Matter (is that a pun)
If its required to travel faster than light to time travel, and no humans have achieved it yet...
What if it's DATA thats being sending info back and forth, Can DATA travel FTL?
BTW Its only 3pm where i am, but its always 420 ;)
There are several theories on how Time-Travel works, but which one?
Ive been watching the third season of The Man in the High Castle and I think it maybe close. (Phillip K. Dick was a genius).
They explain it with Indra's Net and Quantum Entanglement. Indra's Net is the multi-verse, each jewel in the net reflects every other jewel, each jewel is a universe and is connected by quantum entanglement. When something happens in this universe the opposite happens in another, when one particle spins left the other particle instantly spins right.
Thats the basis any how, worth a watch if you're interested in time travel.