Imagine that you’re looking in a mirror and you raise your right hand. The reflection you see appears to raise its left hand. Now imagine you’re a particle, the reflection is another particle, you are separated by great distances, and yet the two particles still affect each other. That’s kind of an analogy for entanglement, a principle of quantum mechanics that says when a pair or a group of particles are entangled, they cannot be described independently from each other.
Measuring a particular property, like velocity, of a single particle affects all the other entangled particles, regardless of distance. Einstein and many other scientists believed that this phenomenon was paradoxical, as it would allow for information to be exchanged instantaneously across vast distances. He dubbed it “spooky action at a distance” and he believed that science was missing hidden variables to account for the phenomenon.
Turns out, he was wrong. Scientists at the National Institute of Standard and Technology have proven beyond reasonable doubt that spooky action at a distance does occur. According to the lead author of the research, “You can’t prove quantum mechanics, but local realism, or hidden local action, is incompatible with our experiment. Our results agree with what quantum mechanics predicts about the spooky actions shared by entangled particles.”
It’s a weird world we live in.