Physicists should take an active role in explaining science to the general public. As an example, I will explain why I think nuclear power is (still) a good idea.
Refreshments will be served in CP 179 at 3:15 PM
Fundamental scientific research, as a majority federally funded initiative, is becoming more deeply embedded in politics. Since the end of the Space Race, funding of basic physical sciences research as a percent GDP has continuously declined, indicating that policy makers see funding scientific research as less of a priority than they once did. Indeed, a lack of understanding about both science and how science is done amongst members of Congress has led to both reduced prioritization and also to misguided attempts at regulation, such as making peer review a public process and considering Congressional oversight for specific grants. Here we will examine a few current issues in science policy and the need for physicists to effectively weigh in on such policy issues. We will also consider the positive or negative effects such public engagement may have on our scientific careers and ways in which you can get involved.
Refreshments will be served in CP 179 at 3:15 PM
I will summarize our current understanding of the formation and evolution of galaxies and supermassive black holes, and emphasize the underlying relationship between these two populations. I will pose several of the most fundamental shortcomings of our current models and then examine how they may be addressed by what we have learned from observations in the local universe of the effects that massive stars and supermassive black holes have on their surroundings. I will do my best to give a "physicist-friendly" talk that minimizes jargon and stresses the basic underlying physical processes.
Refreshments will be served in CP 179 at 3:15 PM
Organic semiconductors are becoming increasingly attractive given their solution processability, which allows for low-cost production on flexible media like paper, plastic, or textiles. But in spite of these advantages, the complexity of film formation resulting from solution growth processes makes it challenging to control the device performance in a reliable way. In this talk I will discuss the growth, structure, and electronic properties of functionalized pentacene and anthradithiophene organic thin-film transistors deposited by scalable solution deposition methods, such as spray deposition or vibration-assisted crystrallization. The results will be compared with those obtained in single crystal devices and several approaches to improve film quality and device performance will be presented. The effect of processing parameters on charge carrier mobilities, on/off ratios and interfacial trap densities will be detailed. Transitioning from mono-mulecular crystals to multi-component materials, such as the organic charge transfer complexes, which are combinations of charge donating (D) and charge accepting (A), I will show examples on how novel functionalities can emerge from D/A intermolecular interactions.
Refreshments will be served in CP 179 at 3:15 PM
Observing the sky in the microwave region of the spectrum allows us to directly image the universe when it was just a few hundred thousand years old. The universe was much simpler then, simple enough that its expected statistical properties, given a model, can be calculated with high accuracy. Recent improvements in measurement resolution and sensitivity, most notably from the Planck satellite, but also from the South Pole Telescope, have provided precision tests of the standard cosmological model. In this colloquium I will introduce the cosmic microwave background (CMB) and the standard cosmological model. I will explain the nature of these precision tests and what we are learning about the origin of all structure in the universe, and about the background of neutrinos thermally produced in the big bang. I will also cover how the improvements in resolution and sensitivity are opening up a new window on the dark universe, via gravitational lensing of the CMB.
Close to the absolute zero of temperature, when pushed to the edge between two phases of matter, simple lattice Hamiltonians of spins can display the incredibly rich phenomena of "quantum criticality". Quantum critical ground states are described by the most complex wavefunctions known to physicists, yet they can be categorized by "universality classes" that are independent of the details of the Hamiltonians that realize them. In this colloquium I will show how such quantum critical spin systems can arise in real-world materials, and explain our successes in developing quantum many-body simulations of a new universality class of deconfined quantum critical points.
Tracing the Formation of Massive Galaxies in the Early Universe
The average rate at which galaxies are forming stars in the Universe has decreased by more than an order of magnitude over the last 10 billion years. Understanding why certain galaxies shut off their star formation activity, while others do not is one of the key unanswered questions in astrophysics today. Observations in the local Universe suggest that the mechanism responsible for quenching star formation in galaxies may be intimately linked to their structural transformation. In order to test quenching scenarios, however, it is vital to look beyond the local Universe and identify the first generation of quiescent galaxies at high redshift. I will discuss my work studying the first massive systems to appear on the quiescent "red sequence" at redshifts z>1, when the universe was less than half its current age. I will show that the properties of these galaxies are challenging not only our understanding of how star formation is quenched in galaxies, but also how mass is assembled in a hierarchical universe. I will also highlight how future work with the CANDELS survey, as well as the next generation of astronomical facilities coming online over the next 5-10 years, will help establish the primary mechanisms responsible for star-formation quenching and will revolutionize our understanding of how the most massive galaxies in the Universe formed.
