Stony Brook University
7:30 pm
ESS Building, Room 001
Friday, September 09, 2022
Think first, Then Calculate: The Art and Power of Estimation in Physics
Prof. Paul M. Goldbart
When imagining what theoretical physicists do, our friends who aren't physicists (yes, we have some!) envision us performing vast thickets of highly technical calculations. The reality is that we do do that, at least some of the time -- but only once we've developed a qualitative, intuition-based feeling for what's going on and wish to sharpen our results into something more quantitative. Before that, we spend much of our time creating storyboard pictures, much as a writer of screenplays might, and, importantly, making simple estimates of the scales of things -- how big, how fast, how cold, how many -- before embarking on more complete analyses. That way, we're able to develop a sense of what's plausible and what isn't.
In this talk, which I intend to be highly informal, I shall illustrate aspects of the way physicists think and work by gently guiding the audience through a sequence of puzzles, which our visitors are welcome (but under no pressure!) to try, themselves. Along the way, we shall see, for example, how long theoretical physicists think it takes to cook a turkey, how big atoms and molecules are, and how many more crew members are needed to double the speed of a rowing boat. We call these types of challenges "Fermi Problems,' in honor of the great twentieth century physicist Enrico Fermi, who was a master solver of them.
Paul Goldbart has had the good fortune to spend much of his life puzzling over the building blocks of the world around us, how they dance and swarm, and how -- when billions of them come together-- surprises like liquid crystals, magnets, and superconductors emerge. He especially loves to think about the quantum world, where particles can annihilate one another or tunnel through barriers, as they do when electrons carry current along metal wires. As a professor at the University of Illinois at Urbana-Champaign and elsewhere, he and his doctoral and postdoctoral collaborators have experienced many moments of challenge, frustration, and (occasionally, at least) satisfaction, as they've wrestled to understand emergent behavior in a variety of settings: from nanoscale superconductors and quantum chaos, to flowing liquid crystals and rubbery materials, to atoms and light and their co-crystallization at temperatures a billion billion times colder than Stony Brook, and on to collective behavior in quantum circuits. He has also explored basic issues in quantum entanglement, co-authored a mathematics text for graduate students, and dabbled in law and economics. For some fifteen years, Goldbart divided his time between theoretical physics and various academic leadership roles, including at Illinois, Georgia Tech, the University of Texas at Austin, and Stony Brook. Grateful for those opportunities and the vistas they brought, Goldbart has now returned to his roots as a researcher-educator, and is reveling in the chance to re-immerse himself, full time, in theoretical physics.
