Okay, so whether it’s warp drives, hyperdrives, wormholes, or any other sort of engine, science fiction used to be dominated by ships that hurled people in faster than light (FTL) travel. Stories sometimes didn’t even really care how it got done, focusing more on the pure whimsy of going from planet to planet on a never-ending odyssey. A really good short example of what I’m talking about is the Spaceman Spiff stories in the old Calvin & Hobbes comics. Nowadays, it’s hard to find that carefree travel kind of story.
Part of it is for good reason: the laws of physics currently don’t allow for FTL travel. The short dirty reason I’ve always been told is that it takes an infinite amount of energy to just get to the speed of light. Science fiction needs to have some amount of science integral to the story, and breaking the laws of physics feels like cheating. Moreover, lacking good science in a science fiction story can quickly turn something into fantasy rather than sci-fi.
But I also see a loss here. Sometimes (like in Star Trek) the story just makes an assumption that humanity will eventually increase its body of knowledge to the point of using new discoveries to tackle current impossibilities. There is a kernel of hope in some brands of science fiction that looks forward to the future with eagerness and not hostility or cynicism. FTL travel can signify that in a way that almost went without saying. It admits that physics are still physics, but people can overcome any problem through using knowledge.
Does this mean that FTL travel is a relic of an idealistic past, or is it something worth keeping around? As a fan of the genre, I think that it depends on the story being told. FTL travel shouldn’t be a crutch to excuse bad science or to gratuitously throw a story into the sci-fi genre. It should be used almost as a literary device, a way to paint a story with an optimistic tone.