Sidney Bludman

Emeritus

Professor of Physics Emeritus

  • Visiting Professor, University of Maryland (2012- )
  • Visiting Professor, Universidad de Chile, Santiago (2006-2012)
  • Visiting Professor, DESY Theory Group, Hamburg (1999-2006)
  • Summer visitor, Institute for Nuclear Theory, University of Washington (1996)
    Laboratory (1994-95)
  • Summer visitor, Institute for Particle and Nuclear Astrophysics, Lawrence Berkeley
  • Scientific Director, Les Houches Summer Institute on Supernovae (1990)
  • Guggenheim Fellow (1983-84)
  • Visitor, Center for Particle Astrophysics, Berkeley (1990-93)
  • Visitor, Institute for Theoretical Physics, University of California, Santa Barbara (1985,1997)
  • Lady Davis Professor, Hebrew University (1976-77)
  • Visiting Professor, Tel-Aviv University (1971-72)
  • Visiting Professor, Imperial College (1967-68)
  • Professor of Physics & Astronomy, University of Pennsylvania (1961-99)
  • Visiting Fellow, Institute for Advanced Study (1956-57)
  • Staff Physicist, Lawrence Berkeley Laboratory and Lecturer, University of California (1952-61)
  • Assistant Professor, Lehigh University (1950-52)
Parenthetical citations in the following, refer to dated publications in Bibliography (​https://www.physics.umd.edu/~sbludman/bibliography.html).
Education

Born to impoverished Polish immigrants, Bludman was lucky enough to attend the Bronx High School of Science (1940-1943) and the American Institute of Science Laboratory (1942). After a few months at City College of New York (1943), he transferred to Cornell University (1943-45, A.B. 1945). After serving a year (1945-46) in the U.S. Navy, he studied under Gregory Breit at Yale University (1946-50, M.S. 1948, Ph.D. 1951). He then became Assistant Professor at Lehigh University (1950-52), before transferring to the Lawrence Berkeley Laboratory staff (1952-61). In 1949, he married Doris Marian Wittenberg (1926-69) and had three sons: Peter (b1953), Joel (b1955), Lee (b1957). After her death, he married Ellen Gore Schaffer (1949- ) in 1988.

Research Interests

Nuclear Physics

Bludman’s Ph.D thesis was on the Born-Oppenheimer approximation (1954c). After graduation, he worked on underwater sound propagation (1951) for one summer at the Woods Hole Oceanographic Institution. At the Lawrence Berkeley Laboratory (1952-61), he began working on high energy physics (1954a, 1954d, 1955a,1960a, 1980b), helping to design an important magnetic spectrometer (1957a).

Neutrino Physics and the Weak Interactions

At the Lawrence Berkeley Laboratory, Bludman soon specialized in the weak interactions (1956a-c, 1958a, 1959a, 1959, 1960a, 1961, 1964a, 1965, 1967a,b). He early proposed that the electron and muon neutrinos were distinct (1959a, 1963b,c).

Field Theory and Statistical Physics

Bludman’s early interest in classical field theory (1954b) quickly morphed into covariant field theory (1957b, 1963a,b, 1966d-e, 1967b), into general relativity(1960d,e), and into the properties of ultradense matter (1968,1970a, 1972, 1976b,c, 1980b). Bludman and Paul Schinder developed general relativistic hydrodynamics (1987a, 1988a,e, 1989) 1960c). He and Kenneth Watson wrote the basic papers on relativistic beams penetrating cold plasma (1960b), important in accelerators and in ABM defense. Together with Dallas C. Kennedy, he studied non-equilibrium thermodynamics of radiation and matter (1993c, 2004b).

Gauge Symmetries and Spontaneous Symmetry Breaking

Bludman’s lifelong obsession with symmetry ultimately led him to the first gauge theory of the weak interactions and the prediction of weak neutral currents (1958b, 1966b, 1979f, 1992c, 1993a). When he came to the University of Pennsylvania, Abraham Klein introduced him to broken symmetry by their discovery that the Goldstone theorem failed in theories with long range interactions (1963d, 1963e, 1966c).

Neutrinos at the Particle Physics-Astrophysics Interface

Bludman’s lifelong obsession with symmetry ultimately led him to the first gauge theory of the weak interactions and the prediction of weak neutral currents (1958b, 1966b, 1979f, 1992c, 1993a). When he came to the University of Pennsylvania, Abraham Klein introduced him to broken symmetry by their discovery that the Goldstone theorem failed in theories with long range interactions (1963d, 1963e, 1966c).

Stellar Collapse and Supernova Dynamics

Hans Bethe at the Aspen Institute for Physics first inspired Bludman’s interest in stellar structure and evolution. At the end of nuclear burning, massive stars suddenly implode emitting 10-15% of their rest mass in prompt neutrinos, ejected matter, and light. Together with Noam Sack and Itamar Lichtenstadt, Bludman showed that ejected matter and radiation could not drive a spherical explosion (1980a,c). After studying neutrino radiation transport out of dense stellar cores (1973a,b, 1995d, 1999d), Bludman and collaborators studied supernova dynamics (1973d, 1974b, 1975a-d, 1976d,e, 1977b,c, 1978a,b, 1979c,e, 1980a,c, 1982a,b, 1983a,b, 1986c, 1987a,b, 1989d, 1989e, 1994b,c, 1995a). He directed the 1990 supernova session of the Les Houches Summer Institute and edited its proceedings (1990c, 1991a). He and Paul Schinder studied the implications of observing the nearby supernova 1987A (1987b-d, 1988b,c, 1989b). We now appreciate that supernova depend on three dimensional hydrodynamic instabilities.

Solar Neutrinos and Stellar Structure

The deficiency in type ve neutrinos (1973c, 1990b, 1991b, 1992b,d, 1993b) led Bludman and Dallas C. Kennedy to study models for solar structure (1996a) and classical scaling symmetry (2010a-c, 2011a-c, 2012a, 2013). They obtained a simple analytic fit to the mechanical and thermal structure of the present Sun, adequately describing and interpreting the energy and neutrino production in standard and non-standard solar models (1999a). They found a variational formulation (1998b) for the four equations of mechanical and thermal equilibrium, identifying variational scaling symmetries with non-conservation laws. In mechanics, the resulting non-conservation law is the Law of Clausius, which leads to the Virial Theorem. In the hydrostatics of self-gravitating spheres, the nonconservation law leads directly to well-known properties of polytropes and of chemically homogeneous stellar cores.

Recently Accelerating Universe

 Bludman’s early interests in cosmology (1983f, 1974a,c, 1977a, 1979a,f, 1981a,b, 1984a, 1989c, 1995b, 1996b,1997a, 1998a) were revived by surprising observations that the  homogeneous cosmological expansion recently started accelerating, because of a small vacuum energy (1999c,e).   Even if dynamic, observational differences between an additional negative-pressure material component within general relativity (Dark Energy) and low-curvature modifications of general relativity (Dark Gravity) are extremely small (2000b,2001a-c, 2003a,b, 2004a,b, 2006, 2007, 2008a,b, 2009).  The standard cosmological model is now the flat LCDM model, consisting of cold dark matter and a small cosmological constant, a constant of nature.  The constants of nature observed in our universe may be a consequence of extending anthropic reasoning to a multiverse of theoretically possible universes.

Popular Lectures and Book Reviews

Bludman won a 1956 Gravity Research Foundation award for an essay On the Existence of Gravitational Insulators.  He addressed the 2004 IAU meeting on the tercentenary of Kepler’s  Supernova (2009b).  Bludman  always involved himself in the rights of scientists, particularly dissidents and refuseniks in the Soviet Union.  In 1984, when the University of Pennsylvania awarded Andrei Sakharov an honorary degree, Bludman made the baccalaureate response  The Blessing and the Curse of Science.  He reviewed the following books:

 

  • T.C. Schelling and M.H. Halperin, Strategy and Arms Control (Twentieth Century Fund, 1961)   (1961b)
  • A. Held, General Relativity and Gravitation (Plenum Press, 1980), Science 209, 1234 (1980),    Physics Today 47, 63 (1994)
  • Y. Ne’eman, To Fulfill a Vision (Addison-Wesley, 1981), Science 217, 528 (1982)   (1982e)
  • R.E. Marshak, Conceptual Foundations of Modern Particle Physics (World Scientific, 1993), Physics Today 47, 63 (1994)