Elementary Particles and the Laws of Physics: The 1986 Dirac Memorial Lectures 1st Edition by Richard P. Feynman (PDF)

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Perhaps the two most important conceptual breakthroughs in twentieth century physics are relativity and quantum mechanics. Developing a theory that combines the two seamlessly is a difficult and ongoing challenge. This accessible book contains intriguing explorations of this theme by the distinguished physicists Richard Feynman and Steven Weinberg. Richard Feynman’s contribution examines the nature of antiparticles, and in particular the relationship between quantum spin and statistics. In his essay, Steven Weinberg speculates on how Einstein’s theory of gravitation might be reconciled with quantum theory in the final laws of physics. Both these Nobel laureates have made huge contributions to fundamental research in physics, as well as to the popularization of science. Anyone interested in the development of modern physics will find this a fascinating book.

User’s Reviews

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⭐This slender volume comprises the first two Dirac Memorial Lectures, endowed by St. John’s College, Cambridge, in honor of one of its most distinguished alumni, Paul Dirac, one of the originators of quantum mechanics, and the first to successfully meld quantum mechanics with special relativity to produce what eventually became quantum field theory and the Standard Model of particle physics. The first lecture is by Richard Feynman, who helped perfect quantum electrodynamics, that portion of quantum field theory dealing with interactions of electrons and photons, the modern view of electricity and magnetism. The second is by Steven Weinberg, who pioneered the unification of electromagnetism with the weak nuclear force, pointing the way towards the Standard Model and beyond to an as-yet-unrealized dream of a Grand Unified Theory encompassing all of physics including gravity.The lectures themselves are terrific. This review is focussed on Feynman’s lecture, which is the reason I bought the book. The target audience for the Dirac lectures according to Weinberg (page 67) was “undergraduates who have had a first course in quantum mechanics”. Such a course would typically not include a lot of the material covered by Feynman. His lecture concerns itself with two very deep topics in quantum electrodynamics: how the inclusion of special relativity predicts antiparticles, and the relationship between a particle’s spin and its behavior in aggregates (statistics). Basically, he starts by showing how a simple mathematical theorem requires that if we restrict our analysis of particle interactions to include only particles with positive energies, then particles travelling faster than the speed of light must be included in the analysis. It is then shown that in some reference frames these particles will be seen to travel backwards in time, which can be interpreted as antiparticles. Using a particularly simple particle interaction as an example, he then shows how in order for the probabilities of all the possible variations which must be included in the analysis to add up to one, particles with spin zero (and other whole integer numbers of spin) obey one kind of behavior in groups (Bose-Einstein statistics, hence the name bosons), whereas particles with spin 1/2 (and other half-integer spin numbers) follow a different kind of behavior in groups (Fermi statistics, hence the name fermions). He shows that a particle obeying Bose-Einstein statistics enhances the probability of a copy of itself spontaneously appearing, whereas a particle obeying Fermi statistics suppresses the probability of a copy of itself spontaneously appearing. The former behavior leads to a phenomenon called stimulated emission, which is the basis for lasers (not discussed further in this lecture). The latter behavior is the basis of the Pauli exclusion principle, whereby no two electrons can occupy the same state in an atom, which in turn is the basis for the periodic table of the elements and all the phenomena of chemistry.Feynman presupposes that the audience is familiar with the basic mathematical formalisms of quantum mechanics, such as the arithmetic of complex numbers, calculation of amplitudes, and their relation to probability. He also presupposes an acquaintance with special relativity, Minkowski diagrams, etc. He uses ingenious simplifications to make the calculation of the amplitudes and probabilities in his simple example more clear.Which brings me to why I give this book as opposed to the lectures only one star. It’s not suitable for the general reader. Yet it masquerades as such. The name Feynman is displayed in large letters across the top, as bait. Look in the science section of any good general bookstore and only four scientists will have any prominence: Darwin, Einstein, Feynman, and Hawking. These are the only four who have achieved significant name recognition with a general audience. Anyone who buys this book thinking they’re getting something on the level of “Surely You’re Joking” or “Six Easy Pieces” or “QED” will be disappointed. No attempt has been made to add any material which will improve the comprehension for the general reader. Not so much as a simple statement that -i times -i equals -1, let alone any definition of amplitudes, or their relationship to probability, or what a light cone is, etc., etc. This is a disservice and smacks of exploitation of the Feynman name.Then the publisher uses the trick of shrinking the size of the pages to try to hide the fact that if the book had regular-sized pages it would be too thin without supplementary material to look worth the price being charged.Plus, despite having gone through at least 8 printings since first published in 1987, there are still typos! Not trivial ones, either. On page 7, Figure 1 has x1 and x2 labelled backwards. On page 14, Figure 3, the sign of the sum on the left hand side should be positive, not negative. On page 18, line 11 should read “those from Fig 7c, d, and f should cancel”, not Fig 7c, d, and e.

⭐This book is a summary of 1986 Paul Dirac memorial lectures delivered by physicists, Richard Feynman and Steven Weinberg. This book requires the knowledge of undergraduate level physics and perturbation theory, and it is described in two chapters; the first is by Feynman under the title “The reason for antiparticle.” This section describes the first attempt of Dirac in 1928 to “wed” newly discovered quantum mechanics and theory of relativity. When relativity was included into Schrodinger’s pure wave equations, the relativistic equation (Dirac equations) would only be satisfied if there were two solutions corresponding to positive and negative energy states, and in the case of the electron, an electron with a positive charge was required for negative energy state. Thus the existence of antiparticles (positron) was predicted as a direct result of combining the relativity with quantum mechanics. Paul Dirac was also able to explain the origin of the electron magnetic moment and spin. Feynman postulated one of the revolutionary thought in quantum field theory, that antiparticles could be viewed as particles going back in time. This should not be taken as a physical reality in which cause – effect sequence could be revered. Because during the Lorentz transformation the time sequence of two events gets reversed, one of them could not have been the cause of the other because the two events are outside each other’s sphere of influence. In frame A, if event 1 occurs first and event 2 occurs after event 1, but in frame B, event 2 occurs before event 1. This is possible in relativity because the time ordering of two events is not an absolute concept; one event can be in the past of another event in one frame, and in its future in a different frame. An observer in frame A will see an electron before event 1, an electron between events 1 and 2, and an electron after event 2, but in frame B, he will see one electron before event 2 and only one electron after event 1.In the second part under the title, Toward the final laws of physics, Steven Weinberg discusses the developments in physics to explain physical reality with one set of physical laws. This has lead to several unsuccessful theories to unify relativity and quantum physics, finally leading to String theory.Paul Dirac believed that physical laws should have mathematical beauty. Both Feynman and Weinberg have made beautiful theories. Weinberg played a key role in the unification of electricity and magnetism with the weak forces of radioactivity, and Feynamn expanded the understanding of quantum electrodynamics; they were best suited to deliver the Paul Dirac memorial lectures.1.

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⭐, I was hoping to understand the reasoning behind the exclusion principle, and was disappointed to find that RPF felt that this was too complex for undergraduates, so he asked them to take it on faith for the moment.Here he is talking to a more advanced audience, and explains it – he was right, it’s tough. I’m still struggling to understand it, but I have confidence that this is a good book to help.[Added nearly a year later] Having reread the book several times, I finally understand Feynman’s lecture! As is often the case, once I understand the principle, I see relationships to various other things I had not fully understood before.I should also comment on Weinberg’s lecture: he’s talking about more speculative areas than Feynman, which is perhaps one reason I found him less enlightening than Feynman, but in a rather vague way I follow what he’s saying. Certainly these are fascinating ideas, but they don’t sing to me like Feynman’s lecture.

⭐This books is really cool. Its targeted to someone already kinda familiar with physics and Quantum Mechanics but you only need the most basic understanding. The book gives reasonably precise explanations (without too much math) of why anti-particles must exist. Feynman’s style is generally quite readable. Overall, I had fun and learned a lot.I would not recommend this book for someone who has studied quantum mechanics at all however. It assumes you’re familiar with a lot of the terminology and concepts.

⭐None of the previous reviews matched my own experience of this book. For a start there is only one picture (of Dirac); perhaps the comment refered to the feynman diagrams?To start with this book contains two lectures by two different people. Weinberg’s lecture is very general, but contains insights from 20+ yearsago. I personally prefer ‘road to reality’ by penrose, but the explanation of why the lagrangian form of the standard model cannot be the form of any final understanding is very clear.Feynman’s lecture is the better one. It leaps forward through some of Dirac’s work, but follows a very unique route. The speed is sometimes rapier like, and there are a couple of changes in direction that you have to read and re read to catch, but it is a wonderful journey and very accessible to people outside of university physics departments (I graduated 25 years ago) despite the plethora of equations.Worth the £2.70 I paid, for a new book, to an amazon dealer.

⭐I loved this book even though the mathematics of Mr Feynman in the first half was way over my head. Mr Weinberg’s lecture is more penetrable.

⭐I haven’t yet read the book, it just got delivered. Therefore I’m unable to make a comment on the content.With that being said, my print came with a tear on the back, that is not quality.It’s not really bad, but I didn’t pay for a book like this.

⭐Libro corto e molto carino scritto da due pezzi grossi del novecento!

⭐Not found.

⭐great book

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