Uh, no shit? That's how light works once you're able to travel at relativistic speeds - communication over interstellar distances using light is going to take ages.
Even within our own solar system interplanetary travel will have significant communication time delays.
Edit: also, we already know that matter and light can't exceed c, but I wouldn't be surprised if we discover that other forces (gravitation, or another that we haven't understood yet) can transmit information at speeds >c. I wouldn't be surprised if we turned to quantum entanglement for instantaneous communication over extreme distances either.
Gravity travels at c. The Alcubierre drive tried to use bubbles in spacetime to "bend the rules" in order to result in apparent >c velocities but recent simulations indicate the bubble becomes unstable when attempting to exceed c.
My first thought was 'no shit' as well. There's a horrible heartbreaking anime about that.. Voices of a Distant Star.
other forces ... can transmit information at speeds >c
I sadly disagree. Even if we figure out a way to instantaneously transport ourselves across the universe, there will be some shitty clause in fine-print that says we can't go back, or it took 0 time for us but 1 billion years for everything else.
Something I’ve not been asked to get through my head about QE: If observing the entangled particle destroys the entanglement, doesn’t that mean we’d need “containers” of entangled particles to send a bunch of information?
The problem with information traveling ftl is, that you're very quickly running into paradoxes. So just by logic wanting to keep intact, I feel like ftl communication will be impossible
Logically it makes sense, but the real world is years and often we don't use the right logical systems. It makes logical sense to most people that a heavy object falls faster then a light object ,but we know that is false (and a also a non obvious logical system that also shows it is false)
If you actually calculate the maximum speed at which information can travel before causing paradoxes, in some situations it could safely exceed c.
For two observers who are not in motion relative to each other, information could be transmitted instantly, regardless of the distance, without causing a paradox.
The faster the observers are traveling relatively to each other, the slower information would have to travel to avoid causing paradoxes.
More interestingly, this maximum paradox-free speed correlates with the time and space dilation caused by the observers' motion.
From your own reference frame, another person is moving at a speed of v*c. The maximum speed at which you could send a message to that observer, without causing a paradox, looks something like c/sqrt(v) (very simplified).
C is more than just the speed of light. It is the speed of Causality. No information can travel faster than C in a vacuum. Gravitational waves already reach us faster than the light from events that cause them (i.e. neutron star collisions) Because small particles slow down the light over long distances, as they absorb and then re-emit the photons.
By the time we invent any sort of lightspeed travel, we'll have long conquered quantum entanglement. If you have a signal transferred over a properly quantum entangled technology, the signal would transfer instantaneously.
Another option would be tiny temporary Einstein Rosen bridges. Sure the energy requirements would be hideous, but if we've figured out how to exceed C, I don't think we really care about energy costs anymore.