Technology

Photons. Not trying to be pedantic.. it's just a massive difference.

Meh, it's a losing battle try to establish what's actually going on mechanically. It's best to just stick to the rules we can prove and leave the underlying "how" as an implementation detail.

What we know is that it is possible for distant particles to become entangled without respect for relativistic limits. There's effectively no difference between saying that the entanglement propagates regardless of distance (simultaneously FTL) or that the entanglement propagates regardless of time (sub-FTL regardless of simultaneity).

The issue is that an observer must at some point have observed both particles to know that they've become entangled. This is already a problem at any scale, but it gets much worse at relativistic distances because you can no longer even be certain when the two tangles are entangled, including and up to whether or not the particle you are locally observing is currently entangled. You're stuck playing relativistic Two Generals' Problem in such a way that if there was an FTL transmission, any useful information from it is rendered inaccessible without first receiving additional sub-FTL information.

This is the fundamentally frustrating thing about quantum mechanics. As far as we currently understand physics, any experiment which would reveal the actual underlying physical nature of the quantum world would itself be physically impossible (e.g.: FTL travel, time travel, violating the uncertainty principle).

Ah yeah kinda, The two particles would be in a super position state. Meaning that there could be a number of possible states and each state has a certain probability.

The reason quantum entanglement is so weird, Is that by measuring one Particle changes the state of the other particle, it is in fact spooky action at a distance. How these particles communicate with each other is unknown but we cannot use it as a communication method because the act of measuring one of the particles destroys the entanglement. The states of the particles are random before we measure it. There is no state at which both particles agree upon before they're separated.

When the two particles are entangled, no "information" is communicated. So we can think of it as The particles exchanging random information that has no use to anything. This solves the faster than light communication problem because no real information is sent, Only random data. They're experiments that try to test this hypothesis called the quantum eraser.

This is a common misunderstanding due to trying to think of things classically. I'd recommend "the road to reality" by Penrose if you want a better understanding.

Also it is not why we cannot use entanglement for FTL info, but you'll understand that more once you understand entanglement better.