- 6/2/2025
In 2009, NASA launched the Kepler space telescope (which has been de-activated in 2018); its mission was to detect the changes in the brightness of distant stars 3,000 light-years away from us. Freeman narrates (that as of 2011) around 300 Earth-like rocky planets orbiting distant non-Sun stars have been discovered by the Kepler Space Telescope.
Sara Seager and William Bains have been studying the exoplanet GJ 1214b, a planet more than 40 light-years away, twice the size of the Earth, and signs of an atmosphere.
Gliese 581d is about 20 light-years away from Earth in the constellation Libra; this planet might harbor "alien life." Its red star Gliese 581 generates half the heat of Earth's Sun.
In 2008, NASA's EPOXI probe sent back images of Earth as our planets would appear to undiscovered alien astronomers. An astro-comb used to reduce "camera shake" to better see planets and stars many light-years away from the Earth.
Thanks for watching. Follow for more videos.
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#season2
#episode9
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Sara Seager and William Bains have been studying the exoplanet GJ 1214b, a planet more than 40 light-years away, twice the size of the Earth, and signs of an atmosphere.
Gliese 581d is about 20 light-years away from Earth in the constellation Libra; this planet might harbor "alien life." Its red star Gliese 581 generates half the heat of Earth's Sun.
In 2008, NASA's EPOXI probe sent back images of Earth as our planets would appear to undiscovered alien astronomers. An astro-comb used to reduce "camera shake" to better see planets and stars many light-years away from the Earth.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#throughthewormhole
#season2
#episode9
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#spacedocumentary
#morganfreeman
#aliens
#whatdoalienslooklike
Category
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LearningTranscript
00:01Across the galaxy lie exotic worlds, some made entirely of water, others stewing with poisonous gas.
00:13What kinds of creatures thrive in these places?
00:18Would they resemble beings on Earth?
00:22Or could life take on new and unexpected forms?
00:26What do aliens look like?
00:35Space, time, life itself.
00:42The secrets of the cosmos lie through the wormhole.
00:57They're out there. We can see them. For the first time in human history, we know the universe is filled with planets stranger than we could ever have imagined.
01:11Planets that might be home to extraterrestrial life.
01:15But what will these creatures look like?
01:19We're all products of our environment.
01:22If I was born on a planet with carbon dioxide, air, and gravity three times weaker than the Earth's, I might look like...
01:30This. On a planet with five times more gravity than Earth, and a star that constantly blasted it with solar storms, I might look like this.
01:43We can't know the face of an alien until we're staring at it. But like detectives on the hunt for an unknown suspect, biologists and planetary scientists are beginning to piece the puzzle together.
01:59Some of the clues are out there. But a lot of them are right here.
02:06To get home from school every day, I had to cut through the yard of a scary old house.
02:14I never saw anyone come in or out of it. But someone, or something, lived there. I could only imagine who or what it might be.
02:33Harvard paleontologist Andrew Knoll has spent his life studying creatures beyond our wildest imaginations.
02:47One of the things you learn when you go through a museum like this is that not only is it hard to imagine what life might be on another planet,
02:57but it's hard to imagine some of the life that has existed on this planet.
03:00Who would guess that there were things like dinosaurs in the absence of their bones?
03:06For the past eight years, Andrew has served as mission biologist on NASA's Mars rovers.
03:12It's a role he's uniquely suited for because of his expertise in the vast array of life on Earth,
03:19and his ability to read the history of a planet from its rocks.
03:23There's a tendency for us to think about the Earth in terms of the things we see around us today.
03:28But the one thing that the geologic record tells us is that there have been a series of Earths,
03:33and that the Earth that we see around us, all the plants and the animals and the composition of the atmosphere,
03:39are really an end member, the end state of a long series of transitions that have happened over four billion years.
03:45For example, this rock, which formed about three and a half billion years ago, is full of iron minerals,
03:52which means that iron had to be able to be transported through seawater, and it can only do that in seawater that contains no oxygen.
04:01The discovery of rocks like this all over Earth shows that for nearly the first four billion years of its existence,
04:12our atmosphere had almost no oxygen.
04:16That Earth would have been toxic to us.
04:18Now there are other things that are sort of unexpected when we actually look at deep Earth history.
04:25This rock was actually deposited by glacial ice about 635 million years ago.
04:31There are rocks like this that formed literally all over the world at this time,
04:35and it shows us that there was glacial ice at sea level, at the equator.
04:42In fact, much of the Earth, perhaps most of the Earth, was covered with ice, sometimes called a snowball Earth.
04:49These various Earths, hotter, colder, with more or less oxygen, were essentially alien worlds.
04:57So for Andrew, the best place to discover what aliens might look like is in our own fossil records.
05:06These are trilobites.
05:08Now when you look at this, you'll see things that are familiar.
05:11There is a jointed, segmented body.
05:15There are jointed, segmented legs.
05:17And you might say, well, that looks like a shrimp or an insect, and that's right.
05:21Biologists call these repeated similarities of life forms over Earth's history
05:27convergence.
05:29One shape that works well gets repeated over and over again.
05:35This giant sea creature looks like a whale, but it is actually an extinct lizard.
05:44Repeatedly over the last 250 million years, vertebrate animals on land have reinvaded the oceans.
05:52And every time they've done so, they've given rise to these giant sea monsters.
05:55Chronosaurus, 70 million years ago, there were lizards in the sea that were equally large.
06:02In our own lifetimes, there's whales.
06:08If Earth in the past has been as alien as planets orbiting other stars,
06:14then aliens you've seen in movies, lizards with two eyes, two arms, and two legs,
06:19might be pretty close to the mark.
06:27I must admit, I watch a lot of old monster movies from the 1950s,
06:32specifically looking at the physics and saying, no, no, no, that's not going to work.
06:36Or, oh, that's really good.
06:38University of Chicago professor Michael LaBarbera is an expert in biomechanics.
06:48He's trying to predict how aliens will walk, fly, and swim by searching for the basic rule of how animals move.
06:56You could call it the lowest common denominator of locomotion.
07:04Things like horseshoe crabs were crawling out on the beach and laying their eggs when pterodactyls were flying in the sky.
07:12One of the features that we share with these animals is a lever-type skeleton.
07:17I have levers in my hands, that's what allows me to do that.
07:22I have levers in my elbows, in my shoulders.
07:26The basic idea is to use a lever that has a high mechanical advantage that delivers a lot of the muscle force to the output side of the lever.
07:38Successful designs like jointed limbs and heart skeletons show up again and again in the fossil record.
07:44We see them all around us today, and Michael expects to see them on other worlds, too.
07:51And it doesn't matter whether the skeleton is made out of hydroxyapatite, like our bones,
07:57made out of chitin, like this animal, or carbon nanotubes.
08:01The principle is easy enough for natural selection to stumble across that it will evolve over and over again.
08:08On this planet, it has evolved independently at least half a dozen different times.
08:12And there's every reason to believe they will be just as common in any other ecosystem on any other planet.
08:19A torso with jointed limbs acting as levers.
08:23It's a good basic anatomy of an alien.
08:26But can we get closer to imagining their true form?
08:29In the 19th century, Charles Darwin kept a series of notebooks chronicling how the shapes of animals had evolved to adapt to the environments they live in.
08:43What would a book of life on other planets look like?
08:47What mind-bending anatomical adaptations might develop in alien surroundings?
08:54The environment shapes creatures depending on their ecology, density of the atmosphere.
09:03Whether or not you have a world covering ocean is going to make a big difference in the history and thus in the shape of the organisms.
09:10Which is why, to know what aliens look like, we must learn more about the planets they live on.
09:20Until very recently, we had no proof other planets existed, let alone any idea what their landscapes or atmospheres might be like.
09:28But now, for the first time in human history, we can see worlds far outside our solar system.
09:38And now that we know where ETs could live, we're getting closer to revealing their hidden faces.
09:47If we want to know what aliens look like, we first have to know something about the places they live.
09:53Until recently, this was impossible.
09:57Our telescopes could only see stars, not the planets that orbit them.
10:02Today, alien hunters have a dedicated research ship floating 20 million miles from Earth.
10:09And it's discovering new worlds by the thousand.
10:13Three, two, engine start, one, zero, and liftoff of the Delta II rocket with Kepler.
10:26In 2009, NASA launched its latest space telescope, Kepler.
10:33It's designed not to take pictures, but to detect the tiniest changes in the brightness of distant stars.
10:39Its target area is a patch of our arm of the Milky Way, stretching out 3,000 light years away from us.
10:48Harvard professor Dimitar Sassilov is one of Kepler's lead scientists.
10:53The beauty of how the Kepler telescope discovers planets as small as the Earth is that the method, which we call the transdink method, is very easy to understand.
11:02So the planet is passing on its orbit in front of the star.
11:08Its shadow causes that light to dip just a little bit.
11:12And that's how we know there is a planet there.
11:15By the time Kepler is done with its mission, Dimitar expects it will have found around 100 planets the size of Earth.
11:22But the vast majority of planets to this finding have almost nothing in common with our world.
11:30Kepler already has a treasure chest of weird planets, if you will, very interesting, diverse planets.
11:36So we have Kepler-10, which is as hard as iron.
11:40Then we have two or three planets in the Kepler-11 system of six, and one or two of them are water planets, endless ocean.
11:48Then we have planets almost the density of a beach ball or styrofoam.
11:58Perhaps the most intriguing of Kepler's discoveries are around 300 supersized versions of Earth.
12:06Planets made of rock, but up to five times as heavy.
12:19If anyone can imagine the landscapes where aliens might jog, swim, or glide, it's Diana Valencia.
12:29Part-time triathlete, she's one of the first geologists to break ground on these super-Earths.
12:36I do not have a hammer. I do not break up rocks.
12:41What I do is I do numerical models to understand how the Earth works and use that to understand how bigger Earths and similar planets work as well.
12:51To understand whether super-Earths could harbor life, Diana is zeroing in on the basic geological engine that powers rocky planets, plate tectonics.
13:01The movement of a planet's hard outer trust is driven by a hot and viscous layer of semi-molten rock below it, moving much like a jar of bubbling honey.
13:14This experiment here shows us in broad lines what happens.
13:20The mantle is a very viscous fluid, and both fluids are very sensitive to temperature.
13:26So as we turn this heat up to simulate Earth's engine, you will start seeing motion underneath the surface.
13:35Now you see the overturn, now you start seeing things that are moving all sorts of directions, it's not just moving up.
13:45As heat rises, it forms convective cells in the mantle, which cause the plates on the surface to shift.
13:54These shifts trigger volcanic eruptions and earthquakes, events we associate more with death than life.
14:01But that's just the short-term view.
14:08From Diana's geological perspective, this cycling of material from the inside of our planet to the atmosphere has been vital to the evolution of life.
14:17Thanks to this process, the surface temperature of the Earth has not swung very much, and it has been around that of liquid water for over billions of years.
14:30Super-Earths are bigger and therefore hotter on the inside, and when you turn up the heat, plate tectonics kicks into a higher gear.
14:46That may mean more volcanoes and more earthquakes, but also are planted with a much more stable temperature.
14:56On Super-Earths, because convection would be much faster, this cycle could respond much quicker, perhaps an order of magnitude quicker.
15:07And then we can speculate that that has enabled the evolution of complex life.
15:11Think about how a Super-Earth would have dealt with the impact of the meteorite that wiped out the dinosaurs.
15:17On Earth, this event triggered an extended global winter that spelled the demise of those cold-blooded giants.
15:27But on a bigger planet, better able to control its temperature, dinosaurs might survive and have the chance to evolve bigger brains.
15:38However, there is one major downside to living on a giant version of Earth.
15:45The core of our world is a spinning ball of liquid metal generating a powerful magnetic field.
15:53That field deflects a torrent of dangerous radiation from the sun and forms a protective cocoon for all life here.
16:02Deanna's models predict that Super-Earths may not have these force fields.
16:09It's very possible that these planets do not have a molten core because their interiors are under so much pressure.
16:15So if you are a creature in a planet that doesn't have a geomagnetic field, you are being bombarded by high energy particles.
16:23And those are interacting with their cells, causing mutations probably.
16:27So you have to be clever as an organism to adapt to those conditions.
16:33What kind of alien could survive on a radiation-soaked Super-Earth?
16:39It would need a protective shell, perhaps laced with heavy metals like lead.
16:43It would have powerful limbs and sharp claws to let it burrow under the ground during heavy radiation bursts.
16:52Most important, it would need effective genetic repair mechanisms to fix the inevitable radiation damage to its cells.
17:01Pure fantasy?
17:03Maybe not.
17:04If you are interested in diverse civilizations, what can would go through the root of the animal,
17:05it would only occur but still would beunto.
17:07It would really appreciate that actually you can also extend as lives.
17:08If you are looking after the entity of a witch that is a colossal, and could you see a superinfl Ji calcium and a dorous magnet.
17:14It forms a gold希望 astronauts for a few years of time.
17:16Similar life form, albeit much smaller created called water bears, survive in boiling hot, radiation blasted regions.
17:18Inhabitants of rocky super-Earths might look surprisingly familiar.
17:22But imagine a world where there is no rock, and where creatures living in the ocean also fly through the sky.
17:34On Earth, evolution has produced countless variations on life.
17:42Animals that glide through the water and soar through the sky.
17:46Beings that slither, crawl, walk, and run.
17:52If life on other worlds follows the evolutionary pattern of life here,
17:57what other mind-bending creatures might arise?
18:00Okay, so you've got the planet, you've got the atmosphere.
18:06Exaggerated, not to scale.
18:07Yeah.
18:08At MIT in Cambridge, astrophysicist Sarah Seda and biochemist William Baines
18:15are beginning to imagine what these distant worlds will be like.
18:19The atmosphere is going to come from somewhere,
18:20so you're going to have volcanoes producing atmosphere.
18:24They're trying to predict how a planet's size and composition
18:28will shape its biosphere.
18:31Before the discovery of exoplanets,
18:33people thought that all planetary systems would be like our solar system.
18:37And since that time, discoveries of exoplanets and exoplanetary systems
18:41have surprised us over and over and over again.
18:44So what has changed?
18:45Everything has changed.
18:47Most science fiction assumes that aliens are going to be walking around,
18:51they're going to be breathing air.
18:52You know, they land on a starship and they share dinner with a captain.
18:55You look at some of the planetary environments out there
18:59and that is not going to happen.
19:01It's going to be very different.
19:04Recently, Sarah and William have been studying GJ 1214b,
19:10a planet about 40 light years away that's more than twice the size of Earth
19:14and show signs of having an atmosphere.
19:18Together, they are working to discover what it might be like
19:22to descend beneath the clouds of 1214b.
19:26Now this planet, we're not totally sure what it's made of,
19:29but it could be a water planet with a seam atmosphere.
19:32And depending on the temperature of the planet,
19:35the clean division between liquid water and air,
19:38with water vapor in it, may not exist.
19:40What sort of life could possibly emerge on a boiling hot steam world?
19:49So on Earth, an environment like this,
19:51with boiling water and steam, is inimicable to nearly all life.
19:55But we're trying to imagine an alien world
19:57in which this is the normal environment.
19:59And we can now start to model a planet
20:01that has a huge ocean covering it
20:04and nevertheless is incredibly hot.
20:06And that leads us to think about,
20:08could there be life in the ocean?
20:10Can the chemistry work?
20:12And if it can, what would it look like?
20:15A molecule like DNA wouldn't survive these conditions.
20:22But William believes more heat-tolerant genetic material
20:25would likely evolve.
20:28And he's beginning to imagine what entries might fill the pages
20:31of a book of life for GJ-1214b.
20:36The atmosphere of this planet would be mostly water.
20:39It would be steam.
20:41It would be very dense.
20:43It would be very hot.
20:44So as you go down through it,
20:46you'll find drifting plants, flying plant life,
20:50and a whole range of organisms that eats that plant life.
20:54Organisms would be sort of flying fish or swimming birds,
20:58depending on how you look at it.
20:59So they'll be able to actually fly through or swim through this zone
21:03almost as if it was ocean.
21:08Earth's oceans gave rise to creatures of all sizes.
21:12But the kings of the deep are the giant filter feeders, whales.
21:191214b could have them too.
21:22So the organism we're imagining here works in a very similar way.
21:25It might have a very different shape.
21:27But it moves through the ocean
21:30and then can move up into this interfacial zone.
21:33But it can spend much longer in the interfacial zone
21:35and move much further up into it
21:38than, say, a whale breaching,
21:39because the density is greater.
21:42This aquatic world is a vision
21:44of what Earth might have been like
21:46if it were larger and wetter.
21:49Humans couldn't survive here,
21:51but could life find a way?
21:54We don't know.
21:56Yet.
21:57There are many important things in science,
21:59and one of the most important ones is imagination.
22:02So what is so fascinating so far,
22:05in exoplanets, anything is possible
22:07within the laws of physics and chemistry,
22:09and anything we imagine will exist somewhere.
22:11Follow the water?
22:14There you'll find life.
22:17That's what the astrobiologists like to say.
22:21But what if there is no water?
22:24What about planets enveloped in toxic air,
22:26where the building blocks of life
22:28are completely different from our own?
22:30Could they also be alive?
22:37Life is tenacious.
22:41Everywhere on Earth,
22:43from the coldest depths of the sea
22:45to the boiling fissues of volcanoes,
22:48living things find a way to thrive.
22:51But the conditions on alien planets
22:53could be even more extreme.
22:56We're discovering worlds of fire and ice,
23:00worlds of permanent night,
23:03worlds where hurricanes are constant and global.
23:08What kind of alien could live in these hellish places?
23:15Gliese 581d floats 20 light years away from Earth
23:19in the constellation Libra.
23:23It's one of the small group of planets we have spotted
23:26that might harbor alien life.
23:30Its red star burns with only half the heat of our sun.
23:35But because the planet spins very slowly,
23:38one side is much hotter than the other.
23:42And its rocky surface is blasted by constant wind.
23:47A great place to fly a kite.
23:50Biomechanics expert Michael LaBavra believes the thick atmosphere
24:00on Gliese 581d would shroud the surface in darkness.
24:06So, life would have to climb up in search of light.
24:10He imagines kite-shaped plants
24:13that rise above the storm clouds
24:15to get their daily dose of solar energy.
24:17These kite plants have to be able to get up
24:21into the higher regions of the atmosphere
24:23in order to get enough light.
24:25And the way they do that
24:26is to utilize the shear in the atmosphere.
24:30Michael's kite requires two forces
24:33to stay aloft and stable.
24:35Wind to lift the kite
24:36and an anchor to keep it from blowing ever upward.
24:40The alien kite plant works much the same way.
24:45So, what we've posited for this particular plant
24:48is a lifting surface on one end of the string
24:51and at the other end of the string
24:53something that functions like a parachute
24:56that produces a drag force
24:59and because the wind changes with altitude
25:01they're moving at different speeds.
25:04You then get a lift force that keeps the kite up
25:07and it pulls on the drag chute
25:09but that keeps the tension on the string
25:11and the whole system is stable.
25:14Sounds unlikely?
25:16Michael doesn't think so.
25:18Years of studying organisms on Earth has convinced him
25:22that life will evolve to suit any environment.
25:26Evolution goes through very strange pathways
25:29to get to an end point.
25:31This particular one,
25:32we don't have an example here on Earth
25:35but on the planet posited here
25:39with low solar input to the ground level
25:42and a high wind shear,
25:43it's entirely possible that it could function.
25:47Closer to the surface of Glees 581D,
25:50the once bright sunlight
25:52dims as this exoplanet enters
25:54a permanent hazy twilight.
25:57The atmosphere is thick and murky
25:59but warm enough to sustain life.
26:02In fact, Michael LaBarbera speculates
26:05that it could host a thriving ecosystem
26:07of hunters and prey.
26:10What kind of predator would evolve here?
26:14An aerial hunter,
26:15thin-winged and bat-like
26:17but able to soar and glide for days
26:20like an albatross.
26:22A batatross?
26:25Now, this animal,
26:27because the atmosphere is relatively opaque,
26:29has to be able to travel long distances
26:31at minimal cost in order to find their prey.
26:34It's got long wings.
26:36It's got relatively narrow wings
26:38because they are more efficient.
26:40It has a big wing area relative to its body.
26:44On Earth, albatrosses use a technique called
26:47dynamic soaring
26:49to travel thousands of miles
26:51while barely flapping their wings.
26:54Gliding in long loops,
26:56the batatross would also conserve energy
26:59by letting air currents carry it along.
27:02The animal actually covers many times
27:06the distance in these loops
27:08that it's covering on the ground,
27:10but it doesn't matter.
27:11It doesn't cost it anything.
27:13It's free.
27:14It's energy that's supplied by the environment,
27:17not by the organism.
27:18But how, in a world of permanent twilight,
27:22does this hunter find its prey?
27:25In the absence of light,
27:27there's got to be some other way of locating prey.
27:29One way is just to sit and listen
27:31and wait for your prey to make noise.
27:33The other way is for you to make noise
27:35and listen for echoes,
27:37what we call sonar,
27:38so that you send a sound beam out
27:40and you wait for a reflection.
27:41I can get a lot of information
27:43from the response of the ball as it comes back.
27:48So the delay between when I throw
27:50and when it returns
27:51tells me how far away the object is.
27:54If it comes back faster than I threw it out,
27:57then the object is coming towards me.
27:59If it's going in the other direction,
28:01it will come back slower.
28:03If you're looking for prey,
28:05this is a wonderful idea,
28:06unless your prey, of course,
28:08can detect the sound.
28:09The batatross would be an effective killer,
28:13so its prey would need
28:15to develop effective defenses.
28:18William Baines imagines an animal
28:20similar to the hard-shelled marine life
28:23that evolved on Earth
28:24hundreds of millions of years ago.
28:27The nautilus is a natural prey for the hunters,
28:29and they'll have three defense mechanisms.
28:31First is, of course, they have a shell.
28:33The second is if you're being hunted by sonar,
28:36then you develop very good ears.
28:37You can hear sonar
28:38and when you hear the ping of a sonar,
28:41you run for it.
28:42And it has a jet propulsion system
28:44that can squirt itself forward in emergencies.
28:47These guys will be able to jet themselves
28:49through the atmosphere
28:50in short bursts, moving very quickly.
28:53So at the last minute,
28:54they'll jet to one side
28:55and escape the need.
28:58But even with these defenses,
29:00the batatross would be a fearsome opponent,
29:02and the nautilus won't always get away.
29:08It's life on the edge.
29:09There always is a top predator.
29:12It's the rarest animal,
29:13but it's not the guy you want to meet in a dark alley.
29:17Brutal conditions bring brutal life forms.
29:20Here on Earth,
29:22over hundreds of millions of years,
29:24billions of different creatures
29:25competed for survival.
29:27But eventually,
29:28a special mutation enabled one animal
29:31to become the planet's top predator.
29:34That mutation
29:35was the human brain.
29:38Somewhere out in space,
29:40alien evolution should have created beings
29:43at least as smart as we are.
29:45What do intelligent extraterrestrials look like?
29:50This man thinks he knows.
29:53And the answer
29:53could be bad news for life on Earth.
30:00With each new world we discover,
30:04we come one step closer
30:05to finding evidence of life beyond Earth.
30:09And perhaps to fulfilling our dreams
30:12of communicating with alien life forms.
30:15But if that day ever comes,
30:18we'd better brace ourselves for a shock.
30:20Because many scientists think
30:22they may not look like living beings at all.
30:28For the past 50 years,
30:30the search for extraterrestrial intelligence, SETI,
30:34has attempted to capture any glimmer
30:37of communication from alien worlds.
30:40For Seth Shostak, SETI's senior astronomer,
30:44it's a search for our distant cosmic image.
30:48For a species with a brain at least as smart as ours.
30:52When it comes to intelligent life,
30:54we haven't found it.
30:55So there are people on all sides of the issue.
30:57But the one thing that can convince you,
30:59I think can convince anybody,
31:01is that even if you think
31:02the processes that could lead to life,
31:04lead to intelligent life,
31:06are not going to occur very often,
31:08there's so many chances for it to happen in the cosmos.
31:11It would be miraculous
31:13if we were the only world with intelligent beings.
31:16Humans aren't the largest or the fastest
31:19or the most agile animals on Earth.
31:23But we are the smartest.
31:26Our brains have put us on top.
31:29There is, however, plenty of room for improvement.
31:32There's an unavoidable tendency
31:33to think that we're kind of the crown of creation.
31:36This is it, you know,
31:37four billion years of evolution
31:39from the beginnings of life to us.
31:41You know, I think if you ask the dinosaurs the same question,
31:44do you think you're the crown of creation?
31:45I bet they would have said yes
31:46if they could have talked.
31:48This is it.
31:49This is the end of evolution.
31:50Well, they were wrong.
31:51And it would be wrong for us
31:52to think we're the end of evolution too, obviously.
31:55So where will evolution take us next?
31:57And where is it likely
31:59to have taken alien civilizations?
32:02Seth thinks we need to look at our computers for the answer.
32:07Since the 1970s,
32:08when floppy disks were the gold standard,
32:11the speed at which computers process instructions
32:14has increased more than 100,000 times.
32:17Today, for $1,000,
32:19you can buy a computer that has the,
32:21if you will, the thinking capability,
32:24or at least the computational capability of a lizard.
32:26Not so interesting.
32:28But by 2020 or 2025,
32:30$1,000 will buy you a laptop
32:32that has the same computational power as a human brain.
32:38The IQs of artificial brains
32:40are going from zero to 200
32:42in the historic blink of an eye.
32:45How would a similar trajectory play out on a planet
32:49that is a mere 500 years ahead of us?
32:53The interesting thing about artificial intelligence,
32:56of course, is its pace of evolution.
32:58I mean, we're stuck with Darwinian evolution,
33:00but the machines wouldn't be.
33:01What it means is that if you develop a thinking machine,
33:04it's going to improve itself very, very quickly.
33:07In 1948,
33:09mathematician John von Neumann
33:11imagined a machine so intelligent
33:13it could make copies of itself.
33:17Each copy would improve on the previous model,
33:19much as nature continually improves on its designs.
33:23But this machine's evolution
33:25would take place much faster
33:26than biological evolution.
33:29Today, von Neumann machines exist
33:32in crude forms.
33:34On a planet more advanced than our own,
33:37could they be the most intelligent life form,
33:40the dominant life form?
33:41Will our first contact be with a race
33:45of superintelligent machines?
33:48You're only going to hear from a species
33:49that's at least as clever as we are.
33:52So what are the odds that they're within 50 or 100 years
33:54of our level of development?
33:56Pretty slim.
33:57They're likely to be thousands, millions,
33:59maybe even more years ahead of us.
34:02So if you think about that for a moment,
34:03you recognize that if we do find a signal,
34:06the odds are pretty good
34:07that that signal's coming from artificial intelligence,
34:10not some soft, squishy little gray guy
34:12with big eyeballs.
34:14On some distant planet,
34:15the book of life may no longer contain
34:17any biological forms.
34:20And if mechanical life has enough power,
34:23there is no limit to how large
34:25or complex it can become.
34:28Or maybe they've reorganized themselves
34:29so that they can share the thinking load
34:32amongst many members of the species,
34:34like distributed processing with computers.
34:36I mean, why should the aliens be content
34:39to be stuck with a kind of intelligence
34:41that can fit inside their heads?
34:47Alien evolution could produce
34:49a living machine planet
34:51throbbing with the combined intelligence
34:53of billions of alien minds.
34:56If such advanced life exists,
34:58how would we spot it?
35:00And should we even want to?
35:02Will aliens welcome us as friends
35:05or view us as threats
35:07or perhaps see Earth
35:08as a world to conquer?
35:11We wonder what aliens look like,
35:13but what do we look like to them?
35:16This woman has put herself
35:17inside their heads,
35:19and she believes
35:21she has the answer.
35:26As long as humans have looked up
35:28at the night sky,
35:30we have wondered whether something
35:32or someone out there
35:34is looking back.
35:36We want to know
35:37what aliens look like.
35:39What do we look like to aliens?
35:42If there is intelligent life out there,
35:46does the Earth look like
35:48a place worth visiting?
35:49May 29th, 2008.
35:5431 million miles out in space,
35:57the eyes of a technologically advanced race
36:00scan our planet
36:01for the signatures of life.
36:03Not aliens,
36:05but this was still a close encounter
36:07of an extraordinary kind.
36:09It was the NASA space probe,
36:12Epoxy.
36:13Set out to get close-ups of comets,
36:16Epoxy briefly turned its lens
36:17back to its mother planet,
36:19and for the first time,
36:21we saw the Earth
36:22as aliens might see us.
36:34Astrophysicist Sarah Seeger
36:35was part of the Epoxy team.
36:38Sarah normally studies exoplanets,
36:40looking for clues
36:41about alien atmospheres
36:42and ecosystems.
36:44The Epoxy probe
36:45gave her the chance
36:46to find out
36:47what Earth might look like
36:49to an alien astronomer.
36:51If you pretend you know
36:52nothing about Earth,
36:52what could you learn about Earth?
36:54An alien would be able
36:55to pick out Earth's rotation rate.
36:58They would be able to notice
36:59that we have surfaces
37:00of very different reflectivity,
37:01that's cloud, land, and ocean.
37:03And they could also see
37:04that we have weather.
37:05They would see variability
37:06that isn't related
37:07to the rotation rate of Earth.
37:09The second thing Epoxy did
37:11was to look at a spectrum of Earth,
37:12that is, take the white light
37:13and split it up
37:14into the different colors,
37:15and to check and see
37:16if any of those colors
37:17were missing.
37:18We call that a spectrum.
37:21The spectrum of Earth's colors
37:23are like a flag
37:24announcing the presence
37:25of life on our planet.
37:27The blue of the oceans,
37:29the white of the clouds,
37:30the green of the land
37:31are all markers
37:33of an active ecosystem.
37:35If an alien is looking back
37:37at us from far away,
37:38the aliens would see
37:39that we have oxygen
37:40in the atmosphere.
37:41In fact, our atmosphere
37:42has 20% oxygen by volume.
37:44What's so fascinating
37:45is that without life,
37:46our Earth would have
37:48basically 10 billion times
37:49less oxygen.
37:51So oxygen would be
37:51essentially non-existent on Earth.
37:53And oxygen on Earth
37:54is created by life.
37:55So those aliens would know
37:56that oxygen in such large quantities
37:58should not be in our atmosphere
37:59unless it is being continually
38:01produced by something.
38:02And nothing that we know of
38:03in geophysics
38:03can produce so much oxygen.
38:06And that's why
38:06we attribute it to life.
38:07Aliens might see
38:10that our planet supports life,
38:12but they might not see
38:14that Earth
38:15is technologically advanced.
38:17They would have to look carefully
38:18to detect things
38:19like atmospheric pollution
38:21or the heat signatures
38:23of our cities.
38:25Reading the colors of our world
38:27and the millions of others
38:28like it out in the universe
38:30would be easy
38:31for an advanced alien civilization.
38:34Unfortunately,
38:34it is not yet easy for us.
38:38Spotting exoplanets
38:39pushes the limits
38:40of current technology.
38:42If we want to see colors,
38:45we need a new set of tools.
38:49Astrophysicist Demetra Sassilov
38:50wants to do something about that.
38:53These are little round planets.
38:57I'm going to just drop a few on
38:59to show transiting planets.
39:02I guess there's two transiting planets.
39:03Demetra's wife, Sheila,
39:07paints scenes of deep space
39:09inspired by his research
39:11on the Kepler planet-finding probe.
39:13This is the kind of thing
39:16we want to discover with Kepler.
39:18A transiting planet
39:19and there is a moon around it.
39:21That will be great.
39:23So there it is.
39:24That's the planet
39:25with life on it right here.
39:29We have a big problem.
39:31This challenge relates
39:33to our inability
39:34to measure the colors
39:35of the star or the planets
39:37separately to very high precision.
39:39And the challenge is
39:41about a factor of 10 to 100
39:43beyond what current technology works.
39:46The biggest barrier we have
39:49to seeing the colors of other planets
39:51is something every photographer
39:52has run into.
39:54Camera shake.
39:56If you take a picture in the dark,
39:58you need as much light as possible,
40:00which means you can't move the camera
40:03or you'll get a blurry image.
40:06Earth-like planets are so small
40:08and so far away
40:09that their images only fill
40:11one thousandth of a single pixel
40:13of a digital camera.
40:14If that pixel moves even slightly,
40:18the camera shake will ruin the picture.
40:22But how can you possibly keep
40:24one pixel perfectly still
40:25over the days and years it takes
40:27to track an object in distant space?
40:31Dimitar's solution is the astrocombe.
40:34It uses lasers to keep
40:36a telescope's camera sensor
40:38precisely calibrated
40:39over a period of decades.
40:41The astrocombe that you see here
40:44is the technological breakthrough
40:46which was needed
40:47to bridge that gap.
40:50When we see the true colors
40:52of other worlds,
40:54we will know where and how
40:56life is distributed
40:57across the universe.
41:00And the next phase
41:01of our quest for alien life
41:03will begin.
41:05Where will it take us?
41:07What exciting new worlds
41:09will we see?
41:11What new and unexpected creatures
41:13might live on them?
41:16Biologists think that life
41:17out there might look Earth-like.
41:20But it won't look human.
41:23With so many planets out there,
41:25so many chances of life,
41:27we could have human-like relatives
41:29on a faraway Earth.
41:31Creatures like us,
41:33perhaps as anxious as we are
41:34to know if they are alone
41:35in the universe.
41:36It is clear that we are
41:45in a new age of exploration
41:47and discovery.
41:48It hasn't been for 500 years
41:50that people have tried
41:52to discover planets
41:53around other stars.
41:54Now we have them.
41:55We have much more to explore,
41:58and the best is yet to come.
41:591,000 years from now,
42:01when people look back
42:03at our generation
42:04and ask,
42:04what are the biggest accomplishments?
42:06I like to think of these people
42:08as making interstellar journeys
42:09and looking back and thinking
42:11we were the ones
42:11who started it all.
42:14What do aliens look like?
42:17What are the limits
42:18of our imagination?
42:20The true face of an alien
42:22will probably defy
42:23our scientific speculations.
42:25But our efforts won't be wasted,
42:28even if we do get
42:29all the details wrong.
42:32Our eternal intrigue
42:34about alien life
42:35and our persistent fear of it
42:38both rise from the same source.
42:41The quest to understand
42:42our place in the family
42:45of life forms
42:45that populate the cosmos.
42:48Know that,
42:49and we'll know
42:51the destiny of humankind.
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