James Bjorken, a theoretical physicist who performed a key function in establishing the existence of subatomic particles referred to as quarks, died Aug. 6 in Redwood Metropolis, California. He was 90 years outdated.
His dying at an assisted dwelling facility close to his Sky Londa, Calif., house was attributable to metastatic melanoma, mentioned his daughter, Johanna Bjorken.
Dr. Bjorken, generally known as BJ, was a professor at Stanford College and the SLAC Nationwide Accelerator Laboratory in Menlo Park, California, within the late Nineteen Sixties when he invented what would develop into generally known as the “Bjorken scaling”, which the lab described as “his most well-known scientific achievement”.
On the time, SLAC physicists have been capturing electrons at nucleons—protons and neutrons—to review their nature. The electrons functioned considerably like magnifying glasses: when shot out at excessive sufficient energies, they allowed physicists to “see” the internal construction of the nucleon.
Two portions helped characterize these collisions: the power at which the affect occurred and the power of the outgoing electron. Dr. Bjorken proposed that the conduct of collisions relies upon not on these two portions individually, however on a sure mixture of them.
This perception gave the physicists conducting the experiment a theoretical foundation for the right interpretation of their knowledge, which ultimately revealed that protons and neutrons include even smaller particles, later recognized as quarks. In 1990, three researchers who led the experiment were awarded the Nobel Prize in Physics.
As much as three folks can share the Nobel Prize annually, and Dr. Bjorken was not amongst them. “But when there was a fourth, it could be him,” Helen Quinn, a physicist at SLAC who studied below Dr. Bjorken, mentioned in an interview.
Lance Dixon, a physicist at SLAC, mentioned: “Quite a lot of us suppose he definitely deserves it as a result of he tells them what to do with the information.” He added: “He was a legend. And this was his most legendary work.
Michael Turner, a cosmologist on the College of Chicago, wrote in an electronic mail that Dr. Bjorken ought to have gained the Nobel Prize for predicting quarks. The issue, he recommended, was that “nobody may perceive his papers.”
Dr. Bjorken’s work was a part of a growth of discoveries within the Nineteen Sixties and Seventies that ultimately coalesced into the Commonplace Mannequin, a principle describing the properties of subatomic particles and the way they behave.
“Once I entered the sector, the Commonplace Mannequin did not exist,” Dr. Bjorken mentioned in a 2020 interview with the American Institute of Physics. “I went by means of a golden age.”
James Daniel Bjorken was born on June 22, 1934, in Chicago to Johan Daniel Bjorken, a mechanical engineer, and Edith (Lindström) Bjorken.
His favourite topics in highschool have been math and chemistry; It wasn’t till he entered faculty on the Massachusetts Institute of Expertise that he turned eager about physics. He later recollects the primary day of his freshman class and his professor’s opening line: “Why are we learning physics? As a result of physics is enjoyable!”
Dr. Bjorken adopted this phrase as his private motto. He too used it as the title of a memoir he revealed in 2020.
Dr. Bjorken graduated from MIT in 1956 and obtained his Ph.D. in physics from Stanford College three years later. He turned a professor at Stanford in 1961.
In 1974, analysis teams at SLAC and Brookhaven Nationwide Laboratory independently found the so-called magic quark, the existence of which Dr. Bjorken and one other theoretical physicist, Sheldon Glashaw of Harvard College, it was predicted a decade earlier. (Two of the physicists who led these experiments have been awarded 1976 Nobel Prize in Physics.) This discovery led to widespread acceptance amongst physicists that quarks have been certainly actual.
In 1979, Dr. Bjorken left California for Illinois, the place he served as Affiliate Director of Physics on the Fermi Nationwide Accelerator Laboratory for 10 years. Throughout his time there, he made influential contributions to the particle accelerator designs and on the physical processes involved in heavy ion collision.
He returned to SLAC in 1989 and retired in 1998.
Dr. Bjorken has gained a number of awards all through his profession, together with in 2015 Wolf Award. — among the many most prestigious prizes in physics and chemistry, thought-about second solely to the Nobel Prize.
That the Nobel prize eluded Dr. Bjorken by no means appeared to hassle him. “I desire to think about awards as windfalls,” he mentioned within the 2020 interview. “It is good if it occurs, however nothing greater than that.”
Physics “was the whole lot to him,” his daughter Johanna mentioned. Rising up, she recalled, she would see him fill the margins of newspapers, the backs of envelopes and different scraps of paper round the home with numbers and Greek letters.
“There’s at all times been a little bit of physics in all places,” she mentioned.
However he had different pursuits, notably music and the mountains. Alternatives to go to the opera, hike, or ski typically led to the place his profession took him. A photograph of Dr. Bjorken taken in 1960 exhibits him climbing Cathedral Peak in Yosemite Nationwide Park. In a winking nod to his analysis, his colleagues dubbed it “Bjorken scaling.”
Dr. Bjorken married Joan Goldthwaite in 1967. She died in 1983. Along with his daughter Johanna, he’s survived by one other daughter, Eliza Davis; his stepchildren, Peter Nauenberg and Maria James; and 9 grandchildren, considered one of whom is now an astrophysicist.
In retirement, Dr. Bjorken delved into extra speculative bodily issues, together with dark energy. He additionally launched into novice discipline geological work, buying a powerful assortment of rocks alongside the best way.
Even the final months of his life have been spent in theoretical reflections. “It is likely to be the geriatric slurs of an 89-year-old man,” Ms. Bjorken recollects, exclaiming to her father, “nevertheless it’s leisure for me!”
Dennis Overbye contributed reporting.
