University Libraries Promotion and Tenure Recognition

In the early 70's, Ray Davis set out to detect neutrinos from the sun in order to confirm the hypothesis that the sun's power derived from fusion interactions in its core. He detected them, but fewer than expected, and the deficit he observed became known as the "solar neutrino problem." Alongside Ray Davis, the late John Bahcall labored for nearly three decades on the theoretical aspects of the solar neutrino problem, creating and constantly improving a detailed, sophisticated "standard solar model" that predicted the solar neutrino flux with increasingly sharp accuracy.

Physicists and astronomers had identified three possible solutions to the solar neutrino problem: Experimental errors, theoretical errors, or solar neutrinos doing something unexpected between the solar core and the earth-bound detector. Over the years John Bahcall responded to criticism after criticism of his solar model, in a way that personified for me the way a true scientist should respond--always dispassionately evaluating criticism of the model he had been working on for decades, never taking it personally.

While an assistant professor at the University of Pennsylvania, as a member of an international collaboration running an experiment that would ultimately solve the solar neutrino problem, I had the pleasure of meeting with John Bahcall on a number of occasions. I had also read and re-read much of this fine book authored by him, "Neutrino Astrophysics." John would drive down from Princeton, and--not to put too fine a point on it--pump us for inside information on how the experiment was going. Eventually, when we announced our result, demonstrating that the solar neutrino problem arose from new properties of the neutrinos themselves, and not from experimental or theoretical errors, it delighted many in the community to see that John's long years of work had been vindicated. John won the National Medal of Science, the USA's highest scientific honor. Many, myself included, felt he should have shared the Nobel Prize for Physics with Ray Davis, but I suspect it bothered other people more than it bothered John. John just wanted to do the science. His attitude is one I strive to emulate.