2000plus | Science Fiction

What lies beyond the year 2000?

Currently we don't know if time travel is even possible. If it is, then it may not even be possible to change the history of this universe, or time line. This is for this very simple reason, what has happened in the past, has already happened. So, if you travelled back to stop John Kennedy from being shot, and you stopped it, that happened in the past, so he never would have been killed and you would not know to travel back in time to save his life. Because of this paradox scientists have also brought up a theory that you can travel back in time, but into a different dimension. Below are some possibilities for time travel, and some inconsistencies from science fiction shows.

If we cannot travel back in time, due to the paradox above, then perhaps it is still possible to travel back in time and alter the timeline of a different universe, or time line. According to relativity, if you travel faster than the speed of light then you will travel back in time. So if you were to travel back in time, then perhaps you would be thrown into another time line, where the changes you make in history will be the history of that universe.

So, if this theory is correct, then the science fiction time traveller is not possible. However, there are physicists that still believe in the one time line theory, and that you can change the history of this universe. Travelling into the future, on the other hand, may be a little easier.

According to relativity, as you get faster, and closer to the speed of light, time starts to slow down for you. Also, according to relativity you cannot travel at the speed of light (unless you and your spaceship have no mass whatsoever) or faster than the speed of light. However, just say you could get to 99% the speed of light, time would travel at a much slower rate for you, than it would for other people, on say, Earth. So, if you went up in your spaceship and travelled at 99% the speed of light for maybe a year, 50 years may have passed on Earth, but you would have only aged and felt one year go by. This is called time dilation. An experiment (known as the Maryland Experiment, that was conducted by two scientists, Keating and Haefle in 1976) was done in which two atomic clocks were perfectly synchronised, and one was put onto a plane that would travel fast, and the other left on earth. When the plane landed and the clock's time checked, the one that was in the plane was a little behind the on on the ground. The plane, however was hardly travelling close to the speed of light, if it were, the amount of time dilation would have been much larger. This is a sort of way of travelling into the future. If you could travel at the speed of light, however, you would experience what is known as infinite time dilation.

Another way to travel into the future (in a way) is to orbit closely to a black hole. According to relativity, gravity distorts space time. Because a black hole is so gravitationally intense, the amount of distortion of space and time is great. So, if you orbit a black hole for say 6 months, 20 years may have passed on Earth.

These are ways of travelling into the future, in a way. It is more bending time, as we perceive it on earth.

Travelling back in time, on the other hand, proves to be a lot more difficult. According to relativity, if we travel faster than the speed of light, we will travel back in time. But because of the paradox at the top of this page, we probably would not be able to travel back in time. There may be ways around this, and some are below.

A popular theory is that we would travel into an another universe. In this universe, the change that you have made to the timeline, becomes the history of that universe. That would mean that the paradox would not exist, as you would have knowledge from the other universe, but you would be changing the history of another universe.