TIME TRAVEL - FOR REAL?
Author: Samantha
Ever since I was small I
was heavily influenced by the cartoon—Doraemon, that it made me believe we can
travel back and forth on timeline, simply with a time machine. My parents
referred me as crazy after they heard my idea. Well, why not? Why must it be crazy?
To solve my questions and
confusions, I got addicted to those thick physics reference books with
born-to-be-boring covers. I flipped them over and over, and found my
answer—several theories mentioning how to time travel.
1.
Single trip—travel to the future
It is different from what
people expected for a real time travel, as you can only travel to the future
but not back to the past. This theory is well supported by Albert Einstein’s
both Special Relativity and General Relativity. As he had mentioned, time can
be extended or suppressed, depending on the relative velocity between the
observer, or the gravity.
To explain the velocity
one, I would get this with an brilliant example. Let’s say, if there is a pair
of twins, Samantha and Pinky, Samantha travels to outer space with 99% speed of
light; while Pinky stays on earth. After 20 years passed on earth, Pinky grows
20 years older; while Samantha grows nearly 3 years older only. If the
spaceship never returns backward, both Samantha and Pinky would see each
other’s clock runs slower while themselves’ ones run normally. If the spaceship
turns backward and get back to the earth, from Samantha’s perspective, she sees
her clock runs normally while Pinky’s clock runs faster; Pinky would also find
her clock runs normally but slower for Samantha’s clock. Simply speaking, time
depends on the speed of the observer. In that way, it can be said that Samantha
travels to the “future” of the earth.
According to Einstein’s
General Relativity, gravity can twist space-time to a certain extent. When the
gravity of an object becomes larger, the observer on that object would see time
runs faster in other places; you may say time tends to run slower on that
object from an observer’s perspective from other places. For example, if the
radius of earth is reduced to 0.9mm with mass unchanged, making a super high
density, the gravity will be so large that even time would stop, just like a
black hole, absorbing everything including light (some high-energy radiation
can “escape”).
2.
Round trip—travel back to the past and go to the future
Well, it it exists, just
use a wormhole. It is a linkage between different spacetime curvatures, or you
may say a pathway. To create a wormhole, there are two proposed ways.
First,
within the spacetime that looks like smooth, there are uncountable numbers of
quantum foams caused by spacetime turbulence. Wormholes may exist in these
quantum foams. However, the size of each spacetime foam is extremely small; its
radius is around 10^-35m, and they are very short-lasting, so it is somehow
quite impossible to get through the wormholes. But some scientists suggested
that we can throw exotic matter (if it exists) into the spacetime foam to
extend its lifespan and enlarge its size, until it is large enough to allow a
person’s entrance.
Second, we can twist the
spacetime and fold them together, then create a wormhole to link the two
spacetime curvatures.
Okay now even assume that
you are technically able to create a time machine, that wormholes do exist plus
they can be manipulated by scientists, there are still problems ahead remained
unsolved. For example, what would happen if a man goes back to the past and
killed his mum? Would he still exist? Some scientists hypotheses “Parallel Universe”
theory to explain it, that at the moment when the man killed his mum, a
parallel universe would be created, in which both his mum and himself would not
exist in there. Also, what would happen if one goes to the future and copied
his future essay? Where does this essay originate from? These are the biggest
questions in my mind.
Apart from the logic, some
scientists proposed that for time travel, we have to have equal exchange of
energy between the two spacetime curvatures, or else chaotic and destructive
results might appear.
So, can we possibly travel
freely on the timeline as we proposed? The answer remained a mystery.
Personally, I believed we can as there are some fields in physics that are
still untouched at the moment, that may explain all our confusions. Well if one
day there is a guy on street telling me he comes from the future, I think I
would be so thrilled to take a picture with him instead of getting scared away
LOL.
