Evolution of primordial neutrino helicities in gravitational inhomogeneities, and cosmic and galactic magnetic fields
Primordial neutrinos from the Big Bang are about 100 times more prevalent than solar neutrinos, and at least two-thirds of them are now non-relativistic. These relic neutrinos, which have never been detected, decoupled in the early universe predominantly in helicity eigenstates. As this talk will discuss, their subsequent propagation through gravitational inhomogeneities and even background gravitational radiation, as well as cosmic and galactic magnetic fields partially flips their helicities, and can produce noticeable effects in their eventual detection.
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Guest SpeakerProfessor Baym received his bachelor's degree in physics from Cornell University in 1956, his A.M. in mathematics from Harvard in 1957, and his Ph.D. in physics from Harvard in 1960. He joined the Department of Physics at the University of Illinois as an assistant professor in 1963. Professor Baym has been a major leader in the study of matter under extreme conditions in astrophysics and nuclear physics. He has made original, seminal contributions to our understanding of neutron stars, relativistic effects in nuclear physics, condensed matter physics, quantum fluids, and most recently, Bose-Einstein condensates. His work is characterized by a superb melding of basic theoretical physics concepts, from condensed matter to nuclear to elementary particle physics. After originally pioneering the application of field-theory methods in quantum condensed matter systems, Professor Baym turned to problems of neutron stars, elucidating the nuclear physics of neutron stars' crusts, neutron star structure and their formation in supernovae explosions. His studies of the unusual states of matter in the deep interiors of neutron stars were seminal—first on the fundamental nature of the pion condensed state of neutron star matter and then on the physics of quark matter and the quark-gluon plasma. With the realization that further progress in the physics of matter under extreme conditions would require dedicated laboratory experiments, Professor Baym was an early advocate for and has taken a leadership role in the current international effort to use ultrarelativistic heavy-ion collisions to test experimentally the behavior of matter under extreme conditions. He has been particularly instrumental in establishing the relativistic heavy ion collider (RHIC) project at Brookhaven National Laboratory, which, when completed, will collide subatomic particles at energies of 100 GeV. At the same time, he has made fundamental contributions to understanding the physics of ultrarelativistic heavy-ion collisions. In addition to his contributions to astrophysics and nuclear theory, Prof. Baym has had an early and continuing influence on theoretical condensed matter physics, most recently on the physics of Bose-Einstein condensed atomic systems. His monograph with C.J. Pethick, Landau Fermi Liquid Theory: Concepts and Applications (J. Wiley and Sons, New York, 1991) is a definitive reference for this topic. His two textbooks, Quantum Statistical Mechanics (with L. Kadanoff, W.A. Benjamin, Inc., New York, 1962) and Lectures on Quantum Mechanics (W.A. Benjamin, Inc., New York, 1969) have been of enormous influence on the education of theoretical physicists. Lectures on Quantum Mechanics has been a basic text for teaching quantum mechanics to graduate students worldwide. Professor Baym has also maintained a lifelong interest in, and has made major contributions to, the scholarly study of the history of physics. Professor Baym is a member of the National Academy of Sciences (where he served as Chair of the Physics Section) and a member of the American Philosophical Society. He was awarded the Hans A. Bethe Prize of the American Physical Society in 2002 "for his superb synthesis of fundamental concepts which have provided an understanding of matter at extreme conditions, ranging from crusts and interiors of neutron stars to matter at ultrahigh temperature."