
Time traveling has always been one of the precious gems in the crown of science. Even if the motivaton behind this is as noble as preventing past catastrophes, or as sex-propelled as impressing the laboratory's slut, every single physicist has thought at some time about the posibility of doing so.

I can't believe it, I dig time travel so much.
There are hundreds of theories of how this could be accomplished. One of the most common is relativistic time dilation using wormholes.
Let's picture a wormhole. It has to openings, one of them being acelerated. If we manage to move through te wormhole, due to time being dilated inside it, we could theoretically exit it through the other side in a point in time prior to our entering.
Another plausible theory, is that accelerating to the speed of light, we might be able to change the time frame in which we exist, being able to travel to the past or to the future.
It is worth noticing that the equation that proves this, also proves that, if we accelerate something to the speed of light, we can turn it into a huge bucket of fliying shitfuck 2.

This happened because of the Japanese Speed of light.
Used as a plot device in hundreds of movies and books, time travel has become as common in science fiction, as plot holes in the terminator franchise. [Note to the reader: YAY! Here it is!]
The methods used vary in scientific content and insanity.
From witchraft to light bending devices, we see how one way on another they manage to figure out how to go back and forth in time. What they seem not to figure out is how to do it withou messing everything right the fuck up. It's like if they were trying to do so on purpouse.

If you didn't see this coming, you have the IQ of retarded manure.
Luckily, there is one simple rule that is followed by almost every work of fiction regarding the subject:
If you need to change something, you won't be able due to some paradox. If you have to avoid altering time in anyway, no matter how carefull you are, you are going to end up with so much shit on your back, that people will confuse you with a regular politician [Wow, I am as original as elevator sex...]
Cracked Talk on | Time Travel