CANCELED: Lauritsen Lecture: John Bahcall: How Does the Sun Shine?

Due to a schedule change, Dr. Bahcall will be unable to present this lecture on March 14th. The Physics Department is attempting to reschedule this event.

In the middle of the 19th century, Charles Darwin, the originator of the theory of evolution, and Lord Kelvin, regarded by many of his contemporaries as the leading theoretical physicist of his era, were on opposite sides of a controversy concerning the age of the sun and the origin of solar energy. This controversy continued through the first half of the 20th century as the physics necessary to answer the question of how the sun shines was gradually discovered. In the latter half of the 20th century, experiments were built to detect elusive particles called neutrinos that scientists believe are produced when the sun burns hydrogen nuclei to supply the energy that the sun radiates. Fewer neutrinos were observed than were predicted by the theoretical models of how the sun shines. The mystery of the missing neutrinos persisted for more than three decades when a dramatic solution was provided by new experiments. This talk will summarize the historical developments that led to the solution of the solar neutrino mystery and will describe the implications of recent discoveries about neutrinos from the Sun.

John Bahcall has been a Professor of Natural Sciences at the Institute for Advanced Study in Princeton, New Jersey since 1971. He was previously on the faculty of the California Institute of Technology. In 1998, he received the Presidential Medal of Science from President Clinton for his theoretical work on solar neutrinos and for his role in the development of the Hubble Space Telescope. In 1992, he received the NASA Distinguished Public Service Medal for his observations and leadership with the Hubble Space Telescope. Bahcall was president of the American Astronomical Society from 1990 to 1992, was elected vice-president of the American Physical Society in 2004, and will become in 2006 the first person to have been president of both societies.

The Lauritsen Memorial Lecture commemorates two former professors of physics at Caltech: Charles C. Lauritsen and Thomas Lauritsen. Together they served the Institute for more than 68 years, and their commitment to excellence played a significant role in Caltech's development and accomplishments.

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