Sheldon Lee Glashow

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Sheldon Lee Glashow
Sheldon Glashow at Harvard cropped.jpg
Born (1932-12-05) December 5, 1932 (age 86)
Alma mater Cornell University (A.B., 1954)
Harvard University (Ph.D., 1959)
Known for Electroweak theory
Georgi–Glashow model
Criticism of Superstring theory
Spouse(s)
Joan Shirley Alexander(m. 1972)
Children4
Awards Nobel Prize in Physics (1979)
Scientific career
Fields Theoretical Physics
Institutions Boston University
Harvard University
University of California, Berkeley
Thesis The vector meson in elementary particle decays (1958)
Doctoral advisor Julian Schwinger

Sheldon Lee Glashow ( /ˈɡlæʃ/ ; born December 5, 1932) is a Nobel Prize winning American theoretical physicist. He is the Metcalf Professor of Mathematics and Physics at Boston University and Eugene Higgins Professor of Physics, Emeritus, at Harvard University, and is a member of the Board of Sponsors for the Bulletin of the Atomic Scientists .

Nobel Prize in Physics One of the five Nobel Prizes established in 1895 by Alfred Nobel

The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for humankind in the field of physics. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

United States federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 17 megadiverse countries.

Theoretical physics branch of physics

Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena.

Contents

Birth and education

Sheldon Lee Glashow was born in New York City, to Jewish immigrants from Russia, Bella (née Rubin) and Lewis Gluchovsky, a plumber. [1] He graduated from Bronx High School of Science in 1950. Glashow was in the same graduating class as Steven Weinberg, whose own research, independent of Glashow's, would result in Glashow, Weinberg, and Abdus Salam sharing the 1979 Nobel Prize in Physics (see below). [2] Glashow received a Bachelor of Arts degree from Cornell University in 1954 and a Ph.D. degree in physics from Harvard University in 1959 under Nobel-laureate physicist Julian Schwinger. Afterwards, Glashow became a NSF fellow at NORDITA and joined the University of California, Berkeley where he was an associate professor from 1962 to 1966. [3] He joined the Harvard physics department as a professor in 1966, and was named Eugene Higgins Professor of Physics in 1979; he became emeritus in 2000. Glashow has been a visiting scientist at CERN, and professor at Aix-Marseille University, MIT, Brookhaven Laboratory, Texas A&M, the University of Houston, and Boston University. [2]

New York City Largest city in the United States

The City of New York, often called New York City (NYC) or simply New York (NY), is the most populous city in both the state of New York and the United States. With an estimated 2017 population of 8,622,698 distributed over a land area of about 302.6 square miles (784 km2), New York is also the most densely populated major city in the United States. Located at the southern tip of the state of New York, the city is the center of the New York metropolitan area, the largest metropolitan area in the world by urban landmass and one of the world's most populous megacities, with an estimated 20,320,876 people in its 2017 Metropolitan Statistical Area and 23,876,155 residents in its Combined Statistical Area. A global power city, New York City has been described as the cultural, financial, and media capital of the world, and exerts a significant impact upon commerce, entertainment, research, technology, education, politics, tourism, art, fashion, and sports. The city's fast pace has inspired the term New York minute. Home to the headquarters of the United Nations, New York is an important center for international diplomacy.

Ashkenazi Jews ethnic group

Ashkenazi Jews, also known as Ashkenazic Jews or simply Ashkenazim, are a Jewish diaspora population who coalesced in the Holy Roman Empire around the end of the first millennium.

Russian Empire Former country, 1721–1917

The Russian Empire, also known as Imperial Russia or simply Russia, was an empire that existed across Eurasia and North America from 1721, following the end of the Great Northern War, until the Republic was proclaimed by the Provisional Government that took power after the February Revolution of 1917.

Research

In 1961, Glashow extended electroweak unification models due to Schwinger by including a short range neutral current, the Z0. The resulting symmetry structure that Glashow proposed, SU(2) × U(1), forms the basis of the accepted theory of the electroweak interactions. For this discovery, Glashow along with Steven Weinberg and Abdus Salam, was awarded the 1979 Nobel Prize in Physics.

Julian Schwinger American theoretical physicist

Julian Seymour Schwinger was a Nobel Prize winning American theoretical physicist. He is best known for his work on the theory of quantum electrodynamics (QED), in particular for developing a relativistically invariant perturbation theory, and for renormalizing QED to one loop order. Schwinger was a physics professor at several universities.

Neutral current

Weak neutral current interactions are one of the ways in which subatomic particles can interact by means of the weak force. These interactions are mediated by the
Z
boson. The discovery of weak neutral currents was a significant step toward the unification of electromagnetism and the weak force into the electroweak force, and led to the discovery of the W and Z bosons.

Steven Weinberg American theoretical physicist

Steven Weinberg is an American theoretical physicist and Nobel laureate in Physics for his contributions with Abdus Salam and Sheldon Glashow to the unification of the weak force and electromagnetic interaction between elementary particles.

In collaboration with James Bjorken, Glashow was the first to predict a fourth quark, the charm quark, in 1964. This was at a time when 4 leptons had been discovered but only 3 quarks proposed. The development of their work in 1970, the GIM mechanism showed that the two quark pairs: (d.s), (u,c), would largely cancel out flavor changing neutral currents, which had been observed experimentally at far lower levels than theoretically predicted on the basis of 3 quarks only. The prediction of the charm quark also removed a technical disaster for any quantum field theory with unequal numbers of quarks and leptons — an anomaly — where classical field theory symmetries fail to carry over into the quantum theory.

James Bjorken American physicist

James Daniel "BJ" Bjorken is an American theoretical physicist. He was a Putnam Fellow in 1954, received a BS in physics from MIT in 1956, and obtained his PhD from Stanford University in 1959. He was a visiting scholar at the Institute for Advanced Study in the fall of 1962. Bjorken is Emeritus Professor at the Stanford Linear Accelerator Center, and was a member of the Theory Department of the Fermi National Accelerator Laboratory (1979–1989).

The charm quark, charmed quark or c quark is the third most massive of all quarks, a type of elementary particle. Charm quarks are found in hadrons, which are subatomic particles made of quarks. Examples of hadrons containing charm quarks include the J/ψ meson, D mesons, charmed Sigma baryons, and other charmed particles.

GIM mechanism

In quantum field theory, the GIM mechanism is the mechanism through which flavour-changing neutral currents (FCNCs) are suppressed in loop diagrams. It also explains why weak interactions that change strangeness by 2 are suppressed, while those that change strangeness by 1 are allowed, but only in charged current interactions.

In 1973, Glashow and Howard Georgi proposed the first grand unified theory. They discovered how to fit the gauge forces in the standard model into an SU(5) group, and the quarks and leptons into two simple representations. Their theory qualitatively predicted the general pattern of coupling constant running, with plausible assumptions, it gave rough mass ratio values between third generation leptons and quarks, and it was the first indication that the law of Baryon number is inexact, that the proton is unstable. This work was the foundation for all future unifying work.

Howard Mason Georgi III is an American theoretical physicist and the Mallinckrodt Professor of Physics and Harvard College Professor at Harvard University. He is also Director of Undergraduate Studies in Physics. He was Co-Master and then Faculty Dean of Leverett House with his wife, Ann Blake Georgi, from 1998 to 2018. His early work was in Grand Unification and gauge coupling unification within SU(5) and SO(10) groups.

Coupling constant

In physics, a coupling constant or gauge coupling parameter is a number that determines the strength of the force exerted in an interaction. Usually, the Lagrangian or the Hamiltonian of a system describing an interaction can be separated into a kinetic part and an interaction part. The coupling constant determines the strength of the interaction part with respect to the kinetic part, or between two sectors of the interaction part. For example, the electric charge of a particle is a coupling constant that characterizes an interaction with two charge-carrying fields and one photon field. Since photons carry electromagnetism, this coupling constant determines how strongly electrons feel such a force and has its value fixed by experiment.

In particle physics, the baryon number is a strictly conserved additive quantum number of a system. It is defined as

Glashow shared the 1977 J. Robert Oppenheimer Memorial Prize with Feza Gürsey. [4] [5]

The J. Robert Oppenheimer Memorial Prize and Medal was awarded by the Center for Theoretical Studies, University of Miami, from 1969. Established in memory of US physicist J. Robert Oppenheimer, the award consisted of a medal, certificate and a $1000 honorarium. It was awarded for "outstanding contributions to the theoretical natural sciences [...] during the preceding decade".

Feza Gürsey was a Turkish mathematician and physicist. Among his most prominent contributions to theoretical physics, his works on the Chiral model and on SU(6) are most popular.

Criticism of superstring theory

Glashow is a skeptic of superstring theory due to its lack of experimentally testable predictions. He had campaigned to keep string theorists out of the Harvard physics department, though the campaign failed. [6] About ten minutes into "String's the Thing", the second episode of The Elegant Universe TV series, he describes superstring theory as a discipline distinct from physics, saying "...you may call it a tumor, if you will...". [7]

Professor Glashow's KHC PY 101 Energy class, at Boston University's Kilachand Honors College (Spring 2011) PY 101 Energy.jpg
Professor Glashow's KHC PY 101 Energy class, at Boston University's Kilachand Honors College (Spring 2011)

Personal life

Glashow is married to the former Joan Shirley Alexander. They have four children. [2] Lynn Margulis was Joan's sister, making Carl Sagan his former brother-in-law. Daniel Kleitman, who was another doctoral student of Julian Schwinger, is also his brother-in-law, through Joan's other sister, Sharon.

In 2003 he was one of 22 Nobel Laureates who signed the Humanist Manifesto. [8] Glashow has described himself as a "practising atheist" and he is a Democrat. [9]

Works

See also

Related Research Articles

In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions. There are four fundamental interactions known to exist: the gravitational and electromagnetic interactions, which produce significant long-range forces whose effects can be seen directly in everyday life, and the strong and weak interactions, which produce forces at minuscule, subatomic distances and govern nuclear interactions. Some scientists speculate that a fifth force might exist, but this is neither widely accepted nor proven.

Weak interaction the fundamental interaction responsible for beta decay and nuclear fission

In particle physics, the weak interaction, which is also often called the weak force or weak nuclear force, is the mechanism of interaction between subatomic particles that is responsible for the radioactive decay of atoms. The weak interaction serves an essential role in nuclear fission, and the theory regarding it in terms of both its behavior and effects is sometimes called quantum flavordynamics (QFD). However, the term QFD is rarely used because the weak force is better understood in terms of electroweak theory (EWT). In addition to this, QFD is related to quantum chromodynamics (QCD), which deals with the strong interaction, and quantum electrodynamics (QED), which deals with the electromagnetic force.

Top quark type of quark

The top quark, also known as the t quark or truth quark, is the most massive of all observed elementary particles. Like all quarks, the top quark is a fermion with spin 1/2, and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. It has an electric charge of +2/3 e. It has a mass of 172.44 ± 0.13 (stat) ± 0.47 (syst)GeV/c2, which is about the same mass as an atom of tungsten. The antiparticle of the top quark is the top antiquark, which differs from it only in that some of its properties have equal magnitude but opposite sign.

Abdus Salam theoretical physicist, and Nobel Prize in Physics recipient

Mohammad Abdus Salam, was a Pakistani theoretical physicist. He shared the 1979 Nobel Prize in Physics with Sheldon Glashow and Steven Weinberg for his contribution to the electroweak unification theory. He was the first Pakistani to receive a Nobel Prize in science and the second from an Islamic country to receive any Nobel Prize.

The W and Z bosons are together known as the weak or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are
W+
,
W
, and
Z
. The W bosons have either a positive or negative electric charge of 1 elementary charge and are each other's antiparticles. The Z boson is electrically neutral and is its own antiparticle. The three particles have a spin of 1. The W bosons have a magnetic moment, but the Z has none. All three of these particles are very short-lived, with a half-life of about 3×10−25 s. Their experimental discovery was a triumph for what is now known as the Standard Model of particle physics.

In physics, a unified field theory (UFT) is a type of field theory that allows all that is usually thought of as fundamental forces and elementary particles to be written in terms of a pair of physical and virtual fields. According to the modern discoveries in physics, forces are not transmitted directly between interacting objects, but instead are described and interrupted by intermediary entities called fields.

The
J/ψ
(J/psi) meson or psion is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as "charmonium". The
J/ψ
is the most common form of charmonium, due to its low rest mass. The
J/ψ
has a rest mass of 3.0969 GeV/c2, just above that of the
η
c
, and a mean lifetime of 7.2×10−21 s. This lifetime was about a thousand times longer than expected.

Jogesh C. Pati is an Indian American theoretical physicist at the SLAC National Accelerator Laboratory.

José Leite Lopes was a Brazilian theoretical physicist who worked in the field of quantum field theory and particle physics.

Benjamin W. Lee Korean American physicist

Benjamin Whisoh Lee or Ben Lee, was a Korean-born American theoretical physicist. His work in theoretical particle physics exerted great influence on the development of the standard model in the late 20th century, especially on the renormalization of the electro-weak model and gauge theory.

Luciano Maiani Sammarinese physicist

Luciano Maiani is a San Marino citizen physicist best known for his prediction of the charm quark with Sheldon Lee Glashow and John Iliopoulos.

John Iliopoulos Greek physicist

John Iliopoulos is a Greek physicist and the first person to present the Standard Model of particle physics in a single report. He is best known for his prediction of the charm quark with Sheldon Lee Glashow and Luciano Maiani. Iliopoulos is also known for demonstrating the cancelation of anomalies in the Standard model. He is further known for the Fayet-Iliopoulos D-term formula, which was introduced in 1974. He is currently an honorary member of Laboratory of theoretical physics of École Normale Supérieure, Paris.

Goran Senjanović theoretical physicist

Goran Senjanović is a theoretical physicist at the Abdus Salam International Centre for Theoretical Physics (ICTP). He received his Ph.D. at the City College of New York in 1978, under the supervision of Rabindra Mohapatra. Before joining the ICTP in 1991, he worked as a staff member at the Brookhaven National Laboratory and as a professor of physics at the University of Zagreb. His major research interests are neutrino physics, unification of elementary particle forces, baryon and lepton number violation and supersymmetry.

Cecilia Jarlskog is a Swedish theoretical physicist, working mainly on elementary particle physics.

References

Notes

  1. Sheldon Lee Glashow – Britannica Encyclopedia. Britannica.com. Retrieved on 2012-07-27.
  2. 1 2 3 Glashow's autobiography. Nobelprize.org. Retrieved on 2012-07-27.
  3. Sheldon Glashow. Jewishvirtuallibrary.org. Retrieved on 2012-07-27.
  4. Walter, Claire (1982). Winners, the blue ribbon encyclopedia of awards. Facts on File Inc. p. 438. ISBN   9780871963864.
  5. "Gürsey and Glashow share Oppenheimer memorial". Physics Today. American Institute of Physics. May 1977. doi:10.1063/1.3037556 . Retrieved 1 March 2015.
  6. Jim Holt (2006-10-02), "Unstrung", The New Yorker. Retrieved on 2012-07-27.
  7. "[T]here ain't no experiment that could be done nor is there any observation that could be made that would say, `You guys are wrong.' The theory is safe, permanently safe." He also said, "Is this a theory of Physics or Philosophy? I ask you" NOVA interview
  8. "Notable Signers". Humanism and Its Aspirations. American Humanist Association. Retrieved October 2, 2012.
  9. Sheldon Glashow, Nobel Prize in Physics for the Electroweak Theory . La Vanguardia, 20 June 2017, raed.academy/wp-content/uploads/2017/06/Sheldon-Lee-Glashow-contraLVeng.pdf.