Abstract Black holes occur when matter collapses inward. So what keeps matter apart? Without this simple fact—that atoms repel each other—all matter would collapse, and there would be no life. The reason that matter stays apart is due to the Pauli principle, named after physicist Wolfgang Pauli. It is a principle of quantum mechanics. However, the basis for this physical “law” is not understood. It just is. Without it, life in our universe would not be possible. This chapter discusses the basics of quantum physics in simple language along with boxes about the physicists who formulated this theory. The goal is to help the reader understand that quantum physics is another balance point in the existence of life.
Abstract Black holes occur when matter collapses inward. So what keeps matter apart? Without this simple fact—that atoms repel each other—all matter would collapse, and there would be no life. The reason that matter stays apart is due to the Pauli principle, named after physicist Wolfgang Pauli. It is a principle of quantum mechanics. However, the basis for this physical “law” is not understood. It just is. Without it, life in our universe would not be possible. This chapter discusses the basics of quantum physics in simple language along with boxes about the physicists who formulated this theory. The goal is to help the reader understand that quantum physics is another balance point in the existence of life.
Abstract The exclusion principle is one of the most far-reaching theorems in physics. In a telegram to the Nobel committee, quoted in [1], Einstein wrote: ‘Nominate Wolfgang Pauli for physics prize stop his contributions to modern quantum theory consisting of so-called Pauli or exclusion principle became fundamental part of modern physics being independent from other basic axioms of that theory stop Albert Einstein.’ It is interesting to note that quantum mechanics, the theory Einstein alluded to, was formulated a little after the Pauli principle.
To date, the physical theory that most accurately describes the behavior of the atomic world is quantum mechanics. Since spectroscopy uses light to probe the atomic and molecular world, it should not be much of a surprise to learn that quantum mechanics is used to describe how spectroscopy works. Nobel Prize-winning physicist Richard Feynmann once said, "If you think you understand quantum mechanics, you don't understand quantum mechanics." This chapter won't bring you to a complete understanding of quantum mechanics, Feynmann's quote notwithstanding. But it will try to point out the important aspects, and hopefully it will at least leave the reader with the understanding that spectroscopy is quantum-mechanically based. Science's job is to try to understand the natural universe. To do this, scientists try to generate models to describe and predict the universe's behavior. (Not the behavior of the entire universe, but small selected parts of it.) If the model and the universe do not agree, there are two choices: change the model, or change the universe. Since all attempts at changing the universe have failed, our only choice is to change the model. Since the 1600s, scientific advance has accelerated at least in part because the proposed models of the universe have been increasingly more acceptable. Perhaps the first true âscientificâ investigation (by the modern definition) was Robert Boyle's investigation of gases in the 1660s. While there were some noteworthy incorrect or improper models developed (phlogiston and vitalism are two that come to mind immediately, but doubtless there are others), incorrect or improper models were ultimately replaced by more viable models. One such group of models was what we now call Newton's laws of motion. In just a few statements, verbal or mathematical, Newton's laws accurately describe the motion of matter. Further, these models withstood the test of multiple examinations, and are accepted as proper models of how matter behaves.
The premise of this book is that by understanding the initial conditions at the origins of reality, we can comprehend how all of our observable physical systems (including chemical and biological systems) have emerged. The book focuses on familiar principles of quantum physics and provides very simple derivations of the Heisenberg Uncertainty Principle, Pauli's Exclusion Principle, Schrodinger's wave equation, Noether's theorem, and the Continuity Equation. Background is provided in group theory and symmetries. Using these concepts, the book explores the nature of vacuum, of fundamental constants and particles, and of physical laws. Building on these basic principles, the book explains the emergence of atoms, the natural elements, chemical reactions, and life. In the process, numerous paradoxes are encountered and solved.
The history of the exclusion principle is already an old one, but its conclusion has not yet been written. It is now eighty years since Wolfgang Pauli introduced an ‘extremely natural’ prescriptive rule, while dealing with some spectroscopic anomalies that beset physicists in the heyday of the old quantum theory. The rule excluded the possibility that any two bound electrons in an atom were in the same dynamic state, identified by a set of four quantum numbers. Hence the name of Ausschlieβungsregel (exclusion rule), or Pauli's Verbot (Pauli's veto) as Werner Heisenberg nicknamed it. The far-reaching physical significance of this rule became clear only later. From spectroscopy to atomic physics, from quantum field theory to high-energy physics, there is hardly another scientific principle that has more far-reaching implications than Pauli's exclusion principle. It is thanks to Pauli's principle that one obtains the electronic configurations underlying the classification of chemical elements in Mendeleev's periodic table as well as atomic spectra. To this same principle we credit the statistical behaviour of any half-integral spin particles (protons, neutrons, among many others) and the stability of matter. Shifting to high-energy physics, it is the exclusion principle that fixes the crucial constraint for binding quarks in hadrons, which together with leptons compose our physical world. This book advances a philosophical analysis of the enduring and far-reaching validity of Pauli's principle. It does not aim to address what a scientific principle is.
One group of physicists simply assumed that atoms exist, picturing them as tiny particles bouncing around in accordance with Newton's laws. The arrival of quantum mechanics gave new insights into the behaviour of matter, and it is now apparent that many important and useful properties of materials are due to quantum mechanical effects. In this course, our discussion of the physics of matter is split into two parts. The central importance of atoms has been emphasized by Richard Feynman, Nobel laureate and one of the greatest physicists of recent times. Ironically, just as the existence of atoms was being demonstrated beyond any reasonable doubt at the beginning of the twentieth century, the foundations of Newtonian mechanics were being shaken by the first glimmerings of quantum theory.
Ordinary matter, composed of electrons and nuclei, is held together by Coulomb forces. These forces are potentially catastrophic for two reasons: the short range attraction could lead too a collapse while the long range repulsion and attraction could lead to an explosion or too strong interaction between macroscopic objects. The fact that neither of these things happens and that matter is essentially inert is a consequence of subtle properties of quantum mechanics and electrostatics outlined here.