This is what a proton looks like

The chair you’re sitting in right now. L’computer where you read this topic. And even thebird that you hear sung by the window opened. The matter that surrounds us is made up ofatoms. Tiny particles invisible to our eyes. Tiny particles themselves made up ofelectronsof neutrons and protons. Even smaller particles. Even more invisible.

Invisible, but still very real. So, have you ever wondered what these tiny particles look like? Kinds of tiny solar systems made up of electrons orbiting around a nucleus made up of neutrons and protons. This is the image that has long been proposed. But the physicists of today know that it is not fair. And since you have to start somewhere, researchers from the Massachusetts Institute of Technology (MIT, United States) invite us to discover what a protona particle no larger than a femtometer – i.e. 10^-15 meters. And spoiler attention, it’s not quite the perfect billiard ball that we are still traditionally presented with at school.

To be honest, MIT researchers have been thinking about it for almost twenty years now. Let them reflect on the best way to give us an accurate picture of what a proton is. The idea of ​​making it a simple robot portrait was quickly dismissed. Because the world of physical particles is somehow…alive! He is evolving. He is in movement. Particles are created. Others disappear. Some are transformed. And only an animation could make this reality palpable.

But the physicists at MIT really wanted to go beyond anything that was known. Of everything that had already been presented so far. They set themselves a real challenge: to collaborate with artists. To provide animation that is both scientifically accurate and visually appealing. Make bold choices that would help “people come away with a better understanding of their interpretation and of physics in general”.

The proton, a particle ultimately not so elusive

Before going any further, remember that the researchers have established that the proton is not a elementary particle. It is made up of three quarks – two called up quarks and one called down quark. And it is this force that physicists call thestrong interaction which binds them together. Through the exchange of gluons. This interaction is so powerful that never before have quarks and gluons been observed separately.

The artists who worked with the MIT teams thus depicted quarks as points of light. Moving points of light whose color is constantly changing, changing from red to green and blue to represent the color charges that appear between the quarks and gluons subjected to the strong interaction. Because according to quantum theory, all systems of quarks and gluons wear an equal amount of these three colors. Even though they are not actually colored blue, red or green.

Experiments carried out using increasingly efficient particle accelerators have also shown physicists that at the heart of the proton, it is generally the gluons that make the law. But in some regions, quarks take over. Within a few years, a new instrument, the Electron Ion Collider (United States), should make it possible to specify what is happening at the limits of these regions. But already, the team that assisted MIT researchers to produce a faithful representation of the proton has succeeded in constructing an animation that accounts for its changing structure. A structure dominated by gluons which constantly separate and recombine when the “exposure time” – which corresponds somewhat to the fraction of the proton momentum carried by a quark or a gluon – is weak. When the “exposure time” increases, it is the process of creation by a gluon of a quark and its antiquark which is shown. Finally, with a “exposure time” high, the three quarks that form the proton appear.

Better than that, the researchers managed to put in image what one observes when one sinks in the heart of the proton. When increasing the resolution spatial. When details appear and a relativistic effect causes the proton to lose its ball shape and turn it into a disc. For a “exposure time” weak, there appears an increasing number of gluons. For a “exposure time” high, it is a rather coarse structure, but all the same defined and comprising three quarks, which becomes more marked.

The researchers now plan to work on developing a 3D version of this visualization of the proton. Before proposing, later, an animation of the atomic nucleus. And frankly, who doesn’t dream of following them into the marvelous world of the physics of the infinitely small?