Tuesday, December 12, 2017
4:00 pm
Dabney Hall 110 (Treasure Room)

Philosophy Job Candidate

The Mass of Fields
Charles "Chip" Sebens, Assistant Professor, Department of Philosophy, UC San Diego

Abstract: We are all familiar with the idea that physical objects have mass. In relativistic physics, fields have mass too. In this talk, I will explain how the fact that fields have mass can be used to solve two extant puzzles in physics. The first puzzle: Newton's third law (for every action there is an equal and opposite reaction) seems to be violated in the theory of electromagnetism. I will argue that the third law in fact holds because the force exerted by the electromagnetic field on matter is balanced by an equal and opposite force from matter on the field. Seeing that the field has mass is helpful in understanding how it can experience forces. The second puzzle: Although we describe the electron as having a property called "spin," there are reasons to think that the electron cannot truly be spinning. If it were spinning, it would have to be spinning faster than the speed of light. Also, the electron's gyromagnetic ratio is twice the value one would expect for an ordinary rotating charged body. Both obstacles can be overcome by examining the mass of the Dirac field—the field of the electron.  Solving these two puzzles helps us to better understand the fields that appear in quantum field theory.

Contact Fran Tise ftise@hss.caltech.edu at 626-395-3609
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