The world lost another giant of the Physics world — Murray Gell-Mann, a winner of the 1969 Nobel Prize in Physics and best known for developing the theory of sub-atomic particles called “quarks”. He passed away on Friday, May 24, 2019 at the age of 89.
Early Life and Education
Murray Gell-Mann was born on Sept. 15, 1929 in lower Manhattan into a family of Jewish immigrants from the Austro-Hungarian Empire. Growing up in a family with meager means, Gell-Mann had a precocious childhood, excelling in school and graduating as valedictorian at age 15. He went on to Yale on a scholarship. But physics was not his first choice as a major area of study. He considered archaeology or a field related to natural history. His father, however, pushed him to choose engineering, saying it would lead to a well-paying job. Murray resisted, and they settled on physics as a compromise — “to please the old man,” Dr. Gell-Mann said — and the rest, as they say, is history.
Gell-Mann earned a bachelor's degree in physics from Yale in 1948, at the age of 18 and a PhD in physics from MIT in 1951. J. Robert Oppenheimer, who had directed the Manhattan Project, brought him to the Institute for Advanced Study in Princeton, N.J. From there he went to the University of Chicago and worked under Enrico Fermi. He joined Caltech in 1955 and retired in 1993.
The Discovery of Quarks
In the early years of particle physics, scientists had discovered that matter was made of elementary particles such as protons, neutrons, and electrons. The 1950’s and 60’s with the advent of powerful atom smashers brought the discovery of a zoo of additional particles. Gell-Mann perceived patterns in the properties of those particles, realizing they could all be related by certain mathematical symmetries and that the particles were clustered in groups of eight. Gell-Mann named his system the Eightfold Way after the Buddha’s eight-step path to enlightenment, unintentionally adding a flavor of mysticism to Physics.
In 1964, Gell-Mann and, independently, George Zweig went on to postulate that particles such as protons and neutrons were composed of triplets of smaller particles.
How these particles got the name “quark” is an interesting story by itself. For some time, Gell-Mann was undecided on an actual spelling for the term he intended to coin for these particles, until he found the word quark in James Joyce's book Finnegans Wake:
– Three quarks for Muster Mark!
Sure he hasn't got much of a bark
And sure any he has it's all beside the mark.
Gell-Mann went into further detail regarding the name of the quark in his book The Quark and the Jaguar -
In 1963, when I assigned the name "quark" to the fundamental constituents of the nucleon, I had the sound first, without the spelling, which could have been "kwork". Then, in one of my occasional perusals of Finnegans Wake, by James Joyce, I came across the word "quark" in the phrase "Three quarks for Muster Mark". Since "quark" (meaning, for one thing, the cry of the gull) was clearly intended to rhyme with "Mark", as well as "bark" and other such words, I had to find an excuse to pronounce it as "kwork". But the book represents the dream of a publican named Humphrey Chimpden Earwicker. Words in the text are typically drawn from several sources at once, like the "portmanteau" words in Through the Looking-Glass. From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar. I argued, therefore, that perhaps one of the multiple sources of the cry "Three quarks for Muster Mark" might be "Three quarts for Mister Mark", in which case the pronunciation "kwork" would not be totally unjustified. In any case, the number three fitted perfectly the way quarks occur in nature.
Quarks and Flavors
The quark is a subatomic particle that is the building block for the entire family of hadrons (protons, neutrons, pions, etc.). There are six types of quarks: up, down, charm, strange, top, and bottom (the last two are sometimes called truth and beauty), and their six antimatter counterparts.
Note that electrons and positrons are not made up of quarks. They are in a separate "family" of particles known as Leptons.
According to en.wikipedia.org/…, there are interesting stories behind the naming of the quark flavors.
- The up and down quarks are named after the up and down components of isospin, which they carry.
- Strange quarks were given their name because they were discovered to be components of the strange particles discovered in cosmic rays years before the quark model was proposed; these particles were deemed "strange" because they had unusually long lifetimes.
- Glashow, who co-proposed charm quark with Bjorken, is quoted as saying, "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world."
- The names "bottom" and "top", coined by Harari, were chosen because they are "logical partners for up and down quarks". In the past, bottom and top quarks were sometimes referred to as "beauty" and "truth" respectively, but these names have somewhat fallen out of use. While "truth" never did catch on, accelerator complexes devoted to massive production of bottom quarks are sometimes called "beauty factories".
Every quark also carries a color (blue, green, and red), while every antiquark carries an anticolor (antiblue, antigreen and antired).
Beyond Quarks
In the 1980s, Gell-Mann moved on from his traditional particle physicist niche at Caltech to the avant-garde approach to science practiced in New Mexico at the Santa Fe Institute, which he co-founded. There Gell-Mann and others pursued the science of complexity, a new field that yielded mixed results at first but with some significant successes (aiding the understanding of the biological complexities of the immune system, for example). At Santa Fe, Gell-Mann advocated new methods of quantifying complexity and explaining complex adaptive systems (he called them IGUSes, for information gathering and utilizing systems). www.sciencenews.org/...
A Few Tributes and Notable Obituaries
Quotes
- Just because things get a little dingy at the subatomic level doesn't mean all bets are off.
- You don't need something more to get something more. That's what emergence means. Life can emerge from physics and chemistry plus a lot of accidents. The human mind can arise from neurobiology and a lot of accidents, the way the chemical bond arises from physics and certain accidents. Doesn't diminish the importance of these subjects to know they follow from more fundamental things plus accidents.
- Superstitions typically involve seeing order where in fact there is none, and denial amounts to rejecting evidence of regularities, sometimes even ones that are staring us in the face.
- (George) Bush is a nice fellow who gives very good parties. I just wish someone would find him a better job than running the country.
- Today the network of relationships linking the human race to itself and to the rest of the biosphere is so complex that all aspects affect all others to an extraordinary degree. Someone should be studying the whole system, however crudely that has to be done, because no gluing together of partial studies of a complex nonlinear system can give a good idea of the behaviour of the whole.
- Sustainability is living on nature's income rather than living on its capital.
A Few Videos
Gell-Mann was a prolific and articulate speaker, infusing his talks with a good dash of humor and a desire to explain complex theories in simple terms. Here is a famous TED talk titled — Beauty and truth in physics.
Here are some highlights from the August 10, 2015 Murray Gell-Mann Building Dedication Ceremony at the Santa Fe Institute -
Gell-Mann on Einstein -
Gell-Mann on collaborating (or not) with Richard Feynman -
Gell-Mann endorsing Obama -
Epilogue
What are your memories of Murray Gell-Mann? Did you get a chance to meet him or attend one of his talks? Where do you think he stands relative to the other great physicists of our time?
Further Reading
- Caltech Mourns the Passing of Murray Gell-Mann (1929–2019) - www.caltech.edu/…
- Murray Gell-Mann — en.wikipedia.org/…
- Murray Gell-Mann gave structure to the subatomic world — www.sciencenews.org/...
- Talks and Interviews — www.youtube.com/…
- A Schematic Model of Baryons and Mesons (1964) — hep.caltech.edu/… Just two pages!
- Quark — en.wikipedia.org/...