The Warp Drive has long been a staple of science fiction adventures. "Warping" magical device the propels our heroes (or villains) at mind-boggling speeds--much faster than light speed--from one star to the next, in the time it takes us to pop down the street to the local Circle K.
Most scientists have scoffed at the idea of traveling at speeds faster than light, dismissing it as an absolute impossibility. And they did so on the foundation of some very hard (and proven) scientific theory: Albert Einstein's Special Theory of Relativity. Einstein's theory states that no physical object in the universe can exceed the speed of light (186,000 m.p.h.).
See, as an object travels closer and closer to the speed of light, its mass (in equivalent energy) gets greater and greater in a geometrically increasing fashion; the closer to light speed, the closer mass-equivalent-energy gets to infinite. The background image shows a cubic lattice as it would appear to an observer approaching at an extremely relativistic velocity.
Also, for any travelers on board a starship traveling close to the speed of light, time outside would appear to pass faster and faster. And as we would see it, time would pass slower and slower for our friends on the starship. This effect is best illustrated in the "Twin Paradox" where one twin accelerates off to a distant star and the other twin stays at home. When traveling twin returns home, he finds that millions of years have past on the Earth.
Imagine that your position is represented by the graph below, a so-called "world line"--your track through space-time. Because of the light-speed limit, you can only affect particles in your "future light cone." Likewise, only particles in your "past light cone" can have effected you. Thus, the existence of an ultimate speed limit defines strictly the temporal relation of events--in other words, cause and effect. To travel faster than light--if one could--could result in all sorts of causal paradoxes; events seeming to precede causes.
However, one physicist thinks that he may have found a way to circumvent this universal speed limit, and allow for the possibility of a real warp drive--someday.
The credit goes not to the fictional Zefrem Cocrane of Star Trek fame, but to Miguel Alcubierre, a physicist at the University of Cardiff in Wales, England. Alcubierre, claims to have found a loop-hole in Einstein's General Theory of Relativity, that allows for this kind of faster than light travel. According to General Relativity, space is not a static entity, but a space and time make up an 4-dimensional "space-time", a "dynamical entity" that can be twisted and distorted by concentrations of matter and energy.
According to Alcubierre's theory, it would be possible to generate a distortion in this "space-time continuum"--a space warp, using something called "exotic matter", both in front of and behind an object, that would propel it faster than light. Specifically, space-time is contracted in front of the ship and expanded behind it. Creating the "warp field" in which the object travels in like a surfer travels on a wave, and with no speed limit.
The spaceship itself would not be accelerating, and experiences no time dilation. Exotic matter is a hypothetical form of matter (predicted in Inflationary Big Bang Cosmology) that has a "negative energy density". In other words; it creates a kind of negative pressure around it, and is repelled--not attracted--by gravity. (The existence of negative energy densities, has been proven in laboratory experiments).
According to Alcubierre's equations, there would be none of the time dilation effects experienced by astronauts traveling close to light speed in normal space. And the ship could slow down or speed up as fast as its pilots pleased, without the fear that they would be reduced to the very consistency of strawberry jam by the inertial forces. Inside the warp field, the astronauts would have zero acceleration relative to the space around them. All of this, remember, depends on the yet unproven existence of exotic matter. It may very well NOT exist. And even if it does, the question remains, could one generate and control it?
This makes many dismiss Alcubierre's theory as nothing more than an interesting mathematical abstraction, (and certainly it is not by any means absolute proof that FTL travel is possible--let alone a blueprint for a starship). But until Alcubeirres theory, even the possibility of FTL travel was dismissed outright. Now a door may have been opened, where it leads, if indeed it leads anywhere, is for another generation of physicists to figure out. (As one pointy-eared fictional space traveller once remarked: "There are always possibilities...") It will still be a long time before Kirks and Picards will be zipping around in starships powered by real warp drives. But until then, sci-fi fans and authors (and dreamers) may take some comfort in the knowledge that their warp drive may not be just a silly fiction, but may be a real possibility someday.
For a more detailed explanation of this theory, check out: the May issue of Classical and Quantum Gravity. and September-October issue of American Scientist, Vol. 82 "Space-Time Hypersurfing". pp(422-423)
Bryce Burchett & Chris C. Stephenson.
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