Astro Seminar:"Probes of Primordial Black Hole Dark Matter"

Ely Kovetz (Johns Hopkins)

The LIGO observatory has reported several detections of gravitational waves from the coalescence of binary black holes. We consider the extraordinary possibility that the detected events involving heavier masses are…

Condensed Matter Seminar: "Tuning Quantum Materials with Uniaxial Strain"

Abhay Narayan Pasupathy (Columbia University)

What is the effect of stretching a crystal along a given direction by a small amount? In general, one might not expect much: a change in lattice constant, accompanied by corresponding changes in the electronic and…

HET & HEE Joint Seminar: "Composite Higgses"

Csaba Csaki (Cornell University)

High Energy Theory Seminar: "What Can Cosmology Tell Us About Gravity?"

Levon Pogosian (Simon Fraser University)

I will review the current status and future prospects of testing theories of gravity using data from large-scale structure surveys. I will then discuss certain aspects of the so-called model-independent tests of dark…

Physics Department Colloquium: "Orientational Transitions: From Liquid Crystals to Viral Capsids"

Robijn Bruinsma (UCLA) hosted by Douglas Durian

Lars Onsager showed in 1948 that there could be a new type of phase transition where a liquid loses rotational symmetry but retains its translational symmetry, unlike the freezing transition where a liquid loses both…

High Energy Theory Seminar: "Spinning Cosmology"

Andrei Khmelnitsky (ICTP)

We study the signatures left by new light particles with a spin on the primordial cosmological fluctuations. In distinction from the pure de Sitter background, where fields with spin have to be massive enough to…

Condensed Matter Seminar: "A change in stripes for cholesteric shells via anchoring in moderation"

Lisa Tran (University of Pennsylvania)

Chirality, ubiquitous in complex biological systems, can be controlled and quantified in synthetic materials such as cholesteric liquid crystal (CLC) systems. In this work, we study spherical shells of CLC under weak…

High Energy Theory Seminar: "Equivalence Principle in Scalar-tensor Theories"

Lasma Alberte (ICTP)

We study the question of whether the equivalence principle holds for extended objects moving on cosmological backgrounds in modified gravity theories. We do so within the framework of effective field theory of dark…

WIP: "A Cosmic Perspective: Searching for Aliens, Finding Ourselves"

Dr. Jill Tarter (Bernard Oliver Chair for Search for Extra-Terrestrial Intelligence (SETI) Institute)

Are we alone? Humans have been asking this question throughout history. We want to know where we came from, how we fit into the cosmos, and where we are going. We want to know whether there is life beyond the Earth…

Condensed Matter Seminar: "The Structure and Function of Organic-Inorganic Hybrid Perovskites"

Cherie Kagan (University of Pennsylvania)

Organic-inorganic hybrid perovskites represent a class of materials composed of corner sharing metal halide octahedra charge balanced by organic cations. The hybrid perovskites may be tailored in their composition…