College of Arts and Sciences

Laser interferometer gravitational wave detectors are poised to launch a new era of gravitational wave astronomy and unprecedented tests of general relativity. I will describe experimental efforts worldwide to detect gravitational waves, and the progress to date. The limits to the sensitivity of the present generation of interferometric gravitational wave detectors and the path to higher sensitivity future gravitational wave detectors will be discussed.

Continue reading… Gravitational wave detection with precision interferometry – Nergis Malvalvala (unofficial colloquium)

I’ll review material from the technical lectures and discuss the difference between entanglement via local and ‘remote’ interactions. I’ll discuss possible methods for constructing remote entangling measurements in superconducting quantum information and detail our experimental efforts to remotely entangle qubits via simultaneous readout and phase-preserving amplification.

Continue reading… Remote entanglement in superconducting quantum information – Michael Hatridge

Cell migration plays an essential role in many important biological processes such as wound healing, cancer metastasis, embryonic development, and the immune response. Recent advances in microscopy have led to an increasing number of qualitative observations of cell migration in 3D environments that closely mimic physiological conditions. In particular, they showed that some cells such as leukocytes, embryonic cells, and cancer cells, migrating through 3D matrices adopt an amoeboid phenotype characterized by round, liquid-filled, pressure-driven protrusions. Blebs are one type of protrusion these cells use to migrate in different environments. Recent experiments involving blebbing cells have led to conflicting hypotheses regarding intracellular pressure dynamics.

Continue reading… Intracellular Pressure Dynamics in Cells – Wanda Strychalski

I will speak about the PETSc library, a community effort that I help lead, which provides scalable parallel linear and nonlinear algebraic solvers. It is very often used to solve complex, multiphysics problems arising from PDEs, and I will show examples from geophysics, fluid dynamics, electrostatics, neutronics, fracture mechanics, and molecular biology.

Continue reading… Enabling High Performance Computational Physics with Community Libraries – Matt Knepley

Relativistic heavy ion collision experiments at Brookhaven National Laboratory and at CERN have made it possible to turn back the clock to approximately one-millionth of a second after the big bang; a time when matter, as we know it, did not exist. At these early times, the temperature of the universe was on the order of 10^12 Kelvin and the protons and neutrons, which now constitute atomic nuclei, had not yet been formed. Instead, the universe was a super hot plasma of quarks and gluons called the quark gluon plasma (QGP). In this colloquium I will review the theoretical tools necessary to understand the quark gluon plasma in the early universe and formed in relativistic heavy-ion collisions.

Continue reading… Quantum Chromodynamics at Five Trillion Degrees Kelvin – Michael Strickland

Following brief reminiscences by Arnie Dahm and Phil Taylor, Walter Lambrecht will review some of Ben Segall’s early papers on the electronic band structure and optical properties of semiconductors. He will tell us what these papers were about, and place them in the context of the time. He will then relate how these topics evolved to the present day and describe the impact they had over the years.

A reception will follow in Tomlinson Hall lobby.

Continue reading… In honor of Ben Segall’s 90th birthday – Arnold Dahm, Philip Taylor, Walter Lambrecht

Conformal Field Theory (CFT) describes the long-distance dynamics of numerous quantum and statistical many-body systems. The long-distance limit of a many-body system is often so complicated that it is hard to do precise calculations. However, powerful new techniques for understanding CFTs have emerged in the last few years, based on the idea of the Conformal Bootstrap. I will explain how the Bootstrap lets us calculate critical exponents in the 3d Ising Model to world-record precision, how it explains striking relations between magnets and boiling water, and how it can be applied to questions across theoretical physics.

Continue reading… The Conformal Bootstrap: From Magnets to Boiling Water – David Simmons-Duffin

One hundred years after “Die Feldgleichungen der Gravitation” by Albert Einstein (The Fields Equations of Gravitation) and perhaps at the eve of direct gravitational detection, the time is right to pause and ponder about the nature of the particle carrier of the gravitational force: the graviton. To unify the theory of gravity with the other forces of nature we expect the theory of General Relativity to be modified at small distances. Could it be that General Relativity is also modified at large distances as large as our current observable Universe ? This may depend on the very nature of the graviton.

Continue reading… Who and where is the graviton? – Claudia de Rham

Isn’t science supposed to be a field of study in which everybody eventually agrees on what is correct and what is mistaken? Yes, it is, but do we agree on how long it will be before “eventually” happens, especially when $5,000,000,000,000 per annum depends on whose science is correct? Probably not. The American Physical Society is laboring mightily on a new version of its 2007 Climate Change Statement, but seems likely to give birth to a mouse. How did it happen that both Pope Francis (“Obstructionist attitudes, even on the part of believers, can range from denial of the problem to indifference”) and Islamic leaders (“The present climate change catastrophe is a result of the human disruption of this balance”) seem to have a better grasp of the problem than our beloved APS?

Continue reading… The Science of Climate Change and the Changing Climate of Science – Philip Taylor