Michel Mayor, Nobel laureate in Physics: ‘People think humanity is eternal, but we are animals and we will become extinct’

Michel Mayor’s life could have ended in one of the worst deaths imaginable. In 1968, this Swiss mountaineering enthusiast fell into a crevasse on an Alpine glacier. One possibility was that he might become trapped between two suffocating walls of ice that would slowly swallow him with every cry for help, with every movement he made to try to escape. In the end, he was lucky: his companions pulled him out, bleeding but alive.

Thanks to his companions, Mayor went on to become an astrophysicist and, in 1995, to discover the first known exoplanet. The discovery of the first world outside our solar system was a revolution that continues today, with more than 6,000 exoplanets identified, many of them in other solar systems, each more different than the last.

In 2019, Mayor received the Nobel Prize in Physics for contributing to the understanding of “Earth’s place in the cosmos” — a planet that is just one among billions. He was in Spain on Tuesday to take part in a colloquium on exoplanets at Madrid’s Conde Duque Cultural Center. In this interview with EL PAÍS, conducted the day before in a hotel in the capital, Mayor — who is 84 years old and professor emeritus at the University of Geneva — speaks with the passion of a young man about a new grand scientific challenge: finding the first exoplanet with life.

Question. In 1968, you fell down a glacier, and humanity orbited the Moon for the first time with the Apollo 8 mission. What do you think about returning to the Moon now, more than half a century later?

Answer. The explanation for that milestone was the competition between the United States and the then, Soviet Russia. Now it’s the same, but with China. The Apollo missions were interesting because they gave us geological information about the Moon, such as the isotopes in its rocks. Now the dream is to have a station on the far side with a radio telescope. Is it a good idea, considering the terrible cost it will entail? I’m not sure. It’s more political than scientific.

Q. What do you think of the idea advocated by new space magnates like Elon Musk, that we must become a multi-planetary species now?

A. I’m very critical. Musk says his dream is to have a million people living on Mars in the next century, all emigrated from Earth. I cannot share this view. Mars barely has an atmosphere. It’s impossible to terraform it to generate as much oxygen as would be needed. It’s completely unrealistic. The worst place on Earth is paradise compared to Mars. And climate change, however severe, won’t change that.

Q. And what about the idea of going to the Moon as a stepping‑stone to going even farther?

A. Imagine we found a twin planet of Earth about 30 light-years away. On the galactic scale, that’s very close. The astronauts [of Artemis 2] took about three days to reach the Moon. At that speed, it would take us millions of years to reach that second Earth. The energy that would be needed to accelerate and then decelerate near our destination is impossible for us to achieve. The dream of colonizing an exoplanet is impossible.

Q. Yet we know there are many exoplanets like ours, don’t we?

A. A great many. In our galaxy alone, there may be more than a million. But they are all too far away. And then, is there life? Determining this is the great challenge of the future. Creating the instruments and the chemistry to detect what are called biomarkers: a mix of molecules saying, “oh, probably this is only produced by a chemical reaction related to life formation.”

Q. How far are we from that?

A. At the present time, the James Webb Space Telescope has detected many molecules, but not on rocky planets like ours. We are still far from finding biomarkers on those. To reach the level of an Earth twin, we need new things, like the 39-meter European telescope. But even then, I’m not sure it can be done. And you have to be careful. There are many supposed discoveries of exoplanets with life that turn out to be nothing.

Q. Could it happen in the next decade thanks to the next generation of observatories?

A. Honestly, I don’t know. I remember when we discovered the first exoplanet, two robotic missions — NASA’s TPF and the European Space Agency’s Darwin — were going to be launched to find terrestrial planets with life within about 10 years. Three decades later, both missions were canceled, and we still have no answers. In any case, I’m optimistic, and I believe that life exists in many parts of the universe.

Q. Is there any other major question in this field that we can answer?

A. Yes. For some years now, we’ve been able to directly image exoplanets, and we’ve discovered some that way. The problem is that these worlds are very large and very far from their stars, about 60 astronomical units [60 times the distance from the Sun to the Earth]. The classical mechanism of planet formation can’t explain this. So now we know that planets can form in other ways that we didn’t even know about before.

Q. Is our view of the universe biased by technology?

A. We are always biased. Most stars in the universe are low-mass, less than our Sun, which isn’t even the most abundant type. Rocky planets like Earth that orbit low-mass stars are much closer to their stars. A real Earth twin around a star like the Sun is much farther away from us, and discovering it is much more difficult. Planets around low-mass stars can receive enormous amounts of radiation: how does that affect the possibility of life? We’re surrounded by biases, but we just have to keep them in mind and keep searching.

Q. Do you think other civilizations exist, and that we’ll ever know they exist, assuming they’re more intelligent than we are?

A. They may be, but they’re governed by the same laws of physics as we have. Thirty light-years is too far for anyone. I find these discussions unproductive, just like the one about deflecting potentially dangerous asteroids. The diameter of those that could actually cause a total catastrophe is about 10 kilometers [6.2 miles] or more. To deflect one of those, we’d have to build the largest atomic bomb imaginable and keep it ready for about 1,000 years. Let’s not forget that we’ve had some very crazy people on Earth, like Hitler, Stalin, and some more recent ones. I don’t think the risks of being hit by an asteroid outweigh the risk of us misusing that bomb against ourselves.

Q. You don’t seem very confident in humanity’s long‑term survival.

A. Many years ago, I was invited to give a talk about exoplanets at the parish church of a small village. The priest wasn’t happy because he expected something more spiritual, something closer to the long-term existence of humanity. So I replied that we might last another million years, at most. We know this from paleontology.

All species appear and disappear; they have a predetermined lifespan. In people’s minds, however, humans appear and never cease to exist. We are eternal. But the truth is that we are animals, and we are going to become extinct. We have to consider the probability of impacts like the one that wiped out the dinosaurs 67 million years ago. Furthermore, in about 2 billion years, we will no longer be in the habitable zone of the solar system. And that’s without taking into account crazy and dangerous humans. We know that our time as humanity is limited.

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