Why is a wormhole called a wormhole and can we use them to travel through time?

It came from one of the earliest metaphors for a wormhole. I can't remember who it was, but some time after our buddy, Einstein and his student, Nathan Rosen proposed the idea of the theoretical possibility of the Einstein-Rosen Bridge, somebody described the idea as being like how a worm burrows a hole through an Apple instead of crawling around the outside of it, saying that the hole is a new, quicker way from point A to point B. This description was to explain how this guy thought an Einstein-Rosen Bridge could be used for faster than light travel. Of course, Einstein and Rosen never actually thought a bridge large enough to allow the passage of anything of any real substance through it was possible; it was thought of as merely a theoretical possibility on a subatomic scale.

Anyway, ever since this, the idea of a TRAVERSABLE Einstein-Rosen Bridge through warped space-time has been called a wormhole, although recently the term "wormhole" has pretty much replaced the term "Einstein-Rosen Bridge" (probably because it's a lot easier to say in a sci-fi movie!).

I'll add new stuff to my friend's answer above: This is how we believe time travel backwards is possible. We know forwards is possible and have done it. It's called space dilation and some guy is actually ten minutes younger than other people on Earth, but we haven't been able to get great leaps in time forward.

Anyway, divagating from the original subject of this question, I'd like to explain my beliefs in how one could use a wormhole, travel back in time, and theoretically kill his grandfather. I personally don't believe in the grandfather paradox. I believe one could actually kill his grandfather and not create a paradox and I shall explain:

First, a paradox cannot occur if time be linear. To believe in a paradox, one would have to believe that everything in his life is predestined, i.e. that it has already happened and that time forever repeats itself, but on different planes of consciousness. This is not the case in my mind. If we believe that time is predestined, then we must also believe that we are just going through the motions like something on television. I believe that time is linear and that we could jump onto different planes of time once they have been formed, which erases any paradoxes and here is why:

Now, just because time is linear doesn't mean that it doesn't have little knots or loops, what I call slubs, in it. For instance, think of time as a ball of yarn: the beginning end is where time starts and the string of yarn unravels from the skein as time moves forward. Well, yarn, just like time, is not a perfect creation. There are slubs in all strings of yarn just as there are in time and space. These "slubs" act like little knots in time wherein space-time has looped over itself. This is how a wormhole works in my mind. The slub has wrapped itself around so that, in theory, multiple planes of time be existing in the same space and time; therefore, for our time traveller, the years 1932 and 2010 are actually touching each other and the wormhole is a gateway or time-gate in essence. This would be how I believe we could use wormholes to travel through time if we were ever to obtain empirical knowledge of their existence and were able to harness their energy and properties. Furthermore, these are my precepts behind how wormholes work when appertaining to time travel and they should not be acribed as facts. They are just my personal views on this topic--my own little theory, as it were. Without further descanting, let's move on, shall we?

So we believe now that time is linear and that events have never occurred in the future. Now, that means that one could actually be born and go back in time to kill his grandfather. It's like a movie. If we were making a movie and, towards the end, we didn't like an earlier scene, we could go back to that point and change it, thereby changing every scene following that instance though, even if it were just a minute change.

The fact is there would be no paradox because that time, the original history, would actually have once occurred: this person would have still been born and he would have still made a conscious, freewill effort to go back in time to kill his grandfather. The fact that one has changed time wouldn't erase the fact that he had still been born. The scenes from the original movie would still be there, but would be recorded over, starting a new chapter in the future and affecting everything else.

In my theory, that person, the time traveller, is still aging and still moving on his own plane of time. His time in the year 2010 has not stopped moving just because he has travelled to 1932 to kill his grandfather. Now, if we believed that time has already been predestined, then we would also have to believe that this event to kill one's grandfather has already occurred in the year 1932 and that a blip in space-time has occurred and that the cycle continues to repeat itself for all of eternity. This is way too complicated. Remember Occam's razor--that the simplest answer is the one to be preferred.

If we take Occam's razor and put it to the test with time travel, we can see that there is no paradox--that time is linear, with the occasional slub, and that travelling through time only causes one to change to a different plane, but time continues to move forward. Again, if we believed in paradoxes then, if one were to go back in time, he should never age because his time has stopped. Really, though, he would not be Methusala if he were to go back in time. He would still age. His time in 2010 would still move forward. Time would never stop and it shall never stop. Time shall always continue forward and there is no way to stop it. It can only be slowed down theoretically.

All right, so if this person were to be successful in killing his grandfather, he would change the scenes of this "purported movie" between 1932 and 2010. I believe he would then disappear because he would not have been born from his original father, but I don't think he would totally vanish. Remember the theory of a higher mind--a creator of this madness in the universe. He would still have plans for this person. I think one would appear back in the year 2010 with no memory of what had happened, but be on a different timeline. If this person had originally been born in the year 1986, he would probably still be born in 1986, but to a different mother and father and his life would go in a different direction.

Remember, no paradox has occurred because the future is not predestined and, in the original history, this person had made a freewill, conscious decision to murder his grandfather before his father was born. All this person has done is record over the original history; thus no paradox. His memories of his new life would fill his head and he would have no memory of his time travel experiment. Life would totally be changed. Every action that his grandfather and father had played originally would be changed and that would affect everyone else's life like a ripple effect when one throws a stone into a pool of water. Again, what happens to the ripple? It diffuses, right? And the universe or God would do everything it or He could to diffuse the ripple effect as best as possible, but, remember, a ripple is not continuous. It eventually loses strength and disappears. His changing time would not cause universal bedlam; the universe would correct itself, i.e., Occam's razor---the simplest answer to phenomena is usually the correct answer. We shouldn't believe that this would cause bedlam in our universe. We should think that our universe is vastly smarter than we are and has already obviated such antinomies.