"Warp Drives", "Hyperspace Drives", or any other term for Faster-than-light travel is at the level of speculation, with some facets edging into the realm of science. We are at the point where we know what we do know and know what we don’t, but do not know for sure if faster than light travel is possible.
The bad news is that the bulk of scientific knowledge that we have accumulated to date concludes that faster than light travel is impossible. This is an artifact of Einstein’s Special Theory of Relativity. Yes, there are some other perspectives; tachyons, wormholes, inflationary universe, spacetime warping, quantum paradoxes...ideas that are in credible scientific literature, but it is still too soon to know if such ideas are viable.
One of the issues that is evoked by any faster-than-light transport is time paradoxes: causality violations and implications of time travel. As if the faster than light issue wasn’t tough enough, it is possible to construct elaborate scenarios where faster-than-light travel results in time travel. Time travel is considered far more impossible than light travel.
Ever since the sound barrier was broken, people have been asking: "Why can’t we break the light speed barrier too, what’s the big difference?" It is too soon to tell if the light barrier can be broken, but one thing is certain -- it’s a wholly different problem than breaking the sound barrier. The sound barrier was broken by an object that was made of matter, not sound. The atoms and molecules that make up matter are connected by electromagnetic fields, the same stuff that light is made of. In the case of the light speed barrier, the thing that’s trying to break the barrier is made up of the same stuff as the barrier itself. How can an object travel faster than that which links its atoms? Like we said, it’s a wholly different problem than breaking the sound barrier.
Here is a snap shot of the theory that sums up the problem: "Special Relativity". Actually Special Relativity is pretty simple in its construction... Just start with 2 simple rules:
Rule Number 1: The distance you’ll travel (d) depends on how fast you move (v), for how long you’re moving (t). If you drive 55 mph for one hour, you’ll have covered 55 miles. - simple.
Rule Number 2: -- This is the mind boggling one -- No matter how fast you’re moving, you’ll always see the speed of light as being the same.
When you combine these together and compare what one traveler "sees" relative to another traveler at a different speed - that’s when the problems come into play. Let me give you another way to picture this. Close your eyes. Imagine that the only sense that you had was the sense of hearing. All that you know is sounds. You identify things by how they sound. So when a train goes by, did its horn really change? We know that the horn was always tooting the same tone, but it was the train’s motion that made it appear to change because of something called the Doppler shift. Its a similar situation with light. Everything we know around us we know by light, or more generally electromagnetism. What we see, what we feel (the air molecules bouncing off our skin), what we hear (air molecules bouncing off each other in waves of pressure), even the propagation of time, are all governed by electromagnetic forces. So when we start moving at speeds approaching the speed by which we are getting all our information, our information gets distorted. In principle it’s that simple. Understanding it well enough to do something about it, well that’s a different matter.
Light Speed Barrier [graphic]
One of the consequences of this Special Relativity is the light speed barrier. Here’s another way to look at it. To move faster, you add energy. But when you get going near the speed of light, the amount of energy you need to go faster balloons to infinity! To move a mass at the speed of light would take infinite energy. It appears that there is a distinct barrier here.
Is there any way around Special Relativity? Maybe.
Is there any work being done to search for these breakthroughs? Yes, but not much.
In addition to the individual theoretical work of such physicists as Matt Visser, Michael Morris, Miguel Alcubierre, and others, there is the new NASA Breakthrough Propulsion Physics program.