Quantum entanglement ("spooky action at a distance") doesn't allow for communication, so there's no causality between the particles.
This led me into another rabbit hole :-) of why c is 299,792,458 m/s and for example not 499,792,458 m/s or some other value, and the fundamental constants that bring this value. [1]
Is there a current theory that tries to justify those constants that bring the current value of c ? Are those values the ones that must be, for the current Universe to be feasible?
Humans choose to express it in metres and seconds.
A meter is huge if you compare it to the Planck length. Humans are pretty big creatures compared to fundamental particles, so we have a big basic unit of length. But seconds are gargantuan, because humans are absolutely glacial if you compare them to the time it takes light to travel a Planck length.
It's like a continental plate asking why humans zip around so fast.
Yes, but why is the value that it is and not higher or lower? From my (basic) research it seems, it could be plus or minus 20% a different value, and the current Universe would still be feasible.