Description:
What if the dimension of time was no different from the three dimensions
of space we live in? What if you could travel to the past and to the future¡¦.
the same way you can move right or left, up or down? Would you be able to
change your past? And if you did, would it create a time paradox?
What kind of time machine would you need to build, anyway?
Transcription:
What if the dimension of time was no different from the three dimensions of space
we live in? What if you could travel to the past and to the future, the same way
you can move right or left up or down? Would you be able to change the past?
And if you did would it create a time paradox?
What kind of time machine would you need to build anyway?
This is what if and here's what would happen if you could travel through time?
How many times have you wished you could jump in a time machine and skip
that boring meeting. Or choose a bitter comeback in that argument last week?
Time travel sounds like some wild fantasy that only happens in sci-fi movies.
But we're actually traveling in time every day. Albert Einstein found that,
time is not a constant but it's continually moving forward and we're moving
forward with it. According to Einstein, time is the fourth dimension.
Together with three-dimensional space it's fused into a single
four-dimensional continuum,space-time. If you think of traveling in space
moving upwards is a bit of a challenge unless we get on a plane or at
least take the stairs, so maybe we just haven't come up with a proper
machine to travel in time yet.Theoretically, building a time machine is possible.
but it wouldn't look like this or like this rather more like this because the
secret to time travel isn't in some exotic form of matter. What you'd need
is a spaceship that could travel almost as fast as light. Einstein's theory
of relativity taught us that the faster we move through space the slower
we move in time. Let's assume you were in a spaceship
traveling at 99.9 percent the speed of light to a potentially habitable exoplanet
some 40 light years away. You find some primitive life-forms and speed back
to earth to share your discovery. But when you finally make it back to earth,
you discover that all your colleagues are now very very old.
From your perspective you'd only been gone for about two years
for people on earth you'd been gone for 80. This phenomenon is known
as time dilation it's not likely to happen to you though because traveling
at the speed of light isn't quite possible with the technology we have now.
The fastest piloted vehicle we've ever created
Apollo 10 reached a speed of 11,000 meters per second. The speed needed
for time travel is somewhere near 299 million meters per second. On top of that,
accelerating at that speed would cause an enormous centrifugal force. A force
that would rip you apart before you came anywhere close to light speed.
But hey, we still have wormholes. Einstein predicted that these theoretical
tunnels linked two separate places and two different times, a shortcut to another
universe and another time.
The problem with wormholes is they're extremely tiny
just a billion trillion trillionth of a centimeter across. No human would be able to
fit through I can barely fit in my jeans from last year.
If only we could capture a wormhole we might be able to enlarge it.
Imagine, a giant tunnel above the earth leading to another planet and
theoretically if we put both ends of a wormhole in the same place but
in different times, we could step into a wormhole and come out in
the distant past.But wormholes have their issues,they're very
short-lived and traveling into the past would create paradoxes.
Like the one in which you go back in time and convinced your grandmother
never to get married, then your grandmother doesn't give birth to your dad
he doesn't have you. But if you didn't exist who went back in time to talk
your grandmother out of marrying your grandfather. Time is linear.
It only goes forward for that reason we can only travel into the future not
to the past. In fact, astronauts that spent about a year on the
International Space Station are now living in the future compared to us.
Even though it's just 13 milliseconds in the future they're proof that
traveling a time is possible. And maybe wormholes could open up a
whole different world where the laws of physics work in different ways
and traveling to the past is possible.
Would you dare step into a time machine not knowing where it would take you?
And if you had the choice where would you go and when?
Questions:
1. Explain why we can¡¯t travel back in the past based on Albert Einstein's
Theory of relativity.
2. What is time dilation phenomenon?
3. If you could travel in the past, which time would you like to be in? Why?