As I mentioned earlier, some of my stories are SF. Now the big nightmare for thinking is faster than light travel, and I’ve been researching various means — mostly Alcubierre/Van den Broeck (hereinafter AvdB). In the process I stumbled across a rather thought-provoking insight.
Almost all the problems go away if the AvdB stays below the speed of light.
The major one remaining is energy, and particularly negative energy. Even that gets impacted, however.
I may use that, later, in some stories. But I thought I’d point it out for those who play on the edge of science and fiction.