Stirring up trouble
I participated in a Twitter chat last Friday with fellow science-fiction/fantasy writers, in which it was suggested by one commenter that it would be a good idea for a writer to study science in order to better his or her writing. I made the perhaps foolish comment that if any writer were to really study physics, they would quickly learn that most of what they have been reading and writing is impossible.
This caused a bit of a debate, to say the very least.
Faster than the speed of light
But it’s a defensible statement; I just needed more than 140 characters to do it.
Start with space travel in science fiction. It’s understood that everything in space is a great distance away from everything else in space, so the only way to go tooling around the galaxy in space ships is to posit the existence of faster-than-light travel (FTL for short). The problem is FTL is impossible.
It’s easier to appreciate this if you look at time and space as parts of the same thing, i.e., spacetime.
Approach #1: Imagine two buckets, one called space and one called time, with enough water to fill only one of the buckets. Sitting on Earth right now, let’s say 1/4 of the water is in the space bucket and 3/4 is in the time bucket.
Got it? Okay, now: per Einstein, the faster you move through space the slower you move through time, so on a rocket ship moving away from Earth at great speed you’re going to be moving some of the water from the time bucket and into the space bucket. (It’s the same water because space and time are part of the same thing; there is a direct trade-off.) The closer you get to the speed of light the more water is added to the space bucket and the less water there is in the time bucket.
When you reach the speed of light all the water is in the space bucket and none is in the time bucket. And here’s the problem: you’re out of water, and buckets.
Approach #2: the faster you go the greater your mass becomes. At the speed of light you become infinitely massive. There is nothing beyond “infinitely massive”.
Approach #3: the cosmic speed limit isn’t really the speed of light: it’s the speed of particles without mass. There is no such thing as negative mass objects, so there is no such thing as particles that can travel faster than that speed.
There is no Stardate
Here’s another problem: time is a strictly local concept. There is no non-local “now”.
As stated above, the faster one moves the slower one passes through time. But this statement presumes the existence of an objective “time” one can pass more slowly through, which is inaccurate. It’s more precise to say that time passes more slowly for a rapid traveler from the perspective of another observer.
What this means is, the Starship Enterprise’s five year mission to explore strange new worlds may be five years of ship time, but it’s thousands of years–conservatively–of Earth time.
There is no Stardate to enter into the captain’s log, because a common “date” would imply a universal measure of time, and there is no such thing. In Einstein’s universe, time and space are both malleable and subjective.
Tooling around in a Newtonian universe
And that’s the real problem with modern science fiction: most of it is set in a Newtonian universe, rather than an Einsteinian one. In Newton’s universe you can travel as fast as technology will allow, time is an objective thing, gravity is a force that can be countered, a laser is something that can be dodged, and so on.
Ah, you might say, Einstein could be wrong! Or better, there are things we simply don’t know yet that could make these things possible!
Okay, but here’s the problem: if you’re writing science fiction and positing that one of the laws of thermodynamics is incorrect, or that Einstein’s theories are incorrect, you’re not writing science fiction any more. You’re writing fantasy. There may not be any magic, but the science you’re using is impossible, so it may as well be magic.
Mutants aren’t real
This doesn’t end at the edge of Einstein, either. Basically every steampunk invention ever imagined is impossible–usually because someone’s violating the second law of thermodynamics, which expressly disallows perpetual motion machines. Likewise, every super-powered comic book character violates the same law. (How much food would The Flash need to eat to run that fast? The energy has to come from somewhere. When Iceman creates an ice ramp to travel on, where is the water coming from? And on a separate note, by what mechanism does Superman fly? There’s no propulsion: he’s just floating. It drives me nuts that nobody even tries to explain this.)
I have seen it written–and I have written it myself–that the difference between science fiction and fantasy is whether one attributes the fantastic to magic or to science. But the truth is, once you get past the masters of hard science– your Asimovs and Bradburys and Clarkes— it’s all fantasy. Whether the writer knows it or not.