Colloquia in Academic Year 2007-2008
Dept. of Physics & Astronomy, Stony Brook University
Colloquium committee: Thomas Weinacht,  Meigan Aronson, Gilad Perez, Mike Zingale

Coffee & Tea served at 3:45 pm.  Talk begins at 4:15 pm.  Location: Harriman 137, which is at the bottom of square C4 on the campus map.



Spring 2008 colloquia:(colloquia already given are listed here):

Apr 29
Stuart Freedman
University of California at Berkeley
Direct Evidence of neutrino oscillations with KamLAND

Experiments performed in the last ten years provide conclusive evidence that neutrinos are particles with mass and that the neutrino states that couple through the weak interaction are mixtures of mass eigenstates.  KamLAND is a 1000 ton scintillation detector located deep underground in western Japan.  KamLAND detects anti-neutrinos from Japanese nuclear reactors hundreds of kilometers away.  The latest results provide the most direct confirmation that reactor anti-neutrinos oscillate between weak flavor states.  KamLAND has also observed geo-neutrinos from radioactivity of the Earth. I will review the present understanding of neutrino mass and mixing in light of the latest results form KamLAND.
Barbara Jacak
May 6
Laszlo Mihaly
Kirean Boyle
Jeremy Holt
 - Awards Colloquium
Stony Brook
Measurements of the Double Helicity Asymmetry in Pion Production in Proton Collisions at \sqrt s = 200 GeV and the Resulting Constraints on the Polarized Gluon Distribution in the Proton

Realistic Nuclear Interactions with Brown-Rho Scaling Medium Modifications
Tom Weinacht


Colloquia already given in academic year 2007/2008:
Date
Speaker
Title
Local host
Sept 11
Peter Koch
Department of Physics
Stony Brook University
Chair's colloquium
Link to Slides

Sept 18
Abhay Deshpande
Stony Brook University
Proton Spin Puzzle, Part II:  The tale of the elusive gluons...

Movie of Presentation
Exciting measurements leading to a new insight in to the gluon's role in determining the proton spin have now been released by the PHENIX Detector Collaboration at the Brookhaven National Laboratory. The measurements were made in 2005 and 2006 using polarized proton beams of the Relativistic Heavy Ion Collider (RHIC) colliding at 200 and 62.4 GeV in center of mass. I will present the new PHENIX results & their impact on our understanding of the nucleon spin. A discussion of their limitations will evolve in to an outlook on what's needed in near & far future to precisely understand the nucleon's spin structure.

Tom Weinacht
Sept 25
Amber Miller
Columbia University
Peeking in Ancient Holes and Seeking the Holy Grail

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The Cosmic Microwave Background (CMB) consists of a bath of photons emitted when the universe was 380,000 years old. Carrying the imprint of primordial fluctuations that seeded the formation of structure in the universe, the CMB is one of the most valuable known tools for studying the early universe. In our modern, post WMAP era, the utility of studying temperature anisotropies in the CMB is clear and much of the work has been done. I will describe two exciting new directions in which the field is currently heading: small-scale secondary CMB anisotropy and CMB polarization anisotropy. In this context, I will discuss preliminary results from our small-scale secondary anisotropy experiment, the Sunyaev-Zel'dovich Array (SZA). I will also briefly describe our two upcoming CMB polarization experiments, the Q U Imaging ExperimenT (QUIET) and the E B EXperiment (EBEX).

Meigan Aronson
Oct. 2 Peter Schiffer
Penn State

Fun in the Sand: Some Experiments in Granular Physics

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In the last two decades, condensed matter physicists have begun an intense study of the dynamic and static properties of granular media (materials made from individual macroscopic solid grains). These materials offer a vast arena of new physical phenomena which are highly accessible and largely unexplored. I will discuss recent work on three different physical phenomena in granular media which demonstrate how relatively simple measurements in this area can reveal surprising results. 1). How interstitial liquid between the grains affects granular properties and leads to the development of correlations between the grains. 2). How grains pack when you heat them up and cool them down. Although grains are macroscopic and not affected by thermal fluctuations, careful measurement shows that the process of heating and cooling them does affect them through irreversible changes in packing. 3). How the motion of an object being pulled slowly through a granular medium is resisted by the "jamming" of grains, resulting in a drag force which differs dramatically from viscous drag in a fluid both in its average properties and in having large fluctuations.

References: Physical Review Letters 82, 205 (1999); Physical Review Letters 84, 5122 (2000); Physical Review E 64, 031307 and 64, 061303 and 64, 061303 (2001); Physical Review Letters 89, 094301 (2002); Physical Review E 67, 051303 (2003); Nature 427, 503 (2004); Physical Review E 70, 041301 (2004); Nature 442, 257 (2006).

Meigan Aronson
Oct. 9 Ed Brown
Michigan State University
Journey to the Core of an Accreting Neutron Star

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A neutron star is born in our galaxy about once every century.  These stars, composed of the densest matter in nature, have long fascinated astrophysicists. Many observed neutron stars accrete hydrogen- and helium-rich matter from a companion. During the slow compression to nuclear density the accreted matter is transmuted from being proton-rich to being proton-poor.  These reactions produce and affect many observable phenomena - from energetic explosions on the neutron star's surface to the recently detected thermal relaxation of the surface layers - that in turn inform us about the nature of dense matter in the deep interior of the neutron star. In this talk I'll describe the journey of matter that is accreted onto a neutron star, highlight some recent exciting discoveries, and discuss what they are telling us about the inner workings of neutron stars.
Mike Zingale
Oct. 16 Drew Shindell
Nasa, Goddard Institute for Space Studies
Climate Change: Causes, Consequences & Solutions

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Changes in the Earth’s climate are driven by shifts in the balance between the planet’s incoming and outgoing radiation. I will compare climate change in the Earth’s past with the current warming, discussing the various drivers and feedbacks at work during these times. I will then discuss the global climate models used to interpret recent climate change, and present projections from these models of how the climate may change in the future. I will talk about the uncertainties in current knowledge, and the consequences associated with projected changes. In addition to global temperature changes, these include shifts in the hydrologic cycle, the frequency of extreme events, and rapid warming of the Arctic with implications for ice sheet stability and sea-level rise. Finally, I will outline some potential strategies for climate change mitigation.
Tom Weinacht
Oct. 23 Thomas Weinacht
Stony Brook
Observing and Controlling Atomic and Molecular Dynamics

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Ultrafast laser pulses can be used to initiate and capture atomic and molecular motion in real time.  Shaping these pulses allows us to control the dynamics we observe.  I will discuss some experiments that follow bond breaking and formation driven by an ultrafast laser pulse. I will also discuss an experiment where a shaped ultrafast laser pulse is used to control lasing of an atomic ensemble. I will conclude with some future prospects and goals.
Hal Metcalf
Oct. 30 Paul Brumer
University of Toronto
Quantum Interference in the Control of Molecular Processes

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Coherent Control offers a powerful approach to the control of atomic and molecular processes. By manipulating quantum interference effects, primarily through laser excitation, control over multipath molecular processes can be achieved. This lecture will provide an introductory overview of coherent control, followed by a summary of new developments in the control of both  bound state and scattering processes.
Tom Weinacht
Nov. 6 Steve Howell
NOAO
Mass Donor Stars in Cataclysmic Variables

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Observations of the low-mass donor stars in cataclysmic variables have had a renaissance in recent years due to the availibility of large aperture telescopes such as Keck and the VLT. Optical and infrared spectroscopy of the faint donor stars have revealed that some are brown dwarf-like objects while others appear to be normal main sequence stars. This talk will review the current state of the data, compare and contrast with the accepted paradigm and theoritical models, and discuss a few specific, highly interesting stars.
Mike Zingale
Nov. 13 Pierre Meystre
Optical Sciences Center, U of Arizona
Cooling of nanoscale mirrors

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The observation of quantum dynamics in truly macroscopic objects appears increasingly feasible as a result of recent experimental advances thatinclude novel cooling techniques and progress in nanofabrication. This is an exciting prospect, as it would enable us to explore the quantum-classical boundary as well as to test quantum mechanics in an entirely new regime. The implementation of characteristically quantum mechanical phenomena at a macroscopic scale also promises technological benefits for areas from quantum measurement to the interferometric detection of gravitational waves and to atomic force microscopy.
A promising route to these objectives is through the use of optomechanical systems, particularly optical cavities where the support of one of the mirrors is a nanoscale cantilever. The talk will review recent developments in the optical cooling of these moving mirrors and discuss the prospects for reaching their quantum mechanical ground state of vibration. Future directions, including the realization of ro-vibrational quantum entanglement in these systems, will also be touched upon.
Hal Metcalf
Nov. 27 Gustaf Brooijmans
Columbia University
 After the Standard Model

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From a particle physics point of view, the past thirty years can rightfully be considered as the golden age of the standard model.  Both the theoretical and experimental knowledge of the structure of the strong and electroweak interactions has reached impressive levels of precision, and the agreement between experimental results and theoretical predictions is stunning.
The standard model doesn't tell us anything about the nature of the particles whose interactions it describes however.  We hope that data taken at the LHC starting in 2008 will allow us to develop some understanding of the origin of particle properties.  According to some models we will learn about particle masses through the discovery of the Higgs boson, while others suggest that dynamics in additional spatial dimensions might be the source of specific properties.  This colloquium will review some key aspects of our current knowledge and how it was acquired, followed by some speculation about what might happen at the LHC.
John Hobbs
Dec. 4 Paul Chaikin
NYU
Experimental Geometry Experiments with candies and colloids

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There are some problems in Physics/Mathematics which can't be solved analytically or computationally (yet). But we can get the answer experimentally.
Packing problems, how densely objects can fill a volume, are among the most ancient and persistent problems in mathematics and science. For equal spheres, it has only recently been proved that the face-centered cubic lattice has the highest possible packing fraction f ~ 0.74. It is also well-known that the corresponding random (amorphous) packings have f ~0.64. The density of packings in lattice and amorphous forms is intimately related to the existence of liquid and crystal phases and is responsible for the melting transition.
The simplest objects to study after spheres are squashed spheres - ellipsoids. Surprisingly we find that ellipsoids can randomly pack more densely; up to f ~0.68 - 0.71 for a shape close to that of M&M'sO Candies, and even approach f ~0.75 for general ellipsoids. Randomly packed ellipsoids can pack more densely than spheres pack in a crystal!. The higher density relates directly to the additional rotational degrees of freedom of the ellipsoids which in turn is related to the number of neighbors, Z, needed to confine a particle.
Quasicrystals can have symmetries which are disallowed for conventionly crystals, amongst them icosahedral symmetry which is the most spherical of discrete symmetries. They might be great candidates for a material that would trap light by having gaps in all directions. But their bandstructure can't yet be calculated. So we built a cm scale Quasicrystal and measured its paroperties int he microwave range. We found that quasicrystals have Brillouin zones despite having a dense set of Bragg peaks, and they are indeed the best candidates for photonic bandgaps.
Meigan Aronson
Jan. 29

Elaine Di Masi

National Synchrotron Light Source Dept,
BNL

Biomineralization: probing protein-mineral relationships with a synchrotron

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Biomineralization is a process which combines mineral crystals with an organic matrix to create composite materials with hierarchical structures. These materials have special strengths well worth imitating in the development of new synthetic materials. Control over biomineral growth depends on proteins. We have developed model organic systems, either protein networks or monolayer organic films, which control mineralization and whose microscale properties can be probed using synchrotron techniques.
Tom Weinacht
Feb 5 Stanley Brodsky The AdS/CFT Correspondence and Novel Effects in QCD

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One of the most interesting recent advances in hadron physics has been the application of the AdS/CFT correspondence to quantum chromodynamics. Although QCD is not a conformally invariant field theory, one can nevertheless use the mathematical representation of the conformal group in five-dimensional anti-de Sitter space to construct an analytic first approximation to the theory. The resulting AdS/QCD model gives accurate predictions for hadron spectroscopy and a description of the quark structure of mesons and baryons which has scale invariance and dimensional counting at short distances, together with color confinement at large distances. In addition, one can compute the form of the frame-independent light-front bound-state wavefunctions, the fundamental nonperturbative entities which encode hadron properties and which allow the computation of hadronic scattering amplitudes. A number of novel applications of light-front wavefunctions to QCD phenomenology will also be discussed, such
as color transparency, hidden color, intrinsic charm, sea-quark asymmetries, dijet diffraction, direct hard processes, and hadronic spin dynamics.
George Sterman
Feb 12 Sol Gruner Putting the Squeeze on Biology: Pressure Effects on Macromolecules

Movie of Presentation (Beginning is missing)
Modest pressures encountered in the biosphere (i.e., below a few kbar) have extraordinary effects on biomembranes and proteins. These include pressure denaturation of proteins, as well as dramatic changes in monomer-multimer association, ligand binding, membrane ion transport, transcription/translation of proteins, virus infectivity, enzyme kinetics and conformational states. Yet all of the biomaterials involved are highly incompressible. The challenge is to understand the structural coupling between these effects and pressure to elucidate the relevant mechanisms. X-ray diffraction studies of membranes and proteins under pressure will be described. It is seen that the key is not the magnitude of the changes, but rather the differential compressibilities of different parts of the structure, leading to a biasing of conformational substates. Examples will be given of pressure studies on biomembranes and proteins. Lessons learned have important implications for the freezing of protein crystals, as is routinely done for protein crystallography and on the role or water in proteins.
Tom Weinacht
Feb 19 Hal Metcalf
Stony Brook
Entropy Exchange in Laser Cooling

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Laser cooling is usually viewed as compression in velocity space by a velocity-dependent force but such forces do not conserve energy.  A proper description must include the light field that absorbs the energy from spontaneous emission, so the light field must be part of the system. It is usually presumed that spontaneous emission is necessary to remove the entropy lost by the atoms, and a closer look suggests that this happens by redistributing the light among the empty states of the radiation field. But the laser beams themselves have sufficient entropy capacity so that stimulated emission can do precisely the same thing.  Thus the system doesn’t undergo a loss of entropy but merely its redistribution among its parts of the system. The entropy in the light field is not dissipated until the outgoing beams hit the walls in a non-conservative, irreversible process.
Tom Weinacht
Feb 26 Martin Schmaltz
Boston University
New Physics at the LHC, why and what?

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With the start of the Large Hadron Collider in 2008 particle physics is likely to enter its most exciting period in over three decades. The physics of the TeV scale will begin to be uncovered, and whatever is found will have profound implications for the field. In this talk I review the argument for why we expect to see new physics at the LHC and present one of the leading proposals for what this new physics might be.
Gilad Perez
Mar 4 Robert Panoff
Shodor Foundation
Many-Body for Anybody: A Computational Science Exploration of the Physics of More Than One Thing

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Computational science continues to advance the accurate description and prediction of the dynamics of many-body systems with new applications, algorithms, and architectures.  Moving from the researcher's workbench to the classroom, real-time model solutions and simulations are now possible in most every area of education and research in physics. These interactive learning environments help us to understand complex systems, while opening up new areas of learner-centered, group-oriented, discovery-based learning.

We will explore such simulation environments from atoms to galaxies. As we progress to petascale computing environments, the use of more complex numerical models of these systems demands a greater emphasis on the fundamentals of quantitative reasoning, computational thinking, and multiscale modeling with special attention to verification and validation: how do you know if it is right?
Alan Calder
Mar 11 Joe Eberly
Department of Physics and Astronomy, Univ. of Rochester
Mysteries of Quantum Entanglement

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The invention of the two-photon Clauser interferometer signalled a completely new domain of spectroscopy.  It allowed direct experimental demonstration for the first time of non-local, non-realist phenomena in physics. I will describe an idealized version of this interferometer and various phenomena at the interface between classical and quantum physics that are related to it (e.g. Schroedinger's Cat). An indirect consequence is that decay to steady state is not always what we were taught. Recent experiments on photons and atoms demonstrate the difference between local decay and non-local decay of entangled quantum systems.  Even when decay of a system is locally smoothly asymptotic, non-local entanglement may be non-smooth and disappear discontinuously. This "sudden death" constitutes a strongly counterintuitive trait of entanglement,
confirming earlier predictions, but not yet really explained.
Tom Weinacht
Mar 25 Max Tegmark
MIT
New clues about inflation, dark matter and dark energy

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With a cosmic flight simulator, we'll take a scenic journey through space and time. After exploring our local Galactic neighborhood, we'll travel back 13.7 billion years back to explore the Big Bang itself and how state-of-the-art measurements and new theoretical insights are
transforming our understanding of our cosmic origin and ultimate fate.
Gilad Perez
April 1
Delia Milliron
Lawrence Berkeley National Laboratory

Chemical routes to phase change memory materials

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Phase change memory technology, a leading candidate for future non-volatile memory, is based on switching small volumes of metal chalcogenide material between the amorphous and crystalline states.  A key remaining concern is the power required to switch from the crystalline to the amorphous state, and optimized low power cell designs call for the phase change material to fill a tall narrow channel between the contact pads.  I will describe our efforts to develop a chemical approach to prepare metal chalcogenide materials.  Molecular precursors are synthesized, deposited by spin coating, then thermally decomposed.  Precursors can be combined in solution to control the composition, and properties, of the final metal chalcogenide film.  By depositing from solution, we can easily fill small and high-aspect ratio holes through capillary action to yield arrays of free-standing nanodots or fill channels for memory devices.  The promise of phase change memory lies in its projected scaling to very high density.  We are therefore also synthesizing sub-20 nm colloidal nanocrystals to fast-forward the technology road map and investigate the fundamentals of phase switching on the nanoscale.
Tom Weinacht
Apr 8 Yuval Grossman CP violation: A solved problem (?)

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CP is the symmetry that made matter and anti-matter identical. CP violation was discovered in 1964 in Long Island. Since then and until recently the origin of CP violation was an open problem in physics. In the last few years this question was answered. Yet,like in many other cases, a solution of one open problem brings with it new problems. In this talk I explain the original problem, the proposed solutions and the experimental verification of the correct solution. I will end up with explaining what are the new problems, how they are going to be addressed experimentally in the near future.

Gilad Perez
Apr 15 David Charbonneau

The Era of Comparative Exoplanetology

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When extrasolar planets are observed to eclipse their parent stars, we are granted unprecedented access to their physical properties. It is only for these systems that we are
permitted direct estimates of the planetary masses and radii, which in turn provide fundamental constraints on models of their physical structure. Furthermore, such planets afford the opportunity to study their atmospheres without the need to spatially isolate the light from the planet from that of the star. I will review the most recent results, and then describe a new observatory that will survey 2000 nearby low-mass stars with a sensitivity to detect rocky planets orbiting within their stellar habitable zones
Mike Zingale
Apr 22 Krishna Rajagopal
MIT
Quark-Gluon Plasma in QCD, at RHIC, and in String Theory

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The realization that the high temperature phase of QCD is quark-gluon plasma, with properties qualitatively distinct from those of the hadronic phase whose quasi-particles make up the quotidian world, goes back more than 30 years. Over that time, we have gained reliable insight into the thermodynamics of quark-gluon plasma at accessible temperatures from lattice QCD calculations, and we have understood much about its dynamics in the high temperature limit where it becomes weakly coupled. However, in the last five years experimental discoveries at the Relativistic Heavy Ion Collider have taught us that, at least at temperatures within a factor of two of that at which hadrons ionize, the dynamics of quark-gluon plasma is closer to the ideal liquid limit than to the ideal gas limit. These experimental data demand a theoretical understanding of the dynamics of strongly coupled quark-gluon plasma. Such calculations in QCD itself are in their infancy, but string theory provides us with robust tools for exactly this purpose, applicable to the quark-gluon plasmas of many QCD-like theories. I will describe some of the many new insights into the properties of strongly coupled plasma obtained recently from these AdS/CFT calculations.
Tom Weinacht

For  upcoming colloquia, go here.