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 half? At some point we would reach the smallest form of matter possible… He named this hypothetical object atomswhich means “indivisible”.

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

According to our knowledge, the visible universe consists entirely of atoms and particles. Our planet is an agglomeration of atoms. The atmosphere, soil, lakes and rivers are all made up 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, records and analyzes the data the body collects about its environment. And strangely enough, the human brain, itself a collection of atoms, has acquired the ability to to understand the atom.

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

The adult human brain has a mass of about 1.5 kg. Thanks to Avogadro’s number (which measures the amount of elementary units that a mole of matter contains), we could estimate how many atoms there are. The result would be gigantic: by comparison, a small sip of water contains 18 ml 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. If you take into account that an average adult 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 the 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 needed to understand the atom. Earth has an approximate mass of 5.97 x 1024 kilo. It was on this agglomeration of atoms that the process of life began nearly three billion years ago. Without all this mass, modern man would never have been able to evolve to understand the atom.

But … hold on! The Earth would be nothing but an insignificant icy 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 occurred.

The Sun has a mass of 334,000 planets Earths. It alone makes up about 99.8% of the mass of our entire solar system. The atoms in the outer layers of the Sun are crushed by gravity those in the core of the Sun. These are so pressurized that they fuse into heavier elements, creating an enormous amount of heat energy. So if we add the Sun, the number of atoms needed to understand the atom just increases exponentially again.

Except… stars don’t form in a vacuum! They are the product of the gravitational collapse of nebulae, the vast clouds of gas and dust that are ubiquitous in galaxies. The Milky Way, our galaxy, is estimated to contain 100 billion stars. That’s a lot of atoms.

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

Conclusion: how many atoms are needed to understand the atom? The answer is both simple and disarming: at a minimum, all atoms in a galaxy. At most, perhaps indirectly, the entire 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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