For decades, researchers have been scouring the universe for signals from extraterrestrials. New discoveries reveal mysterious fast radio bursts from space that may be the key to confirming life in the cosmos.
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LearningTranscript
00:03Throughout human history, we've looked out from our planet and wondered, are we alone?
00:15Today, we could be close to finding an answer.
00:20Scientists from across the globe are scouring the universe for signs of extraterrestrial intelligence.
00:30Some scientists believe advanced aliens really could be out there.
00:36About 10,000 detectable civilizations at present in our galaxy, the Milky Way.
00:46And yet, no solid evidence of their existence has ever been found.
00:54But now, all that could be about to change.
01:20The universe is thought to contain 700 million trillion rocky planets like our own.
01:30Countless worlds, other intelligent beings might call home.
01:40But after more than 50 years of searching, we've yet to find them.
01:47The deafening lack of any communication from extraterrestrials has become known as the Great Silence.
01:59Oh, I believe very strongly that they are out there.
02:03The numbers support that.
02:04There's so many stars in the universe.
02:07Numbers that are so large, they make no sense to us.
02:11We can be very, very wrong, and yet there will be many, many detectable civilizations.
02:38We met in Arecibo in Puerto Rico.
02:41There's a large radio telescope there.
02:43And I used to work at the observatory as a staff scientist.
02:46And you were a grad student at Cornell.
02:49They used to send their students down from Cornell.
02:51So, yeah, we met at the observatory in the control room.
02:58Husband and wife Duncan Lorimer and Maura McLaughlin share a passion for astronomy.
03:04We work here in Morgantown in the Department of Physics and Astronomy.
03:10We're next-door neighbors, aren't we?
03:11Yeah, so our offices are right next door.
03:14And it's typically really useful.
03:16We can just, you know, pop in and out.
03:18So it saves us a lot of time.
03:20I'll see you then.
03:20All right then.
03:21Have a good day.
03:21You too.
03:24Occasionally we have disputes.
03:25I'm in control of the temperature in both offices.
03:28And so I like it really warm, and Duncan likes it a lot colder.
03:33So we have occasional arguments, but generally it's really useful being right next to each other.
03:37Sometimes you'll bang your feet on the wall, and I'll have to tell you to stop.
03:41But generally it's really nice.
03:43Yeah, it's good.
03:44We like it.
03:47In the summer of 2006, Duncan and Maura began a project searching through historical data from the park's radio telescope.
03:56So we'd just arrived at West Virginia University, and we wanted to find some data that already existed so we
04:03could get working on a project straight away.
04:05So we kind of like bandied around some ideas for good projects.
04:08And one of the things we thought of was reanalyzing the data from an old survey taken like in the
04:15late 1990s of the small Magellana cloud and the large Magellana cloud to look for pulsars that had been missed
04:22before.
04:25The project involved painstakingly searching hundreds of data points, work Duncan delegated to a student.
04:33Every week my student would come to me with the results of his analysis from the previous week, and sometimes
04:40those would be known pulsars, sometimes we'd see sources of interference or just noise.
04:46But one week, I remember it very clearly, he came to me and showed me this plot with a signal
04:53that was so bright and apparently so far away that it was completely unlike anything we'd ever seen before.
04:59So this is the plot that my student David brought to me, and you can see straight away this is
05:06the pulse that he found, this big dark feature here.
05:09What you're looking at is a graph of telescope time along the horizontal axis, so this is almost two hours
05:14of observation here.
05:16And on the vertical axis is basically distance, and you can see the background of noise from the telescope and
05:22the sky, these little dots here.
05:24So this feature really stands out because it's so bright and so far up the plot here, which indicates that
05:32it's a bright source that's very, very far away.
05:35Quite frankly, it was unlike anything I'd ever seen before, yet it had all the hallmarks of a signal that
05:41was coming from deep space.
05:47The signal, or fast radio burst Duncan had discovered, became affectionately known as the Lorimer burst.
05:57When people started calling it the Lorimer burst, at first I kind of just chuckled because it seemed just so
06:05funny to have something actually named after a dunk.
06:08And it was even funnier when people didn't realize that I was married to him, we have different last names,
06:13so I'd get lots of questions like,
06:14do you believe in the Lorimer burst, or what do you think about the Lorimer burst, is it real or
06:18not?
06:18And so I kind of got a good chuckle out of it for a little bit, but then that kind
06:21of stuck, and so we started using the name in proposals and things, which was kind of fun.
06:27To have something named after me like this was really, really a great honor.
06:31And yeah, not something I was expecting, but yeah, really, really nice.
06:39But the Lorimer burst was so distant, and yet so bright, it didn't appear to have been produced by any
06:46naturally occurring phenomenon.
06:50I did think that it could be a signal from an extraterrestrial civilization.
06:56We create signals like that on Earth, so it's not crazy to think that radio bursts could be created on
07:02another planet.
07:03Once we actually thought about it, though, and looked at the energetics, you'd need to harness almost an entire solar
07:09system's worth of energy to create something this bright.
07:11And then we realized this is just impossible, unless a civilization is way more advanced than we are.
07:16We couldn't think of how to make something this energetic.
07:29Scientists have been searching the cosmos for strange signals like the Lorimer burst for more than 50 years.
07:36Ever since a secretive meeting took place in the foothills of the Appalachian Mountains.
07:45There had been, over the years, a lot of claims of sightings of extraterrestrials, colonies on the moon.
07:55The subject had gotten to be treated with contempt, really.
07:59It was considered almost taboo.
08:05But in 1961, Frank Drake held a conference behind closed doors in this room, at the Green Bank Observatory.
08:17The National Academy of Sciences of the United States, a very eminent body, asked me to convene a meeting of
08:24all the people I knew of in the world who were actually serious thinkers in the subject.
08:29And I invited them all, all 12 of them.
08:35The group called themselves the Order of the Dolphin.
08:44The purpose of the meeting was to estimate how many extraterrestrial civilizations might be out there, using what's become known
08:52as the Drake Equation.
08:57So we start out with the rate of star formation, which you write R-substar.
09:03Of course, the more stars, the more planets there will be, the more possibilities for life.
09:08We multiply that by the fraction of stars, which actually have planets.
09:13And then again, by the number of habitable planets in each system.
09:19We then multiply this by the fraction on which life develops.
09:24And then by the fraction by which intelligence appears.
09:29And then by the fraction of those which actually give a detectable technology.
09:35One we might detect across the great distances between the stars.
09:40What we have now in these six factors is the rate of production of detectable civilizations.
09:48Well, how many are there?
09:50This rate times the average time that these civilizations remain detectable.
09:56The United States maintains its determination.
09:59For two days, the group worked out best guess values for each step in Frank's equation.
10:06We will continue to be ready.
10:08The answer we came to for the value of N was N equals about 10,000 detectable civilizations at present
10:21in our galaxy, the Milky Way.
10:28It became clear to us that it was very likely that there were radio signals from other worlds passing through
10:35the room in which we were sitting.
10:37And which we could detect if we but pointed our telescopes in the right direction and tuned to the right
10:43frequency.
10:45At the time of the meeting, Frank thought he knew exactly what channel to listen into.
10:53What we needed was a special place in the universe where civilizations might contact.
10:59And we realized it wasn't a place, but it was a radio channel.
11:05The most common element in the universe is hydrogen.
11:10It happens to transmit a very beautiful signal at a certain frequency when it's in its lowest energy state.
11:18And we decided that might be the place you meet your friends when you can't arrange in advance where to
11:25meet.
11:26So we decided to search the hydrogen wavelength.
12:04Transcription by CastingWords
12:34Transcription by CastingWords
13:05Transcription by CastingWords
13:10Transcription by CastingWords
13:15There was also something very suspicious about the new bursts.
13:21They were far more common in winter and always appeared around lunchtime.
13:27It was eventually discovered they weren't coming from space at all.
13:32They were being generated by the observatory's microwave.
13:39So I think it was a hard time for him because he felt like his original paper was discredited.
13:46And I think it made it harder that everyone had been calling it the Lorimer Burst because
13:49then, you know, it felt very personal.
13:52When I first saw the data and I compared their properties with the Lorimer Burst properties,
13:57they looked really similar.
13:58And I thought that, you know, that was too much of a coincidence for them not to be coming
14:02from the same source.
14:04My initial conclusion was that the Lorimer Burst probably wasn't real.
14:15But Duncan wasn't prepared to give up on his discovery so easily.
14:22So what we're looking at here is the original burst from 2007 and then one of the new detections
14:27that was coming out in 2010.
14:29And so you can see that they have quite a lot of similarities.
14:33Both pulses are about the same width.
14:35But then if you look at them in terms of their frequency versus time, you'll see that they
14:40have an overall slope.
14:42They both have the same slope, but the structure within the pulse is quite different.
14:48One of the new signals has this very blotchy appearance, whereas our original signal had
14:53a much smoother, continuous appearance.
14:56And that was the thing that was really giving me hope that this was still real.
15:04But for the scientific community, the most likely explanation for the Lorimer Burst was still interference.
15:14For the time being, the great silence persists.
15:46Dr.
15:47the International Academy of Astronautics,
15:50approved a post-detection protocol.
16:00A code of practice to be put into play by governments,
16:03should we detect an alien transmission?
16:18The document detailed how to control the dissemination of information
16:22and coordinate a unilateral response.
16:33One reason scientists believe such a protocol was required
16:38is because in the mid-70s,
16:41we tried to make contact with aliens ourselves.
16:57There were two purposes to the Arecibo message.
17:00One was to demonstrate that it was possible to send a message
17:04across the interstellar space
17:07that would be detectable and decodable, understandable.
17:13The other was simply to show that we had in fact reached the state
17:17where we ourselves could do this sort of thing.
17:21There were probably 200 people there.
17:24They were sitting in chairs on the edge of the big giant dish,
17:29and we'd tell them we're about ready to send,
17:32and they steered the telescope.
17:34The whole great big thing starts moving,
17:36which in itself is very impressive.
17:42This giant thing is moving,
17:44and you just have the sense that something spectacular is going on.
17:51I will play the tape for you.
17:56This is a recording made in the control room with the Arecibo radio telescope
18:02at the time in November of 1974 when we sent a message to the stars.
18:11That steady tone you hear is the sound of the transmitter being turned on.
18:16It's simply sending out a signal without any information on it
18:21to call attention to itself,
18:23so that people who capture this will know that something is coming.
18:26And here it comes.
18:28That sort of warbling sound you hear is actually a sequence of 10 characters per second being sent out,
18:37with those characters being on two slightly different radio frequencies.
18:47When you listen to the sound, you had the impression that there was a story being told here.
19:00And when it finally ends, everybody was crying on the actual occasion.
19:17It was just the sense that this great big machine was talking to another world.
19:27The message goes to 300,000 stars, so there's a good chance, actually.
19:38The recipient of the Arecibo message is a galaxy 25,000 light years away.
19:46But the 50,000 years it would take for the message to get there,
19:50and for any reply to journey back to Earth,
19:53is far beyond the lifespan of any single human.
19:59Perhaps even longer than the lifespan of civilization itself.
20:20The technologically advanced civilization might provide us with another way of detecting them,
20:27because all technology needs energy.
20:34In 1994, Las Vegas consumed 1,300 megawatts of power.
20:40Today, that figure has nearly doubled to 2,400 megawatts.
20:45And that's the same trend that we see all over the world.
20:47For the last century, every few decades, humanity's power consumption has doubled.
20:53As our technology has increased, so too has our need for power.
20:58And as demand increases, civilizations must look beyond their home world.
21:05Every star, just like our sun, is basically a giant nuclear furnace,
21:10fusing hydrogen into helium and producing energy.
21:13And the ultimate limit to the amount of energy available to any civilization
21:18is just the amount of energy that they can harvest from that parent star.
21:38Deep in the Mahari Desert, halfway between Las Vegas and Reno,
21:47it's possible to glimpse into the future.
21:52What kitchen and the wind?
22:09What Kanal�?
22:21How many comes process for Haiti
22:21The horrific andanche Ted Alves
22:24So this is the Crescent Dunes solar facility.
22:28There are 10,347 of these mirrors.
22:31They all reflect the sun's energy up to that tower
22:34that heats a reservoir of molten salt
22:36that's then used to turn water into steam,
22:39turning turbines and generating electricity.
22:46Crescent Dunes is one of the world's largest solar power plants,
22:49but even this gigantic facility can only collect a small fraction of the sun's energy.
22:56In the future, we might build thousands more of these facilities,
23:00collecting even more of the sun's energy.
23:07The amount of energy a civilization can harness from their star
23:11provides an indication of their technological advancement.
23:18And it's measured on what's known as the Kardashev scale.
23:25A Kardashev type 1 civilization is a civilization that's capable of harnessing
23:30all of the energy that falls on their planet from their parent star.
23:36Human civilization today only consumes about 20 terawatts of power.
23:40That's about one one-thousandth of the amount of energy
23:42that falls on our planet from our sun.
23:47But the amount of sunlight that hits the Earth
23:49is only a tiny fraction of the light that leaves the sun.
23:55Our sun's power output is 400 billion terawatts.
24:00That's 10 million times as much energy in just one second
24:04as the entire United States consumes over the course of a year.
24:10Any civilization capable of harnessing all the energy admitted by its star
24:15would have achieved Kardashev type 2 status.
24:22But to do it would require engineering on a truly astronomical scale.
24:29A Kardashev type 2 civilization would need to build a massive network
24:33of solar collectors that would orbit their star in space.
24:37Something we call a Dyson sphere or a Dyson structure.
24:43A Dyson structure is very much like the solar power plant here,
24:46but billions of times larger in space orbiting an entire star.
24:53But they needn't be a solid surface.
24:55It could be a swarm of individual solar panels,
24:59all interconnected as long as they occluded
25:02a large fraction of the light that came from the star.
25:06To construct a Dyson sphere that envelops the sun
25:10would require all the matter in all the planets in the solar system.
25:15So, until recently,
25:18Dyson spheres were thought to be purely theoretical.
25:21Dyson spheres were thought to be theoretical.
25:21Dyson spheres were thought to be theoretical.
25:25Dyson spheres were thought to be theoretical.
25:28Dyson spheres were thought to be theoretical.
25:33Dyson spheres were thought to be theoretical.
25:38Dyson spheres were thought to be theoretical.
25:40Dyson spheres were thought to be theoretical.
25:41Dyson spheres were thought to be theoretical.
25:44Dyson spheres were thought to be theoretical.
25:45Dyson spheres were thought to be theoretical.
25:45Dyson spheres were thought to be theoretical.
25:45Dyson spheres were thought to be theoretical.
25:46Dyson spheres were thought to be theoretical.
25:47Dyson spheres were thought to be theoretical.
25:49Dyson spheres were thought to be theoretical.
26:02In 2013, some bizarre observations from NASA's Kepler Space Telescope fell onto the desk
26:11of astronomer Tabitha Boyajian.
26:21Kepler looked at over 150,000 stars in our galaxy, and the data for this star looked nothing like
26:29any of those stars and nothing like any other star that we know of today.
26:36For four years, the telescope scoured the Milky Way, hunting for evidence of exoplanets,
26:44meticulously measuring the brightness of stars in search of the telltale dimming in light
26:49produced as a planet passes in front of them.
26:59So, this is what an exoplanet transit looks like.
27:03On the left-hand side, you have the amount of light, and on the bottom, you have time.
27:07And when a Jupiter-like planet transits in front of a star, you have this clean U-shape dip
27:14in the star's light.
27:15And this dip is about 1%.
27:20So, this is the Kepler data for KIC 8462852.
27:24And it shows four years of Kepler photometry of the star.
27:29And as you can see, for most of the time, it is pretty flat.
27:33Nothing is going on.
27:34But then in May 2009, you have this dip that, on face value, it appears to look like what
27:39a transiting planet would look like.
27:41But if you take a closer look, then you actually see that the transit lasts for almost a week,
27:47compared to what a planet-sized object would just last for a couple of hours.
27:52It was also very asymmetric in shape, meaning that instead of having that clean U-shape dip,
27:58it had this strange slope over here on the left-hand side.
28:01This seemed to indicate that whatever was crossing in front of the star was not circular like
28:05a planet.
28:11Things are pretty quiet for a couple of years.
28:13And then in March 2011, we have this very dramatic feature, where the star's brightness drops by 15%.
28:25And this drop is also very asymmetric.
28:30It gradually decreases in brightness for about a week, and then it snaps right back up to normal
28:35in just a few days.
28:37Now after this, nothing happens again for a couple of years, until February of 2013, where
28:43you have this huge complex of dips that last almost for 100 days.
28:48Each of these dips have a different structure.
28:51Some are very shallow, some are very sharp, and the deepest one here drops by over 20%.
28:59And so it seems to indicate that there's some swarm of objects with different sizes and shapes
29:04that were passing in front of the star.
29:09At first, no one had any idea what those objects could be.
29:15Then somebody came along and said, well, what if there was this giant swarm of comets that
29:20was swooping down towards the star and blocking out the starlight?
29:24And this seemed to be consistent with the observations that we had, but it seemed a little bit contrived,
29:31because it would take hundreds, if not thousands, of comets to block out the star's light.
29:37But, nevertheless, this was kind of the best idea, theory that we had to explain the data.
29:47But there was another possibility.
29:51The TABIA detected the deep shadows cast by a Dyson sphere constructed around the star.
30:01The scale of these things is kind of hard to imagine, but you can think of it this way.
30:06So, the Earth-Moon distance is about a quarter of a million miles, and the simplest element
30:11on one of these would be 100 times this size.
30:16Now, imagine these in orbit around the star, and you can see how it would produce anomalies
30:21in the data that we detect.
30:25Scientists now refer to star KIC 84612852 as TABIA's star.
30:35And while the investigation into the precise cause of the dimming is ongoing,
30:40the search for fast radio bursts is speeding up.
31:03The TABIA's star, and the TABIA's star, and the TABIA's star, and the TABIA's star.
31:12See you! Bye!
31:13OK, bye!
31:25Along with the potential discovery of alien megastructures,
31:302013 also brought good news for Duncan Lorimer.
31:37A group at Manchester University announced the discovery of four mole bursts.
31:42They were coming from all over the sky, and they were clearly real, so it was a breakthrough moment.
31:48It meant the Lorimer burst was real, which was just great news, and it also meant that we could learn
31:53a lot about these bursts that we couldn't before. We'd be able to study the population and the energetics
31:58and try to figure out exactly what's causing them.
32:03Duncan was very, very excited when these other bursts were announced, because yeah, he felt vindicated.
32:10By the end of 2013, there had been six confirmed detections of fast radio bursts.
32:18But what was causing them was still unknown.
32:23Now that fast radio bursts are real, you know, it comes back to the point whether they could be caused
32:27by aliens, and I've never really subscribed to that. So if I were looking for a signal from an
32:32extraterrestrial civilization, I'd be looking for it coming from a single point in the sky.
32:36Here we have a population of sources all over the sky, which implies that the aliens are all over the
32:41place, all over the universe. That just seems highly unlikely to me.
32:48But then mathematical analysis of the known signals seems to show they were all placed at
32:54regularly spaced distances.
33:01Maybe whatever was responsible for the fast radio bursts were put there by extraterrestrials,
33:08perhaps even ones on the next level of the Kardashev scale.
33:13Communication beacons placed across the Milky Way by a Type III civilization.
33:20One with the ability to harness the power of an entire galaxy.
33:36But if the Milky Way were home to a Type III civilization, its presence should be written across the sky.
33:47We know from thermodynamics that any energy usage that does useful work produces waste heat.
33:53Our car engines produce waste heat. Our laptop batteries produce waste heat.
33:57So too does any energy usage by any technology, whether it's human technology or an extraterrestrial technology.
34:05If there were a civilization in our galaxy that was using the energy of millions or billions of stars,
34:11we would see evidence of that energy usage in the form of waste heat.
34:17As more fast radio bursts were discovered, the regular pattern disappeared.
34:23And nothing like the heat produced by a Type III civilization has ever been seen in our galaxy.
34:40But wherever those civilizations might be, for as long as we've been looking,
34:47they have remained elusive.
34:52It's the only thing that we've been looking for today.
34:57Breakthrough Listen takes the search for intelligent life in the universe to a completely new level.
35:06In 2015, Russian billionaire Yuri Milner put down a hundred million dollars of his own money
35:12to conduct the most comprehensive search for extraterrestrials ever undertaken.
35:19This was once a dream. It is now a truly scientific quest.
35:25The 20th century, we stepped out from our planet to space, to the moon, to the solar system.
35:35In the 21st century, we'll find out about life at the galactic scale.
35:40And the search begins with Tabby's star.
35:50KIC 8462852 is one of the best targets we've had in a long time for SETI searches.
35:57We're going to be using the 100-meter Greenbank Telescope, the largest fully steerable radio telescope
36:02on the planet, paired with a brand new set of instrumentation we've installed as part of the
36:06Breakthrough Listen project.
36:08This instrumentation allows us to conduct a very sensitive search over a huge amount of the radio spectrum.
36:15Now, if Tabby's star does indeed have a Dyson sphere around it, and it is inhabited by a very advanced
36:21civilization, perhaps that civilization might have technology like we use here on Earth,
36:25perhaps radio technology, and if they do, we could detect it with this telescope.
36:42We're going to be using the Greenbank Telescope in West Virginia, the Breakthrough Team may have
36:51the best chance in human history to make contact with extraterrestrials.
36:59Hey Dave, could you put Vegas back in Mode 1?
37:03This evening is a very exciting night.
37:06Yeah, turn back on and we're programmed in Mode 1 and all of that.
37:09We've been waiting for it for over a year, so yeah, I think we're all pretty excited about
37:14what's happening.
37:15What's next?
37:16Is Tabby start next?
37:17Tabby start next.
37:18All right, it's time for you to push the button.
37:21Okay.
37:24All right, here we go.
37:38Once it's moved into position, the telescope begins to gather radio waves that just might contain messages
37:45from an alien civilization.
37:51There you go.
37:52It's coming in.
37:53All right, here we go.
37:53All right, here we go.
37:56For six hours, the giant dish tracks the star across the sky, scanning billions of radio channels simultaneously.
38:10By 3.30 a.m., the observations are complete.
38:15These four plots represent about 800 megahertz of the radio spectrum.
38:19And this is only about one quarter of the amount of the radio spectrum that we're observing.
38:24So this plot shows the shape of the radio spectrum as a function of frequency.
38:28And here we see the radio spectrum as a function of time.
38:32If there was evidence of technology in these data, what we would expect to see is a spike in one
38:36of
38:36these plots, a lot of electromagnetic energy at just one channel. Now, we don't see that yet,
38:41but in the coming days, weeks, and months, we're going to be looking at these data in many different ways
38:46with much higher resolution that will allow us to be much more sensitive to evidence of technology.
38:55At least for tonight, Tabby's star is holding on to its secrets.
39:02And for the breakthrough team, the search for extraterrestrials is only just beginning.
39:10I don't know if they're out there or not. As a scientist, I have to admit that.
39:15But I think that it would be a pretty strange universe in which life only arose once and intelligence
39:21only arose once. And I think, to me, the most interesting property of the universe is the fact
39:27that intelligence exists at all, that somehow the universe has evolved a capacity to know itself,
39:32to ask questions about itself. And ultimately, I think, until we answer this question,
39:38we won't really understand the universe at all.
39:53Since 2013, many more fast radio bursts have been discovered. And Duncan and Maura now have a theory for
40:02what might be producing them.
40:06So whatever it is that's causing FRBs must be both very compact and very energetic.
40:12They must be compact because the width of the pulses is very narrow.
40:16And they must be very energetic because the distances that we infer are very far away.
40:23In fact, it's thought the bursts could be created during the explosive collisions of neutron stars,
40:31some of the densest, most energetic objects in the universe.
40:37We observe binary systems of two neutron stars that are in orbit around each other. And when we observe
40:44these systems, we see them getting closer and closer together all the time. So what will happen
40:48eventually is that they're going to collide. And when they merge, the neutron stars will be completely
40:56destroyed and form a black hole. As they annihilate, the two stars release in an instant
41:04the energy the sun produces in an entire month. A blinding flash visible to our telescopes as a fast radio
41:15burst. This theory, perhaps, solves the mystery of these strange signals from space.
41:24When you look at the energetics of these events, you can easily explain the FRB energies with them.
41:30You can also explain the durations of the FRB pulses with the expected durations of these merger events.
41:36So that was quite a plausible explanation.
41:45Then, in 2016, a new burst was detected. The distinctive pulse of radio waves released
41:52as the neutron stars collided and were destroyed, followed by nothing. Silence.
42:00Then, in 2016, a new burst. Just as the astronomers expected.
42:10But when they looked again,
42:15the signal came back.
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