These subjects still fascinate me after a lifetime of interest: faster-than-light speed, alternate time streams, parallel universes, time travel, antiparticles moving backward in time, time loops, and the recurring themes of paradox -- all serious but astonishing ideas of science. Something about them inspires infinite possibilities. Am I not alone?
In an interesting test of the theory of relativity they found that gravity travels at the same speed as light. Put simply if the sun were to disappear from existence it would take some 8 minutes before the Earth's orbit would be affected by the loss. Sadly this also means that FTL travel is becoming less and less likely to be possible.