College of Arts and Sciences

New Physics and Unification of Forces

The unification of fundamental forces in nature is one of the most appealing ideas for physics beyond the Standard Model of particle physics. I discuss the beautiful idea of grand unified theories where one can understand the origin of the Standard Model interactions. The experimental predictions are discussed in detail in order to understand the testability of these theories. I discuss an alternative new idea which could change the way we think about physics beyond the Standard Model. The predictions for particle physics experiments and cosmology are discussed.

Continue reading… Pavel Fileviez Perez (CWRU Physics)

Continue reading… Mike Hinczewski (CWRU Physics)

Numerical Relativity and Gravitational Radiation from Binary Black Hole Mergers

In September of 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) made the first-ever direct detection of gravitational waves, propagating ripples in the structure of spacetime itself, confirming a nearly century-old prediction of Einstein’s general relativity, and providing an entirely new medium for astronomical observations. The waves, from these particular events and from others like them to come, encode information about the fully nonlinear dynamics of spacetime itself, as they appear to arise from collisions of vacuum black holes. Computational simulation of these events, via a family of techniques known as Numerical Relativity,

Continue reading… Robert Owen (Oberlin College)

2D Materials Nanosculpting and Bioelectronics Applications

Electron beams constitute powerful tools to shape materials with atomic resolution inside a transmission electron microscope (TEM). I will describe experiments where we push the limits of device size to atomic scale in 2D materials beyond graphene (MoS2, WS2, MoTe2, black phosphorous) and expand their function and precision, while addressing fundamental questions about structure and properties at nanometer and atomic scales. Experiments are performed in situ and ex situ TEM. In situ TEM experiments include fabrication of nanoribbons and field-effect-transistors from novel two-dimensional materials down to sub-nm widths.

Continue reading… Marija Drndic (University of Pennsylvania)

Physics Motivations for Future Colliders

With the milestone discovery of the Higgs boson at the CERN LHC, high energy physics has entered a new era. The Higgs boson is the last member in the “Standard Model” (SM) of particle physics, which describes the physical phenomena at high energies to a very high accuracy. The completion of the Standard Model implies, for the first time ever, that we have a relativistic, quantum-mechanical, self-consistent theoretical framework, valid up to exponentially high energies, perhaps to the Planck scale. Yet, there are compelling reasons, both from observations and from theoretical considerations,

Continue reading… Tao Han (University of Pittsburgh)

Slush Structure and Dynamics in a Relaxor Ferroelectric

Ferroelectric materials undergo solid-solid structural phase transitions between phases with aligned dipoles and randomly oriented dipoles. Incorporating quenched Coulombic disorder by varying the charge of the ions on the lattice disrupts and changes the of this transition; instead of a sharp transition in a small temperature range, these oxide alloys exhibit “relaxed” transition over 100-200 K and are called “relaxor ferroelectrics.” In this talk I will describe how a first-principles based multi-scale model can reveal the dynamic and statically correlated motions of ions that lead to relaxor behavior,

Continue reading… Andrew Rappe (University of Pennsylvania)

Simulating Planetary Interiors in the Lab

This talk will provide an overview of experimental studies on the properties of planetary materials at high pressures, and the constraints they provide on the structure and evolution of planetary interiors.

Continue reading… Jim Van Orman (CWRU EEES)

Paul Erdos, Kevin Bacon, and the Six Degrees of Separation: The Statistical Physics of Networks

There are networks in every part of our lives: the Internet, the power grid, the road network, networks of friendship or acquaintance, ecological networks, biochemical networks, and many others.  As large-scale data on these networks have become available in the last few years, a new science of networks has grown up combining observations and theory and drawing heavily on ideas from physics, to shed light on systems ranging from bacteria to the whole of human society.  This talk will give an introduction to this rapidly-growing interdisciplinary branch of science,

Continue reading… Mark Newman (University of Michigan)

Imaging the Surfaces of Stars

Under even the best atmospheric conditions, telescope diffraction fundamentally limits the angular resolution for astronomical imaging. Using interferometry (Go, Michelson!), we can coherently combine light from widely-separated telescopes to overcome the single-telescope diffraction limit to boost our imaging resolution by orders of magnitude. I will review recent technical and scientific breakthroughs made possible by the Michigan Infrared Combiner of the CHARA Array on Mt. Wilson, CA, with baselines of 330 meters allowing near-infrared imaging with sub-milli-arcsecond resolution. I will present the first resolved images of main sequence stars besides the Sun,

Continue reading… John Monnier (University of Michigan)

Massive Gravitons, the Cosmological Constant and New Directions in Gravity

The solution to the cosmological constant problem may involve modifying the very long-range dynamics of gravity by adding new degrees of freedom. As an example of a conservative such modification, we consider the possibility that the graviton has a very small mass. Massive gravity has received renewed interest due to recent advances which have resolved its traditional problems. It has some peculiar and unexpected features, and it points us towards a different way of thinking about the universe on large scales.

Continue reading… Kurt Hinterbichler (CWRU Physics)

Containment

Abstract

Can we contain some of the deadliest and most long-lasting substances ever produced? Left over from the Cold War are a hundred million gallons of highly radioactive sludge, thousands of acres of radioactive land, tens of thousands of unused hot buildings, all above slowly spreading deltas of contaminated ground water. Stocked around 400 reactors (worldwide) are spent fuel assemblies, growing at a rate of 12,000 tons per year—each one radioactive enough (if unprotected) to kill a carload of people driving by it at full tilt. Not a single country in the world has a well worked-out plan about what to do with the waste stream of such deadly and long-lived materials (plutonium has a halflife of 24,000 years).

Continue reading… Director: Peter Galison (Harvard). Movie. Note unusual end time.

Chemistry Colloquium: Electronic and Thermal Interconversion and Migration in Energy-Relevant Materials

In order to produce energy efficient devices, thorough understanding of fundamental desired and undesired processes of energy and heat interconversion and migration are needed. I will present studies using time-resolved optical methods such as absorption and emission as functions of sample temperature or photon energy that aim to arrive at insights regarding energy transfer, electron transfer, and electron-phonon and phonon-phonon scattering events. Materials examined include nanoscale 0D and 2D semiconductors, bulk phase perovskites, as well as some plasmonic structures.

Continue reading… Richard Schaller (Northwestern University). Not a physics colloquium but of potential interest to physicists. Note unusual location and time.