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2023 Helmut W. Baer Lecture | The Insidious Neutrinos, Entropy, and Gravitational Collapse

George M. Fuller, Distinguished Professor of Physics (University of California, San Diego)
Wednesday, February 8, 2023
3:00-4:00 PM
340 West Hall Map
This will be a hybrid event. Livestream Link:

The Insidious Neutrinos, Entropy, and Gravitational Collapse: what we learn about neutrinos, beyond standard model physics, and the creation of the elements, from the collapse of massive stars

The weakest forces of nature team up to engineer the demise of massive stars, compact objects, and maybe the odd causal horizon volume in the very early universe.

Stars make a Faustian bargain with gravitation and the weak interaction: Energy generation and, hence, promise of a longer life, in exchange for changing composition and the seemingly innocent loss of a little entropy through neutrino emission. It is a good deal for lower-mass stars like the sun. But the price proves to be too high for stars with masses in excess of ~ 8 solar masses, where the neutrino emission-induced loss of entropy and the nonlinear nature of gravitation combine with the weak interaction and exotic nuclear physics to cause collapse of the cores of these stars to neutron stars or black holes. Stars with masses in excess of ~ 100 solar masses likewise are vulnerable to instability because so much of their pressure support comes from radiation.

In fact, the nonlinear nature of gravitation means that self-gravitating systems get into trouble whenever their pressure support involves particles moving near light speed. Such objects are, in the words of my late research mentor, “Trembling on the verge of instability.”

That means that very subtle influences, from known, standard model weak interaction processes, but perhaps also from new, beyond-standard-model physics, can figure in the evolution of these objects. Collapse to neutron stars or black holes is the inevitable outcome, but clues about how these murders were committed may be found in nucleosynthesis (especially of the heaviest nuclei) and in the spectrum of remnant masses.

We will discuss how frontier issues in elementary particle physics, especially those involving the mysterious and ghostlike neutrinos, could figure prominently in what happens in these gravitational collapse events and their aftermath.
Building: West Hall
Event Type: Workshop / Seminar
Tags: AEM Featured, Physics
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