Through The Wormhole Episode Scripts

N/A - Will Eternity End?

Freeman: Eternity.
It's an idea as old as religion.
Perhaps as old as humankind.
But what can modern science tell us about the end of time? Will the Universe end in a cosmic apocalypse? Could time keep on ticking forever Or will eternity end? Space, time, life itself.
The secrets of the cosmos lie through the wormhole.
The Apocalypse.
It's the day when Muslims, Christians, and Jews believe the world will come crashing down around us.
Physicists now have their own version of Apocalypse.
In fact, they have several of them.
The sun will engulf the earth.
Our star will fall into a black hole.
Our entire galaxy will collide with another.
But what if everything came to an end? Destroyed in an Apocalypse so complete that time itself would disappear.
I was just a young boy when time ran out for my grandmother.
The sun continued to rise and set each day.
The seasons cycled on.
I wondered if time for my grandmother really had ended, time when the Universe carried on.
In fact, it seemed impossible that time itself could ever end.
The ancient Greeks and Egyptians thought of eternity as a place outside of time.
They saw time as a giant circle, mirroring the passing of the sun overhead and the rotation of the seasons.
But today, we have rolled out the circle of time into a line stretching from the distant past to the far future.
Now we are forced to contemplate whether this timeline has an end or whether it can stretch on forever.
But perhaps the riddle of eternity is something we've created in our heads.
Anthropologist Vera da Silva Sinha and linguistic psychologist Chris Sinha spend their time thinking about how people think about time.
Chris: We have very large-scale, complex societies.
We could not make our society take over if we didn't have a calendar and a clock.
So we think of time concepts and ways of measuring time as being what we call a "cognitive technology.
" It's a technology of the mind.
Freeman: But Chris and Vera have discovered this organized view of time is not universal.
It's an insight they gained from studying the language and culture of an indigenous Amazonian tribe called the Amondawa.
The Amondawa people live in Rondonia -- the state of Brazil.
They were contacted by the Brazilian government in 1984.
The Amondawa tribe does not live by a calendar, and they don't use clocks.
In fact, there isn't even a word for time in their language.
If you ask an Amondawa speaker to give a translation of the word "time," the nearest thing that they can think of -- they will say "Sun.
" Or they say "raining season," or they say "summertime," but there is no There's nothing which is abstracted from that, right? To try and understand the Amondawa's notion of time, Chris and Vera had them arrange a series of paper plates.
So, we found out there is two seasons, yeah? Rain season and dry season.
So, and they would use the plates to symbolize how these seasons are divided.
An Amondawa man organizes the plates not according to days or months but by the natural events that occur throughout their two seasons.
For each one of these small subdivisions of a season, he'll tell a little story about what kind of planting and harvesting goes on, also what fruits are ripening and what's going on in the forest and in the rivers.
Is their level of the river going up or going down? This kind of thing.
It's a way of mapping out time that would make sense to any farmer.
But in our industrialized cultures, a much more rigid system has taken over.
We might arrange plates in a line of seven -- one plate for each day of the week.
Or we would divide a day into hours arranged in a circle.
But the Amondawa don't arrange events in any particular shape.
Vera: He's not really worried about the shape of the events.
He worry about the contents of each event.
They don't think of time as being analogous to a spacial dimension.
They don't think of time being a sort of line in which there is a future that you look forward to and a past that you look back to.
In English, you can say, "Oh, I look back to my childhood.
" However, in Amondawa, you don't look back to your childhood.
So, in your childhood, you were there, so you don't look back anymore.
So [Chuckles] The Amondawa don't look back on a line that traces their life from past to present.
But in Western cultures, we can't help but impose this time geometry on our lives.
A person's life is like a line that stretches from birth to death, and so we imagine the Universe, too, must have a timeline -- from its birth in the Big Bang, to some far future date when it will die.
There was no time before the beginning, and time will eventually disappear when the Universe meets its apocalyptic end.
Theoretical physicist Fotini Markopoulou, like the Amondawa, rejects this idea.
Well, if you are to say that time will end, you also have to say that time began.
It's like death and birth.
You really can't have deaths and no births.
So now you have to tell me where time came from if there was no time.
Freeman: Fotini is trying to understand the fundamental nature of time, which in the microscopic world of subatomic particles becomes a tricky concept.
The theory of Quantum Mechanics says that particles don't interact as if they are solid, defined objects, but as amorphous clouds.
A particle can be both there and not there at the same time.
And it's impossible to say when two particles meet or whether they did at all.
If you try to apply the laws of Quantum Mechanics to large objects like people or planets, you can imagine some very puzzling possibilities.
I'm sitting here, and I'm talking to you.
Now, if by some accident, in our Universe, there was a huge black hole that would suck me inside the black hole, according to Quantum Theory, that black hole behind me should be there and not there.
And, as a result, you are in a position of our conversation having happened or not happened.
Freeman: Many Quantum physicists argue this uncertainty over whether the events really happened shows that time cannot be a fundamental thing in the Universe.
It's something we've made up.
Albert Einstein disagreed with Quantum Mechanics.
He believed time is real, that it is woven with space into the fabric of the Universe.
And, according to his disciples, space and time were born together in the Big Bang.
But Fotini thinks both these views of time are wrong.
She thinks that time is real and eternal.
But for that to be true, we have to reimagine what space is.
Okay, so let's say that this is space -- the world we live in -- and the little red strings are other stuff in our world.
And the net represents the distances between us in terms of connectivity.
So that means that, for instance, if we say that this is me and this is my friend Oralia and that's my fried Helmut, it takes me -- one, two, three, four, five, six steps to get to Oralia.
And then I need -- 1, 2, 3, 4, to reach Helmut.
Freeman: But right after the Big Bang, the net of space was not spread out like this.
Perhaps, me here was actually just one step away from Helmut back in the early Universe, and these two guys were connected, until everybody is really on top of everybody else.
Freeman: In the very hot and dense Big Bang, everything is shrunk down to a single point.
The idea of space is meaningless.
But time, Fotini is certain, always exists.
If we throw out space, we get to keep time.
Time was always there before.
It will always be there after.
Freeman: If Fotini is right, time can indeed tick on forever.
But one scientist is deeply troubled by an eternal Universe.
Because if time never stops ticking, our very existence could make no sense at all.
It used to be a word that only made sense in religion or to people in love.
Now some scientists also believe time really may last forever.
But if eternity does exist, [ echoing ] some very strange things [ Normal voice ] could happen.
Cosmologist Sean Carroll from the California Institute of Technology, often takes a drive into the mountains above Los Angeles to get a better look at the night sky.
And when he does, he can't help but wonder what that night sky will look like trillions of years from now.
Carroll: Right now, we live in a bright, comfortable Universe with stars shining 100 billion galaxies in the Universe with 100 billion stars in every galaxy.
But those stars can't shine forever.
They burn up fuel.
They have a finite lifetime.
So, about 10 to the 15 years from now, those stars will all have burnt out.
There'll be no more stars shining in the sky.
Freeman: A million billion years from now, the only celestial object remaining will be black holes.
Carroll: You might think, okay, now we're done.
Black holes and empty space.
But those black holes evaporate.
They give off radiation, and the black hole itself shrinks away.
So it will take a long time, but once that happens, there's nothing left but a thin gruel of particles.
And then we're faced with the question, well, what happens in that infinitely long future period after everything has emptied out? What is life like in empty space? Freeman: It turns out that empty space is not truly empty.
In 1998, astronomers discovered a strange cosmic force called "dark energy," an expansive pressure existing everywhere in space.
Even an empty universe, in the far future, would be filled with this energy.
And the laws of Quantum Mechanics say, wherever there is energy, particles can spontaneously appear out of nothingness.
Because that dark energy is lurking in empty space, there's a temperature.
The future of the Universe is not at absolute zero.
There's a tiny thermal fluctuation, even in empty space.
If we imagine this oven represents the whole universe, we can look inside and see things appear.
So if we wait a long time, about 10 to the 10 years -- we'll see a single, lonely photon propagating through the Universe.
Freeman: But give the Universe more time, and more particles appear.
Eventually, after 10 to the power 10 to the power 30 years, something as complex and unlikely as a perfectly wired human brain could simply pop into existence.
And if you wait even longer than that, we'll see an entire new Big Bang, an entire universe fluctuating into existence out of the surrounding chaos.
Freeman: For Sean, these random fluctuations present a big problem.
If the Universe lasts forever, an infinite amount of time means an infinite amount of possibilities, which means everything you could possibly imagine will indeed appear -- including another version of you, who thinks he got here first.
Many, many copies of me will fluctuate into existence, many of them with exactly the same memories that I have.
There will be another version of me that thinks the same as I do and has the same set of memories that I have.
But for most of those versions of me, they won't actually be embedded in a sensible universe with a big bang and other galaxies.
Freeman: Each one of these Seans assumes that he is the first version of himself.
They each think they grew up in Pennsylvania, studied at Harvard, and wrote books on physics.
But they are really just random fluctuations that have popped into existence, future imposters that actually live in empty space.
The scenario that the Universe just lasts forever and there's all these fluctuations into everything we can possibly imagine means that we have no right to accept and believe our memories.
If people and galaxies and universes can randomly fluctuate into existence, the conclusion is that this can't be the right picture of the Universe.
Freeman: If dark energy keeps on expanding our cosmos, countless versions of all of us will eventually come to be, stretching from here to eternity.
There's only one thing that could prevent such a preposterous universe A truly cosmic apocalypse.
[ Pop! ] What does the word "Universe" mean? It used to mean "everything.
" But now some scientists imagine there is more to creation than all the stars and galaxies we could ever hope to see.
We might be just one tiny patch of something much larger, a multiverse, a place that lasts forever, and where a little Universe like ours comes and goes in the blink of an eye.
Raphael Bousso is one of a new generation of cosmologists who grew up with the idea that our Universe may not be the be all and end all of existence.
For him, other universes pop into existence all the time and exist inside a colossal multiverse.
Bousso: The multiverse is made out of many different regions.
These individual regions can be so large that, if you live in them, you're really like a fish in an extremely large tank of water.
You might think that there is nothing else whatsoever.
Freeman: Imagine the Universe we live in is like a balloon.
In the beginning, it was just a miniscule piece of compact space.
At the Big Bang, a powerful force called inflation took over, expanding it in a split second.
we all live deep inside its inflated walls, blind to what's outside.
But Raphael believes inflation is still at work outside of our balloon.
It constantly takes tiny pieces of space and expands them.
So, this room is what we can think of as the multiverse looking like, where every one of these balloons is a single universe, and all these universes are here because of inflation.
Freeman: Raphael's understanding of inflation stems from the view of reality called "String theory," which holds that there are not three dimensions of space but nine.
In our Universe, six of the dimensions are curled up billions of times smaller than the smallest particle.
There might be some places where all nine spatial dimensions have become large.
There might be other places where fewer than three have become large.
So inflation stretches some, but not necessarily all, of the dimensions of space.
Freeman: Just like an inflated balloon, inflated dimensions of space are intrinsically unstable and will eventually re-collapse.
As I'm walking around this room, you can see that these balloons are popping ever so slowly, one after the other.
There are a lot of balloons, but if you train your eye on one balloon, that balloon eventually is going to pop.
And just like that, our piece of space eventually is going to decay.
Freeman: By studying how inflation mutates the curled-up dimensions of space, Raphael has been able to calculate that the rate of creation of inflated universes is much higher than their rate of decay.
So, even though universes are goingall the time, many more are always being created.
So the multiverse keeps on growing and will last forever.
This pattern is called "eternal inflating multiverse.
" If you were watching this room from the outside, time would be eternal.
This would continue forever.
Freeman: This multiverse may be eternal, but it's an eternity no one can ever hope to experience because no one can ever escape the universe they were created in.
You don't get the benefit of seeing this eternity of more and more inflation and more and more balloons.
The speed-of-light limit prevents you from seeing all these other balloons.
You sit around in this one balloon, and sooner or later it's going to go "pop.
" [ Pop! ] Freeman: If you live in a universe, like everything must, then Raphael believes your time is definitely going to end.
[ Pop! ] And all of the problems of an eternal universe that worry Sean Carroll are problems our Universe will never live to see.
We can calculate how rapidly space will decay.
As long as that decay of our Universe happens faster than these unbelievably unlikely events are going to happen, then we know that we don't have to worry about copies of ourselves coming into being.
When our Universe decays, time really does end there.
[ Pop! ] Is our universe destined to die in a cosmic cataclysm? Perhaps not.
Because time may not be what we think it is, and all of eternity might already exist.
Physicists tell us that time is the fourth dimension.
But it's not like the other three that we move around in.
In space, I could walk from here to here and then turn around and go back again.
Time's dimension seems different.
We only move through it in one direction.
But there may be a way to grasp all of eternity if we stop thinking about time as a dimension and start thinking about time as a projection from the future [ Echoing ] to the past.
[ Normal voice ] For Harvard physicist Andy Strominger, the difference between the future and the past is a deep puzzle.
Because, according to the known laws of physics, they should be exactly the same.
There's a very basic principle of physics which begin with Newton.
The past determines the future, and the laws of physics can be run forward or backwards.
So, if I take this motion of this pendulum hanging from the pencil and you run the movie forward or backwards, it looks exactly the same.
But there's a huge white elephant in the room of physics, and that's the Big Bang.
So, the cartoon picture of the Big Bang is that there was nothing.
Somebody flipped a switch, and, all of a sudden, all the something that we know of was present.
So, the past of our Universe and the future of our Universe look fundamentally different.
Freeman: To resolve this paradox, Andy began to imagine the dimension of time a radical new way -- as a hologram.
Holograms are two-dimensional plates from which a third dimension of space appears to emerge.
Andy wondered if he could apply this idea not to space but to time.
Perhaps a dimension of time is just a holographic projection.
Time is a kind of illusion.
And the whole universe is written at a hologram that is sitting there at the end of time and projected backwards through our present era back to the Big Bang.
Freeman: The hologram that contains everything the universe ever was and ever will be is like this intricate ice crystal.
According to Andy, it sits in the far future and projects information back into the past.
Strominger: So, this sculpture represents the holographic plate, which contains all the information about the entire lifetime of the Universe.
As I look at this very closely, I can see more and more detail.
From far away, or more accurately, from further back in time, there would be less and less detail, less and less information present in the universe itself.
Freeman: The further you get from a holographic plate, the less information you can read on it.
So, as we travel back in time from our present day, in a highly complex universe of planets, stars, and galaxies, we move to a simpler past, to a universe the way it was billions of years ago, filled with nothing more than clouds of gas.
Strominger: And, eventually, if you go far enough back in time, before the Big Bang, there is simply nothing there at all.
Freeman: Holographic time is the only theory that logically explains how our Universe began from nothing.
Once you get too far back in time from the holographic plate, it cannot project back any more information.
Before the Big Bang, there is no information in the universe.
In a holographically-emergent universe, we don't have a Big Bang.
There isn't a special moment when, all at once, everything in the universe came into being.
Rather, we have an ongoing continual bang, which started from nothing and kept banging and banging onto the future.
In the past, there was nothing.
In the future, there is everything.
Freeman: The mathematics behind Andy's theory are highly complex.
Holographic time is not laid out like any normal dimension.
As you go further and further into the future, the same increment of time moves you less and less far forward.
So it would take an infinite amount of time to actually arrive at the holographic plate.
Strominger: In this picture, our Universe goes on forever into the future and gets bigger and bigger and keeps growing and creating new elements.
So we don't know that it describes our universe.
We're very far from that.
But we do know that it is something which can be discussed with some mathematical precision and consistency.
And so that's a starting point.
Freeman: Will our Universe survive for an eternity? It depends on who you ask.
Some say time will go on forever.
Others are sure it must end.
But now another physicist thinks we might be able to decide who is right, because the future of the universe may be traveling back in time to meet us.
Is all eternity already out there? Could the present and the past be echoes of the future, rippling back in time? If that's the case, why is it you don't know what I'm going to say next? The fact is, scientists think they found evidence the future really does affect the present.
And knowledge about the fate of the Universe may already be right in front of us.
Physicist Jeff Tollaksen from Chapman University thinks the future is very much connected to the present.
The notions of time, eternity, the end of time -- these are some of the most profound questions that we deal with as human beings.
But you have to listen very carefully to what nature's trying to tell you to discover fundamental truth.
Freeman: Jeff believes most physicists have failed to fully understand the nature of time because of the way they insist on doing experiments -- smashing particles together in giant accelerators.
Maybe, instead of smashing particles to bits, we just need to give them a little push.
What if more physicists took up the gentle sport of curling? Tollaksen: As you can see what our athletes are doing here, they set the stone going and they sweep a little bit to try to direct the stone going somewhere.
In a sense, this sweeping is kind of like a very gentle interaction.
You're not actually touching the stone.
You're kind of making the ice a little bit smoother or melting a little bit so it would tend to go in one direction.
Freeman: Jeff believes you can understand everything about the way time really works in the universe by watching curling.
And you can begin at the beginning, with the idea of time Isaac Newton had.
Tollaksen: So, the stone starts from some definite place in the past, it goes to some definite place in the present, and it goes to a definite place in the future.
So, from that perspective of classical physics, the universe looks like it's a big machine, like a big, very perfectly tuned clock.
Freeman: But then, about a century ago, along came Quantum Mechanics.
It took away all that certainty from the universe by unmasking the subatomic world.
If these curling stones were atoms, the rules of the game would change dramatically.
Tollaksen: So, the quantum world is different.
It makes different predictions from the classical view of things.
In Quantum Mechanics, you could start these stones the same and you notice that, incredibly, one stone goes to the left and the other stone goes to the right.
Freeman: In the microscopic world of atoms, nothing is known for sure.
Atoms are not solid, defined objects.
They are waves of probabilities that tell you where, when you look for a particle, you are most likely to find it.
But in the 1960s, quantum guru Yakir Aharonov dared to ask why atoms are so unpredictable, why it's so hard to pin down what they're doing at any given moment.
And the answer, he discovered, was because the future and the past are both involved in creating the present.
Yakir showed that he could reformulate Quantum Mechanics in a way that dealt with the past and the future on exactly equal footing.
Future information, which is impossible to know now, in principle, maybe that's already relevant to the present moment.
Freeman: Jeff and Yakir have searched for evidence of this revolutionary idea for the past two decades.
They've learned to be very gentle in their measurements.
A subatomic particle will move or disappear if it's observed directly.
It's as if they have to put a particle in a box, not look at it, and allow it to carry on existing as they spread out a wave of probability.
When they do that, they can begin to see the effect of the future on the present.
So, we have the red boxes that are going forward in time.
And now you have to think about the backward evolving state.
So we're gonna represent that by blue boxes.
Same particle, right? We have one particle.
But coming from the future, we're saying the present is created out of a combination of the forward evolving and the backward evolving.
Freeman: As radical as it sounds, Jeff, Yakir, and their colleagues have now tested this idea in the lab.
They give a series of very gentle magnetic nudges to subatomic particles.
They measure them at 2:00 and then at 2:30.
They do this over and over again.
Some but not all of the particles are also measured again at 3:00.
And what they found is that taking their measurement at 3:00 seemed to influence the apparently random readings they got at 2:30.
The future seemed to affect the present, even though it hadn't happened yet.
Tollaksen: If you're trying to understand the present moment, the past is relevant, as we knew before, but the future is just as relevant to the present as the past.
Freeman: So far, these experiments have only been carried out on the microscopic level, and the effects of the future on the present are very subtle.
But to Jeff, it suggests that buried somewhere in the apparently random motion of all the particles in the Universe there is such a thing as cosmic destiny.
Tollaksen: There's an ocean flowing here.
There's a current flowing from past to future and from future to past.
Freeman: The Universe may already have a destiny.
But can we mere mortals ever know it? One scientist thinks he's discovered the mathematical limit of human knowledge.
Scientists have spent trying to learn as much as they can about the world we live in.
We've done pretty well.
We understand how planets, stars, and galaxies work.
But to know the fate of the entire universe, just imagine how much more there is to know.
So perhaps it's time to ask ourselves an important question.
Are there some things we just aren't meant to understand? Theoretical physicist Tom Banks believes the best way to understand eternity is to calculate how much we can ever know.
And what we can know is what we can measure.
So, you can see the Pacific Ocean is here behind me, and the Pacific Ocean is huge.
We couldn't possibly measure it with rulers, so we measure it by using trigonometry, all kinds of math.
Freeman: The Pacific Ocean may be massive, but we've traversed its length and breadth and mapped out all of its 64 million square miles.
However, it isn't even a speck compared with the entire universe.
Banks: It is much too big for us to physically measure.
Our Universe -- we can't even get out there to most of it.
And we measure it by receiving light from it, sending light out to it, and getting all kinds of signals.
And we figure out where things are, how far away they are.
Freeman: But the Universe does not just stretch out over space.
It also extends over time, from its beginning in the Big Bang to the far future.
What would it take to know everything about such a vast place? Tom thinks he can calculate the answer to that question using something he calls "the theory of causal diamonds.
" Banks: I'm drawing a schematic diagram, showing a causal diamond.
This is my past.
This is my future.
And this diamond represents everything I could've done experiments on during that whole history from the beginning to the end.
That region in space-time, it forms a diamond shape because light goes out in sort of a cone like this, and then if I look back from the latest time, it goes backwards in a cone.
You put those two cones together, and they're sort of a diamond shape.
[ Clock ticking ] Freeman: A causal diamond marks the limit of how much of the Universe a measuring device could ever hope to reach.
When that device sends out a light beam, it heads out into the Universe, bounces off some distant galaxies, and finally returns to the device billions of years later.
Tom has been able to calculate that the amount of information existing inside that diamond is related to the area of a sphere that just fits around it at its widest point, a sphere he calls "the holographic screen.
" Banks: So now we can ask the question, suppose there was some machine that lived forever from the beginning of the Universe to the end? How big does the holographic screen of the causal diamond of that infinitely long-lived detector ever get? And it's very important, because that determines how much information there could've possibly been in this region of space and time.
Freeman: Knowing absolutely everything there is to know about every atom and every subatomic particle in existence would mean collecting a truly mind-blowing amount of data.
Banks: This number is 10 to the 10 to the 123.
It's a 1 with 10 to the 123 zeros after it.
That number is so huge that it's hard to imagine it.
If I started trying to write that number down and I wrote a zero every second, I would run out of time long before the whole history of the Universe, and I would never get to the end of it.
Freeman: But could an advanced civilization actually collect this much data and know everything about the Universe and thus learn its fate? The answer, Tom believes, is contained in this tiny cup of water.
So, in this little bit of water I just got out of the Pacific, there are sextillion atoms.
That's trillions of trillions.
If we wanted to measure all those atoms, we'd have to have a really big machine.
We'd need a device that was larger than the United States.
Freeman: But collecting data on the entire Universe is not just a monumental engineering challenge.
The laws of physics actually prevent us from doing it.
If we tried to measure every atom in existence, we would end up using so much equipment that we'd fill space with more stuff than it could handle, and the entire experiment would collapse into a black hole, destroying all that information with it.
Whoa! Tom has calculated that we can measure no more than 10 to the 10 to the 90 bits of information before we cause the entire Universe to collapse into a black hole.
This may seem like a gigantic number, but it is actually just a tiny fraction of 10 to the 10 to the 123, which is all that there is to know.
That number is so incredibly smaller than this number, that there's no hope that any civilization, no matter how sophisticated, could possibly measure all of the information that there is in the Universe throughout its entire history.
Freeman: All we can ever learn about the Universe is an impossibly tiny morsel of what's out there.
And Tom argues, trying to predict the future based on such scant knowledge is utterly futile.
So, perhaps we should quit worrying about the end of time and learn to live for the now.
Banks: It's natural for us to want to know everything.
And we like to make up stories about everything.
And those stories are often wrong.
So peopleare people.
We're finite.
We're not Gods.
We're -- we don't own the Universe.
We're a very tiny portion of the Universe.
And we've now discovered that we're a much tinier portion than we might've thought before.
We don't have the right, in some sense, to expect to know everything that there is to know.
Will the Universe last forever? Is eternity already out there, projecting the present back to us from the far future? Or will a cosmic apocalypse destroy everything in the blink of an eye? We don't know, and we probably never will, because some questions require more knowledge than we can ever get.
And maybe that's not so bad.
After all, what fun would life be if we already knew how it was going to end?