The concept of wormholes pops up in science-fiction movies and books all the time. And the idea is a useful one; allowing characters to move through space and time in a heartbeat. All the while ignoring relativistic effects like time dilation that would cause characters to age differently and so on.
But are wormholes nothing more than literary devices to keep science-fiction plots moving along, are is there actual science involved. Well, as it turns out wormholes are a direct consequence of general relativity. However, that doesn't necessarily mean that they exist.
What are Wormholes?
Simply, a wormhole is a tunnel through space-time that connects two distant points in space.
However, there is no observational evidence that they exist, though this is not an empirical proof that they aren't out there.
In most proposed manifestations, a stable wormhole must be supported by some sort of exotic material with negative mass -- again, something we have never seen. Now, it is possible for wormholes to spontaneously pop into existence, but because there would be nothing to support them they would instantaneously collapse back in on themselves. So using classical physics it does not appear that traversable wormholes would arise on their own.
Black Holes and Wormholes
But there is another type of wormhole that could arise in nature. A phenomenon known as an Einstein-Rosen bridge is essentially a wormhole that is created due to the immense warping of space time resulting from the effects of a black hole. Essentially as light falls into a black hole, specifically a Schwarzschild black hole, it would pass through a wormhole and escape out the other side from an object known as a white hole. A white hole is an object similar to that of a black hole but instead of sucking material in, it repels the material from the object. Light would be accelerated away from a white hole at, well, the speed of light at the light cylinder.
However, the same problems arise in Einstein-Rosen bridges as before. Due to the lack of negative mass particles the wormhole would collapse before light would ever be able to pass through it. Of course it would be impractical to even attempt to pass through the wormhole to begin with, as it would require falling into a black hole. And there is no way to survive such a trip.
The Kerr Singularity and Traversable Wormholes
There is yet a another situation in which a wormhole might arise. The black holes considered earlier were charge neutral and non-rotating (Schwarzschild black holes), but it may be possible for black holes to rotate.
These objects, called Kerr black holes, would look quite different than a normal "point singularity". Instead a Kerr black hole would orient itself in a ring formation, effectively balancing the immense gravitational force with the rotational inertia of the singularity.
Since the black hole is "empty" in the middle it could be possible to pass through the middle. The warping of space-time in the middle of the ring could act like a wormhole, allowing travelers to pass through to another point in space. Perhaps on the far side of the Universe, or in a different Universe all together.
Kerr singularities have a distinct advantage over other proposed wormholes as they don't require the existence and use of exotic "negative mass" in order to keep them stable.
Could We Someday Use Wormholes?
Even if wormholes do exist, it is difficult to say if man could ever learn to manipulate them to travel across the Universe.
There is the obvious question of safety, and at this point we don't know what to expect inside a wormhole. Also, unless you specifically built the wormholes yourself (like constructing two interlinking Kerr black holes) there is almost no way or knowing where (or when) the wormhole would take you.
So while it may certainly be possible for wormholes to exist and function as portals to the nether regions of the Universe, it is considerably less likely that man will ever be able to find a way to use them.