“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 18,416th 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
