Off-topic, but I'm surprised we don't have an Expanse thread here. I've wondered for a while whether the Epstein drive is a real possibility, although the Isp seems to be insanely high. Something like that would really open up exploration of the solar system.
Certainly one of the things I love about The Expanse is the real physics. If it takes 15 hours to get a reply from Titan, it takes 15 hours. You can't just nip through hyperspace to Mars, you have to spend days getting there. And all the things you might not think of, like wounds not healing in zero G, coriolis forces when pouring drinks etc.