Mille mercis à Catherine Peillon de m’avoir demandé la version française de ce texte pour son exposition Le Reste.
The rest: atoms, the Sun and gravity!
The rest … I’ve been asked to write about the rest. It immediately comes to mind in this physicist’s mind: the remainder is what is there anyway, what cannot be removed, those who always remain. This remainder precedes us and will be there for an infinitely long time, on the scale of human existence and probably even of life on earth.
In the end, what’s left are atoms, the sun and gravity. From this perspective, in the search for what’s left, references come thick and fast. It’s quite a story, and we don’t feel alone.
The rest, the atoms, the matter of the Earth.
Today, the exchange of matter between the universe and the Earth is reduced to practically nothing, in terms of quantity. True, there are a few meteorites. The atoms that make up the Earth’s matter have been here for billions of years and will be here for billions more. It stays there. A few transformations here and there, radioactivity. A negligible quantity compared to the rest.
This remnant has a name, it’s called “atom”, atomos, the unbreakable, the indivisible in ancient Greece. Democritus Epicurus, then the Latin Lucretius… each time, the admiration: having only thought of it !
Later came Antoine Lavoisier’s “nothing is lost, nothing is created, everything is transformed”. New admiration. What a vision. The rest, the atoms: they’re about a hundred different atoms. A hundred different atoms. Their ever-changing combinations are innumerable and are the origin of this infinite diversity of matter, form and life, but there are only about a hundred of them in Mendeleev’s table. They are the first element of the rest.
The rest, the Sun, to the divine
And every day, with infinite certainty, the sun shines. We know it will go out, and we know it has appeared. No uncertainty here. But on the scale of humanity’s existence, it has always been there, and it will always be there. Whatever happens, whatever happens to us, it will be there. And for the most part, apart from a few fluctuations, it will always be the same. Water, carbon dioxide, sunlight, a few minerals to go with it – every living thing on Earth, without exception, finds its origin in photosynthesis. Directly for the flora, cascading down to the fauna that eats. Unsurprisingly, this part of the rest, the Sun, has been identified as such since … no idea in fact. It’s been called Ra, Apollo, Helios, Surya, Sol Invictus, Amaterasu, Inti, Utu, Tonatiuh, Lugh, Mithra, Belenos… And thank you ChatGPT who in one second gives a list of more than 10 divinities all over the Earth and in all eras. For a long time, the Sun has been a God, and if we had to look for just one reason: it conditions our existence. Without its electromagnetic radiation, its light, there would be no life on Earth.
For the physicist, it’s the source of extraterrestrial energy from which the Earth benefits. It is at the origin of most of the transformations of matter around us. Life is an immense machine for transforming solar energy. Still far beyond human production of energy by fire, fossil combustion, the age of Prometheus.
The four fundamental interactions
Then, finally, the everyday obvious. We don’t even think about it anymore, because the last remnant defines us. Literally. But before tackling gravity, which is always and everywhere, the four fundamental interactions, including gravity. I’ve overlooked the two nuclear interactions, which are the source of the stability of atomic nuclei. A thought here for the alchemists, led by Newton, who couldn’t possibly have known this, but what a great idea for a researcher as that of transmutation. Sunlight and Lavoisier’s “nothing is lost, nothing is created, everything is transformed” are first and foremost linked to electromagnetic interaction, the fourth here. The properties of this interaction within the framework of quantum physics enable us to understand the structure of atoms, and the chemistry so well summarized forever by Lavoisier.
Gravity, always and everywhere
The last is the gravitational interaction between masses. Even light is affected by gravity, the extreme in the universe and the black hole. On our scale, it’s weight. Even Thomas Pesquet, in a satellite, is in free fall under the effect of weight. On Earth, no mass escapes weight, the gravitational force due to the Earth.
For the rest, I still can’t say it any better than sculptor Richard Serra: “It’s difficult to communicate ideas about the weight of everyday objects, because it would be an endless task; there’s an imponderable immensity of weight.” The words of a sculptor who is constantly grappling with weight. On Earth, whatever you do in the end, the weight stays.
There’s more to it than that: everything moves.
Ah yes! I almost forgot, but the physicist Richard Feynman allows me to complete the picture: “If, in a cataclysm, all our scientific knowledge were to be destroyed and a single sentence passed on to future generations, what statement would contain the maximum amount of information in the minimum number of words? I think it’s the atomic hypothesis (or atomic fact, or whatever you want to call it) that all things are made of atoms – little particles that move in perpetual motion, attracting each other at small distances and repelling each other when you want them to penetrate each other. In this one sentence, you’ll see that there’s an enormous amount of information about the world, if you apply a little imagination and thought to it.“
I almost forgot “little particle that moves in perpetual motion”. At any temperature, all atoms move. All atoms. Everywhere and under all circumstances. We write:
This is Brownian motion, the study of which earned Jean Perrin the 1926 Nobel Prize. Whatever happens, atoms will always move as they have always moved.
What can I add to the rest?
I even thought I belonged to the rest. As a twentieth-century scientist who was listened to because, if not telling the truth, at least seeking accuracy in the obvious sharing of objective, validated knowledge. In the twenty-first century, scientists committed to speaking the truth about climate, biodiversity… find themselves brutally denied against the evidence. More and more. All the same, to their surprise. Could this be the simple consequence of the transition from driving forces and major players in a thermo-industrial society undergoing seemingly infinite growth, to the role of Cassandra?
This attempt to describe the rest as “atoms, the Sun and gravity!” has its origins largely in great questions identified by Galileo. We are reminded of his life: “E pur si muove”. Had we forgotten?
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