Worm holes are probably the most loved physical phenomena by sci if writers, because they simply are so extremely funky, they could offer time travel, travel into parallel universes, as well as just a short cut to places light years away in our own universe.
Let’s talk about the short cuts; when travelling through a worm hole you get from one place to another in a shorter time then it would take you to travell, with the same speed as you travelled trough the wormhole, in ‘the normal way’. But when you travel through a worm hole you don’t really travel faster then light, since what you really do is to “cheat” space-time, so you’re not really travelling through our familiar 3 dimensions but taking a short cut in the fourth dimension called hyperspace.
Imagine a circle and that the outline is the normal three dimensions that we move in. Now if you want to get from one side of the circle to the other and only move in the outline(our three dimensions) you would get to the other side much slower then some one that travelled straight through the circle(through the fourth dimension) and the one that moved through the circle didn’t even have to move faster then you! The outline of the circel reprecents space time, which is the thing on which every thing in the universe exists. And it’s when you warp this spacetime into little pockets on two different places, the place were you are and the place were you want to go, and then connect those two pockets to create a tunnel between the two different places that you get a wormhole. Also note that the universe doesn’t have to be circular in order for wormholes to occur. It could be flat, bent or have any shape it want.
You could say that there’s two different ‘kinds’ of worm holes. It has been suggested that if you fall into a black hole you come out of a white hole. Then there should be a wormhole connecting the black hole to the white hole. However this worm hole would be a oneway street, since you can only fall into a black hole and out of a white hole. They there are worm hole sollutions which work both ways, these are the once you usually talk about when talking about wormholes. And it’s those which I will discuss here.
As you can see this means being able to travel to other galaxies which normally would normally take thousands of years even with a space craft moving at the speed of light(note that the crew on such a ship however wouldn’t age a bit, but when they returned to earth it would be a couple of thousands of years later. Which isn’t very funny if you think about it).
Also travel into other universes. Think of universes as bubbles, and there’s no connection between them. So then, you could make a wormhole between them, as a gate from our universe to another. Pretty neat. But the neatest thing of all is the possibility of time travel, this I will discuss later.
The problem with wormholes is that they will collapse so fast that nothing will have time to travel through them. This is because if a body which is bending spacetime is removed, spacetime wont stay that bend anymore. It will smoothen out and become flat again. And the same thing with wormhole, the severe warping which causes them to exist isn’t natural and spacetime wants to become flat again, so the wormhole collapse really fast. And if that wasn’t enough, as soon as the wormhole opens, radiation will start to travel through it, and the wormholes gravity will accelerate it to very high speeds. And these particles will of course bombard the throat(the throat of the wormhole is the tunnel which you travel through) of the wormhole and make it collapse even faster, not to mention that anyone trying to travel through it will get a hell of a suntan. But there is a way to hold the wormhole open. Normal matter falls downward, then would it be possible to create a type of negative matter which falls upward, matter with anti-gravity? Theoreticly there is something called exotic matter which has this ability, although it has never been seen or created. This matter could be used to hold the wormhole up by pushing outward on the sides of its troat. Thereby keeping it stable. It should be said that energy is a relative thing and it doesn’t have to be negative in all reference frames(reference frames is relativity and basically means different observers), it could be positive in some. But as seen from the wormholes reference frame it has to be negative.
So how do you create a wormhole? Well there are a number of ways.
It has been suggested that wormholes occur naturally, but only on very small scales. Normally on our macroscopically scales, space time is flat(if something is not bending it). But if you zoom in on it through the particle level and down to something called the Planck length(10-33cm) spacetime will get more and more severely warped and not smooth at all any more. So at this level were space time warps naturally and in a chaotic fashion, you should be able to find tiny natural wormholes. And then it would be possible to take one of them and enlarge it so that we could travel through.
Another possibility is to bend spacetime our self, already on macroscopically scales. Then move this little pocket which we just created to the place were we want to go, tear a hole into the space time in our pocket and the space time at the place we wanted to go to, and then “sew” the two rips together to create a tunnel(the worm hole). The problem is that the ripping part would create a singularity, and singularities are very nasty things, which have a tendency to first stretch people into spaghetti and then crush them into very small things. So we don’t want a singularity but is there a way to create a wormhole without a singularity? Yes there is, the problem being that at the moment it is being created, time has to be distorted in all reference frames. Which means that at that particular moment you would be able to travel both forward and backward in time. So it’s not certain that this works.