Time Travel
Is it
possible to travel through time? Time travel has been one of the most popular
themes in Science Fiction. Going to the future is easy; we are all doing that
just now, in the rate of one second per one second. All we need to do is making
the rate faster. According to Einstein’s theory of relativity, we can do
exactly that by approaching the speed of light, and we would be able to travel
to the future. Going to the past is a little bit trickier. Hopefully, Einstein’s
field equations do not explicitly forbid time travel to the past: there are
situations in which time travel to the past is possible. But that leads us to
think what would happen if we had time travel. Such as the famous grandfather
paradox: what would happen if I killed my past self (or my ancestor)? Will I be
able to even perform the act?
The
most convenient solution to this paradox is the parallel universe hypothesis.
This hypothesis states that as I travel back to the past, I move into not only
a different era but also a different universe that would have different
consequences. But because the definition of parallel universes is that they are
exactly the same with the current universe before the moment of time travel,
the parallel universe me is ready to time travel into another parallel universe
as I get ready to travel into the parallel universe. This means whatever I will
have done in the parallel universe, the outcome must be the same with my original
universe and the two universes must be undistinguishable. Therefore, I am
forced to conclude that another me had traveled from another parallel universe
to the past of my original universe, and therefore this hypothesis does not
really solve any paradoxes. If I killed past me in a parallel universe, someone
should have killed me in the past-that someone being me from another parallel
universe.
Another
solution is to accept the deterministic nature of time travel. If I go back to
the past and attempt to kill myself, I will fail, as I am a living proof of it.
I have survived attempted murders from myself in the past, or I will not even
exist. This is interesting considering that I know every move the past me will
make, but still fail to kill myself. But this hypothesis also has a serious
problem: quantum mechanics. Although in the macroscopic world the universe
seems to be governed by Newtonian, deterministic laws, actually we live in a
quantum world where one can only predict the probabilities of something
happening, and never the actual event. But consider this situation: I conduct a
quantum mechanics experiment, and the future me gives me the data to the
experiment even before I start the experiment. If my experiment runs exactly as
the data, quantum mechanics, not deterministic by nature, will be proven
deterministic, which would mean the collapse of physics as we know it. But if
the data and my experiment do not match, this hypothesis about time travel is
wrong.
I have
not been able to conclude what would happen if time travel to the past existed.
It is surprising to see a phenomenon predicted by the equation that most accurately
depicts space and time in the history of mankind has so many paradoxes that
cannot be easily solved.
You have a talent for technical writing. It makes just enough sense to me to not stop me from reading. You have obviously thought a lot about this in the past (or the future). I wonder if you have seen the very amazing and recent film "Looper." If not, you will love it. If you have seen it, you probably loved it. Another good one that looks at time travel comically is "Safety Not Guaranteed." Both of these films are very new and highly rated.
답글삭제I watched "Safety Not Guaranteed" a few days ago! It was more about people than time travel, but I still loved it. Thanks for the recommendation.
삭제