A galaxy to understand | News

Since ancient Greece, people have wondered about the material composition of the material … of the material. The philosopher Democritus had proposed that everything that exists actually consisted of infinitely small and indivisible bodies: atoms. It is clear that Democritus could not scientifically prove the existence of the atom; it was just a guess. His reasoning was: what would happen if you repeatedly cut an object in two? At some point, we would reach the smallest kind of substance possible … He christened this hypothetical object atomswhich means “indivisible”.

We know today that what we call the atom is actually divisible, but Democritus’ explanation is still important in the context of the times. Atoms are made up of particles such as electrons, protons and neutrons. These last two even consist of subparticles called quarks (the electron would actually be elemental).

To our knowledge, the visible universe is composed exclusively of atoms and particles. Our planet is an agglomeration of atoms. The atmosphere, the soil, the lakes and rivers all consist of atoms. And life! Life is also made of atoms.

Man is a collection of billions upon billions of atoms carefully harmonized into complex molecules. Our brain, where electrical impulses from our nervous system are interpreted, registers and analyzes the data that the body collects about its environment. And oddly enough, the human brain, in itself a collection of atoms, has acquired the ability to to understand the atom.

So here is a question: how many atoms are needed to understand the atom?

The adult human brain has a mass of about 1.5 kg. We could, thanks to Avogadro’s numbers (which measure the amount of elemental units that a mole of substance contains), estimate how many atoms there are. The result would be gigantic: for comparison, a small sip contains 18 ml of water more hydrogen and oxygen atoms than there are stars in our galaxy!

Be careful though: the brain alone is not enough. It needs a body to feed itself and develop. The brain needs vital organs to survive, a skeleton and muscles to move, eat and learn. Considering that an average adult human can weigh from 50 to 150 kilos, the number of atoms needed to understand the atom has just increased considerably.

But that’s not all. The human body and its brain cannot develop in empty space! They need a planet to live in, air to breathe, water to drink and nutrients to eat. When you think about it, the whole planet is necessary to understand the atom. The earth has an approximate mass of 5.97 x 1024 kilo. It was on this agglomeration of atoms that the life process began almost three billion years ago. Without all this mass, modern man would never have been able to evolve to understand the atom.

But … stop it! The Earth would be nothing more than an insignificant ice-cold dust without the presence of the Sun. Without the energy it gives us, the atmosphere and oceans would be frozen. There would be no climate to redistribute heat and water over the entire surface of the globe. Without a stable adult star like ours, the chemical reactions that led to life would never have taken place.

The sun has a mass of 334,000 planets Earths. It alone occupies about 99.8% of the mass of our entire solar system. The atoms in the outer layers of the Sun crush them by gravity in the Sun’s core. These are so pressed that they melt together into heavier elements, creating a huge amount of heat energy. So if we add the Sun, the number of atoms needed to understand the atom simply increases exponentially again.

Except that … stars are not formed in a vacuum! They are the product of the nebula’s gravitational collapse, the large clouds of gas and dust that are ubiquitous in galaxies. The Milky Way, our galaxy, is estimated to contain 100 billion stars. There are many atoms.

Does it continue? Does the Milky Way need other galaxies to support life? I do not know.

Conclusion: how many atoms does it take to understand the atom? The answer is both simple and disarming: at least all the atoms in a galaxy. At most, perhaps indirectly, the whole universe is required for the understanding of the atom …

But what do I know? After all, I’m just a collection of atoms trying to figure it out.

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