- 7/6/2025
Morgan Freeman explains that the Amondawa tribe in the Brazilian state of Rondônia "does not live by a calendar, and they don't use clocks."
"Dark energy" was discovered in 1998.
Andrew Strominger views time as a hologram. Holograms are "2-dimensional plates" from which a third dimension of space appears to emerge.
Thanks for watching. Follow for more videos.
#cosmosspacesciecne
#throughthewormhole
#season3
#episode9
#cosmology
#astronomy
#spacetime
#spacescience
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#spacedocumentary
#willeternityend?
"Dark energy" was discovered in 1998.
Andrew Strominger views time as a hologram. Holograms are "2-dimensional plates" from which a third dimension of space appears to emerge.
Thanks for watching. Follow for more videos.
#cosmosspacesciecne
#throughthewormhole
#season3
#episode9
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#morganfreeman
#spacedocumentary
#willeternityend?
Category
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LearningTranscript
00:00Eternity.
00:08It's an idea as old as religion.
00:13Perhaps as old as humankind.
00:17But what can modern science tell us about the end of time?
00:24Will the universe end in a cosmic apocalypse?
00:27Could time keep on ticking forever?
00:34Or will eternity end?
00:42Space.
00:44Time.
00:46Life itself.
00:49The secrets of the cosmos lie through the wormhole.
00:57The apocalypse.
00:59It's the day when Muslims, Christians and Jews believe the world will come crashing down around us.
01:17Physicists now have their own version of apocalypse. In fact, they have several of them.
01:23The sun will engulf the earth.
01:27Our star will fall into a black hole.
01:30Our entire galaxy will collide with another.
01:35But what if everything came to an end?
01:39Destroyed in an apocalypse so complete that time itself would disappear.
01:44Time itself would disappear.
01:54I was just a young boy when time ran out for my grandmother.
01:57The sun continued to rise and set each day. The seasons cycled on.
02:07I wondered if time for my grandmother really had ended.
02:12Time in the universe carried on.
02:13In fact, it seemed impossible that time itself could ever end.
02:24The ancient Greeks and Egyptians thought of eternity as a place outside of time.
02:30They saw time as a giant circle mirroring the passing of the sun overhead and the rotation of the seasons.
02:37But today we've rolled out the circle of time into a line stretching from the distant past to the far future.
02:48Now we are forced to contemplate whether this timeline has an end or whether it can stretch on forever.
02:55But perhaps the riddle of eternity is something we've created in our heads.
03:03Anthropologist Vera da Silva Senha and linguistic psychologist Chris Senha spend their time thinking about how people think about time.
03:19We have very large scale complex societies.
03:22We could not make our society tick over if we didn't have a calendar and a clock.
03:30So we think of time concepts and ways of measuring time as being what we call a cognitive technology.
03:38It's a technology of the mind.
03:43But Chris and Vera have discovered this organized view of time is not universal.
03:48It's an insight they gained from studying the language and culture of an indigenous Amazonian tribe called the Amandawa.
03:58The Amandawa people live in Rondonia, the state of Brazil.
04:03They were contacted by the Brazilian government in 1984.
04:06The Amandawa tribe does not live by a calendar and they don't use clocks.
04:13In fact, there isn't even a word for time in their language.
04:18If you ask an Amandawa speaker to give a translation of the word time, the nearest thing that they can think of, they will say sun.
04:27Or they say rainy season, so they say summertime, but there is no...
04:34There's nothing which is abstracted from that, right?
04:38To try and understand the Amandawa's notion of time, Chris and Vera had them arrange a series of paper plates.
04:45So we found out there is two seasons, yeah? Rain season and dry season.
04:53So, and we use the plates to symbolize how these seasons are divided.
05:01An Amandawa man organizes the plates not according to days or months,
05:06but by the natural events that occur throughout their two seasons.
05:12For each one of these small subdivisions of a season,
05:17he'll tell a little story about what kind of planting and harvesting goes on.
05:24Also, what fruits are ripening and how the...
05:28What's going on in the forest.
05:29What's going on in the forest and in the rivers.
05:30Is the level of the river going up or going down?
05:33This kind of thing, yeah.
05:34Yeah.
05:36It's a way of mapping out time that would make sense to any farmer.
05:40But in our industrialized cultures, a much more rigid system has taken over.
05:47We might arrange plates on a line of seven, one plate for each day of a week.
05:52Or we would divide a day into hours, arranged in a circle.
05:57But the Amandawa don't arrange events in any particular shape.
06:04He's not really worried about the shape of the events.
06:07He worry about the contents of each event.
06:10They don't think of time as being analogous to a spatial dimension.
06:16They don't think of time being a sort of line in which there is a future that you look forward to,
06:22and a past that you look back to.
06:23In English, you can say, oh, I look back to my childhood.
06:28However, in Amandawa, you don't look back to your childhood.
06:31In your childhood, you were there, so you don't look back anymore.
06:34The Amandawa don't look back on a line that traces their life from past to present.
06:43But in Western cultures, we can't help but impose this time geometry on our lives.
06:49A person's life is like a line that stretches from birth to death.
06:52And so, we imagine the universe, too, must have a timeline.
06:59From its birth in the Big Bang 14 billion years ago,
07:04to some far future date when it will die.
07:07There was no time before the beginning, and time will eventually disappear when the universe meets its apocalyptic end.
07:21Theoretical physicist Fotini Markopoulou, like the Amandawa, rejects this idea.
07:29Well, if you are to say that time will end, you also have to say that time began.
07:33It's like death and birth, right? You can't have deaths and no births.
07:38So now you have to tell me where time came from if there was no time.
07:44Fotini is trying to understand the fundamental nature of time,
07:51which in the microscopic world of subatomic particles becomes a tricky concept.
07:57The theory of quantum mechanics says that particles don't interact as if they are solid, defined objects.
08:04But as amorphous clouds, a particle can be both there and not there at the same time.
08:13And it's impossible to say when two particles meet, or whether they did at all.
08:18If you try to apply the laws of quantum mechanics to large objects like people, or planets, you can imagine some very puzzling possibilities.
08:30I'm sitting here and I'm talking to you.
08:33Now, if by some accident in our universe there was a huge black hole, that would suck me inside the black hole.
08:41According to quantum theory, that black hole behind me should be there and not there.
08:46And as a result, you are in a position of our conversation having happened or not happened.
08:50Many quantum physicists argue this uncertainty over whether the events really happened shows that time cannot be a fundamental thing in the universe.
09:03It's something we've made up.
09:06Albert Einstein disagreed with quantum mechanics.
09:09He believed time is real.
09:12That it is woven with space into the fabric of the universe.
09:16And according to his disciples, space and time were born together in the Big Bang.
09:24But Votini thinks both these views of time are wrong.
09:29She thinks that time is real and eternal.
09:33But for that to be true, we have to reimagine what space is.
09:37Okay, so let's say that this is space, the world we live in.
09:42And the little red strings are all the stuff in our world.
09:47And the net represents the distances between us in terms of connectivity.
09:52So that means that, for instance, if we say that this is me and this is my friend Aurelia and that's my friend Helmut,
09:58it takes me 1, 2, 3, 4, 5, 6 steps to get Aurelia and then I need 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 steps to reach Helmut.
10:13But right after the Big Bang, the net of space was not spread out like this.
10:19Perhaps me here was actually just one step away from Helmut back in the early universe.
10:30And these two guys were connected until everybody is really on top of everybody else.
10:38In the very hot and dense Big Bang, everything is shrunk down to a single point.
10:44The idea of space is meaningless.
10:47But time, Fotini is certain, always exists.
10:53If we throw out space, we get to keep time.
10:56Time was always there before, will always be there after.
11:02If Fotini is right, time can indeed tick on forever.
11:07But one scientist is deeply troubled by an eternal universe.
11:13Because if time never stops ticking, our very existence could make no sense at all.
11:22Eternity.
11:24It used to be a word that only made sense in religion or to people in love.
11:29Now some scientists also believe time really may last forever.
11:35But if eternity does exist, some very strange things could happen.
11:43Cosmologist 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.
12:01And when he does, he can't help but wonder what that night sky will look like trillions of years from now.
12:10Right now, we live in a bright, comfortable universe with stars shining a hundred billion galaxies in the universe with a hundred billion stars in every galaxy.
12:22But those stars can't shine forever.
12:24They burn up fuel.
12:25They have a finite lifetime.
12:27So about 10 to the 15 years from now, those stars will all have burned out.
12:31There will be no more stars shining in the sky.
12:33A million billion years from now, the only celestial object remaining will be black holes.
12:41You might think, okay, now we're done. Black holes and empty space.
12:46But those black holes evaporate.
12:48They give off radiation and the black hole itself shrinks away.
12:51So it will take a long time.
12:53But once that happens, there's nothing left but a thin rule of particles.
12:56And then we're faced with the question, well, what happens in that infinitely long future period after everything has emptied out?
13:05What is life like in empty space?
13:08It turns out that empty space is not truly empty.
13:14In 1998, astronomers discovered a strange cosmic force called dark energy, an expansive pressure existing everywhere in space.
13:26Even an empty universe in the far future would be filled with this energy.
13:32And the laws of quantum mechanics say, wherever there is energy, particles can spontaneously appear out of nothingness.
13:43Because that dark energy is lurking in empty space, there's a temperature.
13:48The future of the universe is not at absolute zero.
13:51There's a tiny thermal fluctuation, even in empty space.
13:54If we imagine this oven represents the whole universe, we can look inside and see things appear.
14:01So if we wait a long time, about 10 to the 10 years, 10 billion years, we'll see a single lonely photon propagating through the universe.
14:11But give the universe more time, and more particles appear.
14:18Eventually, 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.
14:29And if we wait even longer than that, 10 to the 10 to the 120 years, we'll see an entire new Big Bang, an entire universe fluctuating into existence out of the surrounding chaos.
14:44For Sean, these random fluctuations present a big problem.
14:50If the universe lasts forever, an infinite amount of time means an infinite amount of possibilities.
14:57Which means, everything you could possibly imagine will indeed appear.
15:02Including another version of you, who thinks he got here first.
15:08Many, many copies of me will fluctuate into existence.
15:12Many of them with exactly the same memories that I have.
15:15There will be another version of me that thinks the same as I do and has the same set of memories that I have.
15:21But for most of those versions of me, they won't actually be embedded in a sensible universe with a Big Bang and other galaxies.
15:32Each one of these Shans assumes that he is the first version of himself.
15:38They each think they grew up in Pennsylvania, studied at Harvard, and wrote books on physics.
15:44But they are really just random fluctuations that have popped into existence.
15:49Future impostors that actually live in empty space.
15:55The scenario that the universe just lasts forever and there's all these fluctuations into everything we can possibly imagine
16:01means that we have no right to accept and believe our memories.
16:05If people and galaxies and universes can randomly fluctuate into existence,
16:09the conclusion is that this can't be the right picture of the universe.
16:17If dark energy keeps on expanding our cosmos,
16:21countless versions of all of us will eventually come to be.
16:25Stretching from here to eternity.
16:30There's only one thing that could prevent such a preposterous universe.
16:34A truly cosmic apocalypse.
16:43What does the word universe mean?
16:47It used to mean everything.
16:51But now, some scientists imagine there is more to creation
16:56than all the stars and galaxies we could ever hope to see.
17:00We might be just one tiny patch of something much larger.
17:06A multiverse.
17:08A place that lasts forever.
17:11And where a little universe like ours comes and goes in the blink of an eye.
17:18A blink of an eye.
17:22Rafael Busso is one of a new generation of cosmologists who grew up with the idea
17:29that our universe may not be the be all and end all of existence.
17:35For him, other universes pop into existence all the time and exist inside a colossal multiverse.
17:42The multiverse is made out of many different regions.
17:46These individual regions can be so large that if you live in them,
17:51you're really like a fish in an extremely large tank of water.
17:54You might think that there is nothing else whatsoever.
17:59Imagine the universe we live in is like a balloon.
18:02In the beginning, it was just a minuscule piece of compact space.
18:08At the Big Bang, a powerful force called inflation took over, expanding it in a split second.
18:1514 billion years later, we all live deep inside its inflated walls, blind to what's outside.
18:23But Rafael believes inflation is still at work outside of our balloon.
18:31It constantly takes tiny pieces of space and expands them.
18:37So this room is what we can think of as the multiverse looking like,
18:43where every one of these balloons is a single universe,
18:48and all these universes are here because of inflation.
18:50Rafael's understanding of inflation stems from the view of reality called string theory,
18:58which holds that there are not three dimensions of space, but nine.
19:05In our universe, six of the dimensions are curled up billions of times smaller than the smallest particle.
19:15There might be some places where all nine spatial dimensions have become large.
19:19There might be other places where fewer than three have become large.
19:23So inflation stretches some, but not necessarily all, of the dimensions of space.
19:30Just like an inflated balloon, inflated dimensions of space are intrinsically unstable and will eventually re-collapse.
19:41As I'm walking around this room, you can see that these balloons are popping ever so slowly, one after the other.
19:49There are a lot of balloons, but if you train your eye on one balloon, that balloon eventually is going to pop.
19:55And just like that, our piece of space eventually is going to decay.
19:58By studying how inflation mutates the curled up dimensions of space,
20:04Rafael has been able to calculate that the rate of creation of inflated universes is much higher than their rate of decay.
20:12So even though universes are going all the time, many more are always being created.
20:18So the multiverse keeps on growing and will last forever.
20:24This pattern is called the eternally inflating multiverse.
20:27If you were watching this room from the outside, time would be eternal. This would continue forever.
20:33This multiverse may be eternal, but it's an eternity no one can ever hope to experience,
20:39because no one can ever escape the universe they were created in.
20:45You don't get the benefit of seeing this eternity of more and more inflation and more and more balloons.
20:50The speed of light limit prevents you from seeing all these other balloons.
20:54You sit around in this one balloon, and sooner or later, it's going to go pop.
21:00If you live in a universe like everything must,
21:03then Rafael believes your time is definitely going to end.
21:10And all of the problems of an eternal universe that worries Sean Carroll
21:15are problems our universe will never live to see.
21:19We can calculate how rapidly space will decay.
21:23As long as that decay of our universe happens faster,
21:26then these unbelievably unlikely events are going to happen.
21:28Then we know that we don't have to worry about copies of ourselves coming into being.
21:34When our universe decays, time really does end there.
21:40Is our universe destined to die in a cosmic cataclysm?
21:45Perhaps not.
21:47Because time may not be what we think it is.
21:51And all of eternity might already exist.
21:58Physicists tell us that time is the fourth dimension.
22:03But it's not like the other three that we move around in.
22:07In space, I can walk from here to here,
22:14and then turn around and go back again.
22:18Time's dimension seems different.
22:21We only move through it in one direction.
22:24In one direction.
22:26But there may be a way to grasp all of eternity
22:30if we stop thinking about time as a dimension
22:34and start thinking about time as a projection
22:38from the future to the past.
22:42For Harvard physicist Andy Strominger, the difference between the future and the past is a deep puzzle.
22:53Because according to the known laws of physics, they should be exactly the same.
22:58There's a very basic principle of physics, which began with Newton.
23:04The past determines the future, and the laws of physics can be run forward or backwards.
23:11So if I take this motion of this pendulum hanging from the pencil,
23:17and you run the movie forward or backwards, it looks exactly the same.
23:27But there's a huge white elephant in the room of physics, and that's the Big Bang.
23:33So the cartoon picture of the Big Bang is that there was nothing.
23:40Somebody flipped a switch.
23:42And all of a sudden, all the something that we know of was present.
23:46So the past of our universe and the future of our universe looked fundamentally different.
23:52To resolve this paradox, Andy began to imagine the dimension of time in a radical new way.
24:03As a hologram.
24:06Holograms are two-dimensional plates from which a third dimension of space appears to emerge.
24:14Andy wondered if he could apply this idea not to space, but to time.
24:19Perhaps the dimension of time is just a holographic projection.
24:25Time is a kind of illusion.
24:27And the whole universe is written at a hologram that is sitting there at the end of time,
24:34and projected backwards through our present era back to the Big Bang.
24:43The hologram that contains everything the universe ever was and ever will be
24:47is like this intricate ice crystal.
24:51According to Andy, it sits in the far future and projects information back into the past.
24:59So this sculpture represents the holographic plate, which contains all the information about the entire lifetime of the universe.
25:07As I look at this very closely, I can see more and more detail.
25:14From far away, or more accurately, from further back in time, there would be less and less detail,
25:22less and less information present in the universe itself.
25:26The further you get from a holographic plate, the less information you can read on it.
25:33So as we travel back in time from our present day in a highly complex universe of planets, stars and galaxies,
25:42we move to a simpler past, to a universe the way it was billions of years ago, filled with nothing more than clouds of gas.
25:50And eventually, if you go far enough back in time, before the Big Bang, there is simply nothing there at all.
26:01Holographic time is the only theory that logically explains how our universe began from nothing.
26:08Once you get too far back in time from the holographic plate, it cannot project back any more information.
26:17Before the Big Bang, there is no information in the universe.
26:22In a holographically emergent universe, we don't have a Big Bang.
26:27There isn't a special moment when all at once everything in the universe came into being.
26:32Rather, we have an ongoing continual bang, which started from nothing and kept banging and banging on to the future.
26:43In the past, there was nothing. In the future, there is everything.
26:48The mathematics behind Andy's theory are highly complex.
26:53Holographic time is not laid out like any normal dimension.
26:56As you go further and further into the future, the same increment of time moves you less and less far forward.
27:05So it would take an infinite amount of time to actually arrive at the holographic plate.
27:11In this picture, our universe goes on forever into the future and gets bigger and bigger and keeps growing and accreting new elements.
27:22So we don't know that it describes our universe. We're very far from that.
27:30But we do know that it is something which can be discussed with some mathematical precision and consistency.
27:40And so that's a starting point.
27:42Will our universe survive for an eternity?
27:49It depends on who you ask.
27:52Some say time will go on forever.
27:54Others are sure it must end.
27:57But now another physicist thinks we might be able to decide who is right.
28:02Because the future of the universe may be traveling back in time to meet us.
28:09Is all eternity already out there?
28:16Could the present and the past be echoes of the future, rippling back in time?
28:22If that's the case, why is it you don't know what I'm going to say next?
28:29The fact is, scientists think they found evidence the future really does affect the present.
28:35And knowledge about the fate of the universe may already be right in front of us.
28:46Physicist Jeff Toloxon from Chapman University thinks the future is very much connected to the present.
28:53The notions of time, eternity, the end of time, these are some of the most profound questions that we deal with as human beings.
29:07But you have to listen very carefully to what nature is trying to tell you to discover fundamental truth.
29:12Jeff 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.
29:28Maybe instead of smashing particles to bits, we just need to give them a little push.
29:37What if more physicists took up the gentle sport of curling?
29:42As 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.
29:56In a sense, the sweeping is kind of like a very gentle interaction.
29:59You're not actually touching the stone.
30:01You're kind of making the ice a little bit, a little bit smoother or melting a little bit so it would tend to go in one direction.
30:08Jeff believes you can understand everything about the way time really works in the universe by watching curling.
30:18And you can begin at the beginning with the idea of time Isaac Newton had.
30:24So 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.
30:33So from that perspective of classical physics, the universe looks like it's a big machine, like a big, very perfectly tuned clock.
30:43But then, about a century ago, along came quantum mechanics.
30:49It took away all that certainty from the universe by unmasking the subatomic world.
30:54If these curling stones were atoms, the rules of the game would change dramatically.
31:02So the quantum world is different.
31:05It makes different predictions from the classical view of things.
31:10In 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.
31:20In the microscopic world of atoms, nothing is known for sure.
31:26Atoms are not solid, defined objects.
31:30They are waves of probabilities that tell you where, when you look for a particle, you are most likely to find it.
31:37But in the 1960s, quantum guru Yakir Aharonov dared to ask why atoms are so unpredictable.
31:48Why it's so hard to pin down what they're doing at any given moment.
31:53And the answer, he discovered, was because the future and the past are both involved in creating the present.
32:00Yakir showed that he could reformulate quantum mechanics in a way that dealt with the past and the future in exactly equal footing.
32:14Future information, which is impossible to know now, in principle, maybe that's already relevant to the present moment.
32:21Jeff and Yakir have searched for evidence of this revolutionary idea for the past two decades.
32:30They've learned to be very gentle in their measurements.
32:34A subatomic particle will move or disappear if it's observed directly.
32:39It'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 wave of probability.
32:48When they do that, they can begin to see the effect of the future on the present.
32:55So, we have the red boxes that are going forward in time.
32:59And now, you have to think about the backward evolving state.
33:05So, we're going to represent that by blue boxes.
33:09Same particle, right? We have one particle.
33:10But coming from the future, we're saying the present is created out of a combination of the forward evolving and the backward evolving.
33:20As radical as it sounds, Jeff, Yakir, and their colleagues have now tested this idea in the lab.
33:29They give a series of very gentle magnetic nudges to subatomic particles.
33:36They measure them at 2 o'clock and then at 2.30.
33:42They do this over and over again.
33:46Some, but not all, of the particles are also measured again at 3 o'clock.
33:51And what they found is that taking their measurement at 3 o'clock seemed to influence the apparently random readings they got at 2.30.
34:02The future seemed to affect the present, even though it hadn't happened yet.
34:07If 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.
34:20So far, these experiments have only been carried out on the microscopic level, and the effects of the future on the present are very subtle.
34:28But 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.
34:42There's an ocean flowing here, there's a current flowing from past to future and from future to past.
34:47The universe may already have a destiny, but can we mere mortals ever know it?
34:57One scientist thinks he's discovered the mathematical limit of human knowledge.
35:07Scientists have spent 3,000 years trying to learn as much as they can about the world we live in.
35:15We've done pretty well.
35:18We understand how planets, stars and galaxies work.
35:23But to know the fate of the entire universe, just imagine how much more there is to know.
35:30So perhaps it's time to ask ourselves an important question.
35:35Are there some things we just aren't meant to understand?
35:40Theoretical physicist Tom Banks believes the best way to understand eternity is to calculate how much we can ever know.
35:54And what we can know is what we can measure.
35:57So you can see the Pacific Ocean is here behind me, and the Pacific Ocean is huge.
36:05We couldn't possibly measure it with rulers, so we measure it by using trigonometry, all kinds of math.
36:11The Pacific Ocean may be massive, but we've traversed its length and breadth and mapped out all of its 64 million square miles.
36:25However, it isn't even a speck compared with the entire universe.
36:32It's much too big for us to physically measure.
36:35Our universe, we can't even get out there to most of it.
36:38And we measure it by receiving light from it, sending light out to it, and getting all kinds of signals.
36:43And we figure out where things are, how far away they are.
36:50But the universe does not just stretch out over space.
36:54It also extends over time.
36:57From its beginning in the Big Bang to the far future.
37:01What would it take to know everything about such a vast place?
37:05Tom thinks he can calculate the answer to that question using something he calls the theory of causal diamonds.
37:15I'm drawing a schematic diagram showing a causal diamond.
37:21This is my past, this is my future, and this diamond represents everything I could have done experiments on during that whole history from the beginning to the end.
37:32To the end, that region in space-time, it forms a diamond shape because light goes out in sort of a cone like this.
37:40And then if I look back from the latest time, it goes backwards in the cone.
37:45You put those two cones together and they're sort of a diamond shape.
37:52A causal diamond marks the limit of how much of the universe a measuring device could ever hope to reach.
37:57When 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.
38:10Tom 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.
38:24A sphere he calls the holographic screen.
38:27So 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?
38:41And it's very important because that determines how much information there could have possibly been in this region of space and time.
38:50Knowing 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.
39:01This number is 10 to the 10 to the 10 to the 123.
39:08It's a one with 10 to the 123 zeros after it.
39:12That number is so huge that it's hard to imagine it.
39:16If 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.
39:27And I would never get to the end of it.
39:31But could an advanced civilization actually collect this much data and know everything about the universe and thus learn its fate?
39:41The answer, Tom believes, is contained in this tiny cup of water.
39:47So in this little bit of water I just got out of the Pacific, there are sextillion atoms. That's trillions of trillions.
39:55If we wanted to measure all those atoms, we'd have to have a really big machine.
40:00We'd need a device that was larger than the United States.
40:05But collecting data on the entire universe is not just a monumental engineering challenge.
40:11The laws of physics actually prevent us from doing it.
40:14If 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.
40:26And the entire experiment would collapse into a black hole, destroying all that information with it.
40:31Tom 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.
40:47This 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.
41:00That 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.
41:14All we can ever learn about the universe is an impossibly tiny morsel of what's out there.
41:24And Tom argues, trying to predict the future based on such that knowledge is utterly futile.
41:31So perhaps we should quit worrying about the end of time and learn to live for the now.
41:41It's natural for us to want to know everything.
41:44And we like to make up stories about everything.
41:48And those stories are often wrong.
41:50So people are people, we're finite, we're not gods, we don't own the universe.
41:58We're a very tiny portion of the universe.
42:01And we've now discovered that we're a much tinier portion than we might have thought before.
42:08We don't have the right, in some sense, to expect to know everything that there is to know.
42:13Will the universe last forever?
42:21Is eternity already out there, projecting the present back to us from the far future?
42:28Or will a cosmic apocalypse destroy everything in the blink of an eye?
42:33We don't know, and we probably never will.
42:39Because some questions require more knowledge than we can ever get.
42:44And maybe that's not so bad.
42:47After all, what fun would life be if we already knew how it was going to end?
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