How The Universe Began

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6 months ago

Documentary, How The Universe Began

Transcript

00:00Our universe, the galaxies, the solar system, our home planet Earth.

00:08Land, sea, air, life.

00:13Where did they all come from?

00:15Look up into space from our planet and what you see is a vast cosmos

00:20teeming with billions of stars and galaxies.

00:24Turn back the clock over 13 billion years

00:27and our universe was a very different place.

00:30Back then it was so small that it could fit inside the palm of your hand.

00:38From this infant universe, everything would be created.

00:41Stars, galaxies and the building blocks of life itself.

00:46The calcium in our bones, the iron in our blood,

00:50the atoms for the air we breathe,

00:54the water we drink.

00:57The raw materials for our cities and machines.

01:04Naked science takes a journey through space and time

01:07to discover how the universe was born

01:10and how it created everything in our world

01:14and how eventually it will die.

01:18everything we see around us is made of matter, atoms and molecules.

01:31Take this car, it's a 1956 Ford Fairlane convertible.

01:48It's constructed from many different materials like steel, rubber and glass.

01:54Go deeper and these materials are made up from combinations of elements like iron, silicon, chromium and carbon.

02:04Each and every atom that makes up this car were created by our growing universe.

02:12Physicist Lawrence Krauss studies how the atoms we see on our planet have come to be here.

02:17We really are part stardust and part big bang dust.

02:22Most of the atoms in our body are from the cores of stars,

02:25but some of them have been around since the earliest moments of the big bang.

02:29So we really are truly cosmic individuals.

02:32Each and every atom was created over billions of years as our universe evolved.

02:38So when we look at this car, of course all the atoms in this car came from stellar explosions,

02:45from supernova processes and from stellar evolution.

02:48But they were created at different times during the evolution of the universe.

02:51To understand how the universe made all the raw material we see here on Earth,

02:59we need to take an incredible journey and travel back through space and time

03:04to the moment our universe was born.

03:09In the beginning, there was nothing.

03:12No space, no time.

03:16And then, there was light.

03:19Suddenly, a tiny speck of light appears.

03:24It was infinitely hot.

03:26Inside this tiny fireball was all of space.

03:31This was literally the beginning of time.

03:37The cosmic clock was ticking.

03:40Time could flow and space expand.

03:44At the earliest moments of the big bang, if you take it back to t equals zero,

03:49everything in our universe, everything we can see,

03:52all the matter and all the energy in all of the galaxies,

03:55was once contained in a region smaller than the size of a single atom today.

04:01The idea that our universe was once tiny,

04:04originated from the brilliant work of American astronomer Edwin Hubble.

04:08Back in the 1920s, most astronomers believed that everything visible in the night sky were stars.

04:17And they were part of our galaxy, the Milky Way.

04:20But Hubble wasn't convinced.

04:25He studied a swirling cloud of light called the Andromeda Nebula,

04:30and showed that it was a star city.

04:33Another galaxy, far outside of our own galaxy.

04:37He showed that these other galaxies were speeding away from ours.

04:44And the further away they were, the faster they seemed to be moving.

04:50The universe was expanding.

04:53And if the universe was expanding, then at some point in the past,

04:57it must have been smaller.

05:00Much smaller.

05:01And that it must have had a beginning.

05:05The idea of the Big Bang was born.

05:12Theoretical physicist David Spergel is a Big Bang expert.

05:17The Big Bang theory is not really a theory of how the universe began.

05:21It's really a theory of how the universe evolved.

05:24No one knows exactly what happened during the Big Bang.

05:27But scientists do know that a fraction of a second after the universe was born,

05:33this tiny, super hot fireball was already starting to expand.

05:38We don't know how the universe began.

05:40So we start our story when the universe was a billionth of a billionth of a billionth of a billionth of a minute old.

05:48Pretty young.

05:50The universe was the size of a marble.

05:52Less than a trillion trillionth of a second after the Big Bang,

05:58the marble-sized universe was very unstable and underwent an enormous growth spurt.

06:06During this period of incredibly rapid expansion, space itself was expanding faster than the speed of light.

06:12In the same way that this hot glass ball inflates, so did the baby universe, expanding in all directions at once.

06:28And as it expanded, it cooled.

06:31A trillion trillionth of a second after the Big Bang, the universe was small enough to fit inside the palm of your hand.

06:41A tiny fraction of a second later, it was the size of Mars.

06:46Another fraction of a second, and the baby universe had grown to 80 times the size of the Earth.

06:58A trillionth of a second after the Big Bang, and our newborn universe was still expanding.

07:05But it didn't contain matter. It was pure energy.

07:08Einstein's famous equation, E equals MC squared, showed that mass and energy are interchangeable.

07:20It gave us the knowledge to build weapons of mass destruction.

07:24It also revealed how the universe created the first matter.

07:28When a nuclear bomb explodes, a tiny amount of matter is annihilated and converted into energy.

07:37In the baby universe, the exact opposite happened.

07:42It converted pure energy into particles of matter.

07:46But there was a problem.

07:50The universe created both matter and its arch-rival antimatter.

07:55And when these two met, they obliterated each other.

07:59The infant universe was a war zone.

08:02A battle to the death between matter and antimatter.

08:06If they mutually annihilated each other, the universe would remain full of energy.

08:12With no galaxies, stars, planets or life.

08:18Fortunately for us, there was an imbalance.

08:22For every 100 million antiparticles formed,

08:25there were 100 million and one particles of matter.

08:31But there was that one extra particle of matter left over in each volume.

08:35And that was enough to account for everything we see in the universe today.

08:40This tiny imbalance led to all matter we see in the universe.

08:45Galaxies, stars, planets, even convertibles and ourselves.

08:51Astrophysicist Carlos Frank from Durham University in England explains.

08:59We are a little bit of debris left over from the annihilation of matter and antimatter.

09:06We're the leftovers of that process.

09:07If the universe had not developed this slight asymmetry between matter and antimatter,

09:13the universe would have been completely boring, there would be no structure,

09:16there would be no galaxies, there would be no planets.

09:20Quite what this newborn universe was like has challenged cosmologists since the Big Bang was first put forward.

09:30Now, in one of the biggest laboratories on Earth, they are able to recreate conditions that almost certainly existed an instant after the Big Bang.

09:39It's called the Relativistic Heavy Ion Collider, RIC for short.

09:47And it's located at the Brookhaven National Laboratory on Long Island.

09:52It's like a time machine, taking us back to 10 millionths of a second after the Big Bang.

09:59Here, scientists like Todd Satogatta accelerates subatomic particles close to the speed of light and then smash them into each other.

10:11The particles race around this two-and-a-half-mile circular tunnel in opposite directions, 78,000 times a second,

10:19and then collide inside this giant detector, bigger than a three-story house.

10:26When they smash into each other, they generate incredible heat, just like the real infant universe.

10:34We believe the early universe was extremely hot, billions of times hotter than the center of the Sun.

10:39And what you're doing when you're smashing these nuclei together is melting matter, creating matter hot enough to give us a glimpse of what the very early universe was like.

10:47When the particles collide, they break open and throw out a shower of even smaller particles.

10:54It's a bit like discovering what cars are made of by watching them smash into each other.

11:00You can race two cars together and smash them into each other head-on.

11:04And when you do that multiple times, you start to see different patterns coming out.

11:08A tire comes out here, a radiator comes out there, and before long you can start to conclude that a race car is made up of these certain pieces.

11:15What the scientists at Brookhaven have discovered is that within these superheated collisions, a completely new form of matter appears.

11:25And this matter contradicts the previous theories on the nature of the early universe.

11:29Because it's not a gas, it's a liquid.

11:33It was super hot, 100 million times hotter than the surface of the Sun.

11:42There was so much energy inside the young universe that the particles vibrated so fast that it had no stickiness.

11:49There was no friction, and it flowed perfectly.

11:55This liquid is perfect. It has no viscosity. In some sense it would be the perfect motor royal except it's a trillion degrees hot.

12:03Inside the Collider, this amazing liquid universe exists for only a tiny fraction of a second.

12:14The Brookhaven scientists have succeeded in recreating conditions that existed over 13 billion years ago.

12:21Despite the universe being a perfect liquid, it was in turmoil.

12:30It was full of subatomic particles smashing into each other, releasing more and more energy.

12:37There was so much energy that unless the particles slowed down, they would never bond and create atoms, the building blocks of matter.

12:48And the universe would never create the galaxies and stars, or even us.

12:54The universe is now one millionth of a second old, and has expanded from smaller than the size of an atom to eight times the size of the solar system.

13:08After the incredible turmoil of the first millionth of a second, the universe was now relatively calm.

13:14Over the next three minutes, the expanding cosmos cooled sufficiently for protons and neutrons to bind together and form the first atomic nuclei, hydrogen and helium.

13:29These were not yet proper atoms.

13:33They were missing a vital ingredient, the electron.

13:37In the hot baby universe, there were plenty of electrons around.

13:43But there was still so much heat and energy, the electrons were moving too fast to form bonds.

13:50And it would stay that way for over 300,000 years.

13:58380,000 years after the Big Bang, the universe had expanded to the size of the Milky Way.

14:05It had cooled from billions of degrees Fahrenheit to a few thousand.

14:12As it cooled, the electrons slowed down.

14:19The universe was now ready to make its first true elements.

14:25One of the scientists who discovered this critical moment in the story of the universe was Arno Penzias.

14:311963, 30-year-old Penzias and his 27-year-old colleague Robert Wilson began work on a new antenna in New Jersey.

14:42Initially, they were only studying cosmic radio waves, but they would stumble on one of the greatest discoveries of all time.

14:49As they started to test their equipment, they detected an unexpected background noise.

14:56It was additional signal, and it appeared to be coming from the sky.

15:00We eliminated very carefully the ground, even the solar system, because we did this winter to summer, seasonal variation.

15:07Man-made sources of equipment, all these things were eliminated.

15:14In desperation, the two scientists began to wonder whether the strange signal might have another more earthly origin.

15:21They found there were pigeons roosting in the antenna, and it was covered with droppings.

15:29They wondered if the pigeons were the source of the strange signal.

15:34There was only one solution. The droppings and the pigeons would have to go.

15:39We finally got around to removing the pigeon droppings. We also had to remove the pigeons.

15:47That was a difficult problem because they turned out to want to come back, and we mailed them off to another site.

15:54But even with the troublesome pigeons gone, the mysterious signal would not disappear.

16:00And so we were left with the almost inescapable conclusion that this radiation was coming from the sky.

16:12I could not account for it.

16:15The strange signal detected by Penzias and Wilson would turn out to be one of the most important scientific discoveries of all time.

16:23But the explanation for their mystery background noise starts not with sound, but with the birth of light.

16:32We usually take light for granted.

16:35But in the early universe 13 billion years ago, we would see nothing at all.

16:40Light was trapped. The universe was foggy.

16:44Imagine a flashlight beam in a fog of smoke.

16:47The light bounces back and forth between the smoke particles and is trapped.

16:51In the hot baby universe, a dense fog of electrons blocked the light from escaping.

16:58But as the universe continued to expand and cool, the electrons slowed down.

17:05Protons then grabbed these calmer electrons to form complete atoms of first hydrogen and then helium.

17:13The universe was suddenly much less crowded with electrons.

17:16The fog lifted and light was no longer trapped.

17:21It hurtled out across the universe, creating a blinding burst of light.

17:26Had we been there, we would have suddenly seen this opaque universe become transparent.

17:32Suddenly the fog would lift and we would see a flash of light coming from everywhere around us.

17:38It must have been a spectacular moment.

17:39Over time this burst of light dimmed and cooled and became microwave radiation.

17:47It was this faint 13 billion year old microwave signal that Penzias and Wilson picked up on their antenna.

17:54What they heard was the quiet echo of the moment the universe formed the first atoms.

18:03It's really the light from the origin of the universe.

18:07If you have an old FM receiver, if you tune between channels, turn the knob and it doesn't capture it and pop to a station.

18:15If you go to a park and there's none, you hear a . That's what we call noise.

18:21If you have a good radio set, one half of one percent of that is actually the sound of the Big Bang.

18:28And we can also see the moment when the first elements were created.

18:32If our television is not tuned to a station, a tiny fraction of the noise is radiation from 13 billion years ago.

18:42But this radiation is not the only reminder of the birth of the universe.

18:47Even the water we drink is a memento.

18:51And it's kind of amazing to think that every time we take a drink of a glass of water,

18:55we're drinking in atoms that have been around since the Big Bang, the hydrogen atoms.

19:02Over the next millions of years, the young universe continued to expand, cool and get dark again.

19:10So far, the universe had only made hydrogen and helium atoms.

19:16But the world we live in is made from more than a hundred different kinds of elements.

19:20Without them, the universe would remain a very boring place, made up of only gas,

19:28a place where complex matter, like planets, cars and people, could never develop.

19:35The universe needed to get hydrogen and helium atoms to fuse.

19:41And to do that, it needed to make stars.

19:50The universe was now 200 million years old, and billions of light years across.

20:00Its temperature had dropped so far that it was colder than liquid nitrogen, minus 367 degrees Fahrenheit.

20:09It was also dark.

20:11It would have remained a very gloomy place, full of gas, but without galaxies, stars or planets,

20:19if it hadn't been for one thing.

20:22The baby universe wasn't born perfect.

20:26Carlos Frank has created an amazing 3D simulation of how the early universe evolved.

20:33It shows that when the universe emerged from the Big Bang, it was uneven.

20:38Little cracks appeared, which were very, very, very tiny, very, very small.

20:45And there was this rash in the face of the baby universe that later developed into the patterns that we see in the galaxies today.

20:53Without these cracks, the universe would have been a very dull place.

20:58The first clues as to how these cracks developed into galaxies and stars came when other scientists started to examine the Big Bang radiation first discovered by Penzias and Wilson.

21:12So what Penzias and Wilson saw was this radiation was, as far as they can tell, uniform.

21:20What cosmologists then did for the next 25 years was work very hard to try to find tiny variations.

21:28And find them they did, using WMAP, a space probe designed to detect and analyze in detail variations in the background microwave radiation.

21:41Launched in 2001, the $150 million probe was fitted with some of the most sensitive instruments ever carried into space.

21:49Our eyes detect only visible starlight, but WMAP can tune into the invisible microwave radiation.

22:00Once in orbit around the Sun, it picked up the faint radiation that has been rippling around the universe since the dawn of time.

22:08So when we look at the cosmic background radiation, we're looking at this radiation that's been streaming towards us since half a million years after the Big Bang.

22:17Initially, the microwave universe looked very dull and seemed to be the same everywhere.

22:24But when WMAP turned up contrast, the results were spectacular.

22:29The baby universe wasn't smooth and boring at all. It was full of fluctuations.

22:35These tiny fluctuations tell us what the variations in density, how much stuff there is and how it varies from place to place.

22:43These denser regions are going to collapse to form clusters of galaxies and superclusters and galaxies themselves.

22:51These low density regions, these will grow and become the empty regions between galaxies.

22:57So this picture really is our connection between the universe when it was a baby, half a million years old, to the universe today, 13.7 billion years old.

23:07These tiny imperfections in the fledgling universe would become galaxies and stars.

23:15And this is one of the most amazing propositions in physics.

23:18The idea that galaxies like a Milky Way that contain a hundred million stars once began life as a tiny little crack in the fabric of the universe.

23:29The material in these cracks was filled with swirling clouds of hydrogen atoms.

23:37The voids between the clouds grew bigger and bigger.

23:42The gas clouds got denser and hotter.

23:46Gravity pulled the gas clouds together on filaments like beads on threads of a web.

23:54Cosmic web.

23:56Where the giant filaments formed large globs, stars and galaxies would grow.

24:02As the universe evolved, gases were able to condense into clouds which collapsed to form stars.

24:12The stars settled into a rotating disk that was later to become a spiral galaxy like the Milky Way.

24:20Over millions of years, the hydrogen atoms clumped together and heated up.

24:25The atoms began fusing and releasing energy and the gas clouds started to burn brightly.

24:33Eventually, a star was born.

24:36All over the universe, millions of stars ignited for the first time.

24:41The appearance of the first stars would have been a truly spectacular event.

24:46Had we been there, we would have really seen fireworks.

24:48Individual enormous flashes of light generated as the stars are born and burn themselves out.

24:57The universe has expanded many trillions of times its original size.

25:06It was full of newborn stars made of hydrogen and helium.

25:11These young stars were nothing like our own sun.

25:14They were very unstable.

25:19But it was their instability that would make the universe a more interesting place.

25:24Because deep inside each new star, something amazing was happening.

25:29They were creating new elements.

25:35The idea that stars build atoms came from the British astrophysicist Sir Fred Hoyle,

25:41one of the greatest astronomers of the 20th century.

25:45Hoyle didn't believe that the universe began in a single explosion.

25:49In fact, he coined the name Big Bang as a term of derision.

25:55Hoyle wanted to know where the elements heavier than hydrogen and helium came from.

26:01He figured out that stars acted like nuclear reactors,

26:05working a bit like a hydrogen bomb in slow motion.

26:08In slow motion.

26:18But many billion times more powerful.

26:22And their nuclear waste was new elements.

26:25But it would take years before scientists were able to confirm his theory,

26:32by analyzing the light from stars.

26:35Each element emits a light at a particular frequency when heated up.

26:40Imagine a sodium street lamp.

26:43It emits light of a yellow color, specific to sodium.

26:46It's the same with stars.

26:49Take our sun.

26:51If you break the light down into a spectrum,

26:54you can see lines like a barcode corresponding to the elements.

26:58Each element has specific colors,

27:01helping scientists identify elements like hydrogen,

27:05which emits mainly red light.

27:06In 1990, NASA launched the Hubble Space Telescope to unravel some of the mysteries of our early universe.

27:16The liftoff of the space shuttle discovery with the Hubble Space Telescope,

27:20our window on the universe.

27:21Hubble promised scientists unprecedented views of the young universe.

27:28It would be able to look back through space and time,

27:32and examine early stars to discover if they were making new elements.

27:37But the dream soon turned into the worst nightmare.

27:41After it was launched, they discovered that Hubble's mirror was distorted.

27:45It saw everything out of focus.

27:51It needed corrective lenses.

27:54And the only way to fix it was to send up another space shuttle.

28:02One of the repairmen was astronaut Jeff Hoffman.

28:06We were working with a $2 billion telescope,

28:09and the last thing we wanted was to break something

28:12and leave it worse off than when we got up there.

28:17First, the crew of the rescue mission had to capture the crippled telescope.

28:26Then, execute a repair mission,

28:29unprecedented in the history of space flight.

28:32First, they had to open the access doors on the side of the telescope.

28:36The one thing about working on Hubble that is very different from working on a car is,

28:43you look over your shoulder, and there you are in space,

28:46and the Earth is going by below you, the stars above you.

28:50The astronauts had to carry out fine, detailed work in the most difficult conditions.

28:56When you're working in a space suit, your hands are encumbered by thick, stiff gloves.

29:02It's sort of like working in ski mittens, and it was quite a challenge.

29:08All went well until Hoffman attempted to close the huge access doors.

29:13I just had to close up the doors, and when I went to close them,

29:17they wouldn't close properly.

29:20The doors were somewhat warped,

29:24and it took a while for it to sink in.

29:26This was very serious.

29:27If you can't get the doors closed, you lose the telescope.

29:35Using improvised tools, Jeff and a colleague were finally able to close the doors.

29:44It took the team five days to repair the stricken telescope.

29:48Cosmologists around the world held their collective breath.

29:51They waited to see if the most expensive telescope ever built

29:57would deliver what its designers originally promised.

30:02I well remember New Year's Eve 1993, December 31st, when my phone rang,

30:09and it was an old friend who worked at the Space Telescope Science Institute in Baltimore.

30:13He said, Jeff, do you have any champagne left over from your party?

30:18I said, yeah, we still have a half bottle in the refrigerator.

30:21He said, well, crack it open again and drink a glass,

30:24because we got the first picture back and Hubble works.

30:29This is what Hubble saw.

30:31The images were beyond anyone's wildest dreams.

30:35Hubble captured the final moments of a star's life

30:38when it explodes and blows off gas and dust.

30:42It also captured interstellar nurseries of newborn stars,

30:47exploding into life billions of years ago.

30:50And dark pillars of cosmic dust, millions and millions of miles long,

30:56ready to spawn a new generation of stars and planets.

31:00I guess it's hard to surpass the famous pillars of creation,

31:05the Eagle Nebula, where you actually see the birth of stars.

31:09I mean, it's almost biblical.

31:11Let there be light.

31:13And I still kind of get goosebumps when I look at it.

31:17But Hubble's true moment of glory was still to come.

31:21Over a ten-day period in 1995,

31:24the mission controllers pointed the telescope

31:25at a distant empty patch of space.

31:28What emerged was the deep field image,

31:31a tapestry of distant galaxies.

31:34Hubble was looking back in time

31:37to some of the first galaxies and stars created.

31:40It revealed thousands of galaxies that hadn't been seen before,

31:45so the universe became, to our consciousness,

31:51far richer after the Hubble Deep Field.

31:55It showed for the first time,

31:58faint images of galaxies formed just a billion years after the Big Bang.

32:03Scientists then examined the spectrum of light from these distant stars,

32:08and showed that these early galaxies had already created elements heavier than hydrogen and helium.

32:14Sir Fred Hoyle may have been wrong about the birth of the universe,

32:19but he was absolutely right about the stars.

32:22The early stars acted like giant thermonuclear reactors creating new elements.

32:28You can think of the creation of all the elements in this room in some sense like a car assembly line.

32:34Because in a car assembly line, each part is sequentially added to the vehicle until it's complete.

32:38Fusion reactions inside these young stars released enormous amounts of energy and heat,

32:46which forced atoms to fuse to form new, heavier elements, one after the other.

32:52Three helium nuclei combined to form carbon,

32:56two carbon nuclei fused to form magnesium,

33:00magnesium to form neon,

33:01and so on over a period of hundreds of thousands of years until silicon fused to form iron.

33:09Iron is a very special atom.

33:12The protons and neutrons inside its nucleus are very tightly bound together,

33:18so that even the extreme temperatures inside the stars couldn't get it to fuse into heavier elements.

33:24It resolutely stays iron.

33:27It was the end of the road.

33:31The production line of element building shut down.

33:35But our universe was still not complete.

33:39There were all the ingredients to make a glass of water,

33:43and some of the elements to build much of our convertible.

33:46There were also quite a few of the ingredients to make a human being.

33:50The oxygen we breathe, the calcium in our bones, and the iron in our blood.

33:57But there still weren't any of the vital ingredients like chromium for our car fender.

34:03And some metals like zinc that our bodies can't survive without.

34:09The universe was about to enter a super creative phase,

34:13where it produces all the elements heavier than iron.

34:16To make the missing pieces in our birth of the universe jigsaw,

34:21would take some of the most powerful explosions the universe has ever seen.

34:31Our universe has already celebrated its 500 millionth birthday.

34:35There are still another 13 billion more to go before humans appear on the face of the Earth.

34:42Giant new stars have made many of the elements in the world we see around us.

34:48But some vital elements are still missing.

34:51Heavy metals like chromium and zinc, and expensive ones like gold and platinum.

34:55To finish the job, the universe conjures up the most amazing phenomena since the Big Bang.

35:03Massive exploding stars called supernovas.

35:08When the giant stars that made the lighter elements ran out of fuel,

35:13they collapsed in on themselves, creating incredible amounts of energy and enormous explosions.

35:19These explosions were so powerful, they could fuse elements even heavier than iron,

35:27and restart the element production line.

35:32Tony Mezzacapa from Oak Ridge National Laboratory in Tennessee,

35:37believes that without exploding stars, life itself would not exist.

35:41Life as we know it certainly would not exist were it not for core-collapse supernova events.

35:50They are very clearly one of the key links in our chain of origin from the Big Bang to the present day.

35:58One of the most recent and biggest supernovas closest to our galaxy was seen in the southern hemisphere in 1987.

36:05When a supernova like 1987A explodes, it emits light containing the signatures of the elements within it.

36:14By examining this spectrum of light, scientists can calculate what elements are being forged inside the exploding star.

36:23Michael Smith from the Experimental Astrophysics Group at Oak Ridge

36:29then recreates these events inside his own star laboratory.

36:32In this 100-foot tower, he accelerates and smashes individual particles into each other, just like inside a supernova.

36:42These subatomic nuclei are the ones that are absolutely crucial in the formation of the heaviest elements.

36:50So the idea is to measure exactly how fast these nuclei will fuse together in the laboratory,

36:57and then translate that information into how fast they'll fuse inside exploding stars.

37:04When the particles collide inside the accelerator, they generate enormous energy.

37:10In these extreme conditions, the particles fuse.

37:14And then you can bring other particles in and they will fuse.

37:16And we believe that exploding stars are just right to form elements much heavier than iron, going all the way up to the top of the periodic table.

37:27Using the data from these experiments, Tony Mezzacapa has created a model of how these massive exploding stars turn into heavy element factories.

37:36Massive stars, they evolve to an onion-like configuration at the end of their lines.

37:44They have an iron core, and outside of the iron core are layers of successively lighter elements.

37:50Inside the iron core, the temperature rises to 8 billion degrees, nearly 300 times hotter than the center of the Sun.

38:01It is so hot that the iron atoms that have sunk to the star's core are torn apart.

38:07The core destabilizes.

38:09The cores then collapse on themselves in a fraction of a second.

38:14The collapse proceeds to very, very high densities.

38:17The core collapses at speeds of more than 43,000 miles per second.

38:24A volume the size of the Earth crunches down nearly six times the size of Manhattan in an instant.

38:32The core becomes super dense.

38:34If one were to take one cubic centimeter of that matter, that would be the size of a sugar cube.

38:40That sugar cube would be so dense that it would weigh as much as the entire human race.

38:47The core rebounds like a compressed rubber ball and launches a massive shock wave.

38:54The shock wave hurdles out, smashing through the different skins of the star.

38:58As it punches through the outer layers of the star, the energy generated restarts the element production line.

39:09Atoms are smashed together to make brand new, heavier elements.

39:13All heavier than iron.

39:14Then the star explodes and the shock wave pushes the shrapnel-like debris outward, further and further into space.

39:26In a very real sense, our lives depend on the stars in the universe.

39:33Without their lives and deaths, we would not be here today.

39:37These astonishing images taken by the Hubble Space Telescope show the aftermath of these giant explosions.

39:46Nebulae, giant clouds of debris thrown off by exploding stars.

39:52Swirling inside are big new atoms, gold, silver, zinc and lead.

39:59Without supernovas, our world would be a very dull place and possibly lifeless.

40:05So I'm sure that Paris Hilton doesn't wake up every day thinking about this fact.

40:12But really, if it weren't for exploding stars, those 200 million stars that exploded so we could be here today,

40:19she wouldn't have anything to wear.

40:21So if it weren't for those supernova explosions, there wouldn't be any bling.

40:26Nine billion years after the Big Bang, and all the ingredients are in place for life as we know it.

40:33The universe has grown up into a vast, complex place made up of billions of galaxies and uncountable stars.

40:44In a quiet corner of the Milky Way, a mass of dust and gas begins to accumulate.

40:50It's full of the rich debris left over from one of the massive supernovas.

40:53And when it reaches a critical mass, it begins to burn brightly.

40:58A star is born. Our own star, the Sun.

41:02What's left over forms a disk of swirling debris in orbit around the new star.

41:09The gas and dust that make up this ring collide, pulled together by gravity.

41:16The clumps of dust and gas become bigger and bigger.

41:19Planets form.

41:21One of these planets is our Earth.

41:24Over the next 500 million years, our planet slowly generates a protective canopy of gas, the atmosphere.

41:34The first life appears, just single cells at first.

41:39But as the eons pass, those tiny single cells evolve into plants and animals, and eventually, humans.

41:46We tend to disassociate ourselves from the universe, but that of course is completely wrong.

41:52We are a vital part of the cosmos.

41:55And so when we talk about the origin and evolution of the universe,

41:58we're actually talking about the origin and evolution of ourselves.

42:02Everything we can see on our planet was either made in the Big Bang or inside a star.

42:08Scientists like Krauss believe they now know the genesis of every atom that has created the world we live in.

42:14These atoms have been around since the dawn of time.

42:19And when I was young, my mother used to tell me, don't touch that, you don't know where it's been.

42:24And she would have been amazed.

42:27But this is not the final chapter in the story.

42:31After almost 14 billion years, the universe has really only just gotten started.

42:36Now we take a journey into the future to see how it all ends.

42:47The universe we live in is nearly 14 billion years old.

42:52It has created the raw materials for everything we see around us.

42:56The stars, the planets, trees, cities, automobiles, even us.

43:01Our world is complete.

43:04But the universe is still evolving.

43:07Scientists have come up with many theories on how it will end.

43:11We know our universe began in the Big Bang.

43:14What we don't know yet is what the future of our universe is going to be.

43:18Our universe may end with a bang or a whimper or something even more exotic.

43:21One theory suggests that our universe will run out of steam and stop expanding.

43:28Every star, galaxy and planet, every atom, will start to collapse.

43:34Ending in a single super-dense pinpoint known as the Big Crunch.

43:38To find out if the universe really is going to crash back in on itself, scientists first need to discover if it's still expanding or if it's slowing down.

43:55Astrophysicist Saul Perlmutter studies the death of the universe by finding beacons in space, exploding stars called type 1a supernovas.

44:04If you have enough of these exploding stars, these supernova, that you've measured their brightness,

44:11the ones that look fainter and fainter and fainter must be further and further and further away.

44:15And so you have some supernova that are a little bit brighter, they're more nearby,

44:18some that are a little bit fainter, so they're a little bit further, and some that are very faint, so they're very far away.

44:23Type 1a supernovas are similar to the supernovas that created the heavy elements.

44:28They differ in one important fashion. They always explode with the same exact brightness.

44:35This is because they are created in the same way.

44:40Two stars circle each other, held together by their gravitational attraction.

44:46One is shriveled and superdense, glowing with white heat. A white dwarf.

44:54The other star has bloated to an enormous size. It's a red giant that is burning the last of its fuel.

45:01As the two stars orbit each other, the white dwarf sucks gas from its companion and begins to grow year after year.

45:09When it is precisely 1.44 times the mass of our Sun, the white dwarf crumples, collapses, then explodes, releasing a blinding burst of energy.

45:21Every Type 1a supernova explodes at the same tipping point, and so are equally bright and visible across the vast distances of the universe.

45:30Perlmutter needs to find hundreds of Type 1a supernovas, and then measure how fast they are moving away from us.

45:42He links up the most powerful telescope on Earth with the most powerful in space.

45:47Using advanced cameras on the Hubble Space Telescope, and a giant telescope officially known as the Very Large Telescope, or VLT for short, he hunts for supernovas.

46:01Once Hubble has detected a particular light source, colleague Chris Lidman at the VLT analyzes the object to see what it's made of, and makes sure it's a Type 1a supernova.

46:14This object is a distant galaxy, and next to it is what we believe is a distant supernova.

46:21The next crucial step is to understand what type of supernova this is.

46:27The VLT breaks down the light from the object into its spectrum.

46:32You want to be able to break up its light into a spectrum, and look for the very characteristic fingerprint that you would see if it really were a Type 1a supernova.

46:41The light emitted from this particular supernova reveals that it's a Type 1a.

46:48Lidman can now calculate how far away this supernova is.

46:53The supernova exploded about 7 billion years ago.

46:57By comparing the positions and dates of all these supernovas stretched over space and time,

47:02Perlmutter can calculate whether the Universe is slowing down.

47:08His results are a shock.

47:11The expansion of the Universe isn't slowing down at all.

47:15When we began the project, of course the goal was to find out how much the Universe was slowing down.

47:20Now, when we actually started looking at the data, it looked like the Universe wasn't slowing enough to come to a halt.

47:27And in fact, it wasn't slowing very much at all.

47:30And in fact, when we finished the analysis, it looked like it wasn't a slowing period.

47:35It was actually speeding up in its expansion.

47:37Perlmutter's astounding discovery means that the Universe will not grind to a halt, then crunch back down into a pinhead of superdense matter.

47:49Quite the opposite.

47:51It will continue to expand faster and faster.

47:55Our Universe is literally flying apart.

47:58The expansion of the Universe will accelerate at ever faster and faster rates, until literally everything will get ripped apart.

48:07Not just galaxies, but eventually, matter, the Earth, all the objects, stars, the Earth, planets, people, atoms,

48:17in a finite time would get ripped apart.

48:19Long after our Sun has burned out, a hundred billion years in the future, galaxies will pull apart.

48:29The Universe will be made up of isolated stars, which are running out of energy.

48:35Some will become white or brown dwarfs.

48:38Others will collapse into neutron stars, or black holes.

48:41Then, thousands of trillions of years after the Big Bang, even the black holes will evaporate, and all matter will decay to its basic ingredients.