system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Now that we know that "spooky action at a distance" is a confirmed phenomena of the quantum world, what does it mean?

I know whatever the average internet surfing Joe would know about Quantum mechanics. Mostly nothing.

What does this mean for general physics? I saw in the comments that this means we are all connected. Does that mean I am somehow connected to my plate of oreos? Or does this 'connection' work only from like to like, humans to humans, oreos to oreos.
gpt
Quantum entanglement, or 'spooky action at a distance', is a phenomenon that can occur when two particles are created. I'll use spin as an example of a property that can be entangled. If two particles are created that are entangled, their spins will have opposite values. You can only know the probability that a particle's spin will be in a particular direction. There's no way to be sure ahead of time.

Say you measure the spin of one entangled particle to be clockwise. You now instantly know that the particle it is entangled with has a counterclockwise spin. Even though it's impossible to describe spin as anything other than a probability, the spin of the second particle is determined by the measurement of the first particle. Whatever measurement you get, the other entangled particle will measure the opposite way.

The second particle 'knowing' which spin to have based on the first particle's measurement happens instantaneously, and this bothered Einstein, the man who first referred to it as "spooky". According to relativity, nothing can move faster than the speed of light. Yet, the second particle's spin is determined instantly. Theoretically, the particles could be separated by light years, and measuring clockwise on the first particle's spin would guarantee that the second particle's spin would be counterclockwise.

This doesn't violate relativity, however, because there is no way to transmit information via entanglement. The second particle's measured quantity will always be determined by the measurement of the first particle, but what that measurement yields is inherently probabilistic. It's random, and the qualities of the second particle will be random too, just in the opposite way. So no physical laws are broken. You can't use quantum entanglement to send a message or intentionally make anything at all happen. And it's something that only really matters on the scale of individual particles. The chances of your left big toe being entangled with your right are about as likely as Jupiter spontaneously appearing in the Andromeda galaxy. It's technically possible, but the odds are so small that they're barely quantifiable.

What does this mean for general physics? Nothing, because we've been aware of entanglement for quite some time now. All that has happened is that yet another rigorous experiment has upheld it to be true.

As an aside, Einstein's resolution to the problem was to say that the two particles contained hidden variables that determined what state they'd be in when measured. He had no evidence, but he imagined that there were some things that we just didn't yet know about the particles that would cause them to measure in opposite ways. The measurement of the first didn't determine the second because, to him, the information about what the measurements would be was contained within the particles all along, unknown to us. Many experiments have shown this to be false; quantum entanglement has withstood all experiments to date. Look up Bell's Inequalities if you want to know how we can prove that there are no hidden variables.