Category
📺
TVTranscript
00:00Space, a maelstrom of chaos and violence.
00:08Stars gobbling up other stars, black holes eating up entire star systems, galaxies colliding
00:15with other galaxies.
00:18The universe is a hostile place.
00:20You are blowing up a star.
00:24There's no way to describe that kind of energy.
00:27The hidden mechanism controlling these phenomena, orbits.
00:32If you understand all possible orbits, you understand the dynamics driving the universe.
00:39Orbits hold everything together and tear it all apart.
00:43Extreme orbits mean colliding galaxies, collapsing dust clouds, the very creation of life as
00:48well as destruction.
00:52Extreme orbits, masters of life and death in our universe.
01:10This is our solar system, eight planets, more than 150 moons, billions of space rocks, dust
01:20and gas, all orbit a single star in a giant whirling disk 10 billion miles across.
01:32It's been this way for 4 billion years.
01:35Everything moves round in an orderly fashion, serene and stable.
01:44But our solar system is unusual.
01:48Elsewhere in our universe, orbits are nothing like this.
01:53They're unstable, chaotic, even destructive.
02:02Even in the nearby universe, we see incredibly violent examples of orbits.
02:07Giant planets that hurtle in toward their stars.
02:10We see shockwaves of thousands of degrees perpetuate through the atmosphere.
02:14There are planets that dip right over the surfaces of other stars.
02:17Huge stars orbiting each other, multiple orbital systems where there's just chaos and entire
02:23objects can be kicked out of the system.
02:25Stars gobbling up other stars, black holes eating up entire star systems, galaxies colliding
02:32with other galaxies, that's the norm.
02:39Earth is an oasis of water and warmth.
02:43Life flourishes because of how we orbit the sun.
02:50Earth's orbit is almost circular.
02:53We stay about the same distance from the sun all year round.
03:00The temperature here is relatively constant, and Earth's orbit has been stable for the
03:05past four and a half billion years.
03:11Without this stability, we would not exist.
03:14To create DNA out of the oceans takes hundreds of millions, perhaps even a billion years.
03:20And for that stability, you need circular orbits.
03:24And so without the stability of the solar system and the Earth's orbit, there's no life
03:29on Earth.
03:35We owe everything to Earth's orbit.
03:38We get a gentle ride.
03:40In an otherwise violent universe, we've hit the orbital jackpot.
03:47Yet chaos is never far away.
03:51Even within our solar system, there are extreme and violent orbits where life could never
03:56survive.
03:59Mercury, the closest rock to the sun and the smallest planet in the solar system, its orbit
04:07stretches into an oval shape.
04:10At its furthest point, Mercury is 43 million miles from the sun.
04:16But at its closest point, it's just 28 million.
04:21This close in, it's hot.
04:24800 degrees Fahrenheit, hotter than a baker's oven.
04:28Also, because there's very little atmosphere on Mercury, you'd choke.
04:32And because there's no air to speak of, the blood in your body would boil and it would
04:37burst your skin.
04:38You would literally explode on the surface of Mercury.
04:45But the temperature can also fall to 300 degrees below zero, three times colder than the coldest
04:53place on Earth.
04:57Mercury has the most extreme temperature variations of any planet in the solar system.
05:03But it's also proof that orbits don't just loop.
05:07With each revolution around the sun, Mercury's path shifts.
05:12Over thousands of years, the planet follows a daisy pattern.
05:19At the other end of the solar system, there's Pluto, four billion miles from the sun.
05:26The further away an object is, the slower its orbit.
05:32Pluto takes 248 years to complete a single loop.
05:37And Pluto is an anomaly.
05:40Its stretched orbit is on a completely different plane from the major planets, and it creates
05:46an amazing spectacle.
05:50During most of its orbit, Pluto is a frozen block of ice and rock.
05:56But as it gets closer to the sun, summer begins.
06:02When Pluto warms up, the frozen ices on the surface of Pluto, these are water ices, carbon
06:09dioxide, even some carbon monoxide, maybe methane ices, they evaporate.
06:14And you get a fog, and the fog gets thicker, and then you get thick clouds, and suddenly
06:19you have an actual atmosphere around Pluto that wasn't there before.
06:25This atmosphere is thickest when Pluto is closest to the sun.
06:30But as the planet heads back into deep space, the temperature plummets to 400 degrees below
06:37zero.
06:40It begins to snow flakes of frozen nitrogen and methane.
06:47As winter comes, these gases slowly begin to freeze out of the atmosphere.
06:52They may rain down in a snow-like way, but gradually they accumulate sort of a glassy,
06:57semi-transparent layer, a frozen atmosphere on the surface of Pluto.
07:03After a bitter winter, Pluto drifts closer to the sun, and the 248-year cycle begins
07:09again.
07:13Extreme changes like these remind us how lucky we are that Earth's orbit is stable and benign.
07:23But it's a delicate balance.
07:24The smallest change could kill us all.
07:28If Earth's orbit were closer to the sun, we would be like our closest neighbor, Venus.
07:35Venus is a pretty good example of what might happen to the Earth if our orbit shifted a
07:39little bit in from where we are now.
07:41Venus has this hugely thick atmosphere that traps all of the heat, and the surface is
07:45close to 900 degrees.
07:47If we moved even just a little bit closer to the sun, we would become more like Venus.
07:53Oceans would boil away.
07:56Our planet would become a desert.
07:59Life would be destroyed.
08:04A small shift in the opposite direction, and instead of boiling, we'd freeze.
08:11You would have snowball Earth, the Earth completely encased in ice, and that's only by moving
08:17the Earth a fraction of its distance from the sun.
08:27The polar ice caps would expand.
08:31Oceans would freeze.
08:33A permanent ice age would begin.
08:37The smallest shift in Earth's orbit, and we'd die by fire or ice.
08:45Orbits allow life to flourish, but they can also cause chaos.
08:55Orbits are even capable of destroying entire stars.
09:09Your planet's orbit makes life possible.
09:14But most orbits are violent.
09:21Space is a cosmic freeway.
09:24Nothing stands still.
09:27Everything moves around everything else, thanks to a single force, gravity.
09:37Gravity is the universal force of attraction that spreads throughout the universe itself.
09:42It's the force that holds stars together.
09:45It's the force that binds the solar system together.
09:49All objects have gravity, so all objects attract each other.
09:54The more mass an object has, the stronger its attraction.
09:59That's why falling apples are pulled toward Earth.
10:05In our solar system, the biggest object is the sun.
10:12It's 700 times more massive than all the planets put together.
10:18The titanic force of the sun's gravity pulls all the planets inward.
10:24But something stops them from falling in.
10:28The planets are in constant motion.
10:31They fly through space at incredible speed.
10:35Not directly toward the sun, but sideways, creating a tug-of-war between the sun's gravity
10:42and the planet's speed.
10:45When the two balance out, the planet loops around the sun.
10:50We call this an orbit.
10:53An orbit is simply the motion, the path of an object around another object due to gravity.
11:00So you can have circular orbits.
11:02You can have elliptical orbits.
11:04Imagine if I were to take a ball and throw it in the air and catch it.
11:07Very briefly, that ball is in orbit around the center of the Earth.
11:11It's just motion affected by gravity.
11:16Imagine what would happen if the sun had no gravity.
11:20The planet's speed would shoot them out into space.
11:25On the other hand, if the planets stopped moving, gravity would pull them into the sun.
11:38All orbits are a balance between gravity and motion.
11:47We like to think the universe runs like clockwork, everything neat and orderly.
11:54The planets moving in cosmic harmony.
11:58But that's wrong.
12:00Orbits can be wild and unpredictable.
12:05And the more objects there are, the more unpredictable their orbits become.
12:12Things can get complicated when you have more than two objects all trying to orbit around
12:15each other.
12:16Then, an orbit can actually loop between one object and another.
12:21Speeds can get faster and slower.
12:22An orbit doesn't have to be just one regular path.
12:29The universe's creativity defies the imagination.
12:34Travel out beyond Pluto, halfway to the nearest star, and you find these.
12:41Comets, chunks of ice and rock.
12:45They float in vast clouds, frozen remnants from the dawn of our solar system.
12:54Every so often, one falls towards the sun.
12:58They can start a trillion miles out and fall right above the surface of the sun.
13:03So when they're really far away, they're hardly moving at all.
13:06When they're whipping past the sun, they're moving really, really fast.
13:10And so these can be some of the most extreme orbits in the solar system.
13:14They can be so elongated, they're almost a straight line.
13:19Comets travel at up to a million miles an hour.
13:24They're cosmic missiles, guided by gravity and speed.
13:30Comets show us how destructive orbits can be.
13:36Many plunge into the sun, or crash into planets.
13:42If a comet were to hit the Earth, perhaps five, six miles across, watch out.
13:50It would be a planet buster.
13:52It would be an object sufficient to wipe out all life as we know it on the planet.
13:59But most comets miss.
14:02They fly in from deep space and out again on million-year orbits.
14:13But move beyond our solar system, and orbits become even more violent.
14:20Death spirals rip apart entire planets, shred stars, and even tear holes in space.
14:49The universe is unimaginably big, so there should be other Earth-like worlds out there.
14:58Scientists looking for habitable planets thought they would find orbits just like ours.
15:04They were wrong.
15:13We have discovered hundreds of planets outside our solar system, but they're not like Earth
15:19at all.
15:20These are strange, alien worlds with unfamiliar orbits.
15:26What we're finding among extrasolar planets is an incredible diversity of these orbital
15:33shapes and sizes.
15:35Some of the orbits are extremely tight around their host star, the planet going around in
15:39just hours or days.
15:41So we're seeing interactions and shapes and sizes of orbits that are like nothing we ever
15:46imagined.
15:52Some worlds are so hostile, life as we know it would be impossible.
15:59This is WASP-18b.
16:02It's a hot Jupiter, a class of huge planets that closely orbit their stars.
16:11WASP-18b is 50 times closer to its star than we are to the sun.
16:18It's so close, it orbits in less than one day.
16:25If you had said, what's the weirdest, least likely orbit you could possibly imagine, I
16:30would have said, take something like Jupiter and plop it down right next to a star, 5 million
16:35miles away.
16:36And it turns out, I would be totally wrong.
16:39That is an extremely common thing that we see in the universe.
16:42In fact, most of the planets that we're discovering around other stars appear to be in orbits
16:46like that.
16:48This cosmic duel produces incredibly powerful physical effects.
16:54WASP-18b burns at 4,000 degrees.
16:59Thermal hurricanes blast across its surface.
17:03And both star and planet are distorted by vast gravitational forces.
17:09The same forces that cause the tides on Earth.
17:13Everybody's familiar with the idea of tides.
17:16In the course of a day, the level of the oceans get higher and then lower.
17:19Well, that's from the influence of the sun and the moon, from the influence of orbits,
17:23things that are going around us or that we're going around.
17:26If you bring things closer together, tides become more extreme.
17:30Planets can actually get pulled into different shapes.
17:36WASP-18b was formed in a cold region of space, far away from its star.
17:43Over millions of years, it spiraled into its present position.
17:49It's locked in a gravitational battle that can only end one way.
17:57Less than a million years from now, it will be consumed by fire.
18:10The key conclusion you have to draw is, when you see the universe today, it won't be that
18:16way tomorrow.
18:17And it won't be that way the week or the millennium or a billion years later, because of gravity.
18:26Our search for Earth-like planets reveals a destructive universe, from the deadly, missile-like
18:32orbits of comets to the searing paths of hot Jupiters.
18:39There are even planets that don't seem to orbit anything at all.
18:44Scientists have recently detected tiny fluctuations in the light from distant stars.
18:49The only explanation?
18:51A massive object between us and them.
18:56These rogue planets don't orbit a parent star.
19:00They are planetary orphans, all alone in space.
19:06Planets by definition go around stars.
19:09So boy, were we shocked to find rogue planets.
19:13Rogue planets are a contradiction in terms.
19:16Planets without a mother star.
19:20Scientists think every rogue planet did once orbit a star, until gravity hurled them away.
19:29New solar systems are chaotic places.
19:33Planets tug on each other and dramatically change course.
19:38Some planets even spiral out to wander the galaxy alone.
19:45The presence of rogue planets shows us that gravity is not just this attractive force
19:50which binds the solar system together, it can also fling entire planets into outer space.
19:57A recent sky survey suggests our galaxy contains more rogue planets than stars.
20:06We've discovered orbits we didn't even know were possible.
20:12Gravity and motion keep our universe in constant turmoil.
20:17Vast orbiting suns cannibalize each other.
20:22Violent vortexes distort space itself.
20:27And powerful forces flick a star like a spinning top.
20:39Gravity causes chaos on an epic scale.
20:45Hurling planets to their destruction or firing them off into space.
20:52But the cosmic roller coaster gets even more extreme.
20:57Orbits become so violent, they rip chunks out of stars.
21:08This is HM Cancri, a binary star system 16,000 light years from Earth.
21:15They're white dwarfs, small but incredibly dense.
21:20One teaspoon of white dwarf matter can weigh five tons.
21:25The stars are just 50,000 miles apart, five times closer than we are to the moon.
21:33They orbit at more than a million miles an hour.
21:38We have two white dwarfs an infinitesimal distance apart, rotating around each other
21:44in five and a half minutes.
21:46This is a world's record for an astronomical body in space.
21:53The forces are immense.
21:56Gravity rips superheated gas out of one star and slams it into the other.
22:04Scientists believe this orbit is so violent, it warps the fabric of space itself.
22:11In the process, the stars lose energy, falling even closer.
22:18Eventually, they'll collide, creating a supernova.
22:33A supernova is one of the most violent energetic events in the universe today.
22:40You are blowing up a star.
22:44There's no way to describe that kind of energy.
22:48Some supernovae are so powerful, they are second only to the Big Bang itself for energy
22:57and sheer power.
22:59They are so magnificent, they can outshine an entire galaxy of 200 billion stars.
23:09Supernovas can create one of the weirdest objects in the universe, a pulsar.
23:17Pulsars are intensely magnetic stars.
23:20They fire out beams of electromagnetic radiation that sweep across space.
23:26There are few things in the universe more dramatic than a pulsar.
23:29Imagine a ball about 10 miles across, rotating hundreds of times a second.
23:34With a density that's almost unimaginable, one cubic centimeter of this material would
23:39have as much mass as Mount Everest.
23:41You would feel a gravity that is millions, millions of times what you're feeling sitting
23:47on the surface of the Earth.
23:49You wouldn't just be crushed flat by this.
23:52You would be crushed into a paste that is only a few atoms thick.
23:58Anything that orbits a pulsar too closely risks being torn to shreds.
24:06This is the Black Widow Pulsar.
24:10It rips through our galaxy at 600,000 miles an hour.
24:17The shock wave is so vast, our telescopes can't detect it 5,000 light years away.
24:25Traveling alongside it, a brown dwarf, bigger than a planet, smaller than a star.
24:32The pair are locked in an orbital dance of death.
24:36The Black Widow, in some sense, is like a vampire, sucking the lifeblood from this brown
24:42dwarf star, eating away at its hydrogen and helium fuel.
24:49Radiation blasts the brown dwarf's gases into space.
24:56A pulsar just 10 miles wide is destroying an object bigger than Jupiter.
25:03Eventually the brown dwarf will evaporate.
25:08A single pulsar has immense destructive power.
25:17But two pulsars together can change the shape of the universe.
25:22This is the only known double pulsar system in our galaxy.
25:29Orbiting at 700,000 miles an hour, their speed and mass make them spin chaotically.
25:41It's incredible to think of the enormous forces, gravitationally, that these two stars exert
25:47on each other, causing the whole geometry, the architecture of the system to change and
25:52spin around like a top on the table.
25:59The gravity of the heavier pulsar makes the smaller one wobble erratically.
26:05It whips around so violently that the whole star almost tips over, just like a spinning
26:11top.
26:14It can't last forever.
26:1685 million years from now, the two pulsars will merge to form a vast gravitational abyss.
26:29The universe's ultimate monster, a black hole.
26:37A black hole, the most extreme object in the universe.
26:45At its center, the laws of physics break down.
27:07Time comes to an end.
27:10Gravity is infinite.
27:14A black hole is a bottomless pit of gravity caused by the death of a star.
27:18There is nothing in the universe more mysterious than how black holes work.
27:22If you want to talk about extreme orbits and extreme gravity, you're talking black holes.
27:26That is at the top of the list.
27:28Nothing has stronger gravity than a black hole.
27:31It is the mass of something like the sun or more compressed down into a ball that's only
27:37a couple of miles across.
27:40Fifty years ago, black holes were dismissed as science fiction, but not anymore.
27:50Now we see them at the center of galaxies, wandering through outer space.
27:56Black holes, we now know, are central to the evolution of the universe.
28:04We now think there may be a hundred million black holes in our galaxy alone.
28:10An encounter with any of them leads to oblivion.
28:19This is one of the largest and hottest stars in the universe.
28:24It's twenty times more massive than our sun and ten times hotter.
28:33Stars like this never live long, but this one is locked in a diabolic waltz, trapped
28:45in the grip of a black hole.
28:48The gravity here is so powerful, the star orbits at half a million miles an hour.
28:56The black hole sucks the star's outer layers into a vast, swirling disk.
29:05A disk so hot, it blasts out x-rays a million times more powerful than our sun.
29:13This configuration, a star orbiting around a black hole, is extreme, and it's unstable.
29:26First of all, the black hole is eating away at the atmosphere of its companion star.
29:31But the star itself is unstable.
29:34It will one day undergo a supernova and perhaps leave a black hole in its wake.
29:39And then we'll have two black holes rotating around each other, one of the rarest sights
29:45in the universe.
29:47Eventually, these black holes will merge to create a new, larger monster, and the cycle
29:55of destruction will continue.
30:00But this black hole is small.
30:03Other black holes take violence to a whole new level.
30:08In 2011, astronomers witnessed one of the biggest explosions ever recorded.
30:15A flash of radiation brighter than a hundred billion suns.
30:20A gamma-ray burst.
30:24It was a spectacular event.
30:31The burst came from a supermassive black hole at the center of a distant galaxy.
30:41It had been dormant, but something had shocked it back to life.
30:48If you pass by the event horizon, an imaginary sphere surrounding the black hole, that's
30:54the point of no return.
30:57It's like the ultimate Reusch motel.
30:59Everything checks in, nothing checks out.
31:10Several stars were orbiting the black hole at a safe distance.
31:15Then one of them got too close.
31:17The sleeping giant suddenly awoke.
31:21Vortices, gravitational forces, stretched the star to its breaking point, until finally
31:28it was torn apart.
31:31Debris swirled around the black hole, heated to millions of degrees.
31:39Two giant jets of gamma rays blasted into space at the speed of light.
31:47A black hole has torn a star apart, swallowed up half of the material of the star, and ejected
31:54the other half in an event that is among the most violent things we have ever seen in the
31:59history of astronomy.
32:02The event was so violent, we saw it from Earth, three billion light years away.
32:10Black holes can suck in planets, and rip apart stars.
32:17But gravity doesn't always pull things in.
32:22Any high school student knows that gravity sucks, it pulls, it never pushes.
32:26But it's actually more complicated.
32:28That's true when you just have two objects.
32:30But the minute you have more than two objects, strange things can happen, and gravity can
32:35actually push you away.
32:37You can get very close to a body, but if you come in at just the right angle and just the
32:41right speed, instead of colliding together, one object can slingshot the other one away.
32:47Recently, scientists discovered stars hurtling away from our galaxy at incredible speed.
32:56Normal stars don't do this.
33:00So what could accelerate a star to hypervelocity?
33:04The answer was a surprise.
33:07You can only eject stars at these very, very high velocities, so close to 700, 800, 1,000
33:13kilometers a second.
33:14You can only eject these with interactions with a supermassive black hole.
33:19Each hypervelocity star was originally one of a pair of stars orbiting a supermassive
33:26black hole.
33:27When they got too close, gravity pulled them apart.
33:32The black hole catapulted one star out of the galaxy at 2 million miles an hour.
33:38Eventually, the other was sucked in and destroyed.
33:43The interesting thing here is that you can get a complete redistribution of stars.
33:48So you have stars that are in the center of the galaxy and suddenly they're ejected out
33:51into intergalactic space.
33:54And it's out here in deep space that orbits are at their most powerful, smashing entire
34:01galaxies together to create the structure of the universe itself.
34:21Across the universe, extreme gravity is a force of destruction.
34:27The orbits of planets and stars can be chaotic, unpredictable, and violent, but on a truly
34:34cosmic scale, gravity is no longer just a destroyer.
34:43It also creates new worlds.
34:46These are galaxies, giant spinning clusters of stars, gas, and dust, a hundred thousand
34:53light years across.
34:57Galaxies orbit each other in the same way planets orbit stars.
35:02Gravity pulls them together.
35:04Their speed keeps them apart.
35:07But ultimately, gravity always wins.
35:12Entire galaxies smash together.
35:15One of the most spectacular events in the universe is when galaxies collide.
35:19We're talking about hundreds of billions of stars, a hundred thousand light years across,
35:25two of these things slamming into each other.
35:32Collisions between orbiting galaxies take place over millions of years.
35:38Gravity slowly pulls them together.
35:45And you get these two galaxies that merge like two fluids mixing together, and you get
35:51long, tidal tails as they pass through each other, but then gravity brings them back together
35:57again, and in the end, you get a full-fledged, more mature, larger galaxy than you had originally.
36:05On this intergalactic scale, gravity and motion are no longer destructive forces.
36:16Now they trigger the creation of life itself.
36:22You would think a galactic collision would be incredibly destructive, and in one sense
36:26it is, but in another sense it's a very creative force.
36:33When galaxies smash vast gas clouds together, huge shock waves rip through them, squeezing
36:40the gas, then something amazing happens, the birth of countless stars.
36:53It's incredible to think about two galaxies that gravitationally attract each other and
36:58collide.
36:58What could be more destructive? But in fact, there's a power of construction in such mergers,
37:05because as two galaxies come together, the gases are compressed, and sometimes the gases
37:11are compressed so much that you get the birth of stars and the associated planets around
37:17those stars. And so in the titanic collision between two galaxies, you can get the birth
37:23of stars and planets, and perhaps eventually life on those planets.
37:33Sometimes these collisions trigger a chain reaction. Two spiral galaxies in mid-collision,
37:46creating stars and planets. But this time, it's a chain reaction.
37:53There's a difference. Some of these new stars are massive, unstable, and short-lived. They
38:07explode. Each explosion blasts out new shock waves and triggers the birth of even more
38:15stars. Astronomers call this a starburst.
38:23It's the ultimate example of gravity's creative power.
38:29A starburst galaxy is one that is creating stars at a much higher rate than we usually
38:34see in normal galaxies. And so it's amazing that you can have such a beautiful creative
38:39process coming out of something so violent and destructive.
38:47Gravity and motion, the two forces that give birth to every new star, also weave together
38:53the fabric of the universe itself. Our cosmos is not random. It has structure.
39:05The universe is a vast, three-dimensional tapestry. Each of these threads and filaments
39:12contains billions of galaxies. It's the scaffolding that holds everything together. The cosmic
39:21web. When we think about scaffolding of a building,
39:26it's just sitting there static. But in fact, this scaffolding is quite dynamic and quite
39:30amazing because all of the constituents are moving around at very high speeds, crashing
39:35into one another, galaxies, stars, black holes, supernovae, all in this tremendous
39:41cosmic dance. The cosmic web is incomprehensibly vast.
39:48Each thread is full of motion. Galaxies form, orbit, and collide. Countless billions in
39:56a constant stream. Every filament is a galactic freeway with
40:01an endless flow of traffic. Each point of light a galaxy.
40:10It's rush hour, 24-7, and sometimes there's gridlock.
40:17Every billion light years, several filaments join to form a knot.
40:25Whole clusters collide to form some of the largest structures we know of. Superclusters.
40:34This is one of them, Abell 2744. Five orbiting galaxy clusters crashed together
40:44in the single biggest cosmic pileup ever discovered.
40:54Gradually the five clusters merged and fused to form a single giant supercluster six million
41:03light years across. The incredible power of orbits can literally
41:10tie the universe in knots. Structures in the universe have evolved over
41:15billions of years through their orbits and their mutual gravitational attraction, and
41:20they've built up into larger and larger structures, and it's all thanks to these same attractive
41:25forces that bring them together, but can also tear them apart.
41:38Again and again we discover orbits dominating the cosmos.
41:44The atom is the basic unit of chemistry. In the same way the orbit is the basic unit
41:50of the universe itself. If you understand all possible orbits, you
41:55understand the dynamics driving the universe. Orbits have created a cosmos full of richness
42:04and complexity. Orbits are changeable, they're chaotic.
42:09Things that we never thought were possible are in fact possible.
42:12From the smallest scale to the largest scale, it's the gravitational interactions and collisions
42:18that actually make our universe the beautiful place that it is.
42:22And behind it all is a curious paradox. Extreme orbits mean variations, collisions
42:30that seems very destructive, but also extreme orbits mean colliding galaxies, collapsing
42:35dust clouds, the very creation of life as well as destruction.
42:42Orbits are the driving force behind this never-ending cycle of creation and destruction.
42:50They're at the very heart of how the universe works.