physics & astronomy

Black Holes: Probes of the Cosmos and Fundamental Physics

The class of spacetimes with event horizons contain some of the most fascinating solutions to the equations of general relativity. Over the past few years, numerical simulations have begun to reveal many dynamical, strong-field solutions not amenable to exact analytical or perturbative treatments. In this talk, I will describe 3 such scenarios. First, the inspiral and merger of two black holes, which is thought to occur frequently in the universe. Such events are powerful emitters of gravitational waves, and a concerted world-wide effort is currently underway to observe them. Second, I will discuss the ultra-relativistic collision of two solitons. Arguments suggest that at sufficiently high velocities gravity dominates the interaction, causing a black hole to form. These arguments underlie claims that the Large Hadron Collider, or cosmic ray collisions with the Earth, will produce black holes in speculative large extra dimension scenarios. Finally, I will show results elucidating the fate of a black string in 5 dimensions, subject to the Gregory-Laflamme instability. Rather remarkably, the event horizon exhibits dynamics akin to a low viscosity fluid stream suffering the Raleigh-Plateau "beading" instability. In the gravitational process arbitrarily large spacetime curvatures are revealed to an external observer, culminating in naked singularities.

New Perspectives for QCD

AdS/QCD, together with ``Light-Front Holography", provides an analytic, frame-independent color-confining first approximation to QCD, accounting for light-quark meson and baryon spectroscopy, hadronic form factors, and other hadronic observables. A remarkable holographic feature of hadron dynamics in AdS space in five dimensions is that it is dual to Hamiltonian theory in physical space-time, quantized at fixed light-front time. This light-front holographic principle provides a precise relation between the bound-state amplitudes in AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The hadronic eigensolutions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schr\"odinger equation. The color-confining potential is determined uniquely using a method based on conformally invariant quantum mechanics. The resulting potential is color-confining and reproduces the observed linear Regge behavior of the light-quark hadron spectrum in both orbital angular momentum and the radial node number. The pion mass vanishes in the chiral limit, and other features of chiral symmetry are satisfied. The elastic and transition form factors of the pion and the nucleons are also found to be well described in this framework. A number of novel phenomenological consequences will be discussed, including hadronization at the amplitude level.

Gauge fields with cold atoms

Gauge fields are ubiquitous in Physics. For example, in the context of high energy physics, they are the fundamental carrier of forces; while in condensed matter systems the associated physical fields (electrical and magnetic) are essential in creating and understanding many-body phenomena. Here I present our experimental work synthesizing static gauge fields for ultracold neutral atoms (bosonic and fermionic alkali atoms), analogous to applied fields in condensed matter systems. I will discuss these static gauge fields in the language of spin-orbit coupling where it consists of an equal sum of Rashba and Dresselhaus couplings. In experiment, we couple two internal states of our alkali atoms with a pair of ``Raman'' lasers and load our degenerate quantum gas into the resulting adiabatic eigenstates. For a Bose gas, a function of the Raman laser strength, a new exchange-driven interaction between the two dressed spins develops, which drives a (quantum) phase transition from a state where the two dressed spin states spatially mix, to one where they phase separate. Going beyond this simple modification to the spin-dependent interaction, we show that in the limit of large laser intensity, the particles act as free atoms, but interact with contributions from higher even partial waves.

Particle-wave duality with and without quantum spookiness.

Quantum interference explains the stability of matter, guided the construction of the laser, and its application led to medical imaging techniques. So what is this quantum interference about? The double-slit experiments for electrons is considered to be “the only mystery”, insofar as it concerns quantum interference. Feynman's account of these experiments is one of the most popular. To get as close to Feynman's description of double-slit diffraction we did some experiments. This includes closing individual slits on demand, and taking a movie of the build-up of the diffraction pattern one particle at a time. In recent work done in Paris, macroscopic particle-wave duality with bouncing oil droplets was demonstrated for the first time ever. This was supposed not to be possible. What does that mean for microscopic or quantum-mechanical particle-wave duality for electrons? This means a lot to an international group of physicists labeled to be a “band of rebels” according to Morgan Freeman’s show “Through the Wormhole”. However this is not what we have taught in the past three years to more than 100,000 high school students through our movie “The Challenge of Quantum Reality.” What is going on?

Skype with an Astronaut at A&S Sneak Peek

Catch a sneak peek of the amazing opportunities with the College of Arts & Sciences!

Dr. Ravat's Exploring the Solar System class had the privilege of doing a Skype interview with NASA Astronaut Dr. Drew Feustel. The Mission Specialist veteran detailed his drive to become an astronaut, his experiences in Space, and how NASA research connects to life on Earth.

Watch the full video here!

Unveiling the Mystery of Mass

One of the prime reasons the Large Hadron Collider (LHC) was built is to resolve the question of how particles acquire their mass. While it is very simple to measure particle masses and we have a model -- the Standard Model of Particle Physics -- which explains quite accurately all presently available measurements the seemingly trivial mechanism of how particle acquire their mass remains a mystery. The Standard Model invokes a new scalar gauge field to resolve this mystery but we have until recently not been able to find experimental evidence for its existence. On July 4, 2012, the CMS and ATLAS experiments have announced the discovery of a new Higgs-like particle at a mass of about 125 GeV. I will review our knowledge about the Higgs boson before the LHC started, discuss the discovery and the most recent updates from the LHC experiments.

Skype with Astronaut Andrew Feustel

Dr. Ravat's AST/EES 310 class had the opportunity to speak with Dr. Andrew Feustel, NASA Astronaut and Mission Specialist for STS-125 and STS-134, on April 2nd, 2013. During this fascinating hour-long conversation, Dr. Feustel described what it is like to go into space, the importance of the scientific advances enabled by NASA, and recounted his experiences on the International Space Station and on the last human service mission to the Hubble Space Telescope.

UK Awards Four Research Professorships

The University of Kentucky Board of Trustees today approved University Research Professorships for 2013-14 for four faculty members. The professorships carry a $40,000 award to support research.

Colloquium: The Future of the Sloan Digital Sky Survey

I describe plans for the next-generation Sloan Digital Sky Survey, to begin in July 2014, and which consists of three programs, APOGEE-2, MaNGA and eBOSS. APOGEE-2 will use both the Sloan Foundation Telescope at Apache Point and the du Pont Telescope at Las Campanas to study Galactic archaeology with high-resolution near-infrared spectroscopy. MaNGA will develop fiber bundle technology for the BOSS spectrograph to perform multiplexed spatially resolved spectroscopy with an unprecedented combination of wavelength coverage and resolution for 10,000 nearby galaxies. eBOSS will study the Universe�s expansion using a massive survey of galaxies and quasars. eBOSS will also perform follow-up spectroscopy on X-ray and variable sources, making it both the largest and most broadly selected quasar survey. I will show how this innovative set of programs will lead to a better understanding of cosmology and galaxy formation, as well as stellar and exoplanetary astronomy.

Speaker / Presenter: Michael Blanton, Dept of Physics, New York University

Colloquium: New Dialogues: Entanglement, Holography & Renormalization

In science, we often see new advances and deep insights emerging from the collision or intersection of what appeared to be separate research areas. The theme of my colloquium will be an ongoing collision between the three ideas listed in my title which has been generating interesting new insights into a variety of fields, eg, condensed matter physics, quantum field theory and even quantum gravity. I will give an introduction to each of these three ideas separately and then discuss the intersections that have been generating new insights in recent years. Speaker/Presenter: Robert Myers, Perimeter Institute for Theoretical Physics


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