|"The Power of Topology in Superstring Theory" (Video)
Superstring theory is the leading candidate for the ultimate unified theory of all the matters and forces in nature. It postulates that fundamental building blocks are not point particles but strings, and it is defined in (9+1)-dimensional spacetime. The rich structure in particle physics in our (3+1) dimensions, such as quark and lepton flavors, gauge forces, and the Higgs boson to break the gauge symmetry, is expected to emerge from the geometry of the extra 6 (= 9 - 3) dimensions, called a Calabi-Yau space. We want to derive quantitative predictions on our universe from the geometry of the Calabi-Yau space. However, the Calabi-Yau space is so complicated that we do not even know an expression for its metric, namely how to measure the distance between two points on the space. Given this limitation, what can we do? In this talk, I will describe techniques we have developed to overcome this difficulty and applications of these techniques to problems in physics and mathematics.
|"Quantum life" (Video)
Nature is the great nanotechnologist: life is based on a myriad of interlinked mechanisms that operate at the molecular scale. The dynamics of these mechanisms are governed by quantum mechanics. Quantum mechanics famously exhibits strange and counterintuitive effects based on quantum coherence and entanglement. Does such `quantum weirdness' play a role in the functioning of living systems? Recent experimental investigations of photosynthesis indicate that quantum coherence may play an important role in optimizing energy transport in photosynthetic complexes. This talk presents a general theory that shows how quantum coherence can dramatically enhance energy transport in photosynthesis and in artificial systems. Optimal energy transport takes place at the point where the timescales for dynamic and static disorder converge, a phenomenon called the quantum Goldilocks effect.
|"The Maps Inside Your Head" (Video)
How do our brains make sense of a complex and unpredictable world? In this talk, I will discuss a physicist's approach to the neural topography of information processing in the brain. First I will review the brain's architecture, and how neural circuits map out the sensory and cognitive worlds. Then I will describe how highly complex sensory and cognitive tasks are carried out by the cooperative action of many specialized neurons and circuits, each of which has a simple function. I will illustrate my remarks with one sensory example and one cognitive example. For the sensory example, I will consider the sense of smell ("olfaction"), whereby humans and other animals distinguish vast arrays of odor mixtures using very limited neural resources. For the cognitive example, I will consider the "sense of place", that is, how animals mentally represent their physical location. Both examples demonstrate that brains have evolved neural circuits that exploit sophisticated principles of mathematics - principles that scientists have only recently discovered.
|9/29/14||David Goldhaber-Gordon||Stanford University||Feldman|
Ten years ago, it was amazing that a single atomic layer of carbon -- graphene -- could conduct electricity. Recent developments have led to graphene in which electrons flow more freely at room temperature than in any semiconductor 2D electron system. At low temperature, electrons can travel more than 10 microns without being deflected [1,2]. In these ultraclean samples, interactions and substrate-induced symmetry breaking lead to novel phenomena . I will speak about a few examples of such phenomena, including:
* Insulating behavior at the charge neutrality point at zero magnetic field 
Terrestrial gamma-ray flashes (TGFs) were discovered in 1991 by the Burst And Transient Source Experiment (BATSE) on the Compton Gamma-ray Observatory as mysterious bursts of high-energy radiation appearing to come from areas of thunderstorm activity. Since then, they have been detected on three additional satellite experiments including the Gamma-Ray Burst Monitor (GBM) on-board the Fermi satellite. Our understanding of the relationship between TGFs and coincident Very Low Frequency (VLF) radio signals has evolved considerably in the Fermi GBM era, with some VLF signals coming from lightning associated with the TGFs and others from the TGFs themselves. This has given us new insights into the physical processes responsible for TGFs and their relationship to lightning processes in general. I will discuss the Fermi GBM TGF observations, with special attention to their association with VLF radio signals detected on the ground.
In terms of visiting with faculty, I would be interested in meeting with anyone who is interested in meeting with me! I have interest in but not expertise in elementary particle experiments and theory. In addition to working in space-based gamma-ray astrophysics I am also involved in the Cherenkov Telescope Array and I think there would be some common interests with Prof. Gaitskell in the area of dark matter detection and with Prof. Koushiappas because of our common interest in Fermi.
|| Texas A&M University
"Bose-Einstein condensation of spin waves in YIG" (Video)
|10/27/14||Nandini Trivedi||Ohio State University||Valles|
|"Quantum Fluctuations and Phase Transitions" (video)
I will discuss the role of quantum fluctuations in driving phase transitions and contrast them with the better understood thermally driven phase transitions. I will show how standard paradigms break down and novel phases of matter emerge in the context of superconductor-insulator phase transitions and discuss our predictions for experimental probes through local spectroscopies and dynamics. These concepts have overlaps with cold atoms and AdS/CFT that I will illustrate.
 Bouadim, Loh, Randeria and Trivedi, “Single- and two-particle energy gaps across the disorder-driven superconductor–insulator transition”, Nature Physics 7, 884 (2011).
 Swanson, Loh, Randeria and Trivedi, “Dynamical Conductivity across the Disorder-Tuned Superconductor-Insulator Transition”, Phys. Rev. X 4, 021007 (2014)
|"Cosmology as a Probe of Physics Beyond the Standard Model" (video)
Abstract: Cosmological observations provide overwhelming evidence that our universe is almost entirely comprised of dark energy and dark matter, both of which have no theoretical explanation within the standard model of particle physics. The former is responsible for a current period of cosmic acceleration, much like that which occurred in the earliest moments of the universe. The early period of cosmic acceleration, known as inflation, was vital in providing the primordial seeds from which galaxies and clusters formed, whereas the late time acceleration could eventually lead to the vanishing of most structure in the universe. The driving force behind cosmic acceleration, as well as dark matter, still remains elusive from the point of view of a microscopic theory. Combined with fundamental questions, such as the origin of particle mass and how electroweak symmetry is broken, these conundrums require physics beyond the standard model. In this talk I will review both the theoretical and observational status of these issues with an emphasis on the excitement surrounding current and upcoming experiments.
|"Emergence from frustration: spin liquid and high temperature superconductivity" (video)
I shall describe some recent development in frustrated spin systems and show that these are prime examples of the notion of emergence: novel particles and fields not present in the original Hamiltonian emerging at low energy. I then show that some of these ideas may be applied to understand the pseudo-gap phase of high temperature superconductors.
|11/17/14||Eric Mazur (MIT) - CANCELLED|
|11/24/14||James Olsen||Princeton University||Landsberg|
|"Nature of the New Boson: a lonely Higgs, or one of many cousins?" (video)
Recent measurements from the ATLAS and CMS experiments indicate that the new boson discovered in 2012 at the Large Hadron Collider (LHC) at CERN is a Higgs boson. In the standard model of particle physics, one Higgs boson is sufficient to give mass to the W and Z particles, as well as the fundamental fermions (quarks and leptons), while also ensuring that the photon remains massless. Although this is the most economical scenario that explains electroweak symmetry breaking and the origin of fundamental particle masses, motivated extensions of the standard model predict multiple Higgs bosons with a rich phenomenology that could be detectable at the LHC. In this colloquium I will present an overview of what we have learned about the Higgs boson from measurements based on the 2011-2012 data run, discuss the status of searches for additional Higgs particles, and close with a brief summary of prospects for the coming LHC run at higher energy scheduled to begin in spring, 2015.
|9/9/13||Stephon Alexander||Dartmouth College||Valles & Jevicki|
|"Observational and Theoretical Implications of a Parity Violating Universe"
So far, only the weak interaction maximally violates parity symmetry. In this colloquium, after a pedagogical overview of modern cosmology, we will explore the possibility that the gravitational force may also violate parity. I show that in the context of early universe cosmology, this parity violation, revealed through gravitational waves during the epoch of cosmic inflation, can explain the observed cosmic matter-anti matter asymmetry. I also discuss current and future CMB polarization experiments which will attempt to detect the signals of cosmic parity violation.
|9/16/13||Baylor Fox-Kemper||Brown University||Marston|
|"Modeling the Earth: Physics, Dynamics, and Numerics"
Not so long ago, the modeling of the atmosphere, ocean, cryosphere, and other components of the Earth System were carried out by distinct groups of investigators with relatively narrow research goals in understanding their own "sphere." However, the drive to understand the climate, and particularly human influences on climate now and in possible future scenarios has led to climate modeling of much grander scope and ambition. I will present the ingredients of a climate model, from the simplest planetary energy balance models to a schematic of the present day models. I will present some of my own work in improving these models and present prospects for future improvements, through better computers and through better understanding.
|9/23/13||Steven Carlip||UC Davis||Lowe|
|"Spontaneous Dimensional Reduction?"
The general theory of relativity tells us that what we call gravity is really a manifestation of the geometry of space and time. The basic unsolved problem of quantum gravity is to understand the structure of this spacetime at the smallest scales.
Several recent lines of evidence hint that spacetime at very small distances may undergo "spontaneous dimensional reduction," behaving as if it had only two dimensions rather than four. I will summarize some of the evidence for this strange behavior, and discuss a further argument based on the effect of quantum fluctuations on light cones. If this description proves to be correct, it suggests an unexpected relationship between small-scale quantum spacetime and the behavior of cosmology near a "typical" big bang.
|9/30/13||Christoph Boehme||University of Utah||Mitrovic|
|"Promises and Challenges of Organic Spintronics"
While the term “Spintronics" was originally introduced as label for technologies that represent information through spin states rather than charge states, it is nowadays oftentimes used solely in the context of spin-polarization, spin-injection, and spin-transport effects for which spin-orbit interaction plays an important role. Silicon and carbon based semiconductors display only weak spin-orbit coupling and - in the case of organic semiconductors - charge transport via hopping through strongly localized states. These materials appear at first glance therefore to be entirely unsuitable for spintronics. However, they also exhibit spin related effects not seen in materials with strong spin-orbit coupling which can be used for alternative, different approaches to spintronics based on spin-permutation symmetry states of charge carrier pairs rather than spin-polarization states. Reading spin-permutation symmetry is straight forward when pronounced spin-selection rules exist1,2. In contrast to spin-polarization, permutation symmetry does not depend directly on temperature and magnetic field strength3. Furthermore, the absence of spin-orbit coupling can also allow for long spin-coherence times and thus, the possibility to connect spintronics to an all spin based memory which may be applicable to spin-based quantum information4 concepts and for similar reasons, it allows for magnetic resonance based spin-manipulation schemes. Crucial for the successful implementation of organic spintronics will be a fundamental understanding of the microscopic electronic processes which are aimed to be utilized for this new technology, a requirement which has only partially achieved. Developing this understanding will be among the most important challenges of this field5. In this talk, our work on the development of this organic spintronics will be presented and the issues at hand as well as the progress made will be discussed.
 D. R. McCamey, H. A. Seipel, S. Y. Paik, M. J. Walter, N. J. Borys, J. M. Lupton, and C. Boehme, Nature Materials, 7, 723 (2008).
 D. R. McCamey, K. J. van Schooten, W. J. Baker, S.-Y. Lee, S.-Y. Paik, J. M. Lupton, and C. Boehme, Phys. Rev. Lett. 104, 017601 (2010).
 W. J. Baker, K. Ambal, D. P. Waters, R. Baarda, H. Morishita, K. van Schooten, D. R. McCamey, J. M. Lupton, and C. Boehme, Nature Commun. 3, 898 (2012).
 W. J. Baker, T. L. Keevers, J. M. Lupton. D. R. McCamey, and C. Boehme, Phys. Rev. Lett. 108, 267601 (2012).
 C. Boehme and J. M. Lupton, Nature Nano. 8, 612 (2013).
|10/7/13||Benjamin Wandelt||Sorbonne University||Tucker|
|Professor Wandelt is Professor and International Chair of Theoretical Cosmology at the Paris Institute for Astrophysics (IAP) at the Université Pierre et Marie Curie, Sorbonne University.
"Cosmic Past, Present, Future: Planck and Beyond"
How can we learn what banged at the Big Bang? We use astronomical observations to probe the epoch in the very early Universe where quantum fluctuations imprinted the seeds of cosmic structure. I will summarize the main results of the analysis of the cosmic microwave background temperature anisotropies as seen by the Planck mission data released in March 2013, with special emphasis on the non-Gaussianity analysis which resulted in the highest precision tests to date of physical mechanisms for the origin of cosmic structure. Then I will turn to the future and highlight the challenges and opportunities of the next generation of probes of the large scale structure of the universe aiming to piece together the outstanding puzzles of cosmic past, present, and future - with some glimpses onto the lab bench of innovative approaches that are now emerging.
|10/21/13||Nina Emery||Brown University (Department of Philosophy)||Marston|
|"Simplicity and Skepticism in Quantum Mechanics"
On a straightforward ontological reading of all viable, realist interpretations of quantum mechanics, we do not inhabit the familiar three-dimensional space of our everyday experience. Instead we inhabit a very high-dimensional configuration space. I examine the arguments for and against this sort of straightforward ontological reading, and compare the resulting theories with more familiar skeptical hypotheses, like the hypothesis that we are in the Matrix, or the hypothesis that we are part of a computer simulation.
|10/28/13||Marc Kamionkowski||John Hopkins University||Koushiappas|
|"Cosmic Beauty and Blemishes"
The vast majority of the wealth of cosmological information we have has come from power spectra (or equivalently, two-point correlation function, for the CMB temperature and for the mass distribution in the Universe today. But there is far more that can be sought in the future with the deluge of data from current and forthcoming surveys. I will discuss how the data can be used to look for new fields during inflation; to test geometrically for their properties; to seek parity breaking in the early and late Universe; to look for exotic dark-energy physics; to inquire about nontrivial cosmic topologies; to identify preferred-frame effects; etc. I will also then comment on a possible surprise in the CMB data.
|11/4/13||Richard Gaitskell||Brown University||Valles|
Professor Gaitskell will present and discuss the first results from the LUX (Large Underground Xenon) dark matter detector experiment at the Sanford Underground Research Facility in Lead, SD. Video
|11/11/13||Andreas Ludwig||UC Santa Barbara||Feldman|
|"Topological Insulators and Superconductors" (Video)
Topological Insulators (and Superconductors) are quantum phases of non-interacting Fermions which are electrical (or thermal) insulators in the bulk, but whose boundaries conduct electrical current (or heat) like a metal. These boundaries are very special and unusual conductors in that they are ("holographically") protected by the topological nature of the quantum state of the bulk material. The first examples of such phases were theoretically predicted less than a decade ago and were discovered experimentally shortly thereafter in two- and three-dimensional electronic systems. Topological Insulators have attracted significant interest as fundamentally novel electronic phases. They can be viewed as generalizations of the Two-Dimensional Integer Quantum Hall effect to systems in different dimensions and with different symmetry properties. For example, they can occur in three dimensions and in the absence of a time-reversal breaking magnetic field. - Here we give an introduction to these systems, and will explain the basic ideas underlying an exhaustive classification scheme of all Topological Insulators (and Superconductors), which links these systems of relevance for Condensed Matter laboratory experiments to a variety of general notions in Theoretical Physics and Mathematics.
|11/18/13||Lyderic Bocquet||Institut Lumière Matière, Université Lyon||Stein|
|"Fluid transport at the nanoscales and application to osmotic energy harvesting" (Video)
"There is plenty of room at the bottom". This visionary foresight of R. Feynman, introduced during a lecture at Caltech in 1959, was at the root of numerous scientific and technological developments, taking benefit of the "strange phenomena" occurring at the smallest scales. There remains however a lot to explore, in particular in the context of fluids at the nanoscales and their specific transport properties. The great efficiency of biological nanopores, such as aquaporins, in terms of permeability or selectivity is definitely a great motivation to foster research in this direction. How to reach such efficiency in artificial nano-systems, and build new devices taking benefit of the strange transport behavior of fluids at nanoscales is still an open question.
I will discuss several results obtained in our group on the fluid transport at the nanoscales, in particular inside nanopores, nanochannels and nanotubes. I will then focus on the study of transport inside a single Boron-Nitribe nanotube. Using a nano-assembly route with nanostructures as building block, we have built a dedicated trans-membrane nanofluidic device allowing to study fluid and ionic transport across a single nanotube. Experiments show unprecedented energy conversion from salt concentration gradients. Applications in the field of osmotic energy harvesting will be discussed.
"Giant osmotic energy conversion measured in a single transmembrane boron-nitride nanotube", A. Siria, P. Poncharal, A.-L. Biance, R. Fulcrand, X. Blase, S. Purcell, and L. Bocquet, Nature 494 455-458 (2013)
"Optimizing water permeability through the hourglass shape of aquaporins",
S. Gravelle, L. Joly, F. Detcheverry, C. Ybert, C. Cottin and L. Bocquet, Proc. Nat. Acad. Sci. USA 110 16367 (2013)
"Soft nanofluidic transport in a soap film", O. Bonhomme, O. Liot, A.-L. Biance, and L. Bocquet, Phys. Rev. Lett. 110 054102 (2013)
|11/25/13||Chandrasekhar Ramanathan||Dartmouth College||Mitrovic|
|"Quantum simulation with nuclear spins" (Video)
It has been three decades since Feynman showed that a quantum computer is required to efficiently simulate a quantum system. While building a quantum computer remains a grand challenge, our improved ability to manipulate and control quantum systems has led to a resurgence of interest in quantum simulations that could help tackle problems in diverse areas such as condensed-matter physics, cosmology and quantum chemistry. In this talk I will discuss how to build quantum simulators using nuclear magnetic resonance (or NMR) techniques. While we can perform any small-scale simulation using liquid state NMR, the highly-coupled spin networks in solids allow us to perform a more limited set of large-scale analog quantum simulations. These solid state spin systems are excellent platforms on which to study the coherent dynamics of large quantum systems. I will illustrate these ideas with experimental examples, and discuss the key challenges to developing large scale, general purpose quantum simulators.
|12/2/13||Cornelia Dean||Brown University/The New York Times||Valles|
|"The Physics of The New York Times" (Video)
In modern times, few realms dominate science -- and the popular imagination -- like physics and cosmology. For more than 100 years, The New York Times has attempted to bring these fields to life for its readers. Cornelia Dean, a science writer and former Science Editor of the newspaper will discuss this coverage in a colloquium on 12/2/13. Ms. Dean, the editor of a new collection of Times articles on physics and astrophysics, will discuss how some notable stories came to be, the difficulties of writing about highly technical subjects for a lay audience, and the difficulties that lie ahead for coverage of science.
"Concrete Quarks - The Beginning of the End" (Video)
A short history of the physics of strongly interacting particles is presented. Events leading to the discovery, and eventual acceptance, of concrete quarks are described.
|2/10/14||Joao Guimaraes de Costa||Harvard University||Narain|
"A Closer Look at the Higgs Boson with the Large Hadron Collider" (Video)
Scientists at CERN have been exploring the high energy frontier with the Large Hadron Collider since March 2010. The substantial dataset accumulated thus far, albeit at lower energy than initially foreseen, already yielded a Nobel prize award for the discovery of the Higgs Boson.
|2/24/14||David Pine||New York University||Stein|
"Colloids with directional interactions" (Video)
We have developed new kinds of colloidal particles with either geometrical or chemical patches that give rise to directional interactions. These interactions allow colloids to interact with each other more like atoms, which in turn are used to build up structures that are not possible with isotropic interactions. These directional interactions are being developed to make self-replicating colloidal motifs and new colloidal crystals.
|3/3/14||Raymond Brock||Michigan State University||Heintz|
"That Spin 0 Boson at CERN Changes Everything: The Future of the Energy Frontier in Particle Physics" (Video)
I’ll argue that the "Higgs Boson" discovery requires us to think differently about planning for the future of Particle Physics. While the decades-long confirmation of the Standard Model itself an historic episode in the history of physics, as a model of nature it is unhelpful as a clear guide to the future. I’ll review the features of the Standard Model that make it superb, I’ll point out why it’s frustrating, and I’ll describe the hints that motivate us in the coming decades. Last year the particle physics community went through a self-study of future opportunities. I’ll review some of the “Snowmass Workshop” especially as it pertains to the future of collider physics.
"Spin-Orbit Interactions for Exoplanets" (Video)
In the Solar system, the planets follow orbits that are aligned with the Sun's equatorial plane to within a few degrees. But what about planets around other stars? Recently we have measured the spin-orbit angles of about 50 stars with exoplanets, using a technique first theorized in the 19th century, as well as several new techniques based on data from the NASA Kepler spacecraft. Many exoplanetary systems have good alignment, as in the Solar system -- but there are also many surprises. I will discuss these results and their implications for theories of planet formation, and tidal spin-orbit interactions. I will also describe the Transiting Exoplanet Survey Satellite, a NASA mission that will improve upon Kepler by discovering exoplanets around stars that are brighter, closer to the Earth, and easier to study.
|3/17/14||Raul Jimenez||University of Barcelona||Koushiappas|
"Large scale structures, their statistics, neutrino masses and fundamental Physics" (Video)
Mapping the large scale structure of the Universe has provided us with an exquisite 3D view of the development and growth of structure since the Big Bang. Now that we have a well established standard cosmology model (LCDM), it is possible to learn fundamental physics from the statistics of large scale structures. In this talk I will describe how we can learn about neutrino physics (in particular about the absolute mass scale and its hierarchy), axion physics, dark energy and dark matter. In summary: the Universe provides an outstanding tool to learn about how nature has decided to extend the standard model of particle physics; I will discuss new developments on this front as well.
|3/31/14||Igor Herbut||Simon Fraser University||Mitrovic|
"Fundamental physics with two-dimensional carbon" (Video)
The two-dimensional form of carbon, also known as graphene, has been hailed as wonder material promising, and already delivering, many useful applications. This is not the only reason, however, why many theoretical physicists have been fascinated with this new material over the last ten years. The reason is also that the electronic structure of graphene provides an unusually simple and affordable playground for studies of some of the basic concepts of modern quantum physics. In this lecture I will attempt to give an elementary discussion of three of these: 1) Mott-insulator (or "Higgs") quantum phase transition, and the emerging relativity, 2) the spontaneous braking of "chiral" symmetry, and the "Dirac masses" of graphene, and 3) the Jackiw-Rebbi zero-modes, topological defects, and their (Clifford) algebras.
||Robert Meyer||Brandeis University||Pelcovits|
In imperial Rome, the use of vaulted structures, arches, domes and other forms of vaults, built of stone and concrete, was developed to a degree never seen before. Bridges and aqueducts were built throughout the empire. Vast spaces could be enclosed with an economy of material, for use as temples, baths, meeting places, markets, and palaces. This lecture seeks to develop an understanding of the principles determining the stability of some of these structures, which served as the basis for later developments, including the great cathedrals of the Middle Ages and the Renaissance.
|4/14/14||Juan Restrepo||University of Arizona
"Estimation Challenges in Climate and the Geosciences" (Video)
Accounting for uncertainties has also led us to alter our expectations of what is predictable and how such predictions compare to nature: in effect, to take on a more Bayesian approach to scientific research as well as to embrace more seamlessly the statistical and deterministic realms. I will enumerate a few important geoscience problems that live in the realm of the deterministic and the statistical and describe, briefly, our Group's approach and progress on these. Among these I will choose a time series analysis project to provide more details on the methods we use to pursue this Bayesian research program.
|4/21/14||Ian Fisher||Stanford University
"Electronic nematic phases in high temperature superconductors" (Video)
In recent years, anisotropic electronic phases have been discovered in a variety of strongly correlated quantum materials. Borrowing language from the field of soft condensed matter physics, such phases are referred to as electronic nematic phases when they break a discrete rotational symmetry of the crystal lattice without further breaking translational symmetry. The physical origin of electronic nematic order is unclear, as are the implications for other broken symmetry states, including superconductivity, motivating the development of tools and techniques that probe electronic nematicity. In this talk I'll outline a new technique that measures an associated quantity, the nematic susceptibility, which provides important insight to nematic fluctuations in a material. Measurements of this quantity directly reveal the presence of an electronic nematic phase transition in a family of high temperature superconductors, and an associated quantum phase transition near optimal doping (i.e. the doping that yields the maximum critical temperature of the superconductor). I'll explain the possible significance of this observation.
|9/17/12||Rouven Essig||SUNY, Stony Brook||Koushiappas|
|"The Hunt for Dark Matter"
Dark matter makes up 80% of the matter in our Universe, but we have yet to learn its identity. Astrophysical probes are becoming powerful enough to inform us on some of its fundamental properties and a wide array of experiments are probing its non-gravitational interactions with ordinary matter. In this talk, I will review the astrophysical evidence for dark matter and give a broad overview of current and future direct and indirect detection experiments, as well as collider probes. I will also discuss some of the hints for dark matter at currently running experiments.
|9/24/12||Robert Hallock||University of Massachusetts, Amherst||Valles|
|"Is Solid Helium-4 an Example of a 'Supersolid'? Come, Listen, and See What You Think"
About 40 years ago it was predicted that it might be possible for solid helium to display some of the properties of a superfluid, thus there might be a 'supersolid'. Experiments in the mid to late 1970’s were negative and the prediction languished. Then in 2004 an experiment was done that was interpreted as positive evidence for the presence of a 'supersolid' in solid helium. But, the interpretation has been very controversial and other evidence has complicated the picture. After a review of some background and a few key experiments, experiments will be described that are conceptually different from all the others. These provide direct evidence to that it is possible to pass helium through a sample cell filled with solid helium . Some of the recent predictions for 'supersolid' behavior due to theorists differ substantially from the original theory of 40 years ago and these are rather consistent with our observations. This will be an experimentally oriented talk, designed to be accessible to all.
|"The Next Muon g-2 Experiment"
There is a discrepancy between the measured and expected values of an intrinsic property of the muon, its anomalous magnetic dipole moment, aka g-2. The discrepancy could be an indication of new physics beyond the current standard model of particle physics and leads to predictions that new particles will be found at the LHC. As an example, within weeks of the discovery of the Higgs at the LHC, papers were submitted correlating the Higgs to gamma gamma branching fraction with the g-2 anomaly. An extraordinary opportunity has arisen with the successful completion of the Tevatron program at Fermilab. The infrastructure used to create antiprotons can readily be repurposed to create muons. The Fermilab accelerator complex will be able to produce close to twenty times more muons than recorded by the last experiment at Brookhaven in less than two years allowing us to measure g-2 to a precision of 140 parts per billion. I will discuss the motivation for the new experiment, the technical difficulties involved in the prediction and measurement, and the progress towards mounting the new experiment.
|10/10/12||Greg Landsberg||Brown University|
|Special Colloquium: "Discovery of the Higgs Boson(?) at the Large Hadron Collider"
On July 4th, 2012 the ATLAS and CMS Collaborations at the Large Hadron Collider announced a discovery of a new boson with the mass of 125 GeV, a likely candidate for a long-sought Higgs boson. In this special colloquium I'll give an inside track of the events that lead to this fundamental discovery, explain its importance, and discuss the next steps in uncovering the true nature of the new particle.
|10/15/12||Douglas Finkbeiner||Harvard University||Koushiappas|
|"The Galactic Center 130 GeV Line: WIMP or Artifact?"
The recent claims of a gamma-ray line in the Galactic center at 130 GeV has generated excitement, not least because it could be a signal of dark matter annihilation. I will summarize the current state of the observations of the Galactic center, clusters, and unassociated halo objects, and speculate about models of particle dark matter that could
explain the data.
Electromagnetic fields carry energy, momentum, and even angular momentum. The momentum density is ε_0 (E×B), and it accounts (among other things) for the pressure of light. But even static fields can harbor momentum, and this would appear to contradict a general theorem: if the center of energy of a closed system is at rest, then its total momentum must be zero. Evidently in such cases there lurks some other momentum, not electromagnetic in nature, which cancels the field momentum. But finding this “hidden momentum” can be surprisingly subtle. I’ll discuss a particularly cute example.
|"Neutrino Physics: This Decade and Beyond"
Neutrinos are one of nature's strangest and most elusive particles. For more than 50 years, they have surprised us: not only by their mere presence, but also by the revelation that these ghostlike particles can oscillate from one type to another. This stunning discovery has opened up a host of new questions about neutrinos and their properties; questions which we will be trying to answer in the next decade and beyond. In this talk, a survey of recent experimental results will be presented, along with projections for what the future holds. If history is any indication, we are in store for an exciting ride.
|"What do the students need?"
The instruction we offer students, at any level, presumably reflects what we believe will help them understand physics. But we don’t often subject our beliefs to scrutiny. Most physics instructors work from common sense assumptions about what students need—clear explanations, demonstrations, motivation and practice. As in physics, however, common sense ideas (e.g. 'objects move because they are pushed') aren't always correct. I will present evidence that these usual assumptions are insufficient and offer an expanded set of possibilities, focusing in particular on how students understand knowledge and learning. In many cases what students most need is help taking a different approach to learning, to start thinking of science as a “refinement of everyday thinking” (Einstein, 1936) rather than as a body of new information to memorize.
||Ohio State University
|"The Puzzle of Charge and Mass"
Beginning with the seminal work of Rutherford, Geiger and Marsden in 1911, physicists have investigated the atom using particle beams (alpha particles, and protons) as probes. They developed new detection methods; the geiger counter, scintillators, cloud and then bubble chambers. This new paradigm for probing matter and new detectors led to many discoveries. To make a long story short, by 1974 the chaos of discovery lead to the Standard Model describing all observed particle phenomena in terms of three fundamental forces (4 including gravity) and the fundamental building blocks of matter, quarks and leptons. Only now, after the dust of this chaotic discovery settles, are we able with hindsight to recognize the underlying principles which define the theory we call the Standard Model. It is these principles and their logical extension which I will attempt to describe in this talk.
||University of Chicago/Fermilab
|"The Dark Energy Survey"
The Nobel Prize in Physics for 2011 was awarded for the discovery that the expansion of the Universe is accelerating. Yet the physical origin of cosmic acceleration remains a mystery. The Dark Energy Survey (DES) aims to address the questions: why is the expansion speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? The Dark Energy Survey will address these questions by measuring the history of cosmic expansion and of the growth of structure through four complementary techniques: galaxy clusters, large-scale galaxy clustering, weak gravitational lensing, and supernovae. The DES collaboration has built and will employ a new, 570-megapixel, digital camera on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile to carry out a deep, wide-area sky survey of 300 million galaxies and a narrower, time-domain survey that will discover 4000 supernovae over 525 nights starting in late 2012. I will overview the DES project, which achieved`first light' in September 2012, describe results from commissioning and science verification of the instrument, and discuss the plans and goals of the survey.
|"Geometry and Genetics"
Developmental genetics has been very successful in attaching a function to thousands of genes whose mutation can lead to developmental defects. This makes the task of quantitative modeling effectively impossible. We have instead used geometric methods from dynamical systems theory plus genetics to posit simple models of phenotype that collapse the activity of many genes onto a few parameters.
|2/11/13||John D. Monnier
||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, 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, focusing on the oblate and gravity-darkened photospheres of rapidly rotating stars. We can now also resolve the interacting components of close binary stars for the first time and I will highlight the recent remarkable eclipse of epsilon Aurigae as viewed by CHARA.
|"Detecting Gravitational Waves (and doing other cool physics) with Millisecond Pulsars"
The first millisecond pulsar was discovered in 1982. Since that time their use as highly-accurate celestial clocks has improved continually, so that they are now regularly used to measure a variety of general relativistic effects and probe a variety of topics in basic physics, such as the equation of state of matter at supra-nuclear densities. One of their most exciting uses though, is the current North American (NANOGrav) and international (the International Pulsar Timing Array) efforts to directly detect nanohertz frequency gravitational waves, most likely originating from the ensemble of supermassive black hole binaries scattered throughout the universe. In this talk I’ll describe how we are using an ensemble of pulsars to try to make such a measurement, how we could make a detection within the next 5-10 years, and how we get a wide variety of very interesting secondary science from the pulsars in the meantime.
||Los Alamos National Laboratory
|"India's Energy [In]Security, China's Growing Consumption, Spain's Options"
Energy security, economic development and climate security are three urgent, pressing and interconnected goals. This talk will examine how different regions of the world aim to meet their energy needs, and sustain development. This presentation will then focus on three major regions, China, India and Europe (using Spain as an example) to illustrate challenges and opportunities. Finally, it will end with some philosophical thoughts on climate change and sustainable development.
|"Levitation by Casimir Forces In and Out of Equilibrium"
A generalization of Earnshaw's theorem constrains the possibility of levitation by Casimir forces in equilibrium. The scattering formalism, which forms the basis of this proof, can be used to study fluctuation-induced forces for different materials, diverse geometries, both in and out of equilibrium. In the off-equilibrium context, I shall discuss non-classical heat transfer, and some manifestations of the dynamical Casimir effect.
||Brookhaven National Laboratory
|"Observation of Electron-antineutrino Disappearance at Daya Bay Nuclear Reactor Neutrino Experiment"
At the Daya Bay Reactor Neutrino Experiment we have measured the last unknown neutrino mixing angle, θ13, to be non-zero at the 6.2σ level, this is the most precise measurement to date. This was done using a careful optimization of the detector systems, the measurement technique and choice of experimental site. I will give a short introduction to neutrinos, what we know about them and how we know these things. I will then talk of the mathematical formalism of neutrino mixing and how we might measure the parameters of mixing. At Daya Bay we use the technique of far/near relative measurement to make a significant reduction of the systematic errors that have been a problem for previous measurements. I will describe this technique and how this drove the design of the hardware of our experiment. Lastly I will describe the backgrounds to our measurement and how they are dealt with and then, of course, the final result. If there is time I hope to discuss the implication of our measurement and what’s in store for neutrino physics.
||City College of New York
|“Searching for topological superconductivity of disordered Dirac fermions”
In the last few years there has been an explosive development in materials’ science – the discovery of a new class of insulators in three dimensions (3D) having a fully insulating electronic gap in the bulk but with metallic Dirac states on their surfaces which can carry spin/charge currents that are topologically protected against (time-reversal-invariant) disorder and perturbations. This discovery launched the search for a topological superconducting analogue characterized by a fully gapped odd parity (p-wave) pairing state that could support Majorana bound states. Such a superconducting phase has important implications for a fault-tolerant quantum computing owing to the non-Abelian exchange statistics obeyed by Majorana fermions. Recently, superconductivity below ~4 K was reported in two 2nd generation 3D topological insulators (TIs): in Bi2Se3 doped with copper and in Bi2Te3 under ~6 GPa pressure. In both cases, however, the topological nature of the superconducting phase has not yet been proved. In my talk I will discuss our most recent results on another 2nd generation TI, Sb2Te3, where we have discovered superconductivity with Tc = 8.3 K, the highest transition temperature among the TIs reported thus far. This state is obtained when the material is synthesized under modest pressure (in the MPa range) in the narrow dome-like pressure range, reminiscent of quantum criticality in other exotic superconductors. The diamagnetic state of this new superconductor is very unusual, since even in the normal state the system supports large orbital currents, while robust van Vleck-like spin response of the disordered Dirac fermions still persists in the superconducting state. We will discuss our observations in the context of recent ideas of how arbitrarily weak disorder can assist fluctuation superconductivity and turn Dirac semimetal into a superconductor.
|"Trillion Degree Matter"
In this talk I will discuss a very simple question: What are the properties of matter at extremely high temperature, in excess of several trillion Kelvin? Experiments at large particle colliders like RHIC at Brookhaven Lab and LHC at CERN have shown that such temperatures can be achieved in collisions of heavy nuclei, creating a plasma of quarks and gluons resembling the universe shortly after the Big Bang. We have found that the produced state of matter exhibits fascinating and somewhat surprising properties: Although its density exceeds that of water by 16 orders of magnitude, the quark-gluon plasma behaves like a near-perfect liquid. I will review the most striking observations made in recent LHC data and discuss the unexpected connections to strongly coupled systems in other areas of physics, ranging from string theory to ultra-cold atoms.
|4/22/13||Lord Martin Rees
||University of Cambridge
|Arthur O. Williams Lecture: “From Mars to the Multiverse” (video)
Astronomers have made astonishing progress in probing our cosmic environment. We can trace cosmic history from some mysterious 'beginning' nearly 14 billion years ago, and understand in outline the emergence of atoms, galaxies, stars and planets.
Unmanned spacecraft have visited the other planets of our Solar System (and some of their moons), beaming back pictures of varied and distinctive worlds. An exciting development in the last decade has been the realization that many other stars are orbited by retinues of planets -- some resembling our Earth.
Looking further afield, we are understanding galaxies and their nuclei in fuller detail, and can check models of their evolution by detecting objects all the way back to an epoch only a billion years after the 'big bang'. Indeed we can trace pre-galactic history with some confidence back to a nanosecond after the 'big bang'.
But the key parameters of our expanding universe -- the expansion rate, the geometry and the content -- were established far earlier still, when the physics is still conjectural but can be pinned down by future observations. These advances pose new questions: What does the long-range future hold? Should we be surprised that the physical laws permitted the emergence of complexity? and Is physical reality even more extensive than the domain that our telescopes can probe? This illustrated lecture will attempt to address such issues.
||University of Massachusetts, Amherst
|"Wandering amongst the Feynman Diagrams"|
||Brookhaven National Laboratory
|"Physics of the Intensity Frontier"|
||Michigan State University
|"Seeking the Origin of Mass: Higgs Searches at Colliders"|
|"Going to the ends of the earth to glimpse the beginnings of time: Observing the Big Bang with the BICEP Telescope at the South Pole"|
|"Maximum Entropy and the Inference of Patterns in Nature"|
|"Dots for Dummies"|
|"Sharpening our Focus on Dark Energy with Baryon Acoustic Oscillations"
|"Untangling Entanglement: Entanglement and Subsystems, Entanglement beyond Subsystems, and All That"
|"Nanostructures for Single-Molecule Biophysics"|
|"Spin Filtering and Interface Driven Spin Tunneling"|
|"Bacterial growth laws: origins and consequences"|
||University of Chicago
|“Certainty and Uncertainty in Dark Matter Searches”|
|Arthur O. Williams Lecture: “The Path to Magnetic Fusion Energy” (video)|
|“The Second Copernican Revolution: Our Changing View of Our Place in the Universe”|
|"Black Holes- the Harmonic Oscillators of the 21st Century"|
|Special Lecture: "A Step Up to Self-Assembly" (video)|
|"Mechanical Resonators in the Quantum Regime"|
||University of Washington
|"Viscosity, the quark gluon plasma, and string theory"|
|"A Research-Based Approach to Transforming Upper-Division Physics Courses"|
|"Spin and Pseudo-Spin in Graphene"|
|"Why are neutrinos so light?"
||University of Wisconsin, Madison
|"High Temperature Superconductors: Where Are We Now?"|
|“Dark Matter is from Cygnus: In Search of a Wind of Dark Matter in the Milky Way”|
|9/27/10||Paul Frampton||University of North Carolina||Tan|
|"Did Time Begin? Will Time End? Maybe the Big Bang Never Occurred"|
|10/4/10||Ted Jacobson||University of Maryland||Volovich|
|“Black Hole Entropy and the Thermodynamics of Spacetime”|
||University of Kentucky
|“Spin-Orbit Interaction Rediscovered in Transition Metal Oxides”|
||University of Pittsburgh
|“Cosmology from Velocities”|
|”Can Simple Biophysical Principles Yield Complicated Biological Functions?”|
|"The Life Cycle of Matter in the Large Magellanic Cloud: Insights from Spitzer and Herschel"|
||Harvard/Center for Astrophysics
|”Stellar Archaeology: New Science with Old Starts”|
|”Quark Soup al dente: Applied String Theory”|
||Brown University, Department of Chemistry
|”Probing the Electronic and Atomic Structures of Nano-Clusters and Multiply Charged Anions”|
|“Perspectives for Discovering New Physics at the CERN Large Hadron Collider”|
|“Scandal in Physics: The Affair of Jan Hendrik Schön at Bell Labs”|
|“Anticipating New Data from the Energy Frontier”|
|“Probing the 1000 TeV Energy Scale: A Search for μ-N -> e-N with Sensitivity of 10-17"|
||University of Maryland
|“Astrophysical Indicators of the Nature of Dark Matter”|
|"DarkSide - Direct Dark Matter Search with Depleted Argon"|
|"Making sense of non-Hermitian Hamiltonians"|
|4/18/11||Lene Hau||Harvard University||Stein|
|“Quantum Control of Light and Matter – from the Macroscopic to the Nanoscale”|
|4/25/11||Jenny Hoffman||Harvard University||Ling|
|"The Competitive Landscape of High-Tc Superconductivity"|
|"Controlling the Quantum World"|
|"The Physics of Information Flow in Biological Networks"|
|9/21/09||Ina Sarvecic||University of Arizona||Tan|
|"Cosmic Neutrinos: a New Window to the Universe"|
|9/28/09||Zvonimir Dogic||Brandeis University||Tang|
|"Order through Disorder: Entropy Driven Phase Transition in Colloidal Systems"|
|10/5/09||Salman Habib||Los Alamos National Laboratory||Koushiappas|
|"The Dark Universe Challenge: Is Theory up to the Task?"|
|10/19/09||Scott Dodelson||Fermilab / University of Chicago||Koushiappas|
|"Quarks to the Cosmos and Einstein"|
|10/26/09||Robert Brandenberger||McGill University||Tan|
|"Testing String Theory with Cosmological Observations"|
|"Are We Descended From Heavy Neutrinos?"|
|"How Might a Fermi Surface Die?"|
|11/23/09||Robert Carey||Boston University||Heintz|
|"The MuLan Experiment - A New Measurement of the Fermi Constant"|
|11/30/09||Eva Andrei||Rutgers University||Kosterlitz|
|“Electronic Properties of Graphene”|
|“Entropy in Quantum Information Theory and Condensed Matter Physics”|
|“New Approaches to and Applications of Neutron Interferometry”|
|2/15/10||Joerg Schmalian||Iowa State University||Mitrovic|
|“Unconventional Pairing in the Iron Based Superconductors”|
|3/1/10||Amir Yacoby||Harvard University||Stein|
|“Spins and Charges in Low Dimensions”|
|3/8/10||Herald Hess||HHMI's Janelia Farm Research Campus||Valles|
|Arthur O. Williams Lecture: "Following the Physics from the Hydrogen Atom to Fly Brains"|
|3/15/10||Mark Tordden||University of Pennsylvania||Koushiappas|
|“Pushing Einstein’s Boundaries: Gravitational Approaches to the Challenges of Modern Cosmology”|
|3/22/10||Nathan Seiberg||Institute for Advanced Study||Spradlin|
|“Supersymmetry and Its Breaking”|
|4/5/10||Vinothan Manoharan||Harvard University||Stein|
|"The Physics and Geometry of Self-Assembly"|
|4/12/10||David Ceperley||University of Illinois||Maris|
|"Is Solid Helium Superfluid"|
|4/26/10||Greg Landsberg||Brown University||Heintz|
|"Unlocking the Mysteries of the Universe at the Large Hadron Collider"|
||University of Chicago
|“Something Old, Something New"|
|“The Casimir Force: Still Mysterious after 60 Years”|
|“Quantum Criticality and Black Holes”
|“Metamaterials: New developments in electricity and magnetism 140 years after Maxwell's equations”|
||University of Pittsburgh
|“A Theory Program to Exploit Weak Gravitational Lensing to Constrain Dark Energy”|
||University of Florida
|“First Glimpse at the LHC Data with the CMS Experiment”|
|“Next Generation Electronic Measurements of Biomolecules”|
|“The Least Luminous Galaxies”|
||Institute for Advanced Study, Princeton
|“A Theory of Dark Matter”
||Karyn Le Hur
|“Entanglement, Decoherence, and Quantum Computer in a World of Many Particles”|
|“Complex fluids in confined flows"|
|2009 Arthur O. Williams Lecture: "Energy, Environment, Security: Can We Have It All?"|
||Ohio State University
|"What is Inside of a Black Hole?"|
||University of Chicago, Urbana-Champaign
|"New States of Quantum Matter"|
|"The Quest towards a Scalable Qubit"
||Ohio State University
|"New Vistas in Astronomy Above 1 TeV (1.6 erg) per Particle"|
||University of Washington
|"Improving Student Learning in Physics: The Challenge of Identifying Effective Instructional Strategies"|
|"Advances and Puzzles in Quantum Chromodynamics"|
|"A New View of the High Energy Gamma-ray Sky with the Fermi Gamma-ray Space Telescope "|
||Brookhaven National Laboratory
|"Parity violation in super-dense matter at RHIC"|
|"Recent Results from the VERITAS Gamma-ray Observatory"