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----------------------------- 2217 - The Standard Model of Physics-
- The Standard Model is the most accurate scientific theory known. 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 of almost everything
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- The Standard Model answers this question: What is everything made of, and how does it hold together?
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- The world around us is made of molecules, and molecules are made of atoms. Chemist Dmitri Mendeleev figured that out in the 1860s and organized all atoms, the elements , into the periodic table of elements. Now there are 118 different chemical elements in the table.
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- By 1932, scientists knew that all those atoms are made of just three particles – neutrons, protons and electrons. The neutrons and protons are bound together tightly into the nucleus. The electrons, thousands of times lighter, orbit around the nucleus at speeds approaching that of light. Physicists Planck, Bohr, Schrödinger, Heisenberg invented a new science, quantum mechanics, to explain how electrons orbit the nucleus. .
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- The negatively charged electrons and positively charged protons are bound together by electromagnetism. But the protons are all huddled together in the nucleus and their positive charges should be pushing them powerfully apart. The neutral neutrons are unaffected by these electric charges.
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- What binds these protons and neutrons together?
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- The photon, the particle of light was the forth particle. The fifth particle was found when Anderson measured electrons with positive charge. He discovered the ‘positrons’ striking the Earth from outer space. Dirac had predicted these first anti-matter particles. Five became six particles, when the pion, that Yukawa predicted would hold the nucleus together.
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- Then came the muon, 200 times heavier than the electron ,but otherwise a twin.
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- By the 1960s there were hundreds of “fundamental” particles. 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 to simplify the table.
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- to complicate thing further “quarks” were discovered to come in six varieties, we call flavors. We have up, down, strange, charm, bottom and top. In 1964, Gell-Mann and Zweig discovered how to mix and match any three quarks to get a baryon. Protons are two ups and a down quark bound together; neutrons are two downs and an up. Choose one quark and one antiquark to get a meson. A pion is an up or a down quark bound to an anti-up or an anti-down.
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- All the material of our daily lives is made of just up and down quarks and anti-quarks and electrons. The Standard Model of elementary particles provides an ingredients list for everything around us.
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- But, how do we keep those quarks together They are tied to one another so tightly that you never ever find a quark or anti-quark on its own. The particles that bind them together are called gluons. And the theory is called “quantum chromo dynamics“.
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- The other aspect of the Standard Model is “A Model of Leptons.” That is the name of the landmark 1967 paper by Steven Weinberg that pulled together quantum mechanics. He provided the vital pieces of knowledge of how particles interact and organized the two into a single theory.
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- Weinberg’s single theory incorporated the familiar electromagnetism, joined with “the weak force” that causes certain radioactive decays. His theory explained how they were different aspects of the same force. His theory incorporated the Higgs mechanism for giving mass to fundamental particles.
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- The Standard Model has predicted the results of experiment after experiment, including the discovery of several varieties of quarks and of the W and Z bosons, which are heavy particles that are for weak interactions in the same way that the photon is for electromagnetism. The possibility that neutrinos aren’t massless and are part of the Standard Model was proposed in the 1990s.
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- Discovering the Higgs boson in 2012, long predicted by the Standard Model and long sought after, was a thrill but not a surprise. Theories like the Grand Unified Theory, Super symmetry, Technicolor, and String Theory have not yet successfully predicted any new experimental phenomenon or any experimental discrepancy with the Standard Model.
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- After five decades the Standard Model is the Theory of “Almost’ Everything.
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-Other Reviews about Physics:
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- 2051 - Paul Dirac discovered the anti-particle in his math before it was discovered in the lab. God used advanced mathematics in constructing the Universe.
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- 2050 - The quest for reality in a strange world. We will be lucky to get out of it alive.
We could not exist without the Universe being 7 billion years old. We needed at least two generations of star explosions to cook the ingredients before life could happen.
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- 2040 - The Earth loses 6.6 pounds of molecules every second in the upper atmosphere. That is 200,000,000 pounds per year that escape Earth’s gravity.
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- This Review lists 9 more Reviews about Physics, 2015 to 1301 which to tries to answer the question , Can bird poop break a car windshield? (Requires 4 pages of math.)
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- December 25, 2018
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-------------------------- Thursday, December 27, 2018 --------------------------
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