French-American mathematical physicist Cécile DeWitt-Morette, who died on May 8 at the age of 94, could abide no obstacle. With her frank demeanor, penetrating eyes, and short-cropped pixie haircut, she projected an air of earnest mission, like a solo pilot determined to set new records. While she deeply loved and respected her more famous (at least, in the world of physics) husband, Bryce DeWitt, her life made it absolutely clear that she was boldly independent and a force in her own right.
Starting with the bombing of her family’s house in World War II that resulted in the tragic deaths of her mother, sister, and grandmother, life was never easy for her. Nor were her choices ever simple. She faced decades of discrimination for being a woman in a male dominated field and, later in life, the challenges of dealing with Bryce’s death from pancreatic cancer, one of her daughter’s struggles with obsessive-compulsive disorder, and the hardships of old age. Yet she endured and flourished, carving out enough time for her many hobbies and intellectual pursuits until the very end.
Cécile Morette (her maiden name) was born on December 21, 1922 to a middle-class family in the French region of Normandy. Originally she aspired to be a surgeon. Her mother suggested that she study mathematics first to hone her logic and broaden her horizons. She enjoyed her studies so much that she decided to complete an undergraduate degree in the field.
In the spring of 1944, Morette was 21 and, like many people her age, wanted to travel around and enjoy some adventures. However, during the Nazi occupation of France (which had begun four years earlier), young women could travel unaccompanied only for good reason. Wanting to see Paris and have some fun, she enrolled in an advanced math class there. On June 6, D-Day, she was taking an exam when calamity struck in her home city many miles away.
The world honors that date for the Allied invasion of Normandy and the beginning of the end of the Third Reich. But often forgotten is the tremendous collateral damage, including civilian casualties caused by the Allied bombing of key coastal towns to prevent the Germans from retreating, regrouping, and/or sending reinforcements. Prominent among the devastated population centers was the city of Caen, where an errant bomb strike, intended for knocking out bridges, hit and flattened many houses, including where the Morettes resided.
Suddenly and tragically, Morette was essentially alone and forced to take sole charge of her life. Continuing her graduate studies at the University of Paris, she found a job working in the nuclear physics lab of Irène Joliot-Curie (daughter of Marie and Pierre) and her husband, Frédéric. In 1947, she completed her PhD on the subject of nuclear forces, and took on two successive postdoctoral positions, one in Dublin under Erwin Schrödinger and Walter Heitler, the other in Copenhagen under Niels Bohr.
The following year, Robert Oppenheimer, director of the Institute for Advanced Study (IAS) at Princeton, invited Morette to become a visiting researcher there. With Albert Einstein, John von Neumann, and Kurt Gödel on its faculty, among others, the IAS was arguably the most prestigious place to work in physics after World War II.
Despite not realizing its stellar reputation at first, she gladly accepted the offer, envisioning it as another adventurous opportunity to travel and do research. She anticipated spending a year or two in the United States, and then ultimately returning to France.
Thanks to Freeman Dyson, another visiting scholar at the IAS, the visit was more fun than she imagined. While Dyson himself was low-key, he had recently met Richard Feynman and found his passion for adventure to be infectious. Dyson told Morette about Feynman’s new path integral formalism (also known as functional integral or “sum over histories”), a novel and powerful method for performing calculations in particle physics and, in particular, quantum electrodynamics, which she found intriguing. He pointed out that the technique was not yet mathematically rigorous.
The path integral method in quantum mechanics generalizes classical Newtonian mechanics by replacing the single trajectory of a particle with a weighted sum of every physically allowed path. It is like calculating someone’s commute time by considering all the routes he could take from home to work and back again, not just the path he actually takes, and weighing each according to how optimal it is. Feynman showed how his techniques applied to the Lamb shift (spectral line shift detected by Willis Lamb) and other quantum quandaries. As Dyson demonstrated, they were equivalent to a less intuitive but mathematically more involved calculational approach developed around the same time by Harvard physicist Julian Schwinger, as well as to a method developed during the war by Japanese physicist Sin-Itiro Tomonaga.
After discussions of Feynman’s methods, Dyson and Morette decided to take the long train ride to Ithaca to visit him. Feynman was, at the time, a professor at Cornell University. After picking them up from the station, he serenaded them with bongo drums (his passion) late into the evening. He also amazed them with some lightning-fast calculations. They returned to the IAS elated.
Impressed with the power of Feynman’s path integral method, Morette decided to apply her mathematical skills to setting it on a firmer footing. In doing so, she helped promote its use for a wide range of applications in physics. Thanks to Morette, not only Feynman diagrams (shorthand sketches of particle interactions), but the mathematical machinery behind their use became broadly known.
By the Fall of 1949, Dyson had left the IAS (he would later return as a permanent member) and another bright young researcher, Bryce Seligman DeWitt (born Carl Bryce Seligman in 1923), arrived. An American physicist in the process of completing his PhD under Schwinger, DeWitt’s main interest was applying quantum electrodynamics to the field of gravitation, which up until that point had been understood only classically. DeWitt and Morette soon grew romantically close, and began to go on outings with each other.
One day, during dinner together after a canoeing excursion, DeWitt proposed marriage. Morette was baffled, as she had not envisioned remaining in America, but rather hoped to return to France. At first, she said no. However, after thinking about her options, she suggested an ingenious plan. She’d get married to him on the condition that they find a way to spend every summer in France. That condition, which he gladly accepted, led her to found the Les Houches Summer School in the scenic French Alps.
Operating each summer since 1951, Les Houches has been a brilliant success, including many esteemed physicists among its faculty and students — such as Nobel Laureates Wolfgang Pauli, Enrico Fermi, John Bardeen, Murray Gell-Mann, as well as esteemed physicists like Yuval Ne’eman and many other notables. In particular, technical theoretical fields such as supergravity and superstrings benefitted from the free, relaxed atmosphere of its summer classes, spreading the word about novel methods used in those disciplines (such as adding dimensions to field theories) before they were taught in universities.
During the early-to-mid 1950s the DeWitts traveled around the world, hopping from one position to another. Similarly adventurous, independent-minded, and unconventional, Cécile and Bryce made a perfect match, reveling in each other’s company.
One offbeat decision made by the latter proved instrumental for their careers. In 1953, Bryce entered an essay contest sponsored by the Gravity Research Foundation, a fringe organization founded by industrialist Roger Babson to research the possible development of a mechanism to shield against gravity (in other words, “anti-gravity”) to produce propulsion systems. Bryce’s essay — thoughtful, serious, and not really fringe at all — won first place in the competition.
After learning about Bryce DeWitt’s prize-winning essay, Agnew Bahnson, a wealthy owner of an air conditioning company who had a strong passion for physics, endowed him to head a new research unit at the University of North Carolina, Chapel Hill, starting in 1956, called the Institute for Field Physics. Bahnson also funded the first major American conference on general relativity and gravitation, held at that university the following year, and organized by Cécile, with Bryce’s assistance.
Settled in Chapel Hill, the DeWitts started to raise a family — ultimately four daughters. Those daughters established a rule for Cécile and Bryce that physics would not be discussed at the dinner table (a rule that, admittedly, they often broke) — thereby promoting a normal family life outside of work.
While Bryce was appointed to a regular tenured professorship, Cécile, though equally capable, was excluded because of archaic, unwritten nepotism rules that seemed designed to leave out women more than men. (A prime example of such exclusion was Nobel laureate Maria Goeppert Mayer, who completed much of her early work unpaid because her husband, Joseph Mayer, was on the faculty of Johns Hopkins, and she was therefore barred from a professorship there.) Despite her Ph.D., organizational talents, and stellar credentials, Cécile was assigned only to be a much lower paid lecturer. Many colleagues unceremoniously allotted Bryce credit for the work she completed; hence her eventual adoption of the hyphenated name DeWitt-Morette.
Believing strongly in equal rights, the DeWitts began to look for a university that would employ both of them as full professors. It would take them more than 15 years to achieve their goal. In 1972, the University of Texas, Austin, hired both of them as professors, enabling them finally to have academic equality. By then Bryce had made a name for himself in quantum gravity, while Cécile was well-published in mathematical physics. They spent more than three happy decades together in Austin.
One of their many achievements together came in 1973 when they traveled to the desert of Mauritania, where the atmosphere was dry, clear, and still. While there, they engaged in precise testing of Einstein’s general relativistic predictions during a solar eclipse. Cécile led the research team, with Bryce and other University of Texas faculty assisting her.
Sadly, on September 23, 2004, Bryce died of pancreatic cancer. Cécile was once again alone — save, of course, the enduring love and support of her daughters, whom she had encouraged to be strong and independent. One of her daughters had been diagnosed with obsessive-compulsive disorder, inspiring Cécile to become president of a group called Planned Living Assistance Network, which helped families with grown children with mental illnesses.
DeWitt-Morette continued to be active until her early 90s, believing in organizing her time to preserve a balanced life, including travel and exercise (she was a brown belt in judo and loved to ski). In 2011, mainly in recognition of Les Houches, she was awarded the prestigious title of Officer in the French Legion of Honor (she had received a Legion of Honor medal years earlier). One of her final tasks was assembling Bryce’s memoirs, titled The Pursuit of Quantum Gravity, from his many personal writings.
Complete equality between women and men is still a dream in science. There is still a great disparity in the number of awards, professorships, and so forth. But Cécile DeWitt-Morette had an indomitable spirit. “Don’t mourn, organize!” an expression associated with labor folksinger Joe Hill, could equally well have applied to her. She lived the dream of equal rights and inspired generations of students, researchers, and others to achieve. Bravo, Professor, for a life well-lived!
Thanks to Chris DeWitt for her suggestions and minor corrections to an earlier version of this piece. She has pointed out that a graduate student fellowship at the University of Texas is being established in memory of both Cécile and Bryce DeWitt.
Paul Halpern is the author of fifteen popular science books, including The Quantum Labyrinth: How Richard Feynman and John Wheeler Revolutionized Time and Reality.