Stephen Hawking and the Israel Boycott

Professor HawkingThere’s an old joke about the definition of chutzpa. A boy murders his parents and pleas to the judge: “Have pity on me – I’m an orphan!”

Sadly, that comic story can be applied this week to Stephen Hawking, the brilliant Cambridge physicist who announced he was pulling out of the “Facing Tomorrow” conference in Israel next month, “based on advice from Palestinian academics that he should respect the boycott” of Israel. For such a clever man, his recent actions are shockingly foolish and short-sighted.

Short-sighted because, given Israel’s central position in scientific and technological fields, to boycott the Jewish state would mean giving up on some of the most important advancements of recent years.

  • Stephen Hawking himself, who has suffered from motor neuron disease for most of his 71 years, communicates using a mechanical voice system run by the Intel Core i7 Processor developed by the Israeli division of Intel.
  • As a partical physicist, he is intimately involved in the most significant development in modern times: the discovery of the Higgs-Boson particle, found last year using Israel-developed particle detectors.
  • Last year, Hawking accepted a prestigious physics award worth $3 million – awarded by Yuri Milner, a major investor in Israeli high-tech.

Clearly, Prof. Hawking is not about to take out his Intel voice chip, return $3 million, and cease engaging in scientific debate. With so many areas of his life impacted and improved by Israeli dynamism, his refusal to visit the Jewish state comes across as a whole lotta chutzpa.

Double Standard

If Hawking wants to boycott a nation for perceived human rights outrages, he is targeting the wrong country.

In a week when the world’s newspapers were filled with gruesome descriptions of profound human rights violations, it’s ironic that Prof. Hawking would choose to target Israel for approbation:

  • Civil war is raging in Syria, with the Assad regime using chemical weapons against civilians
  • Nigeria is massacring Islamist opponents of the government
  • China is enforcing its brutal one-child policy through forced abortions
  • Saudi Arabia is executing political prisoners and homosexuals

Of course, Israel is not be above criticism, but to single it out for special treatment is to hold it to a biased double-standard that is required of no other country in the world. To single out Israel, a liberal democracy with an open press, transparent judiciary, universal suffrage, and enshrined equal rights for all – as a country not only to be criticized, but utterly avoided – is total chutzpa.

Dr. Hawking, whose academic research is world-class, must also realize the key to bettering the world lies in fostering communication, not in shutting it down. By turning his back on all of Israel, he’s sending a reactionary and hate-filled message at odds with the extensive academic collaboration that’s marked his entire career. Chutzpa!

Indeed, serious academics, such as Sari Nusseibeh, the Palestinian President of Al-Quds University, deplore academic boycotts. Dr. Nusseibeh has pioneered joint projects with Hebrew University in Jerusalem and Brandeis University near Boston.

Hawking’s cancellation was such an embarrassment to his employer, Cambridge University, that the school spokesman tried to claim it was due to “health reasons” and not as a boycott of Israel. The university was then forced to backtrack, after Hawking’s office made perfectly clear that the decision was due to the boycott.

Wrong Side of History

Amazingly, the conference that Hawking is boycotting is designed to promote the very sort of tolerant, open world for which he surely yearns.

Held under the auspices of Israeli President Shimon Peres, the annual Facing Tomorrow conference brings together a diverse group of 5,000 world leaders and intellectuals for discussions on an array of pressing world – including geopolitics, economics, environment and culture. Peres, a Nobel Prize laureate and Israel’s elder statesman, is using his considerable political capital to address some of the planet’s most pressing issues. To boycott this effort is not reasoned criticism but rather pure chutzpa – an attempt to destroy an Israeli initiative not on its merits, but simply because it originates in the Jewish state.

As a theoretical physicist, Hawking surely knows that his field was shaped by unsuccessful attempts to silence Jews in the past.

In the 1930s, Jewish scientists in Germany – including Albert Einstein – found themselves edged out of traditional academic fields and into burgeoning scientific areas such as particle physics. Einstein and Enrico Fermi (who left Europe to save his Jewish wife) came to the United States, and built much of the foundation of modern theoretical physics.

This latest boycott attempt to silence Jews has a long and infamous history. Hawking’s synergy with this movement to delegitimize the existence of the Jewish state is destined to prove on the wrong side of history.


As physicists know, electrons, W and Z particles have masses, but neutrinos and photons do not. I wonder somehow that it could be for some reason that neutrinos, and even photons do have masses so small which they have escaped any sort of detection so far. Though, I think these masses if they do exist would be quite different from the masses of electrons and W and Z particles, that is how not what would or should be expected if the symmetry among these particles were so manifest in nature.

Work, work, work…

Working at the Harvard College Observatory at the turn of the 20th Century, Henrietta Leavitt developed the information about Cepheid stars that would make Edwin Hubble’s great discoveries possible. Noticing that these stars varied in brightness at consistent rate that they could be used to measure stellar distances. Applying this yardstick herself, Leavitt showed in 1912 that such variable stars had to be far outside our home galaxy.

She had become especially expert in the characteristics of these variable stars, whose luminosity dims and flares up in cycles, and eventually cataloged about twenty four hundred of them. Most important for Edwin Hubble’s research, she was very able to time the cycles of the Cepheids, By showing that the length of their cycles of luminosity varies in close relation to their brightness, Leavitt provided astronomers with a hitherto unknown celestial yardstick, a method of measuring the distance of stellar objects. If a nearby Cepheid with a certain cycle has a certain degree of luminosity, a remote Cepheid with the same cycle should have the same luminosity. The degree of its relative dimness, from our point of view on Earth, shows how far away it is.

As you can imagine, in this age when very few women were given opportunities in science, these women of the Harvard College Observatory were restricted to classifying celestial phenomena in photographic plates taken by male astronomers. It’s remarkable to notice that in this group of women were to seminal and original thinkers, such as Henrietta Leavitt and Antonia C. Maury. The latter classified stars by the width of the lines they produced on a spectrograph. All of these helped others to nail down the exact dimensions of the Milky Way.


Betelgeuse — the second brightest star in the constellation of Orion (the Hunter) — is a red supergiant, one of the biggest stars known, and almost 1000 times larger than our Sun. It is also one of the most luminous stars known, emitting more light than 100 000 Suns.

Betelgeuse is the 12th brightest star in the sky. It is called Alpha Orionis even though it is fainter than Beta Orionis (Rigel). Other names; Betelguex. Betelgeuze, Beteiguex, Al Mankib, Alpha Orionis,  HR 2061,  HD 39801.

Such extreme properties foretell the demise of a short-lived stellar king. With an age of only a few million years, Betelgeuse is already nearing the end of its life and is soon doomed to explode as a supernova. When it does, the supernova should be seen easily from Earth, even in broad daylight.

Pinned prominently on Orion’s shoulder, the bright red star Betelgeuse hardly seems like a wallflower. But a new study suggests the giant star has been shrinking for more than a decade.

Betelgeuse is nearing the end of its life as a red supergiant. The bright, bloated star is 15 to 20 times more massive than the sun. If it were placed at the centre of the solar system, the star would extend out to the orbit of Jupiter.

But the star’s reach seems to be waning. New observations indicate the giant star has shrunk by more than 15 per cent since 1993. This could be a sign of a long-term oscillation in its size or the star’s first death knells. Or it may just be an artefact of the star’s bumpy surface, which may appear to change in size as the star rotates.

Betelgeuse is enshrouded by vast clouds of gas and dust, so measuring its size is difficult. To cut through this cocoon, astronomers used a set of telescopes that are sensitive to a particular wavelength of the star’s infrared light.

Over a span of 15 years, the star’s diameter seems to have declined from 11.2 to 9.6 AU (1 AU, or astronomical unit, is the distance from the Earth to the sun).

The cause for this reduction is unknown, as it is unclear how red supergiants behave near the end of their lives. The shrinking size could also be evidence of an as-yet-unidentified pulsation in the star.

The surface of Betelgeuse is known to wobble in and out, fed in part by the roiling energy of convection beneath its surface. Two such pulsations are already known – one seems to start anew each year, the other every 6 years.

Since this observation shows a progressive decrease in the size of the star over 15 years with a consistent set of measurements.

The father of Quarks

Back in the 1930s the few known particles included the small squad familiar to many of us from required high school courses—primarily the protons, neutrons, and electrons. By the time of the Nixon-Kennedy debates in 1960s, more than 50 particles had been counted. There are finally more than 150 toted by the 1990s, including such things as muons and taus. Naturally this glut called into question the very notion of “elementary.”

The scientist who made sense of it all was Murray Gell-Mann, who by age twenty-six spoke eight languages, apparently well, and was a full professor of physics at the California Institute of Technology, or Caltech. As cheeky as he was intellectually nimble, Gell-Mann was often called the smartest man in the world.

Taking a cue from classical biology, he began classifying subatomic particles into families in the late 1950s, the better to understand their characteristics. His lists predicted the existence of an unknow particle, the omega-minus. At Brookhaven National Laboratory, after years of tediously reviewing photographs taken in accelerators, the young physicist Nicholas Samios finally discovered the omega-minus in 1964 on experimental photograph No.  97,025. Gell-Mann’s classifications were on target.

Aage Niels Bohr

Aage Bohr, who died on September 8 aged 87, was a pioneering nuclear physicist and Nobel Prize winner; in his youth he escaped from Nazi-occupied Denmark with his father, Niels Bohr, a central figure in the Manhattan Project, to whom Aage was a valuable assistant.

“I was born in Copenhagen on June 19, 1922, as the fourth son of Niels Bohr and Margrethe Bohr (née Nørlund). During my early childhood, my parents lived at the Institute for Theoretical Physics (now the Niels Bohr Institute), and the remarkable generation of scientists who came to join my father in his work became for us children Uncle Kramers, Uncle Klein, Uncle Nishina, Uncle Heisenberg, Uncle Pauli, etc.”

“When I was about ten years old, my parents moved to the mansion at Carlsberg, where they were hosts for widening circles of scholars, artists, and persons in public life.”

“I went to school for twelve years at Sortedam Gymnasium (H. Adler’s fæellesskole) and am indebted to many of my teachers, both in the humanities and in the sciences, for inspiration and encouragement.”

“I began studying physics at the University of Copenhagen in 1940 (a few months after the German occupation of Denmark). By that time, I had already begun to assist my father with correspondence, with his writing of articles of a general epistemological character, and gradually also in connection with his work in physics.”

“In those years, he was concerned partly with problems of nuclear physics and partly with problems relating to the penetration of atomic particles through matter.”

In October 1943, my father had to flee Denmark to avoid arrest by the Nazis, and the whole family managed to escape to Sweden, where we were warmly received. Shortly afterwards, my father proceeded to England, and I followed after him.

He became associated with the atomic energy project and, during the two years until we returned to Denmark, in August 1945, we travelled together spending extensive periods in London, Washington, and Los Alamos. I was acting as his assistant and secretary and had the opportunity daily to share in his work and thoughts.

We were members of the British team, and my official position was that of a junior scientific officer employed by the Department of Scientific and Industrial Research in London. In another context, I have attempted to describe some of the events of those years and my father’s efforts relating to the prospects raised by the atomic weapons

The Bohr family fled from Denmark to neutral Sweden in 1943 after Hitler had ordered the deportation of Danish Jews. From Sweden the Bohrs headed for London where Niels became involved in what Aage was later to call, somewhat euphemistically, “the atomic energy project”.

In fact the Manhattan Project was a race against the Nazis to build the first atom bomb. Niels Bohr’s expertise was crucial to the Allies, and Aage, by then officially a “junior scientific officer employed by the Department of Scientific and Industrial Research” became a laboratory assistant to his father at the Manhattan Project’s headquarters in Los Alamos, New Mexico.

As the extraordinarily devastating power of the atom bomb became clear, however, both men cautioned against using it, and voiced their concerns to British and American leaders. In the end, the bombs that were dropped on Hiroshima and Nagasaki were credited with bringing the war to a speedy end.

In September 1943 Hitler demanded the deportation of Denmark’s more than 7,000 Jews. Within days the community was being smuggled in huge numbers across the narrow Oresund channel to the sanctuary of Sweden. Having established his family in safety, Niels Bohr soon left for London and the Manhattan Project, where he was quickly joined by Aage. They were not to return to Denmark until August 1945.

On their return, Aage Bohr began to craft a reputation as a profoundly gifted physicist in his own right. He resumed his studies at Copenhagen University, and, two years after completing his Masters degree in 1946, he left for America to pursue his research at the Institute of Advanced Study at Princeton. In 1949 he teamed up with the American physicist James Rainwater to study the architecture at the heart, or nucleus, of atoms.

Their work led Bohr to challenge the conclusions of his own father, who had established one of the two theories about nuclear structure then vying for acceptance. Niels Bohr had suggested that protons and neutrons within an atom’s nucleus are held together in the same manner by which molecules are attracted to each other in a drop of liquid.

James Rainwater showed that neither Niels Bohr, nor his rival Maria Goeppert-Mayer, who proposed that protons and neutrons were held in orbits within the nucleus, had fully explained nuclear structure. To explain the inconsistencies in their theories, he suggested that some nuclei were not perfectly round.

Aage Bohr returned to Copenhagen in 1950, determined to resolve the issue. He struck up a collaboration with another American physicist, Ben Mottelson. Bohr felt they were “kindred spirits” and it was a fruitful partnership. Within two years the pair had published their “collective model” of nuclear structure. It combined the two existing theories, noting that, as Rainwater had predicted, centrifugal forces distorted some spherical nuclei into an oval shape.

The men were to refine their study of nuclear structure over the next 25 years, publishing their conclusions in two volumes (1969 and 1975). It was for this work, fundamentally reappraising the central building blocks of atoms, that Bohr, Mottelson and Rainwater were collectively awarded the Nobel Prize in 1975.

By that time Bohr had been head of the Niels Bohr Institute for 12 years, taking over after his father’s death in 1962. He left the Institute in 1967 to dedicate himself to his research.

After winning the Nobel Prize, Bohr ran the Nordic Institute for Theoretical Nuclear Physics, which his father had set up in 1957 to encourage theoretical physics, notably in the fields of astrophysics, condensed matter physics, and subatomic physics.

By the time of his retirement in 1981, Aage Bohr had won many awards, including the Pope Pius XI Medal (1963) and the Ole Romer Medal (1976). He was a member of many scientific academies in Europe and the National Academy of Science in the United States.

Aage Bohr, who enjoyed classical music and himself played the piano, married in 1950, Marietta Soffer, with whom he had two sons and a daughter. After she died, he married, in 1981, Bente Meyer Scharff, who survives him.

The Algol paradox

ALGOL (Beta Persei). Surely one of the most remarkable stars of the sky and appropriately one of the most famed, Algol is the second magnitude Beta star of Perseus, the great mythological hero who rescued Andromeda from Cetus the Sea Monster.

The Arabic name, “al Ghul” (related to our word “ghoul”), means “the demon,” from a longer phrase that refers to the demon’s head. In Greek mythology, Algol represents the Medusa’s head with which Perseus turned Cetus to stone, the star considered an “unlucky” one for centuries.

To the eye, this class B (B8) star appears rather normal, its slightly bluish white light radiating from a surface with a temperature of 12,500 K. Like the Sun, it is a main sequence dwarf star fusing hydrogen in its core, though it is 3.5 times more massive.

From its distance of 93 light years, we calculate a visual luminosity about 100 times that of the Sun, raised to 180 times if we factor in the invisible ultraviolet light radiated by the hot surface.

Steady observation, however, reveals a surprise. As regular as clockwork, every 2.867… days, the brightness of the star plummets from mid second magnitude (2.1) to the dim end of third (3.4, just 30 percent of normal), the whole event (including recovery) taking only a few hours.

Though the variation was discovered in 1667, it was probably known long before that and is probably the reason for the star’s bad reputation. The cause of the sudden drop is a stellar eclipse. Algol is a close double star whose components orbit each other every 2.867… days.

The companion to the visually observed star is a much dimmer yellow-orange class K giant star with a temperature of 4500 Kelvin and a luminosity 4.5 solar, just 2.5 percent that of the class B star.

The uncertain class of the faint star ranges from G5 to K2, from subgiant to giant. For simplicity, let’s call it the “K giant.” The B star, at 2.9 solar radii, is smaller than the K giant (3.5 solar).

Each orbit, when the dimmer, larger K star passes in front of the brighter B star, we see a deep eclipse. The eclipse is only partial, some of the light of the principal component still shining brightly through. Between the deep “primary” eclipses is a smaller dip when the bright star passes partially in front of the dim one.

Algol is famed first as a prototype of the class of eclipsing double stars, of which thousands are known. They are among the most important kinds of stars, as they provide us with information on stellar masses and dimensions.

But Algol is equally famed for the “Algol paradox.” The higher the mass of a star, the shorter its lifetime, as its fuel is used so much faster. The companion to Algol is the dying giant star. Yet carrying but 0.81 solar masses, it is the LESS massive of the two (the B star weighing in at 3.7 solar).

The only explanation is that the dim companion has lost a great deal of mass. The two stars are so close together, separated by only five percent the distance between the Earth and the Sun, that the brighter smaller star produces tides in the larger one.

Matter then flows in from the large one (at a rate of around two hundred- millionths of a solar mass per year) to the small bright one, the effect directly observed through the stellar spectrum as the K giant is being stripped nearly to its core.

A third member of the system, Algol C, a class A or F star of 1.8 solar masses, orbits about 3 Astronomical Units away with a period around the inner pair of 1.86 years. The system is a source of X-rays, though whether they come from a corona around one of the stars or from the flow of matter hitting the B star is uncertain.

Algol is no demon at all, but a true friend, teaching us how stars interact and die, the effects of which you can see from your own backyard with no telescope at all.

Wolfgang Pauli’s neutrino

Austrain theorist Wolfgang Pauli’s name is inseparable from his pioneering hypothesis of the existence of the neutrino, which was confirmed by experiment only after 25 years. The starting point for Pauli was the continuous energy spectrum of beta rays, which could not be interpreted theoretically.

Niels Bohr attempted it with the hypothesis of the restricted validity of the principle of energy conservation, which Pauli could not accept because the principle of the conservation of energy had proved itself in all fields of physics and its proposition seemed to be plausible.

In this critical situation Pauli hit on a desperate way out: he developed the idea that during beta decay, apart from the electron a further, but electrically neutral particle is emitted in such a way that the sum of the energies of both particles is constant.

On 4th December 1930, Pauli wrote his famous letter to the “Dear Radioactive Ladies and Gentlemen” who had gathered in Tübingen. In it, he sketched out his idea and inquired how things stood with the experimental proof. But he considered his idea to be too immature to be published. He dared to hypothesise the existence of new particle – the particle now known as the neutrino.

Pauli proposed the new particle to explain why energy seemed to go missing in the form of radioactivity known as beta-decay. The neutrino would took away energy but without being detected, as it has no electric charge and a very small mass.

It was to be another 26 years before Fred Reines and Clyde Cowan claimed the first detection of Pauli’s “undetectable” particle. Pauli himself went on to receive the Nobel prize for physics in 1945, not for his idea of the neutrino but for his famous “exclusion principle”.

The Italian nuclear physicist Enrico Fermi took up Pauli’s idea and on its basis developed a theory of beta decay. Fermi also coined the term “neutrino”, after Pauli had spoken of “neutron”, but the latter designation was reserved for the heavy component of the atomic nucleus discovered in 1932.

Not until October 1933 at the 7th Solvay Conference in Brussels did Pauli dare to present his hypothesis in public. It then took a further 23 years before the experimental proof of the existence of the neutrino succeeded.

Paul Adrien Maurice Dirac

Paul Dirac’s father was Charles Adrien Ladislas Dirac and his mother was Florence Hannah Holten. Charles Dirac was a Swiss citizen born in Monthey, Valais while his mother came from Cornwall in England.

Charles had been educated at the University of Geneva, then came to England in around 1888 and taught French in Bristol. There he met Florence, whose father had moved to Bristol as Master Mariner on a Bristol ship, when she was working in the library there.

Charles and Florence married in 1899 and they moved into a house in Bishopston, Bristol which they named Monthey after the town of Charles’s birth. By this time Charles was teaching French at the secondary school attached to the Merchant Venturers Technical College in Bristol.

Paul was one of three children, his older brother being Reginald Charles Felix Dirac and his younger sister being Beatrice Isabelle Marguerite Walla Dirac. Paul had a very strict family upbringing. His father insisted that only French be spoken at the dinner table and, as a result, Paul was the only one to eat with his father in the dining room. Paul’s father was so strict with his sons that both were alienated and Paul was brought up in a somewhat unhappy home.

The first school which Paul attended was Bishop Primary school and already in this school his exceptional ability in mathematics became clear to his teachers. When he was twelve years old he entered secondary school, attending the secondary school where his father taught which was part of the Merchant Venturers Technical College.

At about the time Paul entered the school World War I began and this had a beneficial effect for Paul since the older boys in the school left for military service and the younger boys had more access to the science laboratories and other facilities. Paul himself wrote about his school years in:

The Merchant Venturers was an excellent school for science and modern languages. There was no Latin or Greek, something of which I was rather glad, because I did not appreciate the value of old cultures. I consider myself very lucky in having been able to attend the school. … I was rushed through the lower forms, and was introduced at an especially early age to the basis of mathematics, physics and chemistry in the higher forms. In mathematics I was studying from books which mostly were ahead of the rest of the class. This rapid advancement was a great help to me in my latter career.

He completed his school education in 1918 and then studied electrical engineering at the University of Bristol. By this time the University had combined with the Merchant Venturers Technical College so Dirac remained in the same building as he had studied during his four years at secondary school.

Though mathematics was his favourite subject he chose to study an engineering course at university since he thought that the only possible career for a mathematician was school teaching and he certainly wanted to avoid that profession.

He obtained his degree in engineering in 1921 but following this, after an undistinguished summer job in an engineering works, he did not find a permanent job. By this time he was developing a real passion for mathematics but his attempts to study at Cambridge failed for rather strange reasons.

Taking the Cambridge scholarship examinations in June 1921 he was awarded a scholarship to study mathematics at St John’s College Cambridge but it did not provide enough to support him.

Additional support would have been expected from his local education authority, but he was refused support on the grounds that his father had not been a British citizen for long enough. Dirac was offered the chance to study mathematics at Bristol without paying fees and he did so being awarded first class honours in 1923. Following this he was awarded a grant to undertake research at Cambridge and he began his studies there in 1923.

Dirac had been hoping to have his research supervised by Ebenezer Cunningham, for by this time Dirac had become fascinated in the general theory of relativity and wanted to undertake research on this topic. Cunningham already had as many research students as he was prepared to take on and so Dirac was supervised by Ralph Fowler. The authors of write:

Fowler was then the leading theoretician in Cambridge, well versed in the quantum theory of atoms; his own research was mostly on statistical mechanics. He recognised in Dirac a student of unusual ability. Under his influence Dirac worked on some problems in statistical mechanics. Within six months of arriving in Cambridge he wrote two papers on these problems. No doubt Fowler aroused his interest in the quantum theory, and in May 1924 Dirac completed his first paper dealing with quantum problems. Four more papers were completed by November 1925.

Despite the obvious academic success Dirac enjoyed as a research student this was no easy time for him. His brother Reginald Dirac committed suicide during this period.

No reason for the suicide seems to be known but Dirac’s relations with his father, already strained, seemed almost to end completely after this which does suggest that Dirac felt that his father carried at least some responsibility. Already a person who had few friends, this personal tragedy had the effect of making him even more withdrawn.

Although he had already made an excellent start to his research career, even more impressive work was to follow. This was as a result of Dirac being given proofs of a paper by Heisenberg to read in the summer of 1925.

The significance of the algebraic properties of Heisenberg’s commutators struck Dirac when he was out for a walk in the country. He realised that Heisenberg’s uncertainty principle was a statement of the noncommutativity of the quantum mechanical observables. He realised the analogy with Poisson brackets in Hamiltonian mechanics. Higgs writes in:

This similarity provided the clue which led him to formulate for the first time a mathematically consistent general theory of quantum mechanics in correspondence with Hamiltonian mechanics.

The ideas were laid out in Dirac’s doctoral thesis Quantum mechanics for which he was awarded a Ph.D. in 1926. It is remarkable that Dirac had eleven papers in print before submitting his doctoral dissertation.

Following the award of the degree he went to Copenhagen to work with Niels Bohr, moving on to Göttingen in February 1927 where he interacted with Robert Oppenheimer, Max Born, James Franck and the Russian Igor Tamm. Accepting an invitation from Ehrenfest, he spent a few weeks in Leiden on his way back to Cambridge. He was elected a Fellow of St John’s College, Cambridge in 1927.

Dirac visited the Soviet Union in 1928. It was the first of many visits for he went again in 1929, 1930, 1932, 1933, 1935, 1936, 1937, 1957, 1965, and 1973. Also in 1928 he found a connection between relativity and quantum mechanics, his famous spin-1/2 Dirac equation.

In 1929 he made his first visit to the United States, lecturing at the Universities of Wisconsin and Michigan. After the visit, along with Heisenberg, he crossed the Pacific and lectured in Japan. He returned via the trans-Siberian railway.

In 1930 Dirac published The principles of Quantum Mechanics and for this work he was awarded the Nobel Prize for Physics in 1933. De Facio, reviewing, says of this book:-

Dirac was not influenced by the feeding frenzy in experimental phenomenology of the time. This has given Dirac’s book … a lasting quality that few works can match.

The authors of comment that the book:-

… reflects Dirac’s very characteristic approach: abstract but simple, always selecting the important points and arguing with unbeatable logic.

Also in 1930 Dirac was elected a Fellow of the Royal Society. This honour came on the first occasion that his name was put forward, in itself quite an unusual event which says much about the extremely high opinion that Dirac’s fellow scientists had of him.

Dirac was appointed Lucasian professor of mathematics at the University of Cambridge in 1932, a post he held for 37 years. In 1933 he published a pioneering paper on Lagrangian quantum mechanics which became the foundation on which Feynman later built his ideas of the path integral. In the same year Dirac received the Nobel prize for physics which he shared with Schrödinger.

It is an interesting comment on Dirac’s nature that his first thought was to turn down the prize on the grounds that he hated publicity. However when it was pointed out to him that he would receive far more publicity if he turned down the prize, he accepted it.

Another comment about this event is that Dirac was told that he could invite his parents to the award ceremony in Stockholm, but he chose to invite only his mother and not his father.

The academic year 1934-35 was important for Dirac both for personal and professional reasons. He visited the Institute for Advanced Study at Princeton and there he became friendly with Wigner.

While Dirac was there Wigner’s sister Margit, who lived in Budapest, visited her brother. This chance meeting led, in January 1937, to Dirac marrying Margit in London. Margit had been married before and had two children Judith and Gabriel Andrew from her first marriage.

Both children adopted the name Dirac and Gabriel Andrew Dirac went on the became a famous pure mathematician, particularly contributing to graph theory, becoming professor of pure mathematics at the University of Aarhus in Denmark.

In 1937, the same year that he married, Dirac published his first paper on large numbers and cosmological matters. We comment further on his ideas on cosmology below. He published his famous paper on classical electron theory, which included mass renormalisation and radiative reaction in 1938.

Dirac worked during World War II on uranium separation and nuclear weapons. In particular he acted as a consultant to a group in Birmingham working on atomic energy. This association led to Dirac being prevented by the British government from visiting the Soviet Union after the end of the war; he was not able to visit again until 1957.

We noted above that Dirac was elected a fellow of the Royal Society in 1930. He was awarded the Royal Society’s Royal Medal in 1939 and the Society awarded him their Copley Medal in 1952:-

… in recognition of his remarkable contributions to relativistic dynamics of a particle in quantum mechanics.

In 1969 Dirac retired from the Lucasian chair of mathematics at Cambridge and went with his family to Florida in the United States. He held visiting appointments at the University of Miami and at Florida State University. Then, in 1971, Dirac was appointed professor of physics at Florida State University where he continued his research.

In 1973 and 1975 Dirac lectured in the Physical Engineering Institute in Leningrad. In these lectures he spoke about the problems of cosmology or, to be more precise, to the problems of non-dimensional combinations of world constants.

Although Dirac made vastly important contributions to physics, it is important to realise that he was always motivated by principles of mathematical beauty. Dirac unified the theories of quantum mechanics and relativity theory, but he also is remembered for his outstanding work on the magnetic monopole, fundamental length, antimatter, the d-function, bra-kets, etc.

There is a standard folklore of Dirac stories, mostly revolving around Dirac saying exactly what he meant and no more. Once when someone, making polite conversation at dinner, commented that it was windy, Dirac left the table and went to the door, looked out, returned to the table and replied that indeed it was windy.

It has been said in jest that his spoken vocabulary consisted of “Yes”, “No”, and “I don’t know”. Certainly when Chandrasekhar was explaining his ideas to Dirac he continually interjected “yes” then explained to Chandrasekhar that “yes” did not mean that he agreed with what he was saying, only that he wished him to continue. He once said:-

I was taught at school never to start a sentence without knowing the end of it.

This may explain much about his conversation, and also about his beautifully written sentences in his books and papers.

Dirac received many honours for his work, some of which we have mentioned above. He refused to accept honorary degrees but he did accept honorary membership of academies and learned societies.

The list of these is long but among them are USSR Academy of Sciences (1931), Indian Academy of Sciences (1939), Chinese Physical Society (1943), Royal Irish Academy (1944), Royal Society of Edinburgh (1946), Institut de France (1946), National Institute of Sciences of India (1947), American Physical Society (1948), National Academy of Sciences (1949), National Academy of Arts and Sciences (1950), Accademia delle Scienze di Torino (1951), Academia das Ciencias de Lisboa (1953), Pontifical Academy of Sciences, Vatican City (1958), Accademia Nazionale dei Lincei, Rome (1960), Royal Danish Academy (1962), and Académie des Sciences Paris (1963). He was appointed to the Order of Merit in 1973.

Joseph Louis Gay-Lussac

Joseph Louis Gay-Lussac (1778–1850) grew up during both the French and Chemical Revolutions. His comfortable existence as the privately tutored son of a well-to-do lawyer was disrupted by political and social upheavals: his tutor fled, and his father was imprisoned.

Joseph, however, benefited from the new order when he was selected to attend the École Polytechnique, an institution of the French Revolution designed to create scientific and technical leadership, especially for the military.

There his mentors included Pierre Simon de Laplace and Claude Louis Berthollet, among other scientists converted by Antoine-Laurent Lavoisier to oxygen chemistry. Gay-Lussac’s own career as a professor of physics and chemistry began at the École Polytechnique.

By virtue of his skill and diligence as an experimentalist, and by his demonstration of the power of the scientific method, deserves recognition as a great scientist. He shared the interest of Lavoisier and others in the quantitative study of the properties of gases. From his first major program of research in 1801–1802, he concluded that equal volumes of all gases expand equally with the same increase in temperature.

This conclusion is usually called “Charles’s law” in honor of Jacques Charles, who had arrived at nearly the same conclusion 15 years earlier but had not published it.

In 1804 Gay-Lussac made several daring ascents of over 7,000 meters above sea level in hydrogen-filled balloons—a feat not equaled for another 50 years—that allowed him to investigate other aspects of gases.

While Gay-Lussac was a great theoretical scientist, he was also respected by his colleagues for his careful, elegant, experimental work. Not only did he gather magnetic measurements at various altitudes, but he also took pressure, temperature, and humidity measurements and samples of air, which he later analyzed chemically.

In 1808 Gay-Lussac announced what was probably his single greatest achievement: from his own and others’ experiments he deduced that gases at constant temperature and pressure combine in simple numerical proportions by volume, and the resulting product or products—if gases—also bear a simple proportion by volume to the volumes of the reactants.

With his fellow professor at the École Polytechnique, Louis Jacques Thénard, Gay-Lussac also participated in early electrochemical research, investigating the elements discovered by its means.

Among other achievements, they decomposed boric acid by using fused potassium, thus discovering the element boron. The two also took part in contemporary debates that modified Lavoisier’s definition of acids and furthered his program of analyzing organic compounds for their oxygen and hydrogen content.