For a true ELI5, this will require leaving out a lot. This is simply an analogy. Analogies don't hold up perfectly with very complicated things, so be careful about using them in place of complete understanding or learning more.

The basic principle is having two special particles. These particles are kind of like twins. Created together, they become "entangled" and share a special bond. It's not magic but more like a connection that is hard for others to understand and see.

Now, let's say we take Particle A and put it in a box, and Particle B in another box. We take the boxes far away from each other, even on different sides of the world.

Whatever happens to Particle A will instantly affect Particle B, no matter how far apart they are! It's like they can still talk to each other and know what the other is doing.

Another way to think of it is like having two magic coins. If you flip one coin and it lands on heads, the other coin will always land on tails, no matter how far apart they are.

Scientists are still trying to understand exactly how this happens, but it's a very special and strange thing in the world of of very small things. Some think it shows that there is a way that very small parts of the stuff in the universe are connected that we cannot measure yet, or that many different possibilities exist and we only see one of them when we look for it.

If we could create this connection reliably and stably, we could potentially use it send information across distances nearly instantaneously! After all, a lot of the information we send right now is just 1s and 0s which we put together to make more complicated messages. This has uses in protecting information to keep it secret, making very fast computers, and maybe even "teleportation" by creating a duplicate at the other end of the connection, to name a few.

Like many fields of science, we are learning more about quantum stuff all the time, so this could change really fast. If you're interested in learning more about quantum theory and research you'll need a strong background in math and science. Algebra, trigonometry and classical physics would be a good first step (of many).

[–] thebestaquaman@lemmy.world 5 points 1 year ago

Thanks! First of all: I don't think this smells of Dunning-Krüger at all, ref. your other comment ;)

I'm not going to claim any deep understanding of quantum mechanics or relativity, but could you try to say something about how this "instant communication" doesn't break causality?

[–] TauZero@mander.xyz 0 points 1 year ago

Whatever happens to Particle A will instantly affect Particle B, no matter how far apart they are!

Well ok, maybe for some specific sense of "whatever happens" you could describe it this wa-

If we could create this connection reliably and stably, we could potentially use it send information across distances nearly instantaneously!

Nope! You've gone too far! This is provably impossible, and the proof is even called the no-communication theorem 😄. Don't give our 5-year olds false hope that will take years of study to beat out of them later.