Epigraph(s) from my physics MS thesis

"The investigations of the self-energy of the electron by men like Abraham, Lorentz and Poincare have long since ceased to be relevant. All that has remained from those early times is that we still do not understand the problem."
--Abraham Pais, 'Subtle is the Lord...': The Science and the Life of Albert Einstein (1982). The full names of the men mentioned by Pais are Max Abraham, Hendrik A. Lorentz, and Henri Poincare. See thesis for a discussion of their contributions.

"I do not believe that the problem of matter is to be solved by a mere field theory."

--Hermann Weyl, Gravitation and Electricity (1923). Weyl was a mathematical physicist who became an expert in general relativity.
Einstein wasn't very mathematically gifted himself, and had help developing the non-Euclidian geometry used to describe general relativity, mainly from his friend Marcel Grossmann: "Grossmann, you must help me or I will go crazy!" was Einstein's way of initially requesting assistance.

"...'matter' has lost its role as a fundamental concept."

--Albert Einstein, Relativity: The Special and the General Theory. This is a book Einstein wrote for the general public in the early 1920s. The comment here comes from a final short chapter added to the last edition of the book, published in 1952, three years before Einstein died.


"Physics is the study of the fundamental laws of nature, but what constitutes a law and which laws are taken to be fundamental are matters of evolving consensus among physicists."

--Richard A. Matzner and Lawrence C. Shepley, Classical Mechanics (1991). Matzner and Shepley are physicists at the University of Texas at Austin.

 

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These quotes are meant to touch upon a common theme. The theme is that I believe physics is off track in its reliance on virtual particles, quantum field theory and the attempt to quantize gravity.  I would like to see a return to a reliance on physical intuition as being important for understanding physics.  This is one reason I don't like Feynman diagrams.  They're a poor substitute for physical intuition, especially the simplest diagram, which is supposed to show emission of a photon by an electron.  The diagram is a ghastly schematic squiggly line plus two straight lines.

For a humorous mention of the physicist Hermann Weyl, see the 1929 interview with Dirac by the Wisconsin sports writer nicknamed "Roundy." (Somewhere else in this old blog I reference this interview, but it's worth a second link.) For a look at my thesis, see my "old writings" blog, or (maybe) Google books. 

In Dirac's book Principles of Quantum Mechanics, a copy of which can be seen on Larry Gopnik's desk when he discovers the money in the envelope, there's a famous statement about the superposition and interference of light. Normally, interference is something that occurs between two or more waves that overlap or superpose. But the representation of a photon as a coherent superposition (of left and right circular polarization states, for example) is described by Dirac in this book as a self-interference: "Each photon interferes only with itself. Interference between two different photons never occurs."

Radical!  But also maybe limited in it's applicability... 

Uncle Ilya weighs in

There were two Nobel prize winners among the faculty in the physics department at the University of Texas at Austin when I was attending classes, seminars and colloquia there during the landmark years 1987 through 1999. 

One of them was Steven Weinberg, whom UT-Austin managed to recruit from Harvard in 1980, just after Weinberg, Salam, and Glashow won the 1979 physics Nobel for their theory unifying the weak nuclear force with the electromagnetic force.  That theory goes by the name electro-weak, although now maybe the name should be electro-weak-strong, since the strong nuclear force has also been subsumed under the same field theoretical tent, leaving only our dear friend (or enemy if you fall down and get hurt) the gravitational field of force unaccounted for by quantum field theory. 

The other Nobel winner who resided in the physics department at UT-Austin during my years there was Ilya Prigogine, or Uncle Ilya as my friend Tom Mellet liked to call him.  There's some controversy about the value of Prigogine's contributions, as described in one opinionated biographical sketch, but I think he was onto something in his attempts to look at quantum theory and chaotic systems in new and often philosophically interesting ways.  In contrast, I see nothing philosophically interesting in the mathematical tour de force that is quantum field theory.

Weinberg is still living and still at UT-Austin.  Prigogine actually divided his time between the Free University of Brussels and UT-Austin, and died in Brussels in 2003, aged 86.  He was also director (appointed in 1959) of the International Solvay Institute, and it was due to his presence at UT-Austin that original black & white photos from the famous early Solvay Conferences (some with participants signatures on them)  were displayed outside the large ground floor lecture hall in the Physics-Math-Astronomy building (R. L. Moore Hall).  I once went by Prigogine's office to see if he had a copy of a book about the Solvay Conferences that I'd been unable to find elsewhere.  He wasn't there, but his secretary (first name Amy is all I remember) found the book and loaned it to me without asking who I was or when I'd return it. 

Prigogine's Nobel prize was in chemistry, awarded in 1977 for his "definition of dissipative structures and their role in thermodynamic systems far from equilibrium," as the Wikipedia article about him says.  I have a partial paperback copy (and just ordered a full hardback copy) of his 1980 book From Being to Becoming, and offer a quote from it now concering a subject I've discussed here before, the difference in pure states and mixed states in quantum mechanics:

As noted in Chapter 3, a fundamental distinction is made in quantum mechanics between pure states (wave functions) and mixtures represented by density matrices. Pure states occupy a privileged position in quantum mechanics, somewhat analogous to orbits in classical mechanics. As indicated by the Schrodinger equation (see equations 3.17 and 3.18), pure states are transformed into other pure states during the time evolution. Moreover, observables are defined as Hermitian operators mapping vectors of the Hilbert space into itself. These operators also preserve pure states. The basic laws of quantum mechanics can thus be formulated without ever invoking the density-matrix description of states corresponding to mixtures. The use of that description is considered to be only a matter of practical convenience or approximation. The situation is similar to that considered in classical dynamics in which the basic element corresponding to the pure state is the orbit or the trajectory of a dynamical system (see, in particular, Chapters 2 and 7).

In Chapter 3, the question was asked: Is quantum mechanics complete? We have seen that one of the reasons for asking this question in spite of the striking successes of quantum mechanics in the past fifty years is the difficulty of incorporating the measurement process (see the section titled The Measurement Problem in Chapter 3). We have seen that the measurement process transforms a pure state into a mixture and therefore cannot be described by the Schrodinger equation, which transforms a pure state into another pure state.

In spite of much discussion (see the beautiful account by d'Espagnat'), this problem is far from being solved. According to d'Espagnat (p. 161), "The problem [of measurement] is considered as non-existent or trivial by an impressive body of theoretical physicists and as presenting almost insurmountable difficulties by a somewhat lesser but steadily growing number of their colleagues."

I do not wish to take a position that is too strong in this controversy, because, for the present purpose, the measurement process is simply an illustration of the problem of irreversibility in quantum mechanics.

Whatever the position one takes, the fundamental distinction between pure states and mixtures and the privileged position of the pure states in the theory must be given up. Thus, the problem is to provide a fundamental justification for this loss of distinction. It is a remarkable fact that the introduction of the entropy operator M (see the section on irreversibility and the formalism of classical and quantum mechanics in Chapter 8) as a fundamental object of the theory entails just this loss of distinction betWeen pure states and mixtures.