Brian Greene: Time Travel is Possible | BEST OF 2015
Δημοσιεύτηκε στις 25 Δεκ 2015
Is
the time we experience in our day-to-day lives real? Theoretical
physicist Brian Green explores the potential particles of time and why
we could, in theory, travel forward in time but not back.
Read more at BigThink.com: http://bigthink.com/videos/time-travel
Follow Big Think here:
YouTube: http://goo.gl/CPTsV5
Facebook: https://www.facebook.com/BigThinkdotcom
Twitter: https://twitter.com/bigthink
Transcript
- We know a lot about time. We know that time in some sense is at rock
bottom that which allows change to take place, right. When we say that
time has elapsed we notice that because things now are different from
how they were a little while ago. That’s what we mean by time elapsing.
But is time some fundamental quality of reality or is it something that
our brains impose on our perceptions to organize our experience into
some coherent framework that allows us to survive. I mean I can well
imagine that we have been under evolutionary pressure over the millennia
to organize perception so that we can survive, get the next meal, plan
for the future. All of that would seemingly require that we have a
conception of time that we apply to what we experience out there. But
that doesn’t mean time as we experience it is real. It doesn’t mean that
time as we experience it is how the world is actually structured. I
mean there are many ideas that people put forward. The possibility for
instance that, you know, we all know that matter is made of molecules
and atoms. Could it be that time is also made of some kind of
ingredient? A molecule of time? An atom of time? Is that really what
time is at a fundamental level?
Time travel is absolutely
possible. And this is not some sort of weird sci-fi thing that I’m
talking about here. Albert Einstein taught us more than 100 years ago
that time travel is possible if you’re focusing upon time travel to the
future. And I’m not referring to the silly thing that we all age, right.
We’re all going into the future. Sure, I’m talking about if you wanted
to leapfrog into the future, if you wanted to see what the Earth will be
like a million years from now, Albert Einstein told us how to do that.
In fact he told us two ways of how to do it. You can build a spaceship,
go out into space near the speed of light, turn around and come back.
Imagine you go out for six months and you turn around and you come back
for six months. You will be one year older. But he taught us that your
time is elapsing much slower than time back on Earth. So when you step
out of your ship you’re one year older but Earth has gone through many,
many years. It can have gone through 10,000, 100,000 or a million years
depending on how close to the speed of light you traveled.
And he
also taught us if you go and hang out near the edge of a black hole
time again will elapse more slowly for you at the edge of the black hole
than back on Earth. So you hang out there for a while, you come back
and again you get out of your ship and it will be any number of years
into the future, whatever you want all depending on how close you got to
the edge of the black hole and how long you hung out there. That is
time travel to the future. Now of course what people really want to know
about is getting back. Can you travel back to the past? I don’t think
so. We don’t know for sure. No one has given a definitive proof that you
can’t travel to the past. In fact, some very reputable scientists have
suggested ways that you might travel to the past. But every time we look
at the proposals and detail it seems kind of clear that they’re right
at the edge of the known laws of physics. And most of us feel that when
physics progresses to a point that we understand things even better,
these proposals just will be ruled out, they won’t work. But I guess I
would say there’s a long shot possibility based on what we know today
that time travel to the past might be possible. But most of us wouldn’t
bet our life on it.
Directed / Produced by Jonathan Fowler, Elizabeth Rodd, and Aaron Lehmann
the time we experience in our day-to-day lives real? Theoretical
physicist Brian Green explores the potential particles of time and why
we could, in theory, travel forward in time but not back.
Read more at BigThink.com: http://bigthink.com/videos/time-travel
Follow Big Think here:
YouTube: http://goo.gl/CPTsV5
Facebook: https://www.facebook.com/BigThinkdotcom
Twitter: https://twitter.com/bigthink
Transcript
- We know a lot about time. We know that time in some sense is at rock
bottom that which allows change to take place, right. When we say that
time has elapsed we notice that because things now are different from
how they were a little while ago. That’s what we mean by time elapsing.
But is time some fundamental quality of reality or is it something that
our brains impose on our perceptions to organize our experience into
some coherent framework that allows us to survive. I mean I can well
imagine that we have been under evolutionary pressure over the millennia
to organize perception so that we can survive, get the next meal, plan
for the future. All of that would seemingly require that we have a
conception of time that we apply to what we experience out there. But
that doesn’t mean time as we experience it is real. It doesn’t mean that
time as we experience it is how the world is actually structured. I
mean there are many ideas that people put forward. The possibility for
instance that, you know, we all know that matter is made of molecules
and atoms. Could it be that time is also made of some kind of
ingredient? A molecule of time? An atom of time? Is that really what
time is at a fundamental level?
Time travel is absolutely
possible. And this is not some sort of weird sci-fi thing that I’m
talking about here. Albert Einstein taught us more than 100 years ago
that time travel is possible if you’re focusing upon time travel to the
future. And I’m not referring to the silly thing that we all age, right.
We’re all going into the future. Sure, I’m talking about if you wanted
to leapfrog into the future, if you wanted to see what the Earth will be
like a million years from now, Albert Einstein told us how to do that.
In fact he told us two ways of how to do it. You can build a spaceship,
go out into space near the speed of light, turn around and come back.
Imagine you go out for six months and you turn around and you come back
for six months. You will be one year older. But he taught us that your
time is elapsing much slower than time back on Earth. So when you step
out of your ship you’re one year older but Earth has gone through many,
many years. It can have gone through 10,000, 100,000 or a million years
depending on how close to the speed of light you traveled.
And he
also taught us if you go and hang out near the edge of a black hole
time again will elapse more slowly for you at the edge of the black hole
than back on Earth. So you hang out there for a while, you come back
and again you get out of your ship and it will be any number of years
into the future, whatever you want all depending on how close you got to
the edge of the black hole and how long you hung out there. That is
time travel to the future. Now of course what people really want to know
about is getting back. Can you travel back to the past? I don’t think
so. We don’t know for sure. No one has given a definitive proof that you
can’t travel to the past. In fact, some very reputable scientists have
suggested ways that you might travel to the past. But every time we look
at the proposals and detail it seems kind of clear that they’re right
at the edge of the known laws of physics. And most of us feel that when
physics progresses to a point that we understand things even better,
these proposals just will be ruled out, they won’t work. But I guess I
would say there’s a long shot possibility based on what we know today
that time travel to the past might be possible. But most of us wouldn’t
bet our life on it.
Directed / Produced by Jonathan Fowler, Elizabeth Rodd, and Aaron Lehmann
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