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Physical scientific model12/19/2023 ![]() A pion is an up or a down quark bound to an anti-up or an anti-down. Choose one quark and one antiquark to get a meson. Protons are two ups and a down quark bound together neutrons are two downs and an up. In 1964, Gell-Mann and Zweig taught us the recipes: Mix and match any three quarks to get a baryon. Instead of vanilla, chocolate and so on, we have up, down, strange, charm, bottom and top. They come in six varieties we call flavors. No Archimedes leapt out of a bathtub shouting “eureka.” Instead, there was a series of crucial insights by a few key individuals in the mid-1960s that transformed this quagmire into a simple theory, and then five decades of experimental verification and theoretical elaboration. It was not an overnight flash of brilliance. Into this breach sidled the Standard Model. In place of the well-organized periodic table, there were just long lists of baryons (heavy particles like protons and neutrons), mesons (like Yukawa’s pions) and leptons (light particles like the electron, and the elusive neutrinos) – with no organization and no guiding principles. Not only not simple, redundant.īy the 1960s there were hundreds of “fundamental” particles. Then came the muon – 200 times heavier than the electron, but otherwise a twin. Five became six when the pion, which Yukawa predicted would hold the nucleus together, was found. At least Dirac had predicted these first anti-matter particles. Four grew to five when Anderson measured electrons with positive charge – positrons – striking the Earth from outer space. Really four, because we should count the photon, the particle of light that Einstein described. ![]() Meanwhile, nature cruelly declined to keep its zoo of particles to just three. But this scenario seemed like a lot of trouble even for a divine being – keeping tabs on every single one of the universe’s 10⁸⁰ protons and neutrons and bending them to its will. What binds these protons and neutrons together? “Divine intervention” a man on a Toronto street corner told me he had a pamphlet, I could read all about it. ![]() But the protons are all huddled together in the nucleus and their positive charges should be pushing them powerfully apart. But held together how? The negatively charged electrons and positively charged protons are bound together by electromagnetism. That would have been a satisfying place to stop. Physicists Planck, Bohr, Schroedinger, Heisenberg and friends had invented a new science – quantum mechanics – to explain this motion. The electrons, thousands of times lighter, whirl around the nucleus at speeds approaching that of light. The neutrons and protons are bound together tightly into the nucleus. It’s also wrong.īy 1932, scientists knew that all those atoms are made of just three particles – neutrons, protons and electrons. The ancients believed that everything is made of just five elements – earth, water, fire, air and aether. Over a hundred chemical elements is not simple. We want to boil things down to their essence, a few basic building blocks. There’s antimony, arsenic, aluminum, selenium … and 114 more. But there are 118 different chemical elements. ![]() Chemist Dmitri Mendeleev figured out in the 1860s how to organize all atoms – that is, the elements – into the periodic table that you probably studied in middle school. You know, of course, that the world around us is made of molecules, and molecules are made of atoms. In short, the Standard Model answers this question: What is everything made of, and how does it hold together?īut these elements can be broken down further. Every attempt to overturn it to demonstrate in the laboratory that it must be substantially reworked – and there have been many over the past 50 years – has failed. Every fundamental force but gravity is included in it. ![]() But that much-ballyhooed event didn’t come out of the blue – it capped a five-decade undefeated streak for the Standard Model. Many recall the excitement among scientists and media over the 2012 discovery of the Higgs boson. That’s what the Standard Model really is. As a theoretical physicist, I’d prefer The Absolutely Amazing Theory of Almost Everything. Yet its name suggests that if you can afford a few extra dollars a month you should buy the upgrade. More than a quarter of the Nobel Prizes in physics of the last century are direct inputs to or direct results of the Standard Model. What a dull name for the most accurate scientific theory known to human beings. ![]()
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