Standard model. What a stupid name for the most accurate scientific theory known to humanity. More than a quarter of the Nobel prizes in physics in the last century was awarded to works that either directly or indirectly were associated with the Standard model. It is, of course, like for a couple hundred rubles to buy improvement. Any physicist would prefer “amazing theory of almost everything”, which it actually is.
Many remember the excitement among scientists and in the media, caused by the discovery of the Higgs boson in 2012. But his discovery was not a surprise and did not arise from nowhere — it marked the fiftieth anniversary of the successive victories of the Standard model. It includes every fundamental force other than gravity. Any attempt to refute it and demonstrate in the laboratory that it is necessary to rework — and there were many — have failed.
In short, the Standard model answers this question: what is everything made of and how everything is held together?
The smallest building blocks
Physicists love simple things. They want to crush everything to the bottom, find the basic building blocks. To do this in the presence of hundreds of chemical elements is not so easy. Our ancestors believed that everything is composed of five elements — earth, water, fire, air and ether. Much easier five hundred eighteen. And also wrong. You definitely know that the world around us consists of molecules and molecules consist of atoms. Chemist Dmitri Mendeleev discovered it in the 1860-ies and introduced the atoms in the table of elements, which today is taught in school. But these chemical elements 118. Antimony, arsenic, aluminum, selenium… and 114.
In 1932, scientists knew that all of these atoms consists of just three particles — neutrons, protons and electrons. Neutrons and protons are closely related to each other in the nucleus. Electrons are thousands of times easier for them, circling around the nucleus at speeds close to light. Physics Planck, Bohr, Schrodinger, Heisenberg and others have introduced a new science — quantum mechanics — to explain this movement.
This would be fine to stop. Only three particles. It’s even easier than five. But they stick together? Negatively charged electrons and positively charged protons are held together by forces of electromagnetism. But the stray protons in the nucleus and positive charges have to push them away. Not even the neutral neutrons.
What binds these protons and neutrons together? “Divine intervention”? But even a divine being would have caused problems to follow each of the 1080 protons and neutrons in the Universe, hold their willpower.
The expanding particle zoo
Meanwhile, nature is desperately refuses to keep in his zoo is only three particles. Even four, because we need to consider the photon, the particle of light, described by Einstein. Four became five when Anderson has measured electrons with a positive charge — the positron — which hit the Earth from outer space. Five became six when he discovered the pion, holding the core in General, and predicted by Yukawa.
Then came the muon is 200 times heavier than electron, but otherwise his twin. It’s already seven. Is not so simple.
In the 1960s, years was hundreds of fundamental particles. Is well organized periodic table was only long lists of baryons (heavy particles like protons and neutrons) and mesons (like the pion Yukawa) and leptons (light particles such as electron and elusive neutrinos), without any organization and principles of the device.
And in this abyss was born the Standard model. There was no Epiphany. Archimedes jumped from the bath shouting “Eureka!”. No, instead, in the mid-1960s, several smart people have put forward important assumptions that turned this quagmire first in a simple theory, and then in fifty years of experimental verification and theoretical development.
Quarks. They got six options, which we call flavors. Like flowers, only not so delicious smelling. Instead of roses, lilies and lavender we got the top and bottom, strange and charmed, adorable and true quarks. In 1964 Gell-Mann and Zweig has taught us to mix three quarks to baryon. The proton is two top and one bottom quark; a neutron is two lower and one upper. Take one quark and one antiquark – get a meson. Peony is a top or bottom quark associated with the top or bottom antiquark. All matter with which we are dealing consists of top and bottom quarks, recorded the creation of and electrons.
Easy. Though not entirely easy, because to keep the quarks bound is not easy. They fit together so tightly that you will never find a quark or antiquark, the vagus itself. The theory of this, and particles that take part in it, namely the gluons is called quantum chromodynamics. This is an important part of the Standard model, mathematically complex, and sometimes unsolvable even for basic math. Physicists are doing everything possible to make calculations, but sometimes the mathematical apparatus is insufficiently developed.
Another aspect of the Standard model, “a model of leptons”. This title is the most important article of 1967, written by Steven Weinberg, which combined quantum mechanics with important knowledge about how particles interact, and organized them into a unified theory. He included electromagnetism, and bound him with the “weak force”, which causes certain radioactive decays, and explained that they are different manifestations of the same force. This model includes the Higgs mechanism, giving mass to the fundamental particles.
Since the Standard model predicted the experimental results with the results, including the discovery of several types of quarks and of the W and Z bosons – heavy particles, the weak interactions serve the same role as the photon in electromagnetism. The probability that neutrinos have a mass, lost in the 1960-ies, but confirmed the Standard model in the 1990-ies, after several decades.
The discovery of the Higgs boson in 2012, has long predicted by the Standard model and the long-awaited, did not, however, surprise. But it was another important victory for the Standard model over the dark forces of particle physics are regularly waiting on the horizon. Physicists don’t like that the Standard model does not correspond to their notions of a simple, they were concerned about its mathematical inconsistency and looking for the possibility to include gravity into the equation. Obviously, this results in different theories of physics, which can be after the Standard model. So there is a Grand unification theory, supersymmetry, tehnokolor and string theory.
Unfortunately, theories beyond the Standard model is not found successful experimental evidence and serious gaps in the Standard model. After fifty years it was the Standard model closest to the status theory of everything. The amazing theory of almost everything.