Why Have We Not Found Any Aliens? - with Keith Cooper

Well, thank you all for coming to hear me speak, if I seem a little nervous, this is the hallowed ground where all the famous Christmas lectures

have

taken place, including, as Martin mentioned, my idol Carl Sagan. Carl Sagan was one of the main authors on SETI and it is a real privilege for me to be here, especially as it is something very dear to me, a book I

have

been working on for quite some time and a topic that I find completely wonderful and surprising: SETI, the search for extraterrestrial intelligence So what is SETI? They are not flying saucers or UFOs or abductions or anything like that.

It is a scientific search for intelligent life somewhere among the stars. We don't know if it's there, but the only way we'll really know. is to look and see if we can see any evidence of their presence there and you know that many of you will have seen the movie Contacts starring Jodie Foster based on the book of the same name by Carl Sagan and which is about receiving a radio signal from the outer space of an advanced civilization and Jodie Foster goes to meet them briefly and you can see there that she is listening to signals from outer space in our headphones with the radio telescope in the background.

I think in the movie she's sitting on the hood of the car in the desert next to the radio telescope just relaxing listening to these signals from outer space it's not that glamorous unfortunately the computers do most of the analysis of the signals but from radio you know maybe We are talking about an advanced civilization millions of billions of years older than us, why would they use something as low technology as radio? Surely they would use some type of hyperdimensional communication medium. Well, maybe they do, but we can't really detect it because we don't know what.

I mean, first of all, we're kind of limited to detecting things that we know. The second reason we use radio is in 1959 with astronomers Philip Morrison, who I think gave Christmas lectures here, and Giuseppi Cocconi, they wrote a very famous book. article in the scientific journal Nature and they were researching what would be the best means of transmitting a message to nearby stars and then they looked at the electromagnetic magnetic spectrum of lights and things like x-rays and gamma rays and decided that radio would be the best for various reasons now you have to understand that in 1959 radio was a technology that was maturing and had developed a lot in the Second World War, everyone had wireless connection in their homes and listened to BBC One and things like that and a new frontier was opening up . in radio astronomy and radio astronomy it's really cool because as you can see, this is a snapshot of the Milky Way, part of the Milky Way, loads a bunch of stars and some nebulae, you see this big black band running down the middle. and that's all dust, it's all interstellar dust.

Space is not a vacuum, it's full of all kinds of things and you can see that the dust you breathe is black and blocks the light from the stars behind it, so if you tried to send an optical signal of some kind, it wouldn't get very far. far before being absorbed by dust, but radio waves pass directly through dust as if it were not there, so you can detect signals from much further away and give you an idea of ​​how far away we can detect. radio signals many of you will be familiar with this image it was released earlier this year this is the first image of a black hole it was taken with the event horizon telescope which is not just one telescope it is a network of large radio telescopes around of the world working together and this shows the hot disk of gas around the supermassive black hole in the galaxy Messier 87 which is 54 million light years away and those radio waves, yes, it took a lot of large telescopes to detect them, but those Radio waves have traveled unimpeded through space 51 million light years to reach us, so after Baconian Larson published his article here, Frank Drake also independently came to the same conclusion that the bet It would be a really good way to communicate between the stars and in April 1960, he conducted the first SETI search by radio, called Project Ozma, named after the princess from the Wizard of Oz stories and targeted two nearby stars, Epsilon Eridani, which is ten point five light years away, and Tau Ceti, which is I.

I think it's about 12 light years away, so close that on the first day it

found

a signal. They probably sat in his chair and thought grumpily. This is easy. It turned out that they weren't

aliens

, it was actually a U-2 spy plane flying overhead. It was top secret, no one knew at the time. I think this was a month before Gary Powers was taken down and you can see here that he is writing on his whiteboard an equation and this is the famous Drake equation, which he is most famous for. I don't take that literally, it's a way of saying, well, they were basically holding the first SETI conference at the Green Bank Radio Observatory, where Frank Drake worked in 1961 and Drake was put in charge of organizing the agenda.

I mean, you thought grumpily, what the hell? Am I going to talk about how I don't know anything about

aliens

? No one knows, so he came up with this equation as a way to stimulate discussion about how many extraterrestrial civilizations may exist and what factors may be involved in the likelihood that they exist. exists and it's really fun to plug in numbers and see what kind of results we get, so I did that on the next slide, so the first factor is the rate of star formation in our galaxy, which is about one solar mass per year.

Gas in the galaxy turns into an average of one star per year, the fraction of stars with planets. Well, NASA's Kepler space telescope, which you may have heard of, was launched in 2009 and retired in 2018. It was a space mission designed to detect exoplanets which are planets orbiting other stars and based on system statistics Of the planets it

found

, scientists conclude that almost all stars have planets and probably more than one. There are probably more planets in the galaxy than stars, which is pretty surprising considering that in the early 90s we didn't even know if there were any others. planets in this, you know, beyond the solar system, so the next factor is the number of habitable planets per star.

Well, we can't have it or maybe a rough estimate of that because I know a region around stars called the habitable zone. This is the distance from a star where temperatures should be right for liquid water to exist on the surface, provided there is an Earth-like atmosphere, so there are a lot of ifs or maybes. This doesn't necessarily mean that planets within the habitable zone are habitable, so perhaps we should look at our own solar system. We know Earth is habitable because we are here, but are there any of the worlds in the solar system that could potentially be habitable?

I think there is Mars, we know we are looking for life on Mars, microbial life, not intelligent life, but you know there could still be life there, then there is Jupiter's moon Europa, which is an icy moon, it is covered by a thick crust of ice, but below that. The ice is a global ocean and the conditions there may be suitable to support life and similarly, Saturn's moon Enceladus also has a global ocean under the ice and could support life, so I'm going to be very optimistic and I will say based on In our solar system, that four moons or worlds around a star can have life does not mean that they necessarily have life and that is the next factor: the fraction of those planets that develop life well in our solar system , as far as we know, only Earth has developed life and similarly, only Earth has developed intelligent life and only Earth has life transmitting radio leak messages to space.

The final factor is the most interesting. I think the lifespan of a civilization that sends signals into space, so this isn't necessarily the lifespan of a civilization, from its origins to its extinction, it's actually about the amount of time it spends transmitting to space, although A technological civilization would be expected to send signals for most of its existence, whether deliberately or simply. accidental leak we have been sending signals into space for about a hundred years since we started transmitting radio. Hopefully we will be transmitting signals for well over 100 years, otherwise it means we are extinct. Other civilizations think in 10,000. years and millions of years, even a billion years, we don't know and as you can see on the next slide, I multiply all those numbers and I estimate that there are 100 civilizations in our galaxy right now and it's just a guess, nobody knows really, but as You can see that it gives you a way to consider the factors that are involved and you can also see that the larger L is, the longer the lifespan, the more civilizations there are and that's because the longer the civilization lives, the more chancelleries will have. overlap in time with other civilizations if you know if a civilization exists and becomes extinct and then another civilization arises, they are not going to detect the one that became extinct, so they need to overlap to be able to detect, although of course distances in space.

This means that it could take many years for a radio signal to reach us. We can detect a radio signal from a civilization that is already extinct, so let's go back to the radio and this is a radio map of our galaxy and this has been imaged at 21 centimeters. neutral hydrogen lines so neutral that hydrogen atoms in our galaxy emit radio waves when excited at a wavelength of 21 centimeters and this is primarily the wavelength at which astronomers observe the universe because they want to study hydrogen , it is the most common gas in the universe, come on Adam and maybe the aliens know that we are already going to be watching the radio universe at that wavelength, so they will send their signals at that wavelength because we are already going to be watching, so Watch them and in 1960 when Frank Drake did the Ozma project, we could only watch one wavelength channel at a time, we didn't have the equipment, the technology to watch many more channels at a time, today the things are different, we can look at billions. of narrowband radio channels all at once so we can scan the radio spectrum, so whatever wavelength they transmit, we should be able to detect it and you have to understand that SETI has probably been underappreciated by the scientific community because there's a little laugh factor, people think of aliens, flying saucers, little green men and for much of its history it hasn't really been funded very well, the miss scrimped and saved and in the early 90s it seemed like NASA We are going to have a massive SETI project, if we are going to invest millions and millions of dollars in it, but at the last minute this was interrupted by the US Congress canceling NASA's funding for SETI, so which since then has been relying on donations and that means we haven't been able to do many SETI searches and the ones we have done just look at some stars now you could say, well the city has been running for 60 years, why haven't we discovered nothing yet?

It's because we've only sampled a small portion of the galaxy, let me make an analogy if you went to the beach with a glass cup full of water, would you expect to find fish there? Probably not, that doesn't mean there aren't any fish. of the ocean, it just means we haven't sampled enough of the ocean to find those fish and the same goes for SETI: we still haven't sampled enough of the universe to find if there are aliens out there, but in 2016 this guy here in the leftist yuri milner is a billionaire philanthropist launched the groundbreaking project listen is a at least 10 year project in which he is investing a hundred million dollars over the course of those ten years and what is that going to do to SETI?

It's going to revitalize it. It's revitalizing it right now. Before this, we have observed perhaps a thousand stars in detail by listening carefully for signals from extraterrestrials, and when I say listening carefully I mean we listened for perhaps half an hour with a radio telescope before moving. We move on to the next, well maybe the aliens paused for tea or something and we didn't pick up their signal, who knows, not enough time to be sure if there's anyone out there or not. Listen, you'll see a million. stars with great detail we will still only search for half an hour or an hour on each star, but it is still enormous in coverage, it will carry out studies of the night sky by scanning the sky listening to large beacons.

We will be scanning the galactic center where we can see most of the stars in our galaxy and will even look at distant galaxies in case there is a powerful beacon beamed in our direction, who knows, we won't know unless we look that hard.It's really changing things and that produces a lot of data. Dress up Jodie Foster with her headphones listening to signals from space. Well, she can't do that with all this data which is too much and to show how fast SETI has come since the early days, they now use machine learning algorithms to look for patterns amidst the radio static.

There's sort of an artist's rendering of, I guess, a robotic Jodie Foster with her wearing her headphones and the radio telescope in the background. Now this is our galaxy. see the sun we are 26,000 light years from the center of the galaxy our galaxy contains 200 billion stars or so that's a lot of stars to look for so the odds are still against a breakthrough listen to detect any thing, let's say we did the Drake Equation and came up with a value. Of 10,000 civilizations in our galaxy, we would still have to search 20 million stars before finding one of those civilizations.

On average Brickley listens, she will only listen carefully to a million stars, so it is still not enough, we have to be very patient when doing SETI. we might find a signal tomorrow or it might take 10 years it might take 100 years we might never find a signal but we won't know until we look for other ways to improve our chances well we don't have to stay through the radio I know what I said to the principle about how radio is really good because it can go through all the interstellar dust, but you know there are other means.

What if aliens were sending messages not by radio but by lasers in 1960 when Drake made his project? Ozma, the laser, was just being invented when it was invented, the scientists at the time didn't see what good the laser would do, they thought it was a no problem solution, they said on earth we do do it with the laser, which Sounds like a little ridiculous now because we use lasers everywhere in everyday life and this is not a laser sent into space with a message this is actually artificial this is the very large telescope in Chile and it basically shoots lasers into the sky to create an artificial Stan.

It allows the telescope to focus on that artificial star and compensate for the blurring effects of the atmosphere. You know what stars look like shining, but it looks cool, so I thought I'd put it up now. This is a serious laser, this is the laser at the National Ignition facility at Lawrence Livermore National Laboratory in California, it reaches one petawatt, which is a quadrillion watts, so you know how many light bulbs you could light with that and what it did. They use such a powerful laser, they used it for nuclear fusion experiments, so you can see the lasers shining and you can almost see an arm coming out of the bottom at the end of that arm.

They have fuel pellets and lasers. It heats the fuel pellets to millions, hundreds of millions of degrees to the point that the atoms inside them fuse and release energy and it is expected that by the middle of this century we will have nuclear fusion that provides electricity to the National Grid, we will see but These lasers, maybe for a fraction of a second, can outshine the Sun, which is extraordinary, so can you imagine pointing these lasers into space and sending out pulses that contain messages and are we looking for them? Yes we are looking for them and lasers have an advantage over radio radio suffers from what is called dispersion so as I mentioned space is not empty it is full of atoms molecules and particles and in particular when Radio waves encounter electron particles, electron particles interact with radio waves and cause longer wavelength.

The radio waves are delayed so that they arrive at their destination behind the shorter wavelength radio waves and then you know that your message is encrypted upon arrival, which is not great, that doesn't happen with laser light. It has been calculated that if we shined one of those petawatt lasers into space with a message at a distance of about a thousand light years, about 90 percent of that light would have been absorbed by dust, so its range is limited, but Can we get over that? Yes we can, because infrared can pass through some of that dust. Astronomers observe the universe in infrared to see inside the dusty regions of star and planet formation, so Professor Shelly writes that we can see deep down here.

The idea occurred to build an instrument designed to search for infrared laser pulses. She holds an infrared detector. there she is on the nickel telescope at Lick Observatory again, she hasn't found anything yet, but it's a new way of doing SETI that we just started and maybe she'll get to space if we had an infrared satellite in space dedicated to looking for infrared. lasers that would be more beneficial because our atmosphere absorbs some infrared light. This is at the Lick Observatory on top of a mountain, so it's above much of the atmosphere, but unfortunately space missions are expensive, so SETI, I'm going to get one of them.

However, are there other ways to search for life in the universe? And in fact, there is an artistic representation of an Earth-like planet around another star and we can't really visualize these planets, we don't know what they look like. Still the way we discover them is through something called transits and here's a video where a planet moves in front of its star and causes a drop in light and then as it moves away from the star the brightness of The star rises again and the solar system is roughly scaled to a Jupiter-like planet would cause a drop in light of about 1%.

A much smaller Earth-like planet would create a dip in light of about 8%, but our photometers that count photons from these stars are able to measure light dips as small and detect that the light bends as we call them and there's a real-life light curve of an exoplanet. What else can transits do when a planet moves in front? from its star, some of the light from the star shines through its atmosphere and the atoms and molecules within that atmosphere will absorb some of that light and then we will see the spectra of the stars, some examples of stellar spectra when the molecules absorb the light that they create dark. absorption lines in the spectrum at specific wavelengths, so if there is oxygen in the atmosphere, that will cause an absorption line that is a certain wavelength, similarly, carbon dioxide or methane, and then we can look for biosigned gases that can be produced by a life and if we find them. at certain abundances in a planetary atmosphere that could be a sign that there is life there, of course it wouldn't tell us whether that life is microbial, animal or intelligent, but we would certainly know that there is something there otherwise that we could look for.

Extraterrestrial life This is just an artistic representation of the surface of an exoplanet. I think this is Proxima B, which is the planet orbiting the closest star to the Sun, Proxima Centauri, just 4.2 light years away, but there is another way we can look. life is looking for something called techno signatures now this is the buzzword in SETI at the time it was coined when it upset its most famous astronomers Jill Tarter and techno signatures refer to evidence of extraterrestrial technology now technically radio signals and laser signals count as evidence of extraterrestrial technology, but they could also do it in an interstellar probe or maybe if they are mining asteroids that could reduce the dust we could detect or maybe they like to build things megastructures, the Dyson sphere is an artistic representation of a Dyson sphere, this is a concept that was invented by the famous physicist Freeman Dyson again in 1960.

A lot of things happened at that time and he reasoned that an advanced civilization would want energy in the same way that our civilization uses a lot of energy now that the Sun radiates with 400 trillions of trillions. watts in all directions and only a small portion of that falls on Earth, so we only get a little bit of the sun's energy, enough for life on this planet, but advanced civilization may want more, there may be hunger for more and then we want a little more of that is solar energy, so they could build a large swarm of solar energy collectors to surround the star and in the media this is often represented as a solid sphere which would be unstable, gravitational disturbances they could separate it or send it spiraling toward its inner star, destroying it. so most likely if the aliens don't like doing this they will build a swarm of solar collectors or here we see unconnected interconnected acts and that is much more stable and one might wonder how we would go about building something so immense, sighs, well, Dyson just casually said, well, we could dismantle Jupiter.

I have no idea how we would dismantle Jupiter to get the raw materials for a Dyson sphere, but we don't have to, we could start the process, we could start building solar collectors now, just some of them. and then the energy that those solar collectors collect could help build more solar collectors that collect more energy and so on, we could gradually increase it and I always like to joke that you know the way we know leave the construction sites are over we'll look around the galaxy we will not find Dyson spheres we will find Dyson Hemet Dyson hemispheres that were never finished being built now we have ever discovered a Dyson sphere no, but a couple of years ago we thought we could So this is a light curve like the one I showed before in the animation when the planet transits it gets stabbed, but you can see that it doesn't look anything like that very symmetrical light curve in the animation.

This is, I mean, God knows what's going on here, you know? we have falls of all kinds of different magnitudes and sizes, there is no obvious periodicity that you would expect from a planet in orbit, so this was discovered by citizen scientists on the planet hunters website, where the cause of Kepler producing so much data the astronomers had to recruit from citizens. Scientists help analyze everything, so they started this website, planet hunters, don't worry, you can still continue today and they put samples of light curves on the stars, you scroll through it and if you saw something that looked like the transit of a planet , mark it. above, another professional astronomer would follow up now, citizen scientists started finding really strange transits like this in the star kic eight four six two eight five two for some reason astronomers have a tendency to give phone numbers to stars and planets like names, so this caught the attention of an astronomer from Louisiana State University named Tabitha Boyajian, she collected all the data and discovered that there were swarms of mysterious objects transiting this star, there didn't seem to be any rhyme or reason behind it, at one point, a quarter of the starlight was blocked remember what I said about Goethe blocking 1% so whatever was blocking the light was huge now the audience first there was maybe it was a swarm of giant comets each the size of a moon and you can see in this artist's impression how that could create strange dips, the problem was that we had no idea how a swarm of comets the size of moons could grow something that would be completely beyond We're seeing this mega structure transiting its star and for a while this was happening. took it seriously and it was really cool because you know the public got the enthusiasts excited, but so did the scientific community.

As it turned out, whatever is causing the falls is interstellar dust, we don't know if it's an orbit around the star or if it's just between us and the star, we don't know. If it just came from there, it's still an enigma, it's a fascinating mystery, but unfortunately it's not aliens, but I think this and more of the listeners' pause really revitalized SETI for the public and for the scientific community, it's much more now. in the news, people. I write books and I think this is good news, even though they didn't turn out to be aliens, does that mean we haven't detected any evidence of life out there?

I wouldn't say that in 1977 the astronomers in Ohio at the Big Ear Telescope. We are doing a security experiment. Now you can see the telescope at the bottom left. It doesn't look like your typical radio telescope with a dish pointing skyward. It's about the size it's supposed to be. the size of three football fields and on the floor there is an aluminum coating that prevents the floor from absorbing radio waves and two walls can be seen on each side, the wall on the right could be tilted to look at different heights above the horizon and radio waves.

Coming down from space, they would be reflected on its inclined wall to the right, they would bethey would reflect on the wall on the left and then they would go into the two feed horns so you can see it in the image or you can see it better in the background image and that's it. where the receivers were and the telescope was fixed on the ground so you couldn't point it at an object, you had to wait for the Earth's rotation to work in your favor and bring whatever object you wanted to look at up and the object would would move in the field of view and be detected by the receivers at the first feed horn, would move a little further across the sky and would be detected at the receivers at the second feed horn for seven seconds and then would move out of the field of vision and there were actually no astronomers at the telescope doing this, everything was automated every few days and Strummer, our technician, had to travel there and bring all the data back.

Now, in 1977, they didn't have huge hard drives, everything was printed. on that horrible perforated printer paper, reams and reams of that stuff, so just after August 15 of that year, astronomer Jerry Amon went looking for the data and, as he was examining it, he found something really strange, something that had never been had seen before, is the part. From that, on the printout with the signal I can see many numbers and letters there, the numbers and letters denote the intensity of the signals detected by the telescope above the background level, so a number of one is once again stronger than the background level, so the one, two, nine were background forces one to nine times higher than the background and then the letters that meant forces ten are on top, so you can see where he circled them so you have six.

I'm stronger and then possibly got even stronger as I moved. more in the II receivers field of view, that's 14 times stronger, you thirty times stronger than the background, so you went around it because it was the most powerful radio signal I'd ever seen. He got Wow on the margin and the SETI legend was born the WoW signal now we don't know what caused it it could have been terrestrial interference maybe it was some kind of astrophysical phenomenon it could be a black hole swallowing a star an explosion of radio waves its final agony maybe it was extraterrestrials we don't know Amon for his part is convinced that it was an extraterrestrial signal he has ruled out terrestrial interference and other things but we don't know until we detect it again we will never know now I went back and tried to find him again but as I mentioned he said he hasn't had much funding and searches have been scammed.

We tried searching for an hour or two but we didn't detect or detect anything, maybe it's his psyche, the sign is. circling planets and will eventually come back to target Earth at some point in the future, we just have to be looking away to catch it or maybe it was just a one-time astrophysical event that you would never know what it was, it's so tempting and so frustrating . at the same time, it's kind of a quick history of the city, so far, kind of a story of relative wealth with the funding now of a breakthrough, listen, but in telling that story, what I haven't done is really talk about the assumptions we make in the environment and how those assumptions affect our search and our likelihood of success.

Here's a secret. Do not tell anyone. I don't know anything about aliens nor do you. You know as much as I do and together we know as much. Just like professional astronomers, because no one has ever met an alien, so how do we know what they could do right? We can extrapolate from human civilization what we would do in the future if we had advanced technology, how we would behave, how society is going to change. In some ways, that's really good because it allows us to take a closer look at our own civilization and understand ourselves better, but it also brings with it a whole host of assumptions about extraterrestrial life.

Extraterrestrial life may not be like us, but we are looking for something similar. for us we are looking for human civilization, modern civilization extrapolated to the future, so what kind of assumptions are so cool? Well, we are looking for technological intelligence now we always seem to equate intelligence with technology, as if one automatically leads to the other. there is no evidence that this is the case we still do not fully understand the origin the evolution of scientific thinking and technological thinking perhaps most of life in the universe is like dolphins dolphins are intelligent but they will never build a radio telescope with fins and you know, studies have shown that maybe most planets in habitable zones around stars could be water worlds, maybe dolphin life prevails and our kind of life doesn't exist, there could be many planets with a type of life similar to that of dolphins that we would not have. detect them because we are looking for civilizations that produce radio telescopes and transmit radio signals.

Another assumption we make is that the aliens will be able to detect us and will have an easy time detecting detectors or transmitting their own signals afterwards. all your advanced aliens millions or billions of years older than us surely there is nothing they can do, nothing they can't do, rather could they really detect us through our radio leak? Well, this is a representation of our galaxy similar to the one I showed before. And you can see a box in that box, you can see an arrow pointing to little blue dots that are 200 light years across on the scale of the galaxy and that is the volume of space that our radio signals have reached.

So far it's not much compared to the rest of the galaxy's surface. You know, if there's an alien on the other side, they won't know we're here, but it's interesting to talk about our radio leak because you've probably heard that aliens will know we're here because they can detect our television signals, but even if they were 50 light years away, could they really detect our signals? Could they be watching EastEnders? Well, I'm skeptical about that and that's why incest. You are trapped in the SETI Institute. He has done some calculations. This is the Arecibo radio telescope. It is one of the largest radio telescopes in the world.

It used to be the largest, but now the Chinese have the 500 meter aperture telescope into a much larger telescope. But anyway, Szostak calculated that if we put another Arecibo on Alpha Centauri on a planet around Alpha Centauri that is four point three light years away, Arecibo wouldn't be able to detect our radio and television signals, they would be too weak as would be expected. because I know that when we broadcast television and radio it is intended for a terrestrial audience, not an extraterrestrial audience, so the signals will be quite weak. Well, how about in an hour seeing Bo spotting another Arecibo?

If aliens had a telescope the same size as Arecibo, could they detect transmissions? from our Arecibo well, just that calculated that up to a maximum distance of 400 light years could go beyond that, even our C Bose transmissions would be too weak and we have sent message transmissions using Arecibo in 1974, Frank Drake, as I mentioned, the father of SETI. He was the director of the Arecibo radio telescope and it had just been remodeled. That big ball he saw had just been paneled and they had added a transmitter and Drake wanted to play with the transmitter, so at the reopening ceremony he transmitted.

This message to the star cluster on the left Messier 13, which is 22,000 light years away, is now a bit of a silly task because by the time our signal reaches m4m 13 and 13 is going to move, it will be orbiting the galaxy, so what won't go away. be there, that's beside the point, so he created this signal in binary code meant for the aliens to understand that people here understand that not many, not many, so at the top we have those white dots, they are the binary numbers 1 to 10 and are intended to be used as a key to understanding the rest of the message.

Below we have descriptions of the hydrogen, carbon, oxygen, nitrogen, phosphorus atoms, which are the building blocks of nucleotides, which themselves are building blocks of DNA and RNA, and you can see in the middle this means that is a representation of a DNA helix. I'm not entirely sure how the aliens are supposed to figure that out. Below we have a stick figure of a human being, probably the most recognizable thing in the image, we recognize it. The aliens are going to recognize that this is a form of life that we are and what are they going to think if they believe that says so and there is the population of the Earth at that moment, which is 4.3 billion.

Below you can see the representation of the reputation. solar system, the third planet from Earth is raised above to try to indicate that that is where the signal is coming from and you can see that there are nine planets there because at that time Pluto was considered to be a full-fledged planet and at the bottom it is intended to be the Arecibo radio telescope, so this raises its own problems in terms of how the Lian will be able to understand their radio signals, but now there is a reason why there is a squirrel there, so the gist of what I'm trying to understand The reason is that it is difficult to transmit signals and difficult to receive signals.

Szostak calculated that if aliens had a radio telescope the size of the Chicago metropolitan area, which is twenty-five thousand eight hundred square kilometers, then they could detect with technology. our radio leak is hundreds of light years away, thousands of light years away, the only problem is that such a telescope in our economy would cost 53 billion pounds. No, obviously, aliens aren't going to have the same economy as us, so I have pounds. and dollars and we don't know what resources they would have exactly, but the thing is that it is going to require a lot of effort and a lot of resources and all the energy to build telescopes that detect radio signals and, more importantly, transmit messages of their own to that we hear them and not only are they in them at once, if they want to be heard, they have to constantly broadcast them in all directions because they don't know where we are and that takes a lot of power.

Because? If they did that, they would probably have better things to do with their time than spend a disproportionate amount of resources just trying to message someone who may not even be there, they may never get a response, they don't know if anyone is there , just like we do. Not so, what would drive someone to do so well at SETI? SETI scientists think that aliens are advanced not only technologically but also altruistically. They are perfect beings, they will be kind and welcoming and they will have all this pure and selfless altruism. They will be happy to spend all their money and all their resources to build radio transmitters.

Really I do not think so. In nature there are two types of altruism that are dominant so the first is something called kin selection and that's why I have a photo of a squirrel so I have two dogs and every morning I spent with them in the refrigerator through wet and muddy fields and at this time of year the squirrels go out to hunt for nuts and other delicacies to take them to the star to spend the winter and my dogs love to chase the squirrels, they love it and from time to time you hear a school yell a warning from a tree or a branch or where presumably school speak means run for your lives, there's a crazy dog ​​on the loose now that the squirrel doesn't.

I don't know better, just think the dog might be a predator. , so he shouts this warning to his offspring, to his nieces, nephews, run, save yourselves, and in doing so, he puts himself at risk and reveals his location: this supposed predator, why would he do that? doing that because you are safeguarding your offspring, you are safeguarding your genetic information so that it can still be passed on to future generations if the predator eats them all because the squirrel didn't shout a warning, well that's the end of your lineage so nature has done it. This built-in mechanism helps us protect our genetic information and we even do it.

You know, if we have children, there are things that we unconditionally do for them that we wouldn't do for other people because they carry our genetic information and we want to. to help them thrive, another type of altruism is called reciprocal altruism, basically you do something for me and I'll do something for you, and that's how the world really works and you know it's fine, but could it work at interstellar distances? A kind of altruism prompts civilization to invest a lot of resources in building a transmitter to send messages in the vague hope that perhaps they will receive a response from someone, but the distances and time periods in space work against it. of it, but it is not like that.

I don't know we're here and even if we are here they may not receive a signal for hundreds or even thousands of years given the distances between us, so I don't know. I'm skeptical that that will work and all of this goes against it. SETI and our chances of finding evidenceof extraterrestrial intelligence because if their signals are too weak or they deem it not worth sending messages, we won't find them, so some people have suggested that maybe we should send our own messages. Instead, if they don't message us, maybe we should be the ones to say hello and provoke them to respond and this has caused big discussions in the SETI community because some people think it's dangerous, maybe we don't know what's out there.

What's out there is evil, maybe it could be a War of the Worlds scenario or something and I think it's a straw man argument because the distances involved would mean they're unlikely to be able to mount an invasion expedition, no. Interstellar travel is impossible. So here we have an artistic representation. This is the other URI Milner project that is doing an innovative star release. He wants to launch a fleet of small spaceships called star chips and broadcast them. Place them in laser beams that would push them to the end. Even Alpha Centauri will reach a fifth of the speed of light and will arrive there within 20 years.

Now there are still technological hurdles to overcome by focusing lasers to figure out how these small spacecraft, when they reach their destination, will be able to collect information and transmit it. It comes back to us, but in theory it could work and this is not the first time we have thought about sending spacecraft to other stars in the 1970s and the British Interplanetary Society developed the Daedalus project, which was a fusion-powered spacecraft and there are modern ones. day equivalents project project Icarus dragonfly it's okay to build spaceships on paper it's completely different to build one in real life and that's why we haven't built an interstellar spaceship yet but in theory we could we already have the Voyager spaceship venturing into interstellar space There is no reason why aliens couldn't send us a probe.

It's possible they could send some sort of invasion quickly, but I wouldn't worry about that. The analogy or example that many people mention is when the Europeans went to the Americas and with the conquest the doors were for the Aztecs and all the problems that followed one hundred million people died in that European colonization, but it was not all through violence, most of those deaths were caused by diseases brought by Europeans, against which the Native Americans had no built-in defense, now we don't really have to worry about diseases coming from aliens because even if they came here at some point type of organic farm, our biology would probably be completely incompatible, so we would probably do it.

We don't have to worry about that, so I think it's a bad example, but I think we do have to worry a little bit about causing contact with the early tulip flowers. What the hell what kind of problem could cars cause? Actually, in 15th and 16th century Holland they caused a lot of problems, so tulips were imported to the Netherlands at that time and the Dutch loved them, they loved tulips and started buying and selling them. them for ridiculous amounts of money and created an economic bubble the bubble eventually burst people lost their money lost their homes now I called it tulip mania that was just the chaos caused by a simple flower now imagine we make contact with an extraterrestrial civilization and they give us Some of its technology, it could be much more advanced than any technology we have and maybe we wouldn't even understand how it works, but it could do amazing things now, the technology we invented causes those problems, social media on the Internet, it's great.

It's because of the interconnectivity, you know, people from all over the world can connect, but social media is changing society, you know, right in front of the ISM, we don't know how that's going to change us and obviously there are bad things about it. and good things, unintended consequences of that technology, like simple Internet technology, cars that get us from A to B, you know, they're great for the economy, but they produce all kinds of air pollution and we lay waste to the countryside with bulldozers to build roads and parking lots. an unintended consequence of our own technology now let's imagine extraterrestrial technology that we are not prepared for maybe they will give us a replicator like in Star Trek that can allow anything to materialize what would that affect jobs what would affect economies what would that affect In our drive to get something right, could you press a button and make something happen?

On the other hand, poverty would be eradicated, so there are good and bad things, as with any contact civilization in human history, there are good and bad things about it. It's very complex, but I don't think we're ready yet for that kind of alien technology, so the concern is that by transmitting our own messages and potentially causing another civilization to respond, remember that by transmitting our message we have given them our language. so they can understand. us so that we can understand them when they respond, we may not be ready for that contact and this is what I call the contact paradox, name of my book, we spend that time looking for life out there, but when we find it, we are hesitating in making that contact because the unintended consequences are misunderstandings, misunderstandings that could occur, so that's the way out of this paradox.

I think now I mentioned that the scientific community has disparaged SETI and I think that's wrong because I think large areas of science have to do with the cosmology of life. You think cosmology has to do with life. Well, the history of the universe here. Why is the universe fine-tuned for life? It looks suspiciously set up to build stars and planets. Allow life to exist. Why? That's something theoretical physicists in particle physics are investigating. It comes down to life. In the end we study agricultural regions that grow stars and planets because we want to better understand how the Sun formed and how planets like Earth formed. and how plants like me get the water we need for life astrobiologists want to understand the extremes to which life can survive, where life might live, and what that tells us about their own life evolved such large areas of science that deal with about life, so it seems silly to me, scientists avoid SETI, it's just part of the big story we're finding, so I think before we try to contact anyone who might be out there, we should first do a little recognition, you know, scientists should come.

Together they will try to discover everything they can about life and look and see if we can find any using spacecraft as the test mission. We'll see if this animation works, so testing is the Kepler successor we'll be looking for. exoplanets around nearby stars Next December, the European Space Agency will launch the Key Operations Mission, which is a mission that will characterize some of these exoplanets, find out exactly how big they are, and combine that with our understanding of their mass. They will be able to calculate their density and determine if they are solid or gaseous planets and if it is possible that life exists there.

Next decade the European Space Agency is going to launch another exoplanet characterization mission called aerial that will study the atmospheres of the planets as I mentioned before and look for these biosignatures, we have other telescopes online, there is the extremely large telescope in Chile, the Webb Space Telescope, in the future they have plans for missions that will take direct images of potentially Earth-like exoplanets. and we will continue to do SETI and we will continue to do astrobiology and understand more about life and where life could live and I am willing to bet that by the end of this century if there is life on a planet 50 to 100 light years away we will have found it so once we find it we can study it we can learn more about it if it's intelligent life if it's warlike they're like us what kind of technology they have what It's like we can spy on their own leaks and learn more about them and then once we know more about them, then we can think about making contact and opening those call frequencies to me, would that be the most responsible thing to do?

I would expect an advanced civilization to deal with us and treat us with kid gloves rather than convert, so in closing, I think the take home message is that when we do SETI there is a phrase that I use in my book, the stars are like a mirror we look at the stars in search of extraterrestrial life but we see our faces reflected when we do SETI yes of course we are thinking about extraterrestrial life but we are also thinking about human life that we are extracting by extrapolating from our own experience and putting ourselves in context by learning about ourselves and in writing the book, you know, I learned a lot about human altruism and human intelligence and how the Earth formed and created a habitable environment and how we can become extinct and when we look at the advancement when we consider advanced alien civilizations that you already know, like I said, we are really a representative of advanced human civilizations and we have the opportunity to maybe one day be one of those advanced civilizations, but we will not be if we blow ourselves up or if we allow the climate emergency to destroy the environment or the pandemic wipe us out or a million other threats that we face, so we could start right now to address these concerns and build a better future and maybe one day we will be one of those advanced civilizations and we will be able to reach the galaxy and meet other civilizations, but until then we must learn, we must listen and do what we can to build a better future for all, so that's all, thanks for listening.