Department Colloquia

The Physics Department Colloquia are held on Tuesdays at 4 p.m. in Abelson 131 and on Zoom unless otherwise noted. To request a Zoom link, please email jthorne@brandeis.edu.

Fall 2022 Schedule

Berko Symposium

September 13, 2022

Presentions by Berko Prize Recipients:

Francesca Capocasa: Not blinded by the light: how ATLAS will keep seeing particles during the HL-LHC Run

Kanaya Malakar: Origin of polarization correlation in tissues?

Bibi Najma: Multiscale investigation of the emergent behaviors in biomimetic active matter

 

Turbulent Plasmas around Neutron Stars

September 20, 2022

Joonas Nättilä, Columbia University, Flatiron CCA

Abstract: Neutron stars are one of the most extreme objects in the Universe: they are dense stars with a radius of ~12km and a mass of ~1.5 times the mass of the Sun. They rotate with periods from seconds to milliseconds and have exterior magnetic field strengths from 10^8 to 10^15 Gauss. Their rotating magnetospheres are dynamic and evolving; the magnetic topology undergoes explosive reconfigurations similar to that of our Sun. These magnetic eruptions can lead to intense turbulent flares that require coupling between the kinetic plasma physics of the gas in the magnetosphere and quantum electrodynamics of the energized particles and intense radiation field. In my talk, I will discuss the extreme plasma astrophysics of neutron stars. I will also discuss how our recent kinetic simulations of collisionless plasmas in strong magnetic fields start to shed light on many of the observed phenomena from various types of neutron stars like pulsars, magnetars, and neutron star binary mergers.
Towards programmable living materials and quantitative models of active matter

October 11, 2022

Jörn Dunkel, MIT

Abstract: Over the last two decades, major progress has been made in understanding the self-organization principles of active matter.  A wide variety of experimental model systems, from self-driven colloids to active elastic materials, has been established, and an extensive theoretical framework has been developed to explain many of the experimentally observed non-equilibrium pattern formation phenomena. Two key challenges for the coming years will be to translate this foundational knowledge into functional active materials and to identify sparse quantitative models that can inform and guide the design and production of such materials. Here, I will describe joint efforts with our experimental collaborators to realize self-growing bacterial materials, and to implement computational model inference schemes for active and living systems dynamics.

October 25, 2022

Rob Phillips, Cal Tech

Abstract: One of the most important scientific developments in modern history is the realization that the evolution of the Earth is deeply intertwined with the evolution of life. Perhaps the most famous example of this intimate relationship is the chemical transformation of Earths’ atmosphere following the emergence of photosynthesis resulting in the oxygenic atmosphere we depend upon today.   Over the past 10,000 years, humans have become a similarly influential force of nature, directly influencing the rise and fall of ecosystems, the temperature and volume of the oceans, the composition of terrestrial biomass, the planetary albedo and ice cover, and the chemistry of the atmosphere to name just a few of many such examples. The breadth of human impacts on the planet is so diverse that it penetrates nearly every scientific discipline.  In this talk, I will use the style of thinking attributed especially to EnricoFermi and known as Fermi problems to conduct a series of estimates to be compared to corresponding data on a myriad of human impacts ranging from the ratio of artificially fixed nitrogen to its natural counterparts to estimating the basis of the more than 80 billion chickens slaughtered each year to comparing the total human made mass to the entire planetary biomass.  The emphasis is on a broad and coherent picture of the factual backdrop on human impacts as revealed in the recently released anthroponumbers.org database based at the same time upon simple, but careful estimates of a series of dimensionless ratios that capture some of the key ways in which humans interact with the planet.
The roles of student and socio-political factors in college major pursuit

November 1, 2022

Joseph Cimpian, NYU

AbstractUnconditionally, males—specifically, straight-cisgender males—are over-represented in the majors of physics, engineering, and computer science (PECS), while straight-cisgender females are over-represented in nursing. Of course, some portion of this over-representation is attributed to differences in factors like reported interest and career aspirations. But these gender and sexuality/gender-identity gaps are also susceptible to gender and sexuality stereotyping. Using longitudinal, nationally-representative data, we explore the extent to which individuals pursue stereotypical and counter-stereotypical majors, depending on their interests and demonstrated abilities, as well as by the socio-political environment they were raised in. For example, the male-female gap in PECS pursuit is both initially smaller and fully explained by student covariates among high-STEM achieving students; among low-STEM achieving students, males pursue PECS more often, and this cannot be explained by a wide range of factors. The sexuality/gender-identity gaps are, again, smaller and better explained among high-STEM achievers, but this extends through a wider range of majors; among average- and low-STEM achievers, major pursuit follows more stereotypical patterns. Additionally, LGBTQ students raised in more liberal environments more often pursue counter-stereotypical majors, reaching near parity with non-LGBTQ levels. Overall, this work suggests that student ability and the socio-political environment play unique roles in moderating the student factors predicting representation across college majors, suggesting new directions for research and interventions.

November 8, 2022

Ben Rogers, Brandeis

November 29, 2022

Marianna Linz, Harvard