Consider this: Albert Einstein is flying steadily through the cosmos at the speed of light.
In front of Albert, and at arm’s length, is a mirror. The mirror is also travelling at the speed of light. The question is; if Albert looks into the mirror, does he see his own reflection? At the tender age of sixteen, and in the same year HG Wells wrote The Time Machine, this gedanken, or thought experiment, puzzled Einstein greatly.
Since Albert is effectively sitting on top of a light beam, light from him would never catch up with the mirror. His image would disappear. This all struck Einstein as rather odd. He did not believe it. His solution to this puzzle was revolutionary: re-write physics and the concept of time.
Before Einstein, the maximum speed possible was thought to be boundless. But he proposed that everyone sees the same speed for light no matter how they are moving. Not only that. Einstein showed that the speed of light was the maximum speed.
Einstein then wondered what happens if you try to get a massive object, (we might propose the Starship Enterprise) to go beyond the speed of light. This light speed barrier is one of the results of Special Relativity, developed by Einstein in 1905.
To speed along, you need energy. To travel at the speed of light, the amount of energy needed to propel you swells to infinity! To move the Starship Enterprise at the speed of light would take all the energy in the Universe, in fact.
Science fiction, of course, is also a kind of thought experiment. The superluminal speculation of fiction began with French astronomer and writer Camille Flammarion. Flammarion wrote a pre-Einsteinian fantasy, Lumen (1867), in which some of the ‘relativistic’ effects of faster-than-light travel are predicted.
Flammarion conceived of spacetime. Thirty years before Einstein, Lumen was the earliest novel to propose that time and space were not absolute. They exist, said Flammarion, only relative to one another. He also explained how travelling faster than light would render history in reverse.
Much of the early pulp fiction of the twentieth century chose to ignore Einstein’s findings. Soon enough, though, such ignorance became unfashionable. In its place popped up a cottage industry of ideas and devices – the ‘space warp’ into ‘hyperspace’, black hole and wormhole travel, and more recently the tachyon drive.
Tachyons appear in Gregory Benford’s Timescape (1980) as a means of faster-than-light communication. Such sub-atomic particles can never slow down or stop moving. They can decelerate to the speed of light, but never less than that. Could be handy. The trouble is, they’re hypothetical.
In the imagined world of Star Trek, the warp drive is the preferred form of faster-than-light propulsion. So sophisticated is the warp, indeed, that spacecraft jauntily zoom to many multiples of the speed of light.
Warp drive fever has caught on. It has infected videogames such as Stars! and StarCraft, and fictional universes such as those in the movie Starship Troopers universe, and the television programme Red Dwarf.
Mexican theoretical physicist Miguel Alcubierre got the bug too. He theorised a type of warp drive. The Alcubierre Drive would involve a ‘warp bubble’ enclosing a spaceship. Space at the front of the ship’s bubble would swiftly contract, while space at the rear swiftly expands. The result? The bubble would reach a distant destination far faster than a light beam moving outside the bubble.