Actually there is some potential for instantaneous communication over light years through quantum entanglement. As Einstein called it “Spooky action at a distance”.
While nothing can physically move faster than the speed of light, reactions can. For instance, if a massive body suddenly appears in the universe, its gravitational pull would be felt everywhere at once. Its obviously weaker with distance but gravity doesn’t travel, it just is.
I personally think gravity is the key to faster than light communication and possibly travel.
I too share your view of gravity being a key for travel in that if one could reverse the polarity of the gravitational force or lock onto a gravitation force the enormity of the speed acceleration would be nearly instantaneous which could have implications for travel and communication. The polarity of the gravitation force is elusive in constructing an engine able to harness polarity frequencies. There would possibly be a bending or folding of time. If space could be left out of the bending or folding of time, then time would be insignificant as quantum mechanics states. Being here there and everywhere all at the same time to encompass the past, present and future and to view each event simultaneously would have our minds possibly so confused our minds would not be able to perceive what was actual in the past, present, or future. Each event would not take on its own distinguishing characteristics but would instead appear to be the present.
Einstein was a spooky person. His theories and equations and the understanding of such of Einstein's works are understood by only a few. I am not one of the few. Einstein's work is continually being dissected, in the present, and much of it may still be misunderstood (imho) though for myself, I never understood most of his works I read. Einstein was brilliant, and have heard it said he may not have been of this world.
It gets even weirder: scientists have found entanglements exist not only across space, but also across time. It's possible to backdate events and communicate with the past and future. Entanglements are known to occur when two photons are emitted from the same source, which seem to retain the same location for a while despite going separate ways, but it may also be possible to tune into a spacetime location without having previously been there. Space and time are illusions of some kind.
They’ve improved that “spooky action” distance to about 100 miles (news item yesterday).
The catch is that while the information transfer is instant, the time to extract the information remains equivalent to light time. That is, the action across the 100 miles is instant, but figuring out what happened still takes half a millisecond. The “information doesn’t move faster than light” rule holds, though for very strange reasons.