The first Dirac House

**By Hamish Johnston**

Did he live here for 21 years?

The salmon-coloured house in the centre of the photo is 15 Monk Road, the birthplace of Paul Dirac.

This view of suburban Bristol is from our back window and would have been somewhat different in 1902 when Dirac was born. The houses had been built a year earlier and I’m guessing the gardens would have been devoid of trees and large shrubs.

Dirac lived in this house until he was about ten (according to his latest biographer Graham Farmelo or 21 — according to the historical plaque on the house (right).

I sometimes wonder what the current owners make of this plaque — are they worried that Dirac left some antimatter lurking under the floorboards?

In the April issue of *Physics World* the Bristol physicist Sir John Enderby reviews Graham Farmelo’s book *The Strangest Man: The Hidden Life of Paul Dirac, Quantum Genius*.

I asked Sir John about the discrepancy between Farmelo and the blue plaque and he isn’t sure which account is correct. He’s doing a little digging now, so stay tuned for an update.

Farmelo says that the Diracs moved to nearby Julius Rd (photo below) in 1912, so it is fairly certain that Paul spent his formative years in the same Bristol neighbourhood.

Indeed, Dirac went to nearby Bishop Road School , which also counts the actor Cary Grant as one of its former pupils. And if you continue along Bishop Rd, turn left at Gloucester Rd and then right on Ashley Down Rd you will reach the new Dirac Rd

One thing I can tell you about 15 Monk Road is that it has a tiny garden (much smaller than the garden in the foreground of the photo) so there wouldn’t have been much room for young Paul to play. However, the road would have been devoid of cars so he could have been tearing around out there — although after reading Sir John’s review I can’t imagine young Paul tearing around anywhere.

I have to admit a strange kinship to the Diracs. Like Paul’s father I am a foreigner (he was Swiss, I am Canadian); we are also bringing up three children in an identical house; and we are thinking of moving in the general direction of Julius Rd — the gardens are bigger over there!

Julius Rd in Bristol: did Paul Dirac move here in 1912?

I’m afraid the information on the plaque is incorrect. The month in which the Dirac family moved to Julius Road (from memory, April 1913) is recorded in Charles Dirac’s nationalisation papers, stored in the National Archives. It took me years to pin down this date! By the way, the Julius Road address is used in family correspondence long before 1923.

Graham Farmelo

I wonder how aware are the general public of PAM Dirac. A few years back I was visiting Westminster Abbey with my son, and since I hadn’t been there after the plaque of Dirac had been placed, I asked the guide where it was. At first he didn’t know what I was talking about. After some thought he pointed the small plaque on the floor.

As I say in the book, Dirac was – according the convention – Swiss until he was about 17. So there is a case for saying that he was partly Swiss but, in my opinion, the case is weak. He was born and bred an English person, for a start. Perhaps more important, he certainly did not consider himself Swiss as he disliked his Swiss father so much. After a childhood visit, Paul Dirac did not consent to visit Switzerland until he visited CERN when he was in his 70s, as I recall.

Dirac was a unique Black Swan!

Back in 1974 I remember writing from Burma to Dirac then at Florida State University, Tallahasee requesting for his papers on Large Numbers Hypothesis which he sent me through his secretary in a very short period of a few weeks. I also received his 1942/43 publications on Quantum Electrodynamics from the Dublin Institute of Advanced Studies .

Many physicists of his stature would simply not have time for a relatively unknown university physicist from Burma! I think Dirac did care about other people but he cherished his freedom so very much that he would not like anything to interfere with it!

During the war years he did a good deal of consulting work for both Peierl’s group at Birmingham and Simon’s group at Oxford(specifically on atomic bomb design and development and also on the general problem of isotope separation).

According to Eugene Wigner a fellow physicist and Dirac’s brother-in-law “….During the (second world) war Paul, as were many others, was greatly concerned not only about the future of England, but also of the whole world, of freedom,democracy and a diversity of cultures. When Hitler attacked the western part of Europe, and in particular also England, he volunteered to do scientific and technical work for the defence of his country and the freedom of the world. What is very memorable in this connection is that he considered this to be his duty and refused all compensation for his work. ..the special subject he worked on..seems to have been a secret-but the fact that he did it so unselfishly, as a gift to freedom, is worth remembering. And the Free World as we now have some of it has a proud recollection of Paul Adrien Maurice Dirac. His wife is also justly proud of it. So are many of us!”

I was simply delighted to hear and read the reviews and comments –many good ones – about a new book on Dirac’s life and work! There exists a previous biography of Dirac which I have read but was not too pleased with it- a feeling shared by the members of the Dirac family particularly Dirac’s wife, Wigner’s sister. I am particularly pleased that a theoretical physicist has written it!

I still need to read Farmelo’s book! It is still being ordered!

I realize that there also exists “Collected Works of Dirac” . All the same I tend to agree with Chandrashekhar, that a book on the work of such a creative scientist should cover all his life’s work! Silence should not shroud his post 1948 work.

Many would like to say that Dirac’s last important paper was that on magnetic monopole that he wrote he wrote in 1948 Physical Review in October. But according to Freeman Dyson, the memorable 1948 issue of Physical Review (vol 73) contains a number of “wonderful papers on physics ” ; Bloembergen,Purcell and Pound on relaxation effects in nuclear magnetic absorption;Lewis,Oppenheimer and Wouthuysen on the multiple production of mesons; Foley and Kusch on the experimental discovery of the magnetic moment of the electron;J Schwinger on the theoretical explanation of the anomalous magnetic moment and Dirac’s paper on quantum theory of localizable dynamical systems. Dyson said that “Dirac’s is the only one concerned with quantum field theory”

Many believe Dyson did for quantum field theory in 1948/1950 what Dirac did for quantum mechanics in the late 1925/1926 so he should be in a better position to make judgement on the importance of Dirac’s paper!

In 1950’s in his search for a better QED he developed the Hamiltonian theory of constraints (Cand J Math 1950 1 129; 1951 2 1) based on lectures that he delivered at the 1949 International Mathematical Congress in Canada. In his second paper using Hamiltonian methods he derived the Tomonaga-Schwinger equation for mesons in Schroedinger representation.

In the late 50’s he applied the Hamiltonian methods he had developed to cast Einstein’s general relativity in Hamiltonian form (Proc Roy Soc 1958,A vol 246, 333,Phys Rev 1959,vol 114, 924) and to bring to a technical completion the quantization problem of gravitation according to Salam and DeWitt. In 1959 also he gave an invited talk on “Energy of the Gravitational Field” at the New York Meeting of the American Physical Society later published in 1959 Phys Rev Lett vol 2, 368.

In 1964 he published his “Lectures on Quantum Mechanics” which deals with constrained dynamics of nonlinear dynamical systems including quantization of curved spacetime. He also published a paper entitled “Quantization of the Gravitational Field” in 1967 ICTP/IAEA Symposium on Contemporary Physics.

In 1961 he apparently found from his old notes a rather a novel method of deriving the Schwinger term and the Lamb shift (1056.17MHz)without using the usual “joining technique” of utilizing Bethe’s non-relativistic result adopted by a number of workers-including Weisskopf and French, Feynman and Schwinger-in quantum electrodynamics.

This work is also based on his theory of constrained dynamics. He also gave a series of lectures on quantum electrodynamics in 1962/1963 at the Belfer Graduate School of Science, Yeshiva University and at Ban-Ilan University Israel, in 1965. He again gave an invited talk on quantum electrodynamics at the New York Meeting of the American Physical Society in January 1965 which was later published in 1965 Phys Rev vol 139, 684.

In 1962 Dirac put forward the idea that the elementary particles might correspond to modes of vibrating membrane (Proc Roy Soc A 268, 57; Proc Roy Soc A 270, 354 ).Within the context of the string theory, the membrane idea could not be revived. In 1986, however, Hughes,Liu and Polchinski showed that a super-membrane could be introduced by combining membrane and supersymmetry.

In 1963 he published a paper entitled “A Remarkable Representation of 3+2 deSitter Group” in J Math Phys vol 4, 901 which was followed by two related papers on “Positive Energy Wave Equation I & II ” in the 1971 Proc Roy Soc A 322, 435 and 1972 Proc Roy Soc A 328, 1 respectively. In the meantime he had also published in 1971 “Spinors in Hilbert Space” in which he showed amongst other things that starting with fermion variables one can end up with boson variables particularly when dealing with creation and annihilayion operators in Hilbert space.

He put down his ideas of formulating Einstein’s general relativity in a form of a slim book entitled “General Theory of Relativity” published in 1974 soon after his formulation of a scalar –tensor theory of gravity using Weyl’s geometry as opposed to pseudo-Riemann geometry(“ Long Range Forces and Broken Symmetry” 1973 Proc Roy Soc A 403, 333). In his book on general relativity he deals with polarization of gravitational waves and localization of gravitational energy making use of harmonic coordinates. He also introduced a metric now known as Dirac-Lemaitre metric to discuss black holes and singularities. The slim book carries as usual the Dirac stamp of originality.

I believe typical “ Black Swans” like Schwinger and Einstein had the “not unusual” difficulties with the publication of their later research works . Schwinger apparently resigned from the Fellowship of the American Physical Society when Phys Rev refused to publish his later research relating to “source theory”. Although Dirac would certainly qualify as a “Black Swan” and despite his rather overdue and late election to the Honorary Fellowship of the Institute of Physics in 1971 in contrast to his very early election in 1948 to the Honorary Fellowship of the American Physical , the apparent ease with which he managed to publish his post 1948 research work in research journals, books and proceedings is quite unique – and not at all strange-amongst “Black Swans”.

When I was an undergrad at the U.of Florida in 1975, I had the pleasure of meeting Dirac after his colloquium, and coercing him into autographing my QM text.

He was of course quite old by then, and until now, the youngest picture I had ever seen of him was in his 30’s. Farmelo’s book has unveiled a stunning, but grainy photo of a very young Dirac, ~ age 7 I’m guessing. I am curious why there seems to be this 25+ year gap in photographs of him ?

One would think the U.of Bristol would have photos of him in his early 20’s…

Hi, just to say does anyone know which number Julius Road he lived in? I lived at Julius Road for 20 + years, the houses are big but the gardens are not especially huge.

Annie,

According to Farmelo’s book, Dirac lived at Six Julius Road.

Regards

Normally I compile guides to contemporary art, but I was inspired by Graham Farmelo’s gripping book to make a guide and Google map to the rather few Dirac-related spots in Bristol: places he lived and studied, plus memorials and places named after him. In researching it I came across Hamish Johnston’s fascinating blog post (ie this) and the associated learned comments, which is recommended on the blog. It’s only a small guide, but I hope some people may find it useful if planning a Dirac pilgrimage: it’s at http://artanorak.tumblr.com/post/1167260633/dirac

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