course, is that they were entangled from the start, so they don’t really need to “communicate”. But it is still really bizarre; there are lots of parts of quantum mechanics that are weird like that.

Most quantum things come in pairs. For example, electrons have “spin” (no-one really knows what it is – we just call it that – but whatever it is we can measure whether the spin is +1 or -1). And in a pair, one will have one spin, and the other will have the opposite.

Now the really hard thing about quantum mechanics is if you haven’t actually “looked” then you don’t know. But when you look at one and measure its spin, the other one automatically get the opposite valeu.

1@misseden: this is not my area of science, so I went directly to simple wikipedia which says:

When we look at particles, we usually say that each particle has its own quantum state. Sometimes, two particles can act on one another and become an entangled system. When a pair or group of particles can only be described with one big quantum state for the lot, and not as a bunch of little quantum states put together, we say the particles are “entangled”.

Source:

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

Hope that helps! ðŸ™‚

0Quantum entanglement is just what was already described: when you have two particles that are related (say, they came from the same source), you can tell information about one by looking at the other. What is really crazy is that you can take the two particles and separate them by a large distance, and measure their properties at exactly the same time, and you always get the right answer for each of them based on their “entanglement” — as if they communicated with each other faster than the speed of light! The trick, of course, is that they were entangled from the start, so they don’t really need to “communicate”. But it is still really bizarre; there are lots of parts of quantum mechanics that are weird like that.

0