**Geoffrey F. Chew** is an American theoretical physicist.

He has worked as a professor of physics at the UC Berkeley since 1957 and has been an emeritus since 1991. Chew holds a PhD in theoretical particle physics (1944–1946) from the

University of ChicagoThe University of Chicago is a private research university in Chicago, Illinois, USA. It was founded by the American Baptist Education Society with a donation from oil magnate and philanthropist John D. Rockefeller and incorporated in 1890...

. Between 1950 and 1956, he was a physics faculty member at the University of Illinois. In addition, Chew was a member of the National Academy of Sciences as well as the American Academy of Arts and Science.

## Achievements

Chew was a student of

Enrico FermiEnrico Fermi was an Italian-born, naturalized American physicist particularly known for his work on the development of the first nuclear reactor, Chicago Pile-1, and for his contributions to the development of quantum theory, nuclear and particle physics, and statistical mechanics...

, his students including

David GrossDavid Jonathan Gross is an American particle physicist and string theorist. Along with Frank Wilczek and David Politzer, he was awarded the 2004 Nobel Prize in Physics for their discovery of asymptotic freedom. He is currently the director and holder of the Frederick W...

and John H. Schwarz. He was known as a leader of the

S-matrix approachS-matrix theory was a proposal for replacing local quantum field theory as the basic principle of elementary particle physics.It avoided the notion of space and time by replacing it with abstract mathematical properties of the S-matrix...

to the

strong interactionIn particle physics, the strong interaction is one of the four fundamental interactions of nature, the others being electromagnetism, the weak interaction and gravitation. As with the other fundamental interactions, it is a non-contact force...

and the associated bootstrap principle, a theory whose popularity peaked in the 1960s when he led an influential theory group at UC Berkeley. S-matrix theorists sought to understand the strong interaction by using the analytic properties of the

scattering matrixIn physics, the scattering matrix relates the initial state and the final state of a physical system undergoing a scattering process...

to calculate the interactions of

bound-statesIn physics, a bound state describes a system where a particle is subject to a potential such that the particle has a tendency to remain localised in one or more regions of space...

without assuming that there is a point-particle field theory underneath. The S-matrix approach did not provide a local space-time description. Although it was not immediately appreciated by the practitioners, it was a natural framework in which to produce a

quantum theory of gravityQuantum gravity is the field of theoretical physics which attempts to develop scientific models that unify quantum mechanics with general relativity...

.

Chew's central contribution to the program came in 1960. Along with collaborator

Steven FrautschiSteven Frautschi is an American theoretical physicist, Professor of Physics at the California Institute of Technology. He is known for his contributions to the bootstrap theory of the strong interactions....

, they noted that the

mesonIn particle physics, mesons are subatomic particles composed of one quark and one antiquark, bound together by the strong interaction. Because mesons are composed of sub-particles, they have a physical size, with a radius roughly one femtometer: 10−15 m, which is about the size of a proton...

s fall into families where the square of the mass is linearly proportional to the spin, with the same constant of proportionality for each of the families. Since

bound stateIn physics, a bound state describes a system where a particle is subject to a potential such that the particle has a tendency to remain localised in one or more regions of space...

s in quantum mechanics naturally fall into families of this sort, their conclusion, quickly accepted, was that none of the strongly interacting particles were elementary. The conservative point of view was that the bound states were made up of elementary particles, but Chew's more far-reaching vision was that there would be a new type of theory which describes the interactions of bound-states which have no point-like constituents at all. This approach was sometimes called

*nuclear democracy*, since it avoided singling out certain particles as elementary.

## Legacy

Although the S-matrix approach to the strong interactions was largely abandoned by the particle physics community in the 1970s in favor of

quantum chromodynamicsIn theoretical physics, quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons . It is the study of the SU Yang–Mills theory of color-charged fermions...

, a consistent theory for the scattering of bound-states on straight-line trajectories was eventually constructed and is nowadays known as

string theoryString theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...

. Within string theory,

Edward WittenEdward Witten is an American theoretical physicist with a focus on mathematical physics who is currently a professor of Mathematical Physics at the Institute for Advanced Study....

reinterpreted S-matrix theory as a flat-space statement of the

holographic principleThe holographic principle is a property of quantum gravity and string theories which states that the description of a volume of space can be thought of as encoded on a boundary to the region—preferably a light-like boundary like a gravitational horizon...

.

Professor Chew has also participated in religion and science discussions. He has stated that an "appeal to

GodGod is the English name given to a singular being in theistic and deistic religions who is either the sole deity in monotheism, or a single deity in polytheism....

may be needed to answer the 'origin' question, 'Why should a quantum universe evolving toward a semiclassical limit be consistent?'"

## Awards

Chew received the Hughes Prize of the American Physics Society for his

bootstrap theoryIn physics, the term bootstrap model is used for a class of theories that use very general consistency criteria to determine the form of a quantum theory from some assumptions on the spectrum of particles...

of strong interactions in 1962. He also won the Lawrence Prize in 1969.