Spooky Action at a Distance

You know what I don't get? Quantum entanglement.

Okay, sure, lots of people don't. Quantum mechanics in general is just a clusterfuck of physics nonsense to most people, probably. But I consider myself reasonably open to quantum ideas, whether or not I truly understand them.... but quantum entanglement is just fucking weird.



This is the description from Wikipedia:

Quantum entanglement, also called the quantum non-local connection, is a property of the quantum mechanical state of a system containing two or more objects, where the objects that make up the system are linked in a way such that one cannot adequately describe the quantum state of a constituent of the system without full mention of its counterparts, even if the individual objects are spatially separated.

Buuuh, let's rephrase that a little. If two particles are entangled, measuring the state of one particle, whatever that means, tells you what the result of measuring the state of the other particle will be, and it doesn't matter when or where the measurement is taken.

This is the easiest way I have ever been able to think of it: If two children are on a see-saw -- even if it's a thousand miles long -- you know that if one kid is down, the other has to be up. But no communication has to occur between the children for this to be the case; they are still connected and act as one single system. The concept of quantum entanglement is one of the reasons Einstein began to dislike quantum theory (as it was formulated), and he derisively referred to it as "spooky action at a distance."



Here's the kicker: entanglement occurs at roughly 10,000 times the speed of light. And that's a lower bound.




(The above article does a decent job explaining a little more of why entanglement is so damn weird, so I recommend reading it over. It's short, don't worry.)