Physics Department Colloquium

Abstract: In this talk, I will take you on a tour of large language models, tracing their evolution from Recurrent Neural Networks (RNNs) to the Transformer architecture. We will explore how Transformers elegantly sidestep the vanishing and exploding gradient issues that plagued RNNs. I will introduce neural scaling laws—empirical relationships reminiscent of scaling behaviors common in physics—that predict how model performance improves with increased computational investment.

Abstract:  Planetary exploration has unveiled environments that could support life today, or in the past, or contain the ingredients of life. Mars was once habitable; Enceladus’ ocean is today, Europa is a question mark, and Bennu contains most of the basic key monomers of life in abiotic form. I will discuss how this all fits together. 
 

Abstract forthcoming

Abstract: Inflationary cosmology has been widely accepted for decades. Yet there are persistent debates about inflation which raise central questions in philosophy of science. Skeptics have often expressed doubt regarding whether inflation is "testable" or "falsifiable," due to the flexibility of inflationary models. This is an instance of a general question in philosophy of science: to what extent does phenomenological success support the claim that a theory gets the physics right?

Abstract:   Ever since the invention of the laser over 60 years ago, scientists have been striving to create x-ray lasers. In the same way that visible lasers can concentrate light energy far better than a light bulb, a directed beam of x-rays would have many useful applications. The problem was that until recently, ridiculously high powers were needed to make an x-ray laser.

Abstract: Starting from just a sheet of paper, by folding, stacking, crumpling, sometimes tearing, we will explore a diversity of phenomena, from magic tricks and geometry to elasticity and the traditional Japanese art of origami. Much of the lecture consists of table-top demonstrations, which you can try later with friends and family.

So, take a sheet of paper . . .

Abstract:  Inequality is an important and seemingly inevitable aspect of the human society. Various manifestations of inequality can be derived from the concept of entropy in statistical physics. In a stylized model of monetary economy, the probability distribution of money among the agents converges to the exponential Boltzmann-Gibbs law due to entropy maximization.

Abstract: The atomic nucleus emerges from interacting quantum particles called quarks and gluons, but how this happens remains unknown. This might be elucidated with quantum-level "images" of their position, orbital motion, spin alignment, and entanglement. I will describe recent and upcoming experiments at the Thomas Jefferson Laboratory that use a high-intensity, high-energy electron beam to probe a wide range of nuclear targets, from polarized lithium to lead.