Last March, a multinational research team led by Jonathan Jiang, member of a NASA laboratory, proposed sending a new message to contact extraterrestrials. In a paper published in, entitled “A Beacon in the Galaxy”[1], the authors detail the content of the message and the point of the galaxy to which to direct it, as well as the best time to send it. The possibility of understanding through any type of language with beings who have been able to evolve very differently to humans has been ruled out. However, we can rely on an exchange of scientific information, because the physical laws are the same throughout the universe. The message, known by its abbreviation BITG (Beacon in the Galaxy), is largely an update of the Arecibo message sent in 1974. Written in binary code, ones and zeros, it contains prime numbers and mathematical operators, the biochemistry of life, the human form, the location of the Earth and a timestamp. It also includes a return address that allows any alien listener to reply.

It is scheduled to be sent from the world’s largest radio telescope, in China, sometime in 2023. The telescope, measuring 500 meters in diameter, will emit a series of radio pulses over a wide strip of sky. These on/off pulses are like the “1” and “0” of digital information. It will be directed towards a group of millions of stars near the center of the Milky Way, between 10,000 and 20,000 light years from Earth. While this expands the number of potential extraterrestrials the message will reach, it also means that tens of thousands of years will pass before Earth can get a reply.

Contacting extraterrestrials

Speculation about extraterrestrial life is as old as philosophy. Aristotle already held that the Moon was inhabited, while as late as 1941, people believed in the existence of Martians. Human curiosity has led to multiple proposals to contact aliens. In 1820, the mathematician Karl Gauss proposed to construct geometric diagrams of enormous dimensions by planting large trees to draw the outline of a Pythagorean triangle and three squares, covering a distance of twenty miles, as a means of signaling to the Selenites, the inhabitants of the Moon[2]. The advance of science has been ruling out the existence first, of Selenites, then of Martians, and gradually pushing the possibility of any type of intelligent life further and further away. Nevertheless, it has not managed to quench man’s longing to continue trying to contact intelligent beings.

In 1972, NASA launched the Pioneer 10 spacecraft toward Jupiter with a plaque containing a drawing of a man and a woman and symbols showing the origin of the spacecraft; in 1977 a new item was sent with the Voyager 1 spacecraft[3]. These spacecraft, as well as their twins, the Pioneer 11 and Voyager 2, have already left the solar system, but in the vastness of space, the odds of anyone finding these or any other physical object are incredibly miniscule.

The attempt now being planned is a copy of the message that was first transmitted on 16 November 1974 from the Arecibo Observatory in Puerto Rico, improving and updating some points. It was a three-minute signal to the constellation M-13, which is 24,000 light-years away, and which has passed into posterity as the Arecibo message.

Fermi’s Paradox

The search for extraterrestrial life has been very much alive for the last seventy years, employing increasingly powerful telescopes and automated data extraction techniques. The sky remains silent in this regard, and so we continue to ask ourselves the same question that Enrico Fermi rhetorically posed in 1950: “Where are they?” This is a pertinent question, since the notion that there must be multiple civilizations of intelligent beings in the universe, even in our own galaxy, is based on two ideas.

The first is that the emergence of life on Earth, as many scientists claim, is an inevitable fact: given similar conditions it should be repeated. This was the response of influential physicist and popularizer Carl Sagan to biologist Ernst Mayr: “the origin of life must be a highly probable circumstance; as soon as conditions permit, up it pops!”

The second is the evidence, which has been reinforced in recent years, that the observable universe contains a large number of solar systems, many of them with Earth-like planets, at least in the sense of having a similar mass and temperature. We also know that many of these solar systems are much older than ours, so they could have an evolutionary advantage of billions of years.

The reason they should become visible is based on the hypothesis that any advanced civilization should aim at the colonization of space, as Hart suggested in his article “An Explanation for the Absence of Extraterrestrials on Earth”, published in 1975[4]. Since then, different mechanisms have been proposed by which an intelligent species could colonize space. The most plausible would be through so-called “von Neumann probes”, unmanned self-replicating spacecraft controlled by artificial intelligence, capable of interstellar travel. A probe would land on a planet or asteroid, where it would extract raw materials to create multiple replicas of itself. These replicas would allow colonization to continue in all directions. Our galaxy is about 100 billion light years in diameter. If a probe were able to travel at one-tenth the speed of light, all planets in the galaxy could be colonized in a couple of million years[5], a short time in terms of the universe.

The great silence

An explanation had to be sought for this paradox, an inevitability of generation of life on Earth, many planets with similar suitable conditions, and a tendency or need of advanced civilizations for space colonization. Against all this, we see only a quiet and peaceful night sky.

The most acceptable explanation proposed is the existence of a Great Filter[6] at some stage in the evolution towards an intelligent civilization, which makes it extremely unlikely. Evolutionary biology, for the time being, does not allow us to calculate from early principles how likely or unlikely the evolution of intelligent life on Earth was. What we do know is that life on our planet in its 4.5 billion years of existence has been generated only once: all living beings, from bacteria to human beings, have the same origin, and intelligent life has also originated only once. We also know that in the evolution from inert matter to intelligent life there are different critical steps, and at least one of these steps must be highly unlikely. It is what is defined as the Great Filter, which turns the existence of intelligent civilizations into something highly unlikely. The answer to Fermi’s question (“Where are they?”) would be simple: “They’re not there.”

Are we alone?

More than sixty years after Cocconi and Morrison (1959) first pointed out the possibility of looking for extraterrestrials in the microwave spectrum[7], the sky remains silent with no signs of intelligent life and the question of the existence of simple or complex life beyond the Earth remains unanswered. Accordingly, it is worth asking what is the point of undertaking enterprises like the one proposed by Jonathan Jiang’s team. The answer could have been given two centuries ago by the great naturalist and geographer Alexander von Humboldt, when he said that “the most dangerous worldview is the worldview of those who have not viewed the world”[8]. It cannot be said that there has been a statistically representative sample of searches, and at the moment, we are facing an indeterminate problem. We have to keep looking. We need to know everything about the universe in depth, not least of which is finding out if we are alone. Moreover, we are aware that space research in general will undoubtedly bring benefits, many of which will be unpredictable, with consequences that will affect other branches of life. Astrobiology is essentially multidisciplinary and intertwines astronomy, the cognitive and life sciences, geology and planetary science, together with communication theory, bio-neural computing, machine learning and big data analysis. It also includes ethics, since the debate is open as to whether it is appropriate to send messages into space or to simply listen. The opinion of the influential physicist Stephen Hawking, who spoke openly about the danger of contacting extraterrestrials with superior technology, is well known. He argued that they could be evil and, if given the location of the Earth, could destroy humanity[9].

A project that invites reflection

This project invites us to meditate on the vastness of the universe. Dealing with values of time and space that go so far beyond the material dimension of the human being can induce feelings of insignificance. But in the face of the vertigo that seems to invade us as we contemplate the vastness of the universe, we must affirm the importance of the humanity to which we belong, aware that intelligent life is the only source of value.

Manuel Ribes

Bioethics Observatory – Institute of Life Sciences

Catholic University of Valencia


[1] Jonathan H. Jiang et al. A Beacon in the Galaxy: Updated Arecibo Message for Potential FAST and SETI Projects 2022

[2] David Lamb The Search for Extraterrestrial Intelligence 2001 SBN 0-203-99174-5

[3] Chris Impey Blasting out Earth’s location with the hope of reaching aliens is a controversial idea – two teams of scientists are doing it anyway 2022

[4] Michael H. Hart An Explanation for the Absence of Extraterrestrials on Earth, 1975 Quarterly Journal of the Royal Astronomical Society, 16:128-135.

[5] Nick Bostrom Where are they? 2008

[6] Robin Hanson The Great Filter – Are We Almost Past It? 1998

[7] Nathalie A. Cabrol Alien Mindscapes—A Perspective on the Search for Extraterrestrial Intelligence Article in Astrobiology · July 2016 DOI: 10.1089/ast.2016.1536

[8] Mike Gasparovic The Genius Of Alexander Von Humboldt, Latin America’s “Second Columbus” 2017

[9] Chris Impey Blasting out Earth’s location with the hope of reaching aliens is a controversial idea – two teams of scientists are doing it anyway 2022



Subscribe to our newsletter:

We don’t spam! Read our privacy policy for more info.