What are synchronicities?

Are they just "coincidences"?

Are they proof that everything is predetermined?

Or something else?

Coincidence and synchronicity....

Don't they literally mean the same thing?

no, they don't. Don't you ever read Carl Jung?

That doesn't explain to me the difference.

Something happening at the same time?

Co incident

Sync chrono

See, I can't tell the difference.

a synchronicity has an acausal connection. A coincidence has no connection.

I don't believe in coincidence then, because I believe that everything in the entire universe is causally linked with everything else.

I believe there are both acausal and causal connections

It's hard to prove that they aren't mere coincidence. It very well could be. However, since i believe that there is an infinite intelligence and we are part of it... i would say synchronicity's happen bc we tap into that infinite intelligence. Think of an A.I. in the future so advanced that it could think of every possible chess move that there is. Furthermore, this A.I. knows every chess move against anyone you put it against. That still doesn't scratch the surface of an infinite intelligence ("source"). This source would not only know every possible chess move, it would know any possible in any world, it would know every chess move you and everyone could and will make, it knows everything. Therefore, the future doesn't have to play out in order for this source to know what will happen. You come from this source, therefore, if you can momentarily tap into it... you will also know what is about to happen. I believe your higher self is still in source state. Synchronicity's are just one way it guides you through this experience.   

I'm going to go with Bell's Theorem.