Department Colloquia

The Physics Department Colloquia are held on Tuesdays at 4 p.m. via Zoom. Please contact Dawn Mitchell <dmitchell@brandeis.edu> for Zoom passwords.

Fall 2020

Extending classical ideas in fluid mechanics: Thin films, a novel similarity solution, nanoscale instabilities, and molecular biology

September 15, 2020

Howard Stone, Princeton University
Host: Guillaume Duclos

Abstract: Many modern research themes in science and engineering introduce new questions, some of which can be understood using fundamental concepts. We will provide examples of research discoveries from the subjects of thin film dynamics and cellular biology and in each case illuminate the phenomenon using fundamental ideas in fluid dynamics, with experiments and theory.

In the first example, we will document experimentally the time and (three-dimensional) space variations of the shape of a falling film near the edge of a vertical plate and rationalize the quantitative features using a similarity solution. This example seems particularly unusual since we are able to theoretically show that the shape is described by a nonlinear partial differential equation, involving three independent variables, yet the equation can be reduced by a similarity.

Schrodinger’s What is Life? at 75: The Physical Aspects of the Living Cell Revisited

September 22, 2020

Rob Phillips, California Institute of Technology
Host: Jané Kondev

Abstract: 2019 marked the 75th anniversary of the publication of Erwin Schrodinger's ``What is Life?'', a short book hailed by Roger Penrose as ``among the most influential scientific writings'’ of the 20th century'’. In this talk, I will briefly review the long argument made by Schrodinger as he mused on how the laws of physics could help us understand ``the events in space and time which takes place within the spatial boundary of a living organism.'' Though often chronicled for its influence on some of the titans of the rise of molecular biology, my talk takes a different tack. I pivot to the idea of Schrodinger’s classic as a timeless manifesto. Rather than a dated historical curiosity, I argue that ``What is Life?'' is full of stylish approaches to understanding the mysterious livingworld around us and instead, might be viewed as a call to arms to tackle the unfinished business of the scientific study of living matter. To make those points, I will focus on two key case studies from my own laboratory that pursue several of the key threads laid out in Schrodinger’s book: i) how does the control of hereditary information buried within the genome look from the point of view of physics and ii) how do the spatiotemporal structures (mitotic spindle, organelles, tissues, etc.) so familiar in biology arise as the playing out of underlying laws of non equilibrium physics?

No Colloquium

September 29, 2020

Modern Explorations of Theoretical Physics

October 6, 2020

Henriette Elvang, University of Michigan, Ann Arbor
Host: Brian Swingle

Abstract: There is a wide range of physical phenomena -- from boiling water to pion scattering -- that can be described theoretically in a common mathematical language, namely that of quantum field theory. In recent years, there has been a resurgence of new powerful approaches to explore this theoretical framework. In the talk, without assuming any prior knowledge of field theory, I will present some of these ideas and give examples of their application in contexts that range from ferromagnets to nonlinear electrodynamics and quantum gravity.

Hands-on Astrophysics: Using Stardust Grain Analysis to Further our Understanding of Stellar Nucleosynthesis and Galactic Chemical Evolution

October 13, 2020

Reto Trappitsch, Brandeis University

Abstract: Nuclear astrophysics and the evolution of elements in the Milky Way are topics generally associated with theory, large-scale nuclear physics experiments, and astronomical observations. Primitive meteorites, which are Solar System rocks that represent the original composition of the solar nebula, however preserved micrometer-sized, bona fide stardust grains. These grains formed in the death throes of dying stars and subsequently travelled through the interstellar medium until they were incorporated into the first solids that formed in the solar nebula. Each stardust grain represents a fingerprint of its parent star. Therefore, by analyzing these samples we can directly probe the stellar environment they formed in.

In my talk I will give an overview of stellar nucleosynthesis and galactic chemical evolution and discuss how stardust grain measurements done in the lab have contributed to our understanding of these fields. Additionally I will discuss how open questions in these fields pose challenges that need to be addressed in the future with a multi-disciplinary approach combining theoretical and experimental nuclear physics, nucleosynthesis modeling, and stardust grain analyses.

 

Dark Matter halos from parametric resonance and their signatures

October 20, 2020

Zoom link: https://brandeis.zoom.us/j/99541469549

Asimina Arvanitaki, Perimeter Institute
Host: Brian Swingle

Abstract: While there is undisputed evidence for Dark Matter, its nature and properties remain one of the biggest questions of our time. What is Dark Matter(DM)? How is it produced? Does it have interactions other than gravitational? In this talk, I will describe how a large class of bosonic particles can account for the DM of the Cosmos. These particles can be much lighter than those of the Standard Model with Compton wavelengths that are bigger than the size of our solar system or smaller than a millimeter. In the presence of attractive self-interactions, there is a parametric resonance effect in the early universe that can cause growth of structure at small scales, an effect so dramatic that can cause structures to collapse well before matter-radiation equality. The signatures of this effect span several experiments and orders of magntude in parameter space. When the DM boson is heavy, the dense DM halos can alter the optimal search strategies in direct detection experiments. When the DM boson is light, these halos may leave their imprint in searches for dark matter substructure, primordial gravitational waves and alter the star formation history of the universe.

Graphene Statistical Mechanics

October 27, 2020

Mark Bowick, University of California, Santa Barbara
Host: Brian Swingle

Abstract: Thermalized two-dimensional metamaterials, such as graphene at room temperature, exhibit novel mechanical properties by virtue of being bending, rather than stretching, dominated. A wide variety of responses can be obtained simply by varying purely geometrical properties such as size and shape. Furthermore, by slicing and dicing to change the topology of the sheet, one can realize long sought-after phenomena such as the thermal crumpling of elastic surfaces and multiple origami-like folding. I will discuss recent developments in this area including theory, simulations and experimental tests and challenges.

No Colloquium

November 3, 2020

Title TBA

November 10, 2020

Ana Maria Rey, University of Colorado, Boulder
Host: Brian Swingle

Title TBA

November 17, 2020

Jay Deep Sau, University of Maryland
Host: Brian Swingle

No Colloquium (Thanksgiving Break)

November 24, 2020

TBD

December 1, 2020