Dives into the caves of the universe with astrophysicist David Elbaz: “Life is not a coincidence”

He may well be in the industry after seeing other images of the universe, but this time David Elbaz recognizes it: he was “a little amazed.” “With my colleagues, we were amazed. We did not expect the pictures to be so fine, so beautiful. The details, the amount of information in it … it all exceeded our expectations, even though we had prepared”. Interview with the scientific director of the astrophysics department at CEA Saclay, author of “The Most Beautiful Ruse of Light” (Odile Jacob).

Why do we say that these images go back more than 13 billion years?

I will give a simple example. When the Jesuit Matteo Ricci went to China to convert the people, he wrote to his father, who answered him, but when he received the letter from his father, he was dead. The ink that was drawn during his lifetime came from a bygone era when the letter had taken years to arrive. The image we receive from a galaxy is exactly the same! Information comes to us after being conveyed by objects, in this case photons, light particles. Our telescope is perhaps 1.5 million km from Earth, but it is very, very close to us on the scale of the universe. The image traveled through space, and one fine day a telescope captured it. This is the object as it was more than 13 billion years ago. It is difficult to imagine because it also means that we cannot see the state of the universe in the present. For example, we see the nearest galaxies, as they were 200,000 years ago. And if I had the power to turn off all the stars in the universe now, we would not realize it in our lifetime!

the carina trains. “This is the largest star nursery. We can see all the evolutionary stages before their birth, which is still one of the greatest riddles in astronomy.” NASA, ESA, CSA, STSCI

premium First image of the James Webb Telescope, a new era of astronomy

What exactly will these images be used for, and how are they revolutionary?

It is a revolution in the sense that for some time we have known that observatories like the Hubble Space Telescope have a limit. He could not dive into the invisible, into depths that were never reached, for the purpose of seeing what is called the dawn of the universe, that is, the birth of the first stars and galaxies.

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With the James Webb satellite, we go from diving suits to submarines.

We will also be able to see something quite incredible: We know 5,000 planets orbiting other stars, we keep discovering more, but now we want to know if they have molecules that organize themselves, structure themselves , to give rise to complexity, in conditions similar to those that may have existed on Earth in the past. We will also be able to dive into the interstellar dust and see through it. A bit like making an ultrasound of the areas where stars are born.

Planetary nebula. “You have the future of the sun there in 5 or 6 billion years, when it will have exhausted its fuel reservoir. It will collapse about itself and become this little white star in the middle. We are witnessing both the death of a star and the birth of the universe. complex matter that we see around the mantle of interstellar dust. ”NASA, ESA, CSA, STSCI

Is it science fiction to discover an exoplanet with a habitable atmosphere? Nothing is guaranteed, and we also start with planets that we know are uninhabitable, such as WASP-96B observed there, and which are a gas giant that looks more like Jupiter or Saturn than an Earth. At CEA here, we participated in the construction of the MIRI instrument, placed aboard the James Webb Telescope, which made it possible to observe the atmosphere of the planets closest to Earth possible, including TRAPPIST-1b, such as beer, because it was Belgians who discovered it! We can find out if there is an atmosphere, water, if it is floating on the surface of the planet … The idea that we can find a habitable planet is now a reality. It is estimated that there are approximately 10 billion “Earths” in our galaxy and the Milky Way alone that could potentially carry liquid water. It’s not proof, it’s statistics. We have other telescopes under construction to go even further. This is not science fiction at all anymore.

premium James Webb: Ariane 5 has successfully injected the space telescope into its final orbit

Our wildest dream is to know that there is life on another planet.Astrophysicist David Elbaz. © François Palluau

Do not the reflections on the universe put us back in our place?

In the beginning, when men and women began to observe the universe, they realized that they were on a grain of sand in an infinite universe. Remember Pascal’s famous phrase about this “eternal silence of infinite space, which frightens me” … And then, afterwards, they understood that the universe had a history, and it changed things. In the past, this universe was very little organized, a little structured. The common thread in its history is that it has never stopped organizing itself in complex forms.

Sometimes people tell themselves that life is pure coincidence in the universe. However, this does not lead to more disorder, mainly thanks to light, which plays a major role in the organization of matter.

The universe made atoms, then molecules, dust grains, stars, planets and life. Some believe that they see evidence of the existence of God in it, others confirm that these are the simple laws of physics … The fact is that life in this universe is the result of a history, of an eternal organization. It makes me feel like she is even more valuable. We can say that we are nothing in this universe.

The quintet of Stephan. “Here we observe a cosmic ballet with galaxies that intersect and mutually influence each other by creating tidal effects (starburst, exhaust dust, black hole, etc.) such as the Moon over the ocean”. NASA, ESA, CSA, STSCI

But life is much more structured than the stars. Man is not a fault in the system. Today, the planetary challenges we face indicate to us that we must rediscover ourselves in this history in order to take on our responsibilities as living beings. It is, in my opinion, a good thing that man is confronted with problems on a large scale because it puts him in his place, that which inscribes it in the history of the universe. It was before, when we thought we could live our lives as if we had no influence on the world, that we did not belong.

Earth is a wonderful oasis bathed in a cosmic desert.

There are not many like that!

Florence Chedotal

To find the first images provided by the James Webb Telescope, here is the link to the photo gallery.

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