Time Travel

“The Time Traveler vanished three years ago. And, as everybody knows now, has never returned.”

H. G. Wells, The Time Machine

There’s something about time travel that fascinates people. Perhaps it’s because, like space, it’s mysterious and vast, as well as we’re simply curious about it. There’s also the fact that we can freely move about in the other three commonly accepted dimensions of length, width and height, but can’t in time.

The theory of relativity allows for time travel. In its bare bones basics the closer we travel to the speed of light the slower time goes for a us compared to an observer who is not travelling at those speeds. Theoretically if we were able to go faster than the speed of light we would then move backwards in time.

Can we do it without using black holes or worm holes? The simple answer is yes. One possible way to travel at or faster than the speed of light is to slow light down. This has been done experimentally. But could we both slow the speed of light down and build a machine capable of travelling faster than it at the same time is the big question.

A simpler way, which would be very awkward, but doable, with today’s technology would be to reach and surpass the speed of light by layering. Build tubes within tubes each one going at so many miles per second. At the speed of a rocket departing earth at about 10.1 miles per second you’d need 18,416 tubes to reach the speed of light, more if you wanted to go faster. And remember each tube would only be going 10.1 miles per second faster than the one before. A person in the 18,416^th tube would only be going the speed of light relative to a person who is stationary on the outside of this contraption. You wouldn’t be able to go further back in time than the day this machine started and if you limited it to slightly less than the speed of light you’d only be able to travel into the future and not into the past.

This machine would be the equivalent to a 1940s vacuum tube computer, which took up a whole room to do what a cheap calculator can now do better. Eventually ways could be found to speed things up and shrink things down.

As for time paradoxes there are several possible ways that this can be dealt with. We never develop a time machine in the first place or at least one that can go further back in time than the date it was turned on, which solves the problem neatly. Let’s say we do develop a time machine capable of travelling back in time and a young, very attractive woman goes back in time, meets her second great grandfather a few days before his first date with her second great grandmother. He becomes enamored of it and cancels the date. Here are several ways that this might be dealt with: 1 the two never marry, a new dimension is formed and the great great granddaughter returns to her time where everything is the same as when she left it; 2 the date is postponed, but eventually go out and marry, the chronology is changed, but not the ultimate outcome; 3 the second great grandfather has second thoughts, the date is back on the day it happened, his great great granddaughter returns to her time and discovers his diary in which he mentions the incident. She hasn’t changed time. She is part of it. In the later scenario may have already have come, but we’re not aware of it as they’re not numerous and are a part of time. There is one final way that the paradox could be dealt with. We can go back in time, but we’re incapable of interacting with it.

Whether we should travel threw time is another matter. It is one that depends on the ultimate answers to the paradox question.

Here are two good books on time travel:

Breaking The Time Barrier: The Race To Build The First Time Machine, By Jenny Randles

How To Build A Time Machine: The Real Science Of Time Travel, By Brian Clegg