Quantum mechanics: How the future might influence the past. In 2022, the Physics Nobel prize was awarded for experimental work showing that the quantum world must break some of our fundamental ...A brief overview of the history and basic concepts of quantum mechanics, the study of physics on very small length scales. Learn how quantum mechanics is related to …The book Mathematical Foundations of Quantum Mechanics (1932) by John von Neumann is an important early work in the development of quantum theory. Publication history. The book was originally published in German in 1932 by Julius Springer, under the title Mathematische Grundlagen der Quantenmechanik. An ...Feb 10, 2022 · 🌎 Get Our Merch designed with https://www.youtube.com/channel/UCNYaxPiba3oxmeL_3jKxnYA/store💫Get 10% off Under Lucky Stars and enjoy our star maps comple... Quantum Mechanics Concepts and Applications Second Edition Nouredine Zettili Jacksonville State University, Jacksonville, USA A John Wiley and Sons, Ltd., PublicationThe new theory ignored the fact that electrons are particles and treated them as waves. By 1926 physicists had developed the laws of quantum mechanics, also called wave mechanics, to explain atomic and subatomic phenomena. When a beam of X-rays is aimed at a target material, some of the beam is deflected, and the scattered X-rays have a …Feb 10, 2022 · 🌎 Get Our Merch designed with https://www.youtube.com/channel/UCNYaxPiba3oxmeL_3jKxnYA/store💫Get 10% off Under Lucky Stars and enjoy our star maps comple... Instead, classical mechanics is now considered an approximate theory to the more general quantum mechanics. Emphasis has shifted to understanding the fundamental forces of nature as in the Standard Model and its more modern extensions into a unified theory of everything. Classical mechanics is a theory useful for the study of the motion …Quantum Mechanics is a branch of physics that focuses on understanding the behavior of matter and energy at the smallest scales. It describes the fundamental principles that govern the behavior of particles, such as atoms and subatomic particles, and allows us to explain phenomena that classical physics cannot account for.The new theory ignored the fact that electrons are particles and treated them as waves. By 1926 physicists had developed the laws of quantum mechanics, also called wave mechanics, to explain atomic and subatomic phenomena. When a beam of X-rays is aimed at a target material, some of the beam is deflected, and the scattered X-rays have a … A fundamental concept in quantum mechanics is that of randomness, or indeterminacy. In general, the theory predicts only the probability of a certain result. Consider the case of radioactivity. Imagine a box of atoms with identical nuclei that can undergo decay with the emission of an alpha particle. In a given time interval, a certain fraction ... An interpretation of quantum mechanics is an attempt to explain how the mathematical theory of quantum mechanics might correspond to experienced reality. Although quantum mechanics has held up to rigorous and extremely precise tests in an extraordinarily broad range of experiments, there exist a number of contending schools of thought over ...quantum mechanics. Space We finally know why Stephen Hawking's black hole equation works Stephen Hawking and Jacob Bekenstein calculated the entropy of a black hole in the 1970s, but it took ...Mar 15, 2022 · 1. The quantum world is lumpy. (Image credit: getty) The quantum world has a lot in common with shoes. You can’t just go to a shop and pick out sneakers that are an exact match for your feet ... Quantum mechanics has played an important role in photonics, quantum electronics, and micro-electronics. But many more emerging technologies require the understanding of quantum mechanics; and hence, it is important that scientists and engineers understand quantum mechanics better. One area is nano-technologies due …Page ID. Quantum mechanics explains the aspects of nature at ordinary (macroscopic) scales but extends this description to the small (atomic and subatomic) scales. There are …David Tong: Lectures on Topics in Quantum Mechanics. This is an advanced course on quantum mechanics. It covers a wide range of topics, including an introduction to atomic physics, quantum foundations and scattering theory. Please do email me if you find any typos or mistakes. PostScript PDF. Content.4.8 stars. 6 ratings. Learn the fundamental notions of quantum mechanics at a level that is accessible to everyone. This course is listed as one of the best online courses of all time by Class Central and was a finalist for the 2018 edX Prize for Exceptional Contributions to Online Teaching and Learning. Play Video. 6 weeks. 7–10 hours per week.There are 3 modules in this course. Course 2 of Statistical Thermodynamics presents an introduction to quantum mechanics at a level appropriate for those with mechanical or aerospace engineering backgrounds. Using a postulatory approach that describes the steps to follow, the Schrodinger wave equation is derived and simple solutions obtained ... This 9 week course aims to teach quantum mechanics to anyone with a reasonable college-level understanding of physical science or engineering. Quantum mechanics was once mostly of interest to physicists, chemists and other basic scientists. Now the concepts and techniques of quantum mechanics are essential in many areas of engineering and science such as materials science, nanotechnology ... of his research is in electrodynamics and quantum mechanics. He is the author of over fty arti-cles and four books: Introduction to Electrodynamics (4th edition, Cambridge University Press, 2013), Introduction to Elementary Particles (2nd edition, Wiley-VCH, 2008), Introduction to Quantum Mechanics (2nd edition, Cambridge, 2005), and Copenhagen Interpretation of Quantum Mechanics. First published Fri May 3, 2002; substantive revision Fri Dec 6, 2019. As the theory of the atom, quantum mechanics is perhaps the most successful theory in the history of science. It enables physicists, chemists, and technicians to calculate and predict the outcome of a vast …Quantum Physics. The expectation value of in the state . A 90 degree rotation about the z axis. The parity of the pion from . Applying the Operator to and . Adding any plus spin . Counting the States for . H.O. with anharmonic perturbation ( ). Hydrogen Atom Ground State in a E-field, the Stark Effect.Feb 10, 2022 · 🌎 Get Our Merch designed with https://www.youtube.com/channel/UCNYaxPiba3oxmeL_3jKxnYA/store💫Get 10% off Under Lucky Stars and enjoy our star maps comple... Page ID. Quantum mechanics explains the aspects of nature at ordinary (macroscopic) scales but extends this description to the small (atomic and subatomic) scales. There are …The index n n is called the energy quantum number or principal quantum number. The state for n = 2 n = 2 is the first excited state, the state for n = 3 n = 3 is the second excited state, and so on. The first three quantum states (for n = 1, 2, and 3) of a particle in a box are shown in Figure 4.5.2 4.5. 2.These examples show that commutators are not specific of quantum mechanics but can be found in everyday life. We now want an example for QM operators. The most famous commutation relationship is between the position and momentum operators. Consider first the 1D case. We want to know what is \(\left[\hat{x}, \hat{p}_{x}\right] \) (I’ll omit ...The stochastic optimal control approach to quantum mechanics can be traced back to Edward Nelson 3. Among others, Yasue 4 and Papiez 5 have worked with stochastic control and quantum mechanics in ...Course Description. This course covers the experimental basis of quantum physics. It introduces wave mechanics, Schrödinger’s equation in a single dimension, and Schrödinger’s equation in three dimensions. It is the first course in the undergraduate Quantum Physics sequence, followed by 8.05 Quantum Physics II and 8.06 Quantum …. His record of successful theoretical research with undergraduate students was recognized in 2011 when he was named as a KITP-Anacapa scholar. AI generated results by. Discover Introduction to Quantum Mechanics, 3rd Edition, David J. Griffiths, HB ISBN: 9781107189638 on Higher Education from Cambridge. Notes 1: The Mathematical Formalism of Quantum Mechanics, pdf format. Notes 2: The Postulates of Quantum Mechanics, pdf format. Notes 3: The Density Operator, pdf format. Notes 4: Spatial Degrees of Freedom, pdf format. Notes 5: Time Evolution in Quantum Mechanics, pdf format. Notes 6: Topics in One-Dimensional …Figure 2.1: In quantum mechanics the right hand side of the Schrödinger equation is written shortly as ˆHΨ(x, t), so (2.2) can be written as. iℏ∂Ψ ( x, t) ∂t = ˆHΨ(x, t) (2.3) This notation has a deeper reason, which is explained here shortly. The operation − ℏ2 2m ∂2Ψ ( x, t) ∂x2 + V(x)Ψ(x, t) can be considered as a ...It introduces some of the important model systems studied in contemporary physics, including two-dimensional electron systems, the fine structure of hydrogen, lasers, and particle scattering. The lectures and lecture notes for this course form the basis of Zwiebach’s textbook Mastering Quantum Mechanics published by MIT Press in April 2022. Mass defect and binding energy. Nuclear stability and nuclear equations. Half-life plot. Exponential decay and semi-log plots. This unit is part of the Physics library. Browse videos, articles, and exercises by topic. Sep 15, 2014 · View full lesson: http://ed.ted.com/lessons/particles-and-waves-the-central-mystery-of-quantum-mechanics-chad-orzelOne of the most amazing facts in physics i... This is the first semester of a two-semester graduate-level subject on quantum theory, stressing principles. Quantum theory explains the nature and behavior of matter and energy on the atomic and subatomic level. Topics include Fundamental Concepts, Quantum Dynamics, Composite Systems, Symmetries in Quantum Mechanics, and Approximation Methods. Modern Quantum Mechanics is a classic graduate level textbook, covering the main concepts from quantum mechanics in a clear, organized and engaging manner. The original author, J. J. Sakurai, was a renowned particle theorist. This third edition, revised by Jim Napolitano, introduces topics that extend its value into the twenty-first century ...Nov 19, 2023 · Quantum mechanics is an essential branch of physics that explains the properties and behaviors of particles at the atomic and subatomic scale. It challenges the principles of classical mechanics with concepts like quantization, where properties like energy exist in discrete units, and wave-particle duality, where particles exhibit both particle ... Lewis presents quantum mechanics as a theory of matrix mechanics and then, in the continuum limit, as a theory of wave mechanics. He gives a clear visual explanation of the use of different bases for spin, which nicely sets up the proof of Bell's theorem in chapter 2. All of this is done without requiring the reader to multiply matrices …The quantum mind or quantum consciousness is a group of hypotheses proposing that local physical laws and interactions from classical mechanics or connections between neurons alone cannot explain consciousness, positing instead that quantum-mechanical phenomena, such as entanglement and superposition that cause nonlocalized quantum …Quantum physics is sometimes called quantum mechanics or quantum field theory. It also has various subfields, as discussed above, which are sometimes used interchangeably with quantum physics, though quantum physics is actually the broader term for all of these disciplines. 1. Key Features of Quantum Mechanics: Linearity of the Equations of Motion, Complex Numbers are Essential, Loss of Determinism, Quantum Superpositions, Entanglement (PDF) 2. Experiments with Photons: Mach-Zehder Interferometer, Elitzur-Vaidman Bombs (PDF) 3. Particle Nature of Light and Wave Nature of Matter: Photoelectric Effect, Compton ... Mass defect and binding energy. Nuclear stability and nuclear equations. Half-life plot. Exponential decay and semi-log plots. This unit is part of the Physics library. Browse videos, articles, and exercises by topic. This is the first semester of a two-semester graduate-level subject on quantum theory, stressing principles. Quantum theory explains the nature and behavior of matter and energy on the atomic and subatomic level. Topics include Fundamental Concepts, Quantum Dynamics, Composite Systems, Symmetries in Quantum Mechanics, and Approximation Methods. The quantum mechanical model of the atom (Opens a modal) Heisenberg uncertainty principle (Opens a modal) Quantum numbers (Opens a modal) Quantum numbers for …Becker questions the hegemony of the Copenhagen interpretation of quantum mechanics. Propounded by Bohr and Werner Heisenberg in the 1920s, this theory holds that physical systems have only ...This textbook, now in an expanded third edition, emphasizes the importance of advanced quantum mechanics for materials science and all experimental techniques which employ photon absorption, emission, or scattering. Important aspects of introductory quantum mechanics are covered in the first seven chapters to make the subject self-contained …Mathematically, quantum mechanics can be regarded as a non-classical probability calculus resting upon a non-classical propositional logic. More specifically, in quantum mechanics each probability-bearing proposition of the form “the value of physical quantity \(A\) lies in the range \(B\)” is represented by a projection operator on a Hilbert …Quantum Mechanics: The Theoretical Minimum – Buy Now. Source: Leonard Susskind, Art Friedman/Amazon. Theoretical Minimum is a rare New York Times’ bestseller on quantum mechanics, written by ...1.1: Why Quantum Mechanics is Necessary; 1.2: The Schrödinger Equation and Its Components; 1.3: The Born-Oppenheimer Approximation One of the most important approximations relating to applying quantum mechanics to molecules and molecular ions is known as the Born-Oppenheimer (BO) approximation. 1.4: Free Particle Motions in More …QUANTUM MECHANICS An innovative approach to quantum mechanics that seamlessly combines textbook and problem-solving book into one Quantum Mechanics: Concepts and Applications provides an in-depth treatment of this fundamental theory, combining detailed formalism with straightforward practice. Thoroughly integrating close to seven hundred …Beginning with a review of the history of quantum mechanics and an account of classic solutions of the Schrödinger equation, before quantum mechanics is developed in a modern Hilbert space approach, Weinberg uses his remarkable expertise to elucidate topics such as Bloch waves and band structure, the Wigner–Eckart theorem, magic numbers ...Figure 2.1: In quantum mechanics the right hand side of the Schrödinger equation is written shortly as ˆHΨ(x, t), so (2.2) can be written as. iℏ∂Ψ ( x, t) ∂t = ˆHΨ(x, t) (2.3) This notation has a deeper reason, which is explained here shortly. The operation − ℏ2 2m ∂2Ψ ( x, t) ∂x2 + V(x)Ψ(x, t) can be considered as a ... Lecture 1: An overview of quantum mechanics. Quantum mechanics as a framework. Defining linearity (17:46) Linearity and nonlinear theories. Schrödinger’s equation (10:01) The nature of superposition. Mach-Zehnder interferometer (14:30) Lecture 2: Overview of quantum mechanics (cont.). Interaction-free measurements. 1.2 Quantum Mechanics, what’s up? As a warmup, some quick questions and answers about Quantum Mechanics... Why would I learn Quantum mechanics? Let’s think a bit about the physics you have learned so far. Throughout the past years, you got to know how bodies experience and exert forces, how gases behave, how electro-magnetic forces act …Quantum mechanics was once mostly of interest to physicists, chemists and other basic scientists. Now the concepts and techniques of quantum mechanics are essential in many areas of engineering and science such as materials science, nanotechnology, electronic devices, and photonics. This course is a substantial introduction to quantum mechanics ... Quantum Mechanics. In day to day life, we intuitively understand how the world works. Drop a glass and it will smash to the floor. Push a wagon and it will roll along. Walk to a wall and you can't ... Quantum mechanics describes the properties of atoms and molecules. For humans, who can only perceive the macroscopic world, or what’s visible to the naked eye, quantum mechanics can seem ...Page ID. Quantum mechanics explains the aspects of nature at ordinary (macroscopic) scales but extends this description to the small (atomic and subatomic) scales. There are …Quantum physics is sometimes called quantum mechanics or quantum field theory. It also has various subfields, as discussed above, which are sometimes used interchangeably with quantum physics, though quantum physics is actually the broader term for all of these disciplines.A brief overview of the history and basic concepts of quantum mechanics, the study of physics on very small length scales. Learn how quantum mechanics is related to …Quantum mechanical laws are usually only found to apply at very low temperatures. Quantum computers, for example, currently operate at around -272°C. At higher temperatures, classical mechanics ...Learn what quantum mechanics is, how it differs from classical physics, and what are its key features and applications. Explore the origins, developments and …start, in Chapter 3, by examining how many of the central ideas of quantum mechanics are a direct consequence of wave-particle duality—i.e., the concept that waves sometimes act as particles, and particles as waves. We shall then proceed to investigate the rules of quantum mechanics in a more systematic fashion in Chapter 4. Quantum mechanics isQuantum mechanics is a fundamental theory in physics that describes the behavior of nature at and below the scale of atoms. It is the foundation of all quantum physics, which includes quantum chemistry, quantum field theory, quantum technology, and quantum information science. Quantum … See moreBecker questions the hegemony of the Copenhagen interpretation of quantum mechanics. Propounded by Bohr and Werner Heisenberg in the 1920s, this theory holds that physical systems have only ... An interpretation of quantum mechanics is an attempt to explain how the mathematical theory of quantum mechanics might correspond to experienced reality. Although quantum mechanics has held up to rigorous and extremely precise tests in an extraordinarily broad range of experiments, there exist a number of contending schools of thought over ... Quantum Credit. The first skeptic of quantum energy teleportation was Hotta himself. In 2008, he was searching for a way of measuring the strength of a peculiar quantum mechanical link known as entanglement, where two or more objects share a unified quantum state that makes them behave in related ways even when separated …Quantum mechanics is the best tool we have to understand how the universe works on its smallest scales. Everything we can see around us, from far-off galaxies to our own bodies, is made up of...Lewis presents quantum mechanics as a theory of matrix mechanics and then, in the continuum limit, as a theory of wave mechanics. He gives a clear visual explanation of the use of different bases for spin, which nicely sets up the proof of Bell's theorem in chapter 2. All of this is done without requiring the reader to multiply matrices …Mar 15, 2022 · 1. The quantum world is lumpy. (Image credit: getty) The quantum world has a lot in common with shoes. You can’t just go to a shop and pick out sneakers that are an exact match for your feet ... Quantum physics is the result of applying the framework of quantum mechanics to di erent physical phenomena. We thus have Quantum Electrodynamics, when quantum mechanics is applied to electromagnetism, Quantum Optics, when it is applied to light and optical devices, or Quantum Gravity, when it is applied to gravitation. In this quantum physics introduction for beginners, we will explain quantum physics, also called quantum mechanics, in simple terms. Quantum physics is possibly the most fascinating part of physics that exists. It is the amazing physics that becomes relevant for small particles, where the so-called classical physics is no longer valid.Quantum mechanics Abstract Although complex numbers are essential in mathematics, they are not needed to describe physical experiments, as those are expressed in terms of probabilities, hence real ...Subscribe to BBC News www.youtube.com/bbcnewsBritish physicist Brian Cox is challenged by the presenter of Radio 4's 'Life Scientific', Jim Al-Khalili, to ex...Quantum mechanics was once mostly of interest to physicists, chemists and other basic scientists. Now the concepts and techniques of quantum mechanics are essential in many areas of engineering and science such as materials science, nanotechnology, electronic devices, and photonics. This course is a substantial introduction to quantum mechanics ...The quantum mechanical model of the atom (Opens a modal) Heisenberg uncertainty principle (Opens a modal) Quantum numbers (Opens a modal) Quantum numbers for the first four shells (Opens a modal) Nuclei. Learn. Mass defect and binding energy (Opens a modal) Nuclear stability and nuclear equationsGravity and quantum mechanics tend to stay out of each other's way, but this might change as we devise new experiments to test the applicability of quantum theory to macroscopic systems and larger ... Mass defect and binding energy. Nuclear stability and nuclear equations. Half-life plot. Exponential decay and semi-log plots. This unit is part of the Physics library. Browse videos, articles, and exercises by topic. Quantum Mechanics Concepts and Applications Second Edition Nouredine Zettili Jacksonville State University, Jacksonville, USA A John Wiley and Sons, Ltd., Publication Course Description. Together, this course and 8.06 Quantum Physics III cover quantum physics with applications drawn from modern physics. Topics covered in this course include the general formalism of quantum mechanics, harmonic oscillator, quantum mechanics in three-dimensions, angular momentum, spin, and addition of angular momentum. …. Quantum physics is the result of applying the framework of quantum mechanics to di erent physical phenomena. We thus have Quantum Electrodynamics, when quantum mechanics is applied to electromagnetism, Quantum Optics, when it is applied to light and optical devices, or Quantum Gravity, when it is applied to gravitation. 4.8 stars. 6 ratings. Learn the fundamental notions of quantum mechanics at a level that is accessible to everyone. This course is listed as one of the best online courses of all time by Class Central and was a finalist for the 2018 edX Prize for Exceptional Contributions to Online Teaching and Learning. Play Video. 6 weeks. 7–10 hours per week.quantum computing, and closes with a discussion of the still unresolved prob-lem of measurement. Chapter 6 also demonstrates that thermodynamics is a straightforward consequence of quantum mechanics and that we no longer need to derive the laws of thermodynamics through the traditional, rather subtle, arguments about heat engines.Modern Quantum Mechanics is a classic graduate level textbook, covering the main concepts from quantum mechanics in a clear, organized and engaging manner. The original author, J. J. Sakurai, was a renowned particle theorist. This third edition, revised by Jim Napolitano, introduces topics that extend its value into the twenty-first century ... Quantum Mechanics. In day to day life, we intuitively understand how the world works. Drop a glass and it will smash to the floor. Push a wagon and it will roll along. Walk to a wall and you can't ... Quantum mechanics - Heisenberg, Uncertainty, Principle: The observables discussed so far have had discrete sets of experimental values. For example, the values of the energy of a bound system are always discrete, and angular momentum components have values that take the form mℏ, where m is either an integer or a half-integer, positive or negative. …Lecture 22: Metals, Insulators, and Semiconductors. video. 263 MB. Lecture 23: More on Spin. video. 265 MB. Lecture 24: Entanglement: QComputing, EPR, and Bell's Theorem. MIT OpenCourseWare is a web based publication of virtually all MIT course content. OCW is open and available to the world and is a permanent MIT activity.This is a superposition of waves. Similarly, in quantum science, objects such as electrons and photons have wavelike properties that can combine and become what is called superposed. While waves on the surface of a pond are formed by the movement of water, quantum waves are mathematical. They are expressed as equations that describe the ...
Modern Quantum Mechanics is a classic graduate level textbook, covering the main quantum mechanics concepts in a clear, organized and engaging manner. The author, Jun John Sakurai, was a renowned theorist in particle theory. The second edition, revised by Jim Napolitano, introduces topics that extend the text's usefulness into the twenty-first .... Pdf text to speech
Mass defect and binding energy. Nuclear stability and nuclear equations. Half-life plot. Exponential decay and semi-log plots. This unit is part of the Physics library. Browse videos, articles, and exercises by topic. Quantum mechanics: How the future might influence the past. In 2022, the Physics Nobel prize was awarded for experimental work showing that the quantum world must break some of our fundamental ... This course presents the fundamental concepts of quantum mechanics: wave properties, uncertainty principles, the Schrödinger equation, and operator and matrix methods. Key topics include commutation rule definitions of scalar, vector, and spherical tensor operators; the Wigner-Eckart theorem; and 3j (Clebsch-Gordan) coefficients. In addition, we deal with many-body systems, exemplified by ... Subscribe to BBC News www.youtube.com/bbcnewsBritish physicist Brian Cox is challenged by the presenter of Radio 4's 'Life Scientific', Jim Al-Khalili, to ex...That theory is known as quantum mechanics, and it is now the basic framework for understanding atomic, nuclear, and subnuclear physics, as well as condensed-matter (or ”solid-state”) physics. The laws of motion (due to Galileo, Newton,...) which preceded quantum theory are referred to as classical mechanics.Modern Quantum Mechanics, often called Sakurai or Sakurai and Napolitano, is a standard graduate-level quantum mechanics textbook written originally by J. J. Sakurai and edited by San Fu Tuan in 1985, with later editions coauthored by Jim Napolitano.Sakurai died in 1982 before he could finish the textbook and both the first …Quantum mechanics of time travel. Until recently, most studies on time travel have been based upon classical general relativity. Coming up with a quantum version of time travel requires physicists to figure out the time evolution equations for density states in the presence of closed timelike curves (CTC). Novikov [1] had conjectured that once ...The index n n is called the energy quantum number or principal quantum number. The state for n = 2 n = 2 is the first excited state, the state for n = 3 n = 3 is the second excited state, and so on. The first three quantum states (for n = 1, 2, and 3) of a particle in a box are shown in Figure 4.5.2 4.5. 2. In this quantum physics introduction for beginners, we will explain quantum physics, also called quantum mechanics, in simple terms. Quantum physics is possibly the most fascinating part of physics that exists. It is the amazing physics that becomes relevant for small particles, where the so-called classical physics is no longer valid. Subscribe to BBC News www.youtube.com/bbcnewsBritish physicist Brian Cox is challenged by the presenter of Radio 4's 'Life Scientific', Jim Al-Khalili, to ex...Feb 10, 2022 · 🌎 Get Our Merch designed with https://www.youtube.com/channel/UCNYaxPiba3oxmeL_3jKxnYA/store💫Get 10% off Under Lucky Stars and enjoy our star maps comple... Quantum Nanomechanics. The Quantum Nanomechanics group focuses on the quantum-mechanical behavior of macroscopic moving objects, using micro- and nanomechanical resonators at the ground state of motion. In our unique efforts, we seek to experimentally address the elusive interface between quantum mechanics and gravity.Current Weather. 8:54 PM. 71° F. RealFeel® 67°. Air Quality Unhealthy. Wind WNW 12 mph. Wind Gusts 13 mph. Partly cloudy More Details.The Principles of Quantum Mechanics is an influential monograph on quantum mechanics written by Paul Dirac and first published by Oxford University Press in 1930. Dirac gives an account of quantum mechanics by "demonstrating how to construct a completely new theoretical framework from scratch"; "problems were tackled top-down, ….