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00:00We live in a galaxy called the Milky Way, an empire with hundreds of billions of stars.
00:10How did we get here, and what's our future?
00:13In every way, those questions involve galaxies.
00:15There are 200 billion galaxies in the known universe, each one unique, enormous, and dynamic.
00:25Galaxies are violent.
00:26They were born in a violent history.
00:28They will die a violent death.
00:31Where do galaxies come from?
00:34How do they work?
00:35What is their future?
00:37And how will they die?
00:54This is our galaxy, the Milky Way.
00:59It's around 12 billion years old.
01:04The galaxy itself is a huge disk with giant spiral arms and a bulge in the middle.
01:14It's just one of a huge number of galaxies in the universe.
01:19Galaxies are first and foremost large collections of stars.
01:23The average galaxy may contain 100 billion stars.
01:29There are really stellar nurseries, the place where stars are born and where they also die.
01:38The stars in a galaxy are born in clouds of dust and gas called nebulas.
01:45Galaxies are the pillars of creation in the Eagle Nebula, a star nursery deep in the Milky
01:56Way.
01:58Our galaxy contains many billions of stars, and around many of them are systems of planets,
02:08moons.
02:10But for a long time, we didn't know much about galaxies.
02:14Almost a century ago, we thought that the Milky Way was all there was.
02:21Scientists called it our island universe.
02:25For them, no other galaxies existed.
02:29Then in 1924, astronomer Edwin Hubble changed all that.
02:35Hubble was observing the universe with the most advanced telescope at the time, the 100-inch
02:40hooker on Mount Wilson near Los Angeles.
02:46Deep in the night sky, he saw fuzzy blobs of light that were far, far away.
02:53He realized they weren't individual stars at all.
02:58They were whole cities of stars, galaxies way beyond the Milky Way.
03:06Astronomers had an existential shock.
03:09In one year, we went from the universe being the Milky Way galaxy to a universe of billions
03:18of galaxies.
03:23Hubble had made one of the greatest discoveries in the history of astronomy.
03:28The universe contains not just one, but a great number of galaxies.
03:36This is the Whirlpool Galaxy.
03:38It has two giant spiral arms and contains around 160 million stars.
03:49And Galaxy M87, a giant elliptical galaxy.
03:54It's one of the oldest in the universe, and the stars glow gold.
04:06And this is the Sombrero Galaxy.
04:09It has a huge glowing core with a ring of gas and dust all around it.
04:19Galaxies are gorgeous.
04:21They represent, in some sense, the basic unit of the universe itself.
04:25They're like gigantic pinwheels twirling in our space.
04:29Just like fireworks created by Mother Nature.
04:37Galaxies are big, really, really big.
04:41On Earth, we measure distance in miles.
04:44In space, astronomers use light-years, the distance light travels in a year.
04:55That's just under six trillion miles.
05:00Here we are, 25,000 light-years away from the center of our galaxy, and our galaxy is
05:05over 100,000 light-years across.
05:07But even that, as large as it is, is kind of a speck in the cosmic distance scale.
05:13Our Milky Way galaxy may seem big to us, but compared to some others out there, it's actually
05:21pretty small.
05:23Andromeda, our nearest galactic neighbor, is over 200,000 light-years across, twice
05:30the size of the Milky Way.
05:33M87 is the largest elliptical galaxy in our own cosmic backyard, and much bigger than
05:39Andromeda.
05:44But M87 is tiny compared to this giant.
05:50Six million light-years across, IC 1011 is the biggest galaxy ever found.
05:59It's 60 times larger than our Milky Way.
06:04We know galaxies are big, and they're everywhere, but why is that?
06:10One of the very big questions we have in astrophysics is where galaxies come from.
06:15We really don't have a complete understanding of that.
06:22The universe started in what we call a Big Bang, an extremely hot, extremely dense phase
06:27about 13.7 billion years ago.
06:30We know that nothing like a galaxy could have existed at that time.
06:34So galaxies must have been born, they must have formed out of that very early universe.
06:40It takes gravity to make stars, and even more gravity to pull stars together into galaxies.
06:48The first stars formed just 200 million years after the Big Bang.
06:52Then gravity pulled them together, building the first galaxies.
07:00The Hubble Space Telescope has allowed us to peer back in time to almost the dawn of
07:05time, a period when galaxies have just begun to form.
07:13The Hubble sees lots of galaxies, but the light we see today from those galaxies left
07:19there thousands, millions, even billions of years ago.
07:25It's taken all that time to reach us.
07:27So what we see today is the ancient history of those galaxies.
07:34When we look at the Hubble Deep Field, what we see are little smudges.
07:37They don't look much like the galaxies we see today.
07:40They're just little smudges of light that we can barely discern.
07:44Those smudges of light contain millions or billions of stars that have just begun to
07:49merge together.
07:51These faint smudges are the earliest galaxies of all.
07:57They were formed around one billion years after the beginning of the universe.
08:04That's as far back as Hubble can see.
08:07If we want to go even further back in time, we need a different kind of telescope, one
08:12too big to launch into space.
08:19Well, now we have one, in the high desert of northern Chile.
08:27This is ACT, the Atacama Cosmology Telescope.
08:33At 17,000 feet, it's the highest ground-based telescope in the world.
08:43I really like working in the extreme environment of ACT.
08:48It's very, very cold often, and the wind blows violently, but the good thing about it from
08:54our point of view is that the sky is very, very clear almost all the time.
09:02Clear skies are important for ACT's precise mirrors to focus on the earliest galaxies.
09:10With ACT, we're able to zoom in with unprecedented detail on parts of the sky.
09:15We can also study the progress of growth of structures, where structures are things like
09:21galaxies and clusters of galaxies, with very fine-scale detail.
09:28ACT doesn't detect visible light.
09:31It detects cosmic microwaves from the time the universe was just a few hundred thousand
09:37years old.
09:39The telescope not only detects early galaxies, it actually sees how they grew.
09:46We're able to track the progress of the formations of galaxies and clusters of galaxies.
09:51We see the footprints of all the galaxies that have grown in the time between when the
09:57universe was a few hundred thousand years old until now.
10:02ACT has helped astronomers understand how galaxies have evolved since almost the beginning
10:07of time itself.
10:10And we can start answering the question, what did galaxies look like when they were young?
10:16How did they compare with modern-day galaxies?
10:20How have they grown?
10:25Astronomers are seeing how galaxies evolve from groups of stars into the patchwork of
10:30systems we see today.
10:32Our current understanding is that stars form clusters that build into galaxies, that build
10:38into clusters of galaxies, that build into superclusters of galaxies, the largest structures
10:42we observe in the universe today.
10:45Early galaxies were a mess, lumpy bunches of stars, gas and dust.
10:51But today, galaxies look neat and orderly.
10:55So how do messy galaxies transform into beautiful spirals and pinwheels?
11:02The answer is gravity.
11:05Gravity shapes galaxies and controls their future.
11:14There is an unimaginably powerful and incredibly destructive source of gravity at the heart
11:20of most galaxies, and there's one buried deep at the center of our own Milky Way.
11:38Galaxies have existed for over 12 billion years.
11:44We know these vast empires of stars come in all shapes and sizes, from swirling spirals
11:50to huge balls of stars.
11:54But there's still a lot about galaxies we don't know.
11:58How did galaxies come to have the shapes they do?
12:00Was a spiral galaxy always a spiral galaxy?
12:04The answer is almost certainly no.
12:08Early young galaxies are messy and chaotic, a jumble of stars, gas and dust.
12:16Then, over billions of years, they evolve into neat, organized structures, like the
12:22Whirlpool Galaxy, or our own Milky Way.
12:30Our Milky Way began not as a single baby galaxy, but many.
12:35Because now our Milky Way was once comprised of lots of small structures, irregularly shaped
12:40objects that began to merge.
12:44The thing that pulls the small structures together is gravity.
12:49Gradually, it pulls stars inward.
12:53They begin spinning faster and faster, and flatten into a disk.
13:00Stars and gas are swept into huge spiral arms.
13:06This process was repeated billions and billions of times across the universe.
13:16Each of these galaxies looks different, but they do have one thing in common.
13:22They all seem to orbit something at their center.
13:29For years, scientists wondered what could be powerful enough to change how a galaxy
13:34behaves.
13:35They found out, a black hole.
13:41And not just any kind of black hole, a supermassive black hole.
13:49The first clue that supermassive black holes existed was that at the heart of some galaxies,
13:53there was an immense amount of energy emanating out from the center.
13:57What we're seeing is the black holes and these galaxies feasting on the material around
14:03them.
14:04So it's like having a huge Thanksgiving dinner.
14:07The meal is gas and stars, and it's being eaten by the supermassive black hole.
14:16When black holes eat, they sometimes eat too fast, and spit their dinner back out into
14:22space in beams of pure energy.
14:29It's called a quasar.
14:33When scientists see a quasar blasting from a galaxy, they know it has a supermassive
14:41black hole.
14:47But what about our galaxy?
14:49There's no quasar here.
14:52Does that mean there's no supermassive black hole?
14:58Andrea Ghez and her team have spent the last 15 years trying to find out.
15:06So the key to discovering a supermassive black hole at the center of our Milky Way is to
15:10watch how the stars move.
15:12The stars move because of the gravity, just like the planets orbiting the sun.
15:18But the stars closest to the center of the galaxy are hidden by clouds of dust.
15:24So Ghez used the giant Keck telescope in Hawaii to look through the clouds.
15:30What she saw was a strange and brutal place.
15:36Everything is more extreme at the center of our galaxy.
15:39Things move really fast, and stars are going to be whizzing by one another.
15:44It's windy.
15:45It's violent.
15:47It's unlike any place else in our galaxy.
15:53Ghez and her team began to take pictures of a few stars orbiting near the center.
16:01The task has been to make a movie of the stars at the center, and so you have to be patient
16:06because you take a picture and then you take another one and you see it move.
16:11The pictures of the orbiting stars revealed something amazing.
16:18They were moving at several million miles an hour.
16:24When we had the second picture, it was the most exciting point in this experiment because
16:29it was clear to us that these stars were moving so fast that the supermassive black hole hypothesis
16:36had to be right.
16:40And it was right.
16:42Ghez and her team tracked the movement of the stars and pinpointed what they were orbiting.
16:50There's only one thing powerful enough to sling big stars around like that, a supermassive
16:56black hole.
16:57It's the gravity of the supermassive black hole that makes these stars orbit.
17:02So the curvature was the definitive proof of a supermassive black hole at the center
17:06of our galaxy.
17:08The black hole at the center of the Milky Way is gigantic, 15 million miles across.
17:17So is Earth in any danger?
17:20We are in absolutely no danger of being sucked into our supermassive black hole.
17:25It's simply too far away.
17:31In fact, the Earth is 25,000 light years away from the supermassive black hole at the center
17:38of the Milky Way.
17:39That's many trillions of miles.
17:43The Earth is safe, for now.
17:55Supermassive black holes may be the source of huge amounts of gravity, but they don't
17:59have enough power to hold galaxies together.
18:03In fact, according to the laws of physics, galaxies should fly apart.
18:11So why don't they?
18:13Because there's something out there even more powerful than a supermassive black hole.
18:19It can't be seen, and it's virtually impossible to detect.
18:24It's called dark matter, and it's everywhere.
18:35Astronomers have figured out that supermassive black holes live at the heart of galaxies
18:39and pull stars at incredible speeds.
18:44But they're not strong enough to hold all the stars in a gigantic galaxy together.
18:50So what does hold them together?
18:55It was a mystery until a maverick scientist came up with the idea that something unknown
19:00was at work.
19:04Back in the 1930s, Swiss astronomer Fritz Zwicky wondered why galaxies stayed together
19:10in groups.
19:14By his calculations, they didn't generate enough gravity, so they should fly away from
19:19each other.
19:21And so he said, well, I know that they haven't flown apart.
19:25I see them all gathered together in this nice collection.
19:28Therefore, something must be holding them in place.
19:32But our own gravity was just not strong enough.
19:35And so he concluded that it must be something which nobody had detected before, nobody had
19:39thought about, and he gave it this name, dark matter.
19:42And this was really a stroke of genius.
19:48Fritz Zwicky was decades ahead of his time, and that's why he graded on the astronomical
19:54community.
19:55But, you know, he was right.
20:01If what Zwicky called dark matter held galaxies together in groups, perhaps it also holds
20:07individual galaxies together.
20:10To find out, scientists built virtual galaxies in computers with virtual stars and virtual
20:17gravity.
20:18We did a simulation where we put a lot of particles in orbit in a flat disk, which was
20:26just like the picture of our galaxy, and we expected to find that we'd get a perfectly
20:32good galaxy, and we were looking to see if it had a spiral or whatnot.
20:36But we found it always came apart.
20:40There just wasn't enough gravity in the galaxy to hold it together.
20:44So O'Stryker then added extra gravity from virtual dark matter.
20:49It seemed like a natural thing to try, and it solved the problem, it fixed it.
20:55Gravity from dark matter held the galaxy together.
21:00Dark matter acts as a sort of protective scaffolding for galaxies that really holds them up and
21:05holds them in place and prevents them from falling apart.
21:10Now scientists are discovering that dark matter doesn't just hold galaxies together.
21:16It might have sparked them into life.
21:20We think that dark matter was created out of the Big Bang, and dark matter began to
21:25clump, and these clumpings of dark matter eventually became the nuclei, the seeds for
21:31our galaxy.
21:32But scientists still have no idea what dark matter actually is.
21:38Dark matter is weird because we don't understand it at all.
21:42It's clearly not made of the same stuff that you and I are made of.
21:44You can't push against it, you can't feel it, yet it's probably all around us.
21:49It's a ghost-like material that'll pass right through you as if you didn't exist at all.
21:59We might not know much about dark matter, but the universe is full of it.
22:07So the dark matter, weight for weight, makes up at least six times as much of the universe
22:13as does normal matter, the stuff that we're all made from.
22:16And without it, the universe just wouldn't work the way that it seems to work.
22:21But the universe does work, so maybe dark matter is real.
22:28Strange stuff.
22:30And recently, it's been detected in deep space.
22:34Not directly, but by observing what it does to light.
22:39It bends it in a process called gravitational lensing.
22:45Gravitational lensing really allows us to test the presence of dark matter.
22:50And the way that works is that as a beam of light from some distant galaxy is traveling
22:54towards us, if it passes by a large collection of dark matter, its path will be deflected
23:00around that dark matter by the gravitational pull.
23:06When the Hubble telescope looks deep into the universe, some galaxies do seem distorted
23:11and stretched.
23:15That's caused by the dark matter which warps the image.
23:19It's sort of like looking through a goldfish bowl.
23:23By probing the shapes of those galaxies and the degree of distortion, we can really measure
23:28very accurately the amount of dark matter that's there.
23:35It's clear now that dark matter is a vital ingredient of the universe.
23:42It's been working since the dawn of time and affects everything, everywhere.
23:49It triggers the birth of galaxies and keeps them from falling apart.
23:56We can't see it or detect it, but nevertheless, dark matter is the master of the universe.
24:11Galaxies look isolated.
24:13It's true, they are trillions of miles apart, but actually they live in groups called clusters.
24:23And these clusters of galaxies are linked together in superclusters containing tens
24:28of thousands of galaxies.
24:31So where does our Milky Way galaxy fit in?
24:34If you take a look at the big picture, you realize that our galaxy is part of a local
24:40group of galaxies, perhaps 30, and our galaxy and Andromeda are the two biggest galaxies
24:47in this local group.
24:49But if you look even farther out, we are part of the Virgo supercluster of galaxies.
24:58Scientists are now mapping the overall structure of the universe and the position of clusters
25:03and superclusters of galaxies.
25:10This is Apache Point Observatory in New Mexico, home to the Sloan Digital Sky Survey, or SDSS.
25:20It's a small telescope with a big price tag, and it has a unique mission.
25:30SDSS is building the first 3D map of the night sky, a process that's identifying the exact
25:43positions of tens of millions of galaxies.
25:51To do it, SDSS goes galaxy hunting way out into space, far beyond our Milky Way.
25:59It pinpoints the positions of galaxies, and this information is copied onto aluminum disks.
26:08These aluminum disks are about 30 inches across, and they have 640 holes each.
26:15And these holes correspond to the objects of interest in the sky.
26:20Each object is a galaxy.
26:22Light from the galaxy is channeled through a hole and down a fiber optic cable.
26:27This method records data on distance and position from thousands of galaxies and plots their
26:33location in 3D.
26:35It's telling us about their shape.
26:37It's telling us about their makeup.
26:40It's telling us how they're distributed.
26:42And all of this is very important to astronomy in understanding our universe.
26:50And this is what they're creating, the biggest 3D map ever.
26:59The map is showing us things we've never seen before.
27:03It shows galaxies in clusters and superclusters.
27:09But pull back even more, and we see that these superclusters are connected into structures
27:15called filaments.
27:17SDSS has found one that's 1.4 billion light years across.
27:29It's called the Great Sloan Wall, and it's the largest single structure ever discovered
27:35in the history of science.
27:40You get a sense that you are in something quite vast.
27:44You can see the clusters and filaments as the data would scroll by.
27:49And each one of these little fuzzy spots were actually galaxies, not stars, but galaxies.
27:55And so you're seeing whole clusters of these things.
27:58SDSS is showing galactic geography on a vast scale.
28:04Scientists have taken it even further.
28:08They've built the whole universe in a supercomputer.
28:13Here you can't see individual galaxies.
28:17You can't even see galaxy clusters.
28:21What you can see are superclusters linked together on filaments in a vast cosmic web.
28:30As one begins to come back from the whole scale of the universe, one begins to reveal
28:35a filamentary pattern, a cosmic web of containing galaxies and clusters of galaxies that light
28:42up the universe where there are as many galaxies in that direction as that direction is that
28:46direction and that direction.
28:48And in fact, on larger scales, the universe kind of looks like a sponge.
28:54Each of the filaments is home to millions of galaxy clusters, all bound together by
29:00dark matter.
29:02In this computer simulation, the dark matter glows along the filaments.
29:08Dark matter affects where in the universe galaxies will form.
29:12When we look at galaxies, they're not sprinkled around at random.
29:15They actually tend to form in little groups, and that's really reflecting the large-scale
29:20distribution of dark matter.
29:24Dark matter is the glue holding together the whole superstructure of the universe.
29:32It binds galaxies in clusters and clusters in superclusters.
29:39All these are locked together in a web of filaments.
29:45Without dark matter, the whole structure of the universe would simply fall apart.
29:51This is the big picture of our universe.
29:57It's a giant cosmic web, and hidden deep in one of these filaments is the Milky Way.
30:04It's been around for nearly 12 billion years.
30:13But in the future, it's going to be destroyed in a gigantic cosmic collision.
30:29Galaxies are vast kingdoms of stars.
30:33Some are giant balls, and others, complex spirals.
30:39The thing is, they never stop changing.
30:43While it may seem when we look out at our galaxy that our galaxy is static and been
30:48here forever, it's not.
30:50Our galaxy is a dynamic place.
30:52Its very nature has been changing over cosmic time.
30:59Galaxies not only change, they move as well.
31:05And sometimes, they run into each other.
31:08And when they do, it's eat or be eaten.
31:16There's a zoo of galaxies that you can find out there, and this entire zoo can interact
31:23or collide with any of the other members of the zoo.
31:28This is NGC 2207.
31:33It looks like an enormous double spiral galaxy, but it's actually two galaxies colliding.
31:43The collision will last millions of years, and eventually, the two galaxies will become
31:49one.
31:54Collisions like this happen all over the universe.
31:58Our own Milky Way is no exception.
32:03The Milky Way is, in fact, a cannibal.
32:05And it exists in its present form by having cannibalized small galaxies that it literally
32:13ate up.
32:14And today, we can see small streams of stars that are left over from the most recent mergers
32:19that have formed the Milky Way galaxy.
32:24But that's nothing compared to what's coming up.
32:28We are on a collision course with the galaxy Andromeda.
32:34And for the Milky Way, that's bad news.
32:41Our Milky Way galaxy is approaching Andromeda at the rate of about a quarter of a million
32:46miles per hour, which means that in five to six billion years, it's all over for the Milky
32:53Way galaxy.
32:55You would see the entire Andromeda galaxy speeding towards us, really barreling straight
33:02into us.
33:03As the two galaxies interact, they both become more and more disturbed and closer and closer
33:10together.
33:11And the whole process starts to snowball.
33:13The two galaxies will enter a death dance.
33:18This is a simulation of the future collision, sped up millions of times.
33:28As the galaxies crash together, clouds of gas and dust are thrown out in all directions.
33:43Gravity from the merging galaxies rips stars from their orbits and shoots them deep into
33:48space.
33:51As we approach doomsday for the Milky Way galaxy, it would be spectacular.
33:56We would have a front row seat on the destruction of our own galaxy.
34:02Eventually, the two galaxies will go right through each other and then come back and
34:10then coalesce.
34:12It's strange, but the stars themselves won't collide.
34:16They're still too far apart.
34:19All the stars are basically just going to pass right by each other.
34:23The probability of one individual star hitting another individual star are basically zero.
34:31However, the gas and dust between the stars will start to heat up.
34:38Eventually, it ignites and the clashing galaxies will glow white hot.
34:47So at a certain point, the sky could be on fire.
34:56The Milky Way and Andromeda as we know it will cease to exist and Milkomeda will be
35:02born and it will look like a whole new galaxy.
35:18This new galaxy, Milkomeda, will become a huge elliptical galaxy without any arms or
35:24spiral shape.
35:28There's no escaping what's going to happen.
35:31The question is, what's it mean for planet Earth?
35:35We may either be thrown out into outer space when the arms of the Milky Way galaxy are
35:41ripped apart or we could wind up in the stomach of this new galaxy.
35:50Stars and planets will be pushed all over the place.
35:54So this may well be the end of planet Earth.
36:06Galaxies all over the universe will continue to collide.
36:13But this age of galactic cannibalism will eventually pass because there is an even more
36:21destructive force in the universe, a force that nothing can stop.
36:31It will ultimately push galaxies away from each other, stretching everything until the
36:38universe rips itself apart.
36:49Galaxies are home to stars, solar systems, planets and moons.
36:55Everything that's important happens in galaxies.
37:01Galaxies are the lifeblood of the universe.
37:02We arose because we live in a galaxy and everything we can see and everything that matters to
37:08us in the universe happens within galaxies.
37:13But the truth is, galaxies are delicate structures held together by dark matter.
37:19Now scientists have found another force at work in the universe.
37:24It's called dark energy.
37:27Dark energy has the opposite effect of dark matter.
37:31Instead of binding galaxies together, it pushes them apart.
37:35The dark energy, which we've only discovered in the last decade, which is the dominant
37:40stuff in the universe, is far more mysterious.
37:43We don't have the slightest idea why it's there.
37:50What it's made from, we don't really know.
37:53We know it's there, but we don't really know what it is or what it's doing.
37:57Dark energy is really weird.
38:00It's as if space has little springs in it which are causing things to repel each other
38:06and push them apart.
38:09Somewhere in the future, scientists think that dark energy will win the cosmic battle
38:14with dark matter, and that victory will start to drive galaxies apart.
38:22Dark energy is going to kill galaxies off.
38:24It's going to do that by causing all the galaxies to recede further and further away from us
38:28until they're invisible, until they're moving away from us faster than the speed of light.
38:32So the rest of the universe will literally disappear before our very eyes.
38:36Not today, not tomorrow, but in perhaps a trillion years, the rest of the universe
38:40will have disappeared.
38:43Galaxies will become lonely outposts in deep space.
38:48But that's not going to happen for a very, very long time.
38:55For now, the universe is thriving, and galaxies are creating the right conditions for life
39:02to exist.
39:05Without galaxies, I wouldn't be here, you wouldn't be here, perhaps life itself wouldn't
39:10be here.
39:13We're lucky.
39:15Life has only evolved on Earth because our tiny solar system was born in the right part
39:19of the galaxy.
39:24If we were any closer to the center, well, we wouldn't be here.
39:32At the center of a galaxy, life can be extremely violent.
39:36And in fact, if our solar system were closer to the center of our galaxy, it'd be so radioactive
39:41that we couldn't exist at all.
39:45Too far away from the center would be just as bad.
39:53Out there, there aren't as many stars.
39:56We might not exist at all.
40:00So in some sense, we are in the Goldilocks zone of a galaxy.
40:04Not too close, not too far, but just right.
40:08Scientists believe that this galactic Goldilocks zone might contain millions of stars.
40:17So there may be other solar systems that can support life right here in our own galaxy.
40:24And if our galaxy has a habitable zone, then other galaxies could, too.
40:30This is immense.
40:31And the amazing thing is that we're always discovering more.
40:35Every time we think we know the answer to one problem, we find it's embedded in a much
40:40bigger problem.
40:42And that's exciting.
40:46There are endless questions to ask and mysteries to solve in our own galaxy, the Milky Way,
40:53and in galaxies all across the universe.
40:57Ten years ago, who would have thought that we would be able to identify the black hole
41:01at the center?
41:02Who would have thought ten years ago that the astronomical community would believe in
41:06dark matter and dark energy?
41:09More and more, scientific research is focusing on galaxies.
41:14They hold the key to how the universe works.
41:18We should be amazed to live at this time here at a random time in the history of the universe
41:23on a random planet at the outskirts of a random galaxy where we can ask questions
41:28and understand things from the beginning of the universe to the end.
41:33We should celebrate our brief moment in the sun.
41:40Galaxies are born, they evolve, they collide, and they die.
41:53Galaxies are the superstars of the scientific world, and even the scientists who study them
42:02have their favorites.
42:04The Whirlpool Galaxy, or M51.
42:11I'd kind of like the Sombrero Galaxy if I had to put one on a wall.
42:18The Sombrero Galaxy, Ring Galaxies, they're just beautiful to look at.
42:26My favorite galaxy is the Milky Way Galaxy.
42:30It's my true home.
42:42We're lucky that the Milky Way provides the right conditions for us to live.
42:47Our destiny is linked to our galaxy and to all galaxies.
42:56They made us, they shape us, and our future is in their hands.