In the spring of 2019, the Parkes Observatory in Australia detected a series of intense and coherent radio waves, accompanied by a long emission of light, from Proxima Centauri, the closest star to the solar system. That same year, China’s FAST radio telescope picked up a signal with a frequency similar to that of a radio station. It was coming from the direction of Kepler 438 b, a planet slightly larger than Earth, a few hundred light-years from our planet.
Both broadcasts were labeled as potential extraterrestrial messages.. Two years later, researchers have concluded that in both cases it could be human interference.
What prompted you to think of messages from other civilizations in the first place? In addition to the strangeness of those signs, the appetite for the alien seems to be increasing in science. In fact, scientific articles on the search for extraterrestrial intelligence (SETI, in its English initials) published in peer-reviewed journals have not stopped increasing since 2000. For example, Penn State University (USA) has just organized for the first time a symposium that brings together experts on the subject. And this very month of June, NASA surprised by allocating $ 100,000 to investigate UFOs. What has turned a subject bordering on friquism into an attractive subject for more and more scientists?
millions of planets
Perhaps the main reason is that the universe is full of planets, a fact unknown until three decades ago: In 1992 the first exoplanet was discovered; that is, a planet outside the Solar System that orbits around another star. Since then, more than 5,000 have been found.
But there could be millions upon millions. “For every star in the Milky Way there is at least one planet, or more. The most common is that there is a group around each star,” says José Caballero, a researcher at the Center for Astrobiology (CAB-INTA) in Madrid. That means at least 100 billion planets.
Many of them are in all probability in the habitable zone: at the right distance from their star to have a temperature compatible with life. Caballero estimates that the exoplanets in the habitable zone are between one in ten and one in a hundred of the total. That calculation throws billions of potentially habitable planets into the Milky Way.. “We do not know the probability that life has been generated. But there is some agreement that if a planet has a correct separation from its sun and an atmosphere with the correct composition and with its lightning… sooner or later life will appear”, comments the researcher .
Intelligent life?
That this life is also intelligent life is another very different matter, about which Caballero is completely skeptical.. The ability to emit signals from Earth has existed for a century, a tiny amount of time compared to the history of life. According to the expert, the probability that the same thing has happened elsewhere in the Universe is too low.
This is not shared by Yuri Milner, a Russian physicist and entrepreneur who in 2015 allocated 100 million dollars to the Breakthrough initiative. This SETI project – sponsored by physicist Stephen Hawking and joined by Facebook founder Mark Zuckerberg – is the other major driver of the recent resurgence in the search for extraterrestrial intelligence.
The stigma of the alien hunter
Nevertheless, scientists looking for ET continue to suffer a stigma. “There’s the giggle factor. They tell you: oh, you do SETI, but that’s not serious science!” says Seth Shostack, an astronomer at the SETI Institute in California, a pioneer institution in the sector. “That happens more in Europe. In America we take more risks,” he says.
“There are people who pull back because it can represent a loss of prestige. If we did not have the discredit of people who make unfounded speculation, SETI would be a more active and funded area. We miss the possibility of finding answers to one of the most great questions of humanity”, says Ignasi Ribas, director of the Institute of Space Sciences (ICE-CSIC) in Barcelona. Ribas assures that he intends to dedicate himself to the matter in the future.
Gentleman is more sarcastic. “When you hear at a conference that so-and-so is in SETI, you clear your throat. Then you approach that person and see that he has taken a postdoctoral position in that sector because astronomers also need to eat,” he jokes. This astronomer believes that it is not worth investing more in something so unlikely.
Technological advances
“The investment debate is not new. If we collect data and find nothing, the interest in the subject will go away by itself. But if we look and find something, it would be an important finding. What would have happened if we had stopped looking exoplanets?” says Joseph Lazio, a NASA researcher and committee member of the Breakthrough initiative.
The truth is that there is no shortage of innovative ideas to find ET. One of the most talked about among experts is to look for laser signals instead of radio. After the invention of radio, experts assumed that an advanced civilization would develop the same technology.
Thus, they set out to search for broadcasts with a very tight frequency range (such as that of the stations, which are captured if the device’s wheel is moved to an exact frequency). Natural phenomena emit much less precise radio signals.
Today, laser technology has reached great maturity. For example, it is being studied how to communicate with space probes by means of laser pulses, instead of radio waves. “If we are thinking about it, there could be extraterrestrials who are already doing it,” observes Lazio. High power lasers could carry a lot of information in an interstellar communication. The search for light pulsations of this type – the so-called “optical SETI” – is on the agenda of the most ambitious programs.
technology firms
Another buzzword is technosignatures. In 2015, huge and irregular dips in luminosity were detected from a distant star, the “tabby star”. It was speculated that there must be large technological structures around it that obfuscated it as they operated. That would be a potential example of a technosignature – although it is ultimately believed that the cause could be huge clouds of dust.
Another potential example was the observation of Oumuamua, an object that passed through the Solar System in 2017. Its unusual shape, similar to that of a spaceship, and other characteristics led to the suspicion that it could be an alien probe, although today the idea prevails that it is a special asteroid. Other clear signs of technology would be to observe light sources on the dark side of an exoplanet – something that telescopes will soon be able to do, according to Lazio – or to measure excess temperature in a star – which would suggest that there is technology in its solar system. that dissipates heat, as is the case with terrestrial technology.
Earth calling ET
Another way to look for aliens is not to wait for their message, but to try to send them ours.. It is the METI (the English initials of messaging to extraterrestrial intelligences). For example, in 2017, the Sónar festival and the Institut de Ciències Spaces sent music and information from a Norwegian radio telescope to a star 12 light years from Earth. If there is someone there, their answer could reach us by 2042.
“Discredit penalizes financing and we lose the possibility of finding answers to one of humanity’s biggest questions”, says Ignasi Riba, from the Institute of Space Sciences
There are those who have been alarmed by messages like this. Is it wise for us to let ourselves be noticed by civilizations that we don’t know how friendly they are? Ignasi Ribas plays down the matter: we have been sending objects and signals for a century, so an advanced civilization would have found us anyway. Jordi José, an astrophysicist at the UPC and passionate about science fiction, observes that the opposite scenario cannot be ruled out either: good aliens who teach us how to make vaccines or clean energy. However, there are other more subtle questions, according to Lazio. For example, who has the right to speak on behalf of humanity? What messages should be sent?
What if we’re really alone?
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Shostack believes that the ability to observe millions of stars could yield exciting results for SETI within a couple of decades. “I’ve been in this business since I was 24 years old and I wouldn’t want to be buried before I found ET,” he jokes.
Caballero believes that “there is one civilization”. “We have a huge responsibility to those many planets with life that are probably in the galaxy,” he says. What would happen if we accidentally contaminated an inhabited exoplanet, for example, with bacteria? We could wipe out an entire world. “We are not capable of taking care of our planet. Will we continue to deplete the other planets wherever we go? On the contrary, we should be the gardeners of those other worlds,” concludes Caballero.