The video discusses the structure of protons and how our understanding of these structures has evolved over time. Protons, the most common part of visible matter in the universe, are composed of three quarks: two up quarks and one down quark. This structure was confirmed in the 1960s. However, as particle accelerators became more powerful, physicists started observing a more complex structure. This complex structure, referred to as the quark sea, is a dense network of gluons that constantly transform into pairs of virtual quarks and antiquarks, which quickly annihilate each other, turning back into gluons.
Despite the complexity, there is order within the chaos. If you took all the contents of the quark sea in one instant, you could list all the quarks and all the antiquarks, and see that they cancel each other out except for two up quarks and one down quark. These “valence” quarks are what the first SLAC experiments detected.
The video also discusses the evidence of a charm quark inside the proton. The charm quark is more massive than the entire proton. However, the energy carried by the electron can create brand new particles, which means that the particles discovered after smashing an electron into a proton aren’t necessarily inside the proton to start with. This means that the charm quarks detected could have been created in the collision itself.
The video concludes by discussing the potential of artificial intelligence in understanding the structure of protons. A neural network was trained to analyze nearly 30 years of proton collisions and was able to find a model with intrinsic charm that predicts the data much better than any previous model. However, the team reported a 3-sigma result, which means there is still a 1 in 1000 chance they found the wrong model by random chance. The video ends with a call to action, encouraging viewers to continue exploring this fascinating field of study.
1. People are made of cells, which are composed of molecules, which are made of atoms.
2. Atoms are made of electrons, protons, and neutrons, and these last two are composed of three quarks.
3. Protons and neutrons are actually made of many quarks, which appear as three quarks when viewed a certain way.
4. Most of the visible matter in the universe comes from protons, either as solitary hydrogen nuclei or bound with neutrons into the nuclei of various elements.
5. The interiors of protons remain a profound mystery, even though it was confirmed in the late 60s that protons are not elementary particles but are composed of three quarks.
6. Thanks to AI, there is evidence suggesting that protons may be made of five quarks at least sometimes.
7. To understand the smallest scales of nature, physicists need to understand the physics of scattering.
8. Every time you open your eyes, you're performing a scattering experiment. Photons from a light source like the Sun bounce off objects into your particle detectors—aka your eyes.
9. It's also possible to "see" the subatomic world if we do a different type of scattering experiment.
10. In general, the higher the energy the scattering particle has, the smaller the object you can see.
11. To see subatomic scales, it's better not to use photons at all, but instead to use particles of matter.
12. Earnest Rutherford first discovered the nucleus by shooting a beam of alpha particles at a thin gold foil.
13. Since Rutherford’s 1911 experiment, we’ve gotten much better at doing this. For example, we now have electron microscopes which shoot electrons into a sample and measure how they’re deflected.
14. Electron scattering can be used to study the structure of anything larger than an electron.
15. The interior of the proton was revealed to be a complex cluster of energy—a dense network of gluons that are constantly transforming into pairs of virtual quarks and antiquarks.
16. The quantum properties of charge, spin, and colour must be conserved, which means there is order within the chaos.
17. The particles we discover after smashing an electron into a proton aren’t necessarily inside the proton to start with.
18. The energy carried by the electron can create brand new particles.
19. The more the energy of the electrons increases, the more fine detail we saw.
20. The interior of the proton is the realm of the strong nuclear force, which is described by quantum chromodynamics.
21. The calculations are easier at high energy than at low energy because it’s easier to implement a favorite hack of quantum mechanics called perturbation theory.
22. It's very difficult to calculate the state of the interior of the proton in the absence of a collision.
23. There is actually a way to get quantum chromodynamics to give us intrinsic charm quarks by taking advantage of the Heisenberg uncertainty principle.
24. It should be possible to generate a charm-anticharm quark pair, even inside a proton, as long as it exists only for a very short duration.
25. A neural network was trained to analyze nearly 30 years of proton collisions, not constrained by a single model, but in the limit of all possible models.
26. The neural network was able to find a model with intrinsic charm that predicts the data much better than any previous model.
27. The team reports a 3-sigma result which means a 1 in 1000 chance they found the wrong model in favor of intrinsic charm just by random chance.
28. The gold standard for claiming a victory is 5-sigma, which means a 1 in a million chance the result came from an unlucky streak.
29. Computers can come up with and test models much faster than any physicist, which means the physicists can get on with the more interesting work of interpreting the successful models.
30. There's something charming about this cooperation between artificial and natural intelligences working towards the common goal of deciphering the inner workings of space time.