Toutes les particules de l'univers expliquées

If you clicked on this video, it means you're a bunch of atoms. who are trying to understand what he is made of. A question that philosophers were already asking more than 2,000 years ago, wondering what is what they would see if they zoomed, zoomed, and zoomed some more. And just as at the time, they didn't have a scanning tunneling microscope or an accelerator. able to shoot particles at each other to see what was inside All they could do was philosophize. And after pondering extensively, they arrived at the conclusion that perhaps, even if On our scale, the world appears smooth and continuous; everything could be. are made up of tiny particles of matter, particles of matter to which They gave the name of atoms. Atom, which in ancient Greek means indivisible, indivisible which in modern French means something that cannot be cut or divided In short, an idea that, at the time, plunged humanity into an existential crisis unprecedented. No, I'm kidding. Back then, everyone didn't care except for a small handful. of researchers and philosophers. Somewhat like now, actually, but at least today we have the means to be able to prove by experimentation that matter is indeed composed of of atoms. Thanks to the emergence of quantum mechanics during the 20th century, it became possible understand the rules that govern the world of the infinitely small. Rules that are absolutely not intuitive and bear no resemblance to anything we can see in everyday life. For example, suppose you know nothing about it, not even a single atom—you surely represent it Like that. Basically, a nucleus with small balls orbiting around it, somewhat like an image of the Earth revolving around the Sun, with a trajectory, speed, and position well-defined. Except that an atom actually looks more like this. Because according to one of the rules of quantum mechanics, the Heisenberg uncertainty principle One cannot accurately know the position and amount of movements. of a particle. But we can simply know the probability of her being in a certain place or to another. And moreover, no, we will never be able to see an atom, not even with a hypothetical technology. futuristic, simply because to see something, it needs to interact with the light. And an atom is thousands of times smaller than the wavelength of light. visible At the very least, we will never be able to see them in the classical sense, since we can still detect them atoms and even manipulate them using tunneling microscopes, for example. Yes, of course, the best description we'll ever have of an atom is this thing Moche Oh, there it is. Yeah, it's very stylish and kudos to the guy, but still, it's just the version In 8K, this sketch is a bit sad. Briefly, let's take a helium atom. It has two electrons orbiting around a nucleus. And if we represent it like this, it's because, according to the uncertainty principle Once again, we cannot say whether he is here or there, but only that he has more. the chances of being there rather than there. We call this an atomic orbital, which is a mathematical function that describes the wave-like behavior of an electron or a pair of electrons in an atom. This function gives the probability of finding an electron of an atom in a region. data of this atom. We browse Wikipedia and feel scientific. Because yes, no matter how stylishly my team and I create visuals, the Quantum mechanics is mostly just mathematics. And math that looks like this, or at the very least, diagrams, but these diagrams In the end, they represent equations. No luck. In brief, the nucleus of an atom, which contains more than 99.9% of its mass, is composed of protons and neutrons, two of each in the case of helium. Protons and neutrons, which in turn are composed of even smaller entities, quarks. which are part of the family of the famous elementary particles. And pay attention, a small terminological point: one can say that all elementary particles are subatomic particles, as they are smaller than an atom, but all Subatomic particles are not elementary. A proton, for example, is a subatomic particle, being smaller than an atom, but is not not an elementary particle, as it is composed of quarks, which are even smaller units. Quarks, which are subatomic and elementary particles, since they are not known their internal composition, or even if, precisely, they are made up of things even smaller. All these elementary particles are neatly arranged in this table, or the dream humid to all physicists of the 20th century, and which is even sometimes called the theory almost everything, the Standard Model of particle physics. So I know it doesn't look very appealing like this, but don't worry, we'll get there step by step The main particles on the matter side are fermions, characterized in part by through their obedience to the Pauli exclusion principles. The thing that makes two electrons unable to occupy the same quantum state. Reason why they repel each other, which makes matter solid, and this What prevents you from passing through your chair, the floor, and the earth? Finally, that and Coulomb's law. At the fermion's, there are two categories. Already the quarks, which we've already seen, and which come in six flavors. Strawberry, chocolate, vanilla, double apple, icy mint, and blue raspberry. No, I'm joking—that would be the case if physicists were funny, but unfortunately for We're just as good at naming things as I am at placing a public cut. At the right moment. You didn't see that one coming. Briefly, the actual six flavors of quarks are up, down, charm, strange, top, and bottom. No, top and up, or bottom and down, are not the same. Two up quarks plus one down quark make a proton, and one up quark plus two down quarks make a neutron. a neutron Protons and neutrons, which make up the atom's nucleus, you follow. It is physically impossible to isolate a quark, because the more one tries to separate them, The stronger the nuclear force becomes, the more intense it will be between them. The nuclear force that binds quarks together within atomic nuclei, in short, of What's up? But we'll see that just afterward. So why talk about six flavors if only two of them are used to make it? the protons and neutrons? Well, because the so-called exotic quarks, namely charm, strange, top and bottom appear only at very high energies, such as in collisions cosmic rays or particle accelerators, and decay almost instantly in ordinary matters. Then come the leptons, and there are also six of them, surely because the table had to to be symmetric We already have the electron, you know that one—negative charge—and it revolves around the nucleus of the atom. Then the muon, an electron that eats well at the cafeteria, since it has the same properties bodies other than his, except for his mass, which is 207 times greater than that of the electron. Then the mass, similar to the electron and the muon, but even more massive. And finally, neutrinos—tiny particles with almost no mass and no charge that pass through almost all matter without interacting with it. In fact, there are billions passing through you and me at this very moment. And those ones also come in three flavors: electronic, muonic, and thionic. Magnificent, we've finished with the fermions. Damn it, every fermion has an antiparticle, identical in every way except for its charge. electricity as well as other quantum properties such as spin are reversed. The proton has the antiproton, the electron has the positron, and even neutrinos have their antineutrino It is from these antiparticles that antimatter is made, which, when it enters Upon contact with matter, both come to life and release a huge amount of energy. So fermions make up matter, but this matter must interact, after all. and it is there that bosons enter the scene, the particles responsible for the famed fundamental forces For example, the strong nuclear force we discussed earlier, the glue that holds the quarks in the nucleus of atoms and carried by the gluon. And she's a bit like Gimli—formidable and extremely powerful over short distances. distances Yeah, the two towers are my favorite. But not that one, the movie! The photon is the carrier of the electromagnetic force, so light, magnetic fields and all that stuff. Without mass, it mediates the interaction between charged particles, and incidentally It allows us to see. Chief cook. Then we have the W+, W−, and Z0 bosons. And already up to this point the names weren't great, so now there's absolutely none left. effort Carriers of the weak nuclear force, they enable the transformation of particles. one inside the other For example, a neutron turning into a proton. Process that partly enables nuclear fusion inside the Sun or radioactivity with beta decay. So in short, the one that creates the radioactivity of nuclear waste by transforming the neutrons and protons. And finally, there's one left, the famous Higgs boson, the most renowned one because detected in 2012 at the LHC. A particle that testifies to the existence of the Higgs field, a field that permeates everything the universe and is the origin of the mass of most particles. Think of the Higgs field as a kind of enormous invisible net that fills the entire space. When a particle passes through it, it catches slightly on the net and slows down. A bit as if she had to drag something behind her—that's what we call it. the mass Without this net, electrons and quarks would slip without ever resisting, and nothing could come together to form atoms, planets, and even stars. The more a particle adheres to this field, the heavier it becomes, and the less it adheres. plus she stays light-hearted, after all. And when it does not interact at all with it, like photons or gluons, it finds itself without mass. In short, here is a complete map of everything that makes up matter and forces. of the universe. Or, the graviton, the hypothetical particle that would be the boson mediating gravity. Well, as you can see, it doesn't appear on this chart, because for the moment, we are incapable of detecting gravity at the scale of particles, at least for now describe how it works at the quantum scale, which gives rise to one of among the greatest problems in modern physics, the unification between the two major theories which describe the universe, general relativity, and quantum mechanics. So there are many approaches: string theory, superstrings, quantum gravity loop, twister, or even some that suggest gravity might not be quantum, but if you want to know more, you'll have to check out my next big video where we You will see why these two theories are incompatible, and what solutions have been proposed. to reconcile them, and even a theory that claims to unify all of them the laws of physics in a single, unique model capable of explaining the entire universe. On my part, I'm awaiting your opinion on this new format, and please don't hesitate to let me know Leave your ideas for upcoming topics in the comments. In that case, I'm off to smoke, whether in clear or in shadow.