What's the greatest number out there


Is there life elsewhere in the universe? Mankind has never been so close to answering this ancient question. However, the Martians could just be bacteria and the little green males could stay out of reach for a long time - or even forever.

This content was published on August 9, 2018 - 1:00 p.m.

During the first years of my career, I worked in the western Swiss regional press (print and radio). In 2000 I came to Schweizer Radio International, during the transition to www.swissinfo.ch. Since then I have been writing on a wide variety of topics, from politics to economics to culture and science; sometimes I also report in the form of short video clips.

More about the author | French-speaking editorial team

Barely a month now goes by without reports of new advances in the search for extraterrestrial life. And in this search, the Swiss researchers - they were the first to prove the existence of exoplanets - did not stop behind the mountain.

At the end of June, the University of Bern announced an unusual collaboration between medical technology and astrophysicsExterner Link. With a common method, thanks to machine learning, planets outside our solar system are to be examined.

Both areas are interested in finding molecules. While the doctor looks for biomarkers that reveal the presence of a disease in the body, the astrophysicist tries to identify substances in the atmosphere of a planet that suggest the existence of life on its surface. And for both, the review of images can be entrusted to a machine that learns over time.

Machine learning in medical technology research was developed at the "ARTORG Center for Biomedical Engineering Research" External Link at the University of Bern and can now also be used by the "Center for Space and Habitability" External Link (CSH, also at the University of Bern).

Signatures in azure blue

The University of Geneva is also working on the detection of molecules in the atmosphere of distant planets. Last month, she announced testing of a new, apparently promising technology, external link.

An international team led by a Geneva researcher - who is also a member of the National Research Program "PlanetS" external link - found a way to overcome the major problem researchers have with the blinding light of a star when trying to discover its planets to see. It's usually like trying to see the light of a match next to the headlights of a truck.

The team at the University of Geneva has now focused its research on a specific type of molecule that is believed to be found only on the planet or in its atmosphere, and not near the star.

The tests carried out with archive images are meaningful: If you only look for water (H2O) and carbon monoxide (CO), the planet becomes perfectly visible, while the star is as if "wiped out". Because H2O and CO molecules cannot exist on its surface because they would be immediately destroyed by the great heat.

However, this new technology is still in its infancy, and the researchers are impatiently waiting for the opportunity to test it with very accurate spectrographs mounted on large or extremely large telescopesExternal Link.

But why is the search for specific molecules in the atmosphere of distant planets so important? Because the latter really deserve their name - they are tens of thousands of billions of kilometers away from us - and even the best instruments will never allow us to see details on the surfaces of these planets.

Molecules, on the other hand, leave a signature in the light that our spectrographs can decipher very well. And science believes that some of them could suggest extraterrestrial life.

For example oxygen. In nature, this chemical element does not stay in its pure state for long. It systematically combines with other elements to form oxides. This also happened on the planet Mars, where the oxygen mainly combined to form iron oxide - i.e. rust - in the ground, which explains the red-orange color of Mars.

The earth's atmosphere, on the other hand, has almost 25% oxygen, because the plants constantly renew it through photosynthesis. Therefore, an oxygen-rich atmosphere could very well suggest another inhabited planet. At least as long as the chemistry of life is similar to that on earth and the oxygen does not come from another source.

The search for "biosignatures" mobilizes numerous researchers from all disciplines around the world. Three years ago the US space agency Nasa founded the network "Nexus for Exoplanet System Science" External Link (NExSS), which is dedicated to determining the habitability of distant worlds.

There are also two astrophysicists from the University of Bern. The two are convinced that the new generation of telescopes, including the famous Hubble successor, the James Webb Space TelescopeExterner Link, will provide answers. But in a message from External Link they warned against too high hopes: "What we discover will by no means be unambiguous," they wrote.

Our neighbors, the bacteria

But why does science look for life at such a great distance? Life, at least some form of life, can perhaps be found on Mars or one of the moons of Jupiter or Saturn, practically in front of our noses - if that can be said of planets that are 60 to 1,500 million kilometers away from Earth .

Humans have been working on this question: For 50 years their probes and vehicles have been exploring, sniffing, photographing and scratching the surface of the moon and Mars and transmitting data to Earth. Today it is known that Mars had water in abundance on its surface four billion years ago (see NASA video).

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Eau sur Mars

It is therefore not impossible that a simple way of life could have evolved. It is known that the elements that are responsible for the living mass on earth are abundant in the universe and that so-called "prebiotic" complex molecules can form practically anywhere, even under the most extreme conditions.

They have already been found on comets, meteorites and even in clouds of dust or gas, from which stars or planets emerge over time. Just last month, the European Space Agency (ESA) announced in a messageExterner Link that its Cassini probe had discovered complex molecules in the geysers that shoot up through layers of ice on Saturn's moon Enceladus.

Europa and Ganymede, two of Jupiter's moons, have similar properties. They are also protected from the cold by thick pack ice and warmed by the tides because of their proximity to their huge planet. And here, too, it is possible that bacteria, i.e. another form of life, have developed.

Without forgetting about titanium. Saturn's largest moon is the only one that is known to this day to have a dense atmosphere, seasons and even large lakes - the latter, however, made of liquid methane. Despite the extreme cold out there, scientists see numerous similarities between Titan and early Earth. And prebiotic molecules have also been identified as the elementary building blocks of life on titanium. But a few bricks don't make a house ...

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SRF Tagesschau from 6.8.2018: Nasa is looking for life on Mars

Nasa is looking for life on Mars

"You are already among us"

As science advances in small steps, people believe in all sorts of theories. A call on Facebook to prepare this article reached 12,000 people. And it was no surprise that some of the dozen comments came from people for whom the aliens have already visited us on Earth.

For others, a visit is much less likely, but the existence of life in the universe is very likely. "If we were alone, that would be a nice waste of space," said Carl SaganExterner Link, astrophysicist and author of popular science works.

Another reader writes: In order for a visit to be possible at all, one would have to admit that "General relativity is wrong and one can move at the speed of light or even faster. And that our existence would be a sufficiently interesting topic to make an expedition lasting several generations to send to our planet ".

In the absence of formal evidence, there is only one scientifically honest answer to the question of the existence of life and even civilizations in the infinite space at the moment:

We don't know anything!

A recently published book recalls this fact loudly: "Aliens" Externer Link by Jim Al-KhaliliExterner Link, whose somewhat lurid cover of the French-language edition is reminiscent of the movie posters for the masterpiece by Ridley Scott as well as the series X-Files.

The Anglo-Araker Al-Khalili is a physicist and a star of popular scientific literature in Great Britain. In his collection of essays he provides an overview of "what science knows about life in the universe".

But as exciting as the book is, proponents of conspiracy theories will be disappointed. In 19 chapters, each written by a different author, some of whom have dedicated their lives to the search for the truth, it examines the aforementioned hopes of finding life in our solar system, but also the likelihood that we are all wrong because we're just looking for a life similar to what we know.

Because even on earth there are organisms that live under extreme conditions (extremely low or high temperatures, high air pressure or the absence of oxygen) and who do not care whether we consider their surroundings to be "habitable" or not.

In the book one also encounters the Fermi Paradox External Link ("If extraterrestrials exist, why don't they see us?") And the Drake equation External Link, which can be used to estimate the number of potential civilizations in our galaxy and which can be estimated by the radio astronomer Frank Drake, father of the SETI program External Link. Unfortunately, SETI's radio telescopes have not recorded any extraterrestrial signals for more than 50 years.

And one of the chapters on the origin of life on earth (according to current knowledge) shows well that we are the fruit of a series of very unlikely events, the chances of which they will occur more than once are less than infinitely small.

Worse than "alien"

As far as mythology is concerned, the authors are not satisfied with just a disdainful smile. On the contrary, they delve back to their roots and remind us that the famous flying saucer sightings, very popular in the US in the 1950s, were based on a misunderstanding.

The private pilot Kenneth Arnold was the first to witness "flying saucers" in 1947, although he had never said that they were in the shape of saucers but that they flown "as if you took a plate and let it jump over the water". The rumor and the local media, who smelled a scoop, finally cemented the term, as the following video shows.

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Kenneth Arnold UFO

Another chapter of "Aliens" is devoted to the thousands of eyewitness accounts of people who are convinced they were kidnapped by aliens. Here, too, the author of the chapter offers, without denying a priori the truthfulness of your descriptions, an alternative explanation based on two well-known psychological phenomena: sleep paralysis and false memories.

Disappointing? Maybe. But the "good news" for science fiction lovers is that Ridley Scott's alien and disgusting reproductive technique are perfectly realistic: even on Earth, numerous species are known to reproduce in even creepier ways!

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