Can Quantum Information go Faster Than Light?

Most recent answer: 09/03/2011

Q:
I have read that quantum entanglement yields faster than light communication. Being able to change a particles spin and instantaneous knowing the other "entangled" particles spin no matter the distance.
- Jim G (age 21)
Houston, TX harris
A:
Some people do write that, but they're wrong.

Let's look at the most familiar quantum entanglement situation, in which two particles emitted from a common source are required to have opposite spin, even though neither has any particular value of spin. If you measure the spin of one particle, you now have information about the spin of the other, even if it's far away. However, you have sent no information to that other spin. The reason is that your measurement made no controllable or predictable change in the spin, contrary to the implicit assumption of what you read. For a sequence of these spins, you and the remote observer each see a completely random sequence of values, regardless of what the other one does. Exactly zero information is transmitted.

Mike W.

(published on 09/03/2011)