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Events on Tuesday, May 9th, 2023

Academic Calendar
Final exams
Abstract: *Note: actual end time may vary.* URL:
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Network in Neutrinos, Nuclear Astrophysics, and Symmetries (N3AS) Seminar
Neutron Star Weather Forecasting
Time: 2:00 pm
Place: Join Zoom Meeting Meeting ID: 912 3071 4547
Speaker: Joonas Nättilä , Columbia University, Flatiron Institute
Abstract: Neutron stars are extremely compact stellar remnants with a mass of ~1.5 Msun and a radius of ~12km. They have an upper layer consisting of a plasma atmosphere and a Coulomb-liquid ocean. Like any stratified fluid envelope on a rotating spherical body, the layers will develop complex lateral motions---weather & climate. I will use well-known results from geophysical fluid dynamics to predict what kind of "weather" we can expect on neutron stars. Understanding the spatiotemporal variability of atmospheres and oceans on neutron stars is important for interpreting observations of their X-ray emissions.

Host: A. Baha Balantekin
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Graduate Program Event
PhD Final Defense
Mathematics of evolving ecologies in chemical reaction networks and the origins of biochemical life
Time: 3:00 pm - 5:00 pm
Place: 4274 Chamberlin
Speaker: Praful Gagrani, Physics Graduate Student
Abstract: Modern physics and biology satisfactorily explain the passage from the Big Bang to the formation of Earth and the first cells to present-day life, respectively. However, the origins of biochemical life still remain an open question. Any answer to the question must explain how an evolving ecology of polymers of ever-increasing length could come about on a planet that otherwise consisted only of small molecules. In this work, we use chemical reaction network theory to develop a formalism for defining a notion of ecology as well as different categories of evolution. We then construct abstract polymer models that can exhibit dynamics such that attractors in the polymer composition space with a higher average polymer length are also more probable. Furthermore, we demonstrate a polymerization model in two monomers that exhibits historical contingency. While this work provides a step forwards towards understanding the origins of biochemical life, we conclude with a discussion of the limitations of our formalism and directions where future work is needed.
Host: Eric Smith
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