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The Fall 2015 colloquia will be held in the lobby of the Physical Sciences Complex

Each week during the semester, the Department of Physics invites faculty, students and the local community to hear prominent scientists discuss intriguing physics research. The Fall 2015 colloquia will be held Tuesdays in the Physical Sciences Complex lobby at 4:00 p.m. (preceded by light refreshments at 3:30 p.m.)

Parking is available in the Regents Drive Parking Garage (PG2). An attendant will direct visitors within the garage. Additionally, a free ShuttleUM bus runs between the College Park Metro Station and Regents Drive at about eight-minute intervals.

For further information, please contact the Physics Department at 301-405-5946 or email This email address is being protected from spambots. You need JavaScript enabled to view it..

September 8
Paul Steinhardt, Princeton University
Hosted by: Jordan Goodman

Once Upon a Time in Kamchatka: The Extraordinary Search for Natural Quasicrystals

Quasicrystals are exotic solids that exhibit symmetries that were once thought to be impossible for matter. The first known examples were synthesized in the laboratory 30 years ago, but could Nature have beaten us to the punch? This talk will describe the search that took over a dozen years to answer this question, resulting in one of the strangest scientific stories you are ever likely to hear.

September 15
Eric Prebys, Fermi Lab
Hosted by: Sarah Eno

Searching for Muon to Electron Conversion at Fermilab

With the observation of the Higgs Boson at the LHC, we find ourselves for the first time in almost half a century with no concrete predictions on which to base the energy scale and luminosity of future discovery machines. In the past, such guidance has always come from indirect measurements, and so it will likely be in the future. Charged lepton flavor violation (CLFV) is a virtually universal feature of  physics models beyond the Standard Model, and the
observation of CLFV would be a vital clue to the mass scale of new physics. The Mu2e experiment at Fermilab is designed to search for the conversion into an electron of a muon which has been captured on a nucleus, via the exchange of a virtual neutral particle.  This has the advantage of an extremely clean experimental signature, as well as sensitivity to a broad range of new physics.

September 22
Zackaria Chacko, University of Maryland

Neutral Naturalness

I explain the hierarchy problem of the standard model of particle physics, and discuss some of the ideas which have been put forward to resolve it. I then show that a specific class of theories, built around a framework known as neutral naturalness, can solve this problem while remaining consistent with all current experimental tests. I explain that while certain theories in this class give rise to striking signals, others are extremely difficult to test, and require a detailed study of the properties of the Higgs boson. I consider the implications of these results for the Large Hadron Collider, and for future experimental programs.

October 6
Peter Hoffmann, Wayne State University
Hosted by: Edward Redish & Arpita Upadhyaya

Molecular Machines and other Adventures in Nanomechanics

Living beings are ultimately based on classical nanoscale systems. Such systems have the unique ability to easily transform different types of energy into each other and to assemble themselves into ordered structures. These astonishing feats are only possible because the nanoscale is dominated by thermal motion. Although living cells have taken advantage of the physics of the nanoscale for billions of years, technology is just beginning to exploit the very different rules governing this scale. In addition to examples from the mechanical behavior of nanoconfined liquids and the mechanics of single molecules, the talk will especially focus on the story of molecular machines, which connect physics to biology and illustrate how life is a game played at the nanoscale. Here, thermal noise meets molecular structure, and chaos becomes order.

October 13
Alison Peterman,University of Rochester
Hosted by: Andrew Baden

Physics and Intelligibility

Many of the most important theories in physics - from Aristotelian physics to Newtonian gravitational theory to quantum mechanics - have been accused by other important physicists of being "unintelligible" or "unexplanatory" even if they satisfy obvious theoretical desiderata like empirical adequacy, simplicity, and elegance. I'll talk about a few interesting episodes in the history of physics in order to try to figure out what this kind of criticism could mean - if it means anything at all - and what it tells us about how the goals of physics have shifted throughout its history.

October 20
Shih-I Pai Lecture
Chung S. Yang, Rutgers University
Hosted by: IPST

U.S. Training of Chinese Scientists and its Impact

In the 19th century, the agrarian Chinese society and the Manchu government could not defend China against the invasion of the industrialized Western powers. After a series of humiliating defeats, the Chinese leaders realized the need to learn Western industry and military technology. The government thereafter selected top students for training abroad. Many of the scholars, such as Hu Shi and Zhu Kenzhen who came to the U.S. in 1910, made a major impact in China, not only in science and education but also in cultural movement and societal change. This lecture will highlight the stories of Professor Shih-I Pai and his contemporaries, who came from China to the U.S. to study in the 1930s and 1940s, and their contributions to both China and the U.S. This group of scientists included the gifted inventor Yao-Tzu Li, the famous rocket scientist Qian Hsusen and the Nobel laureates Chen-Ning Yang and Tsung-Dao Lee. After the normalization of diplomatic relationships between the U.S. and China in the mid-1970s, there has been tremendous scientific interactions, and many U.S.-trained Chinese scientists have actively contributed to the advancement of science and technology. I will highlight some activities in the biomedical field that I witnessed. In conclusion, U.S-trained Chinese scientists contributed greatly to the scientific development in both the U.S. and China and to societal change in China. They continue to benefit not only the U.S. and China, but the entire world.

October 27
Douglas C. Hamilton, University of Maryland

Voyagers in Interstellar Space and Cassini at Saturn

The Voyager 1 and 2 spacecraft were launched in 1977.  Both carry charged particle instruments built by the University of Maryland Space Physics Group.  Voyager 1 has (probably) entered interstellar space, crossing the heliopause on Aug. 25, 2012 at a distance of 122 AU from the Sun.  Voyager 2, traveling 3.3 AU/year and currently at 109 AU, has not yet reached the heliopause.  Both Voyagers explored the magnetospheres of Jupiter and Saturn (also Uranus and Neptune for Voyager 2) during flybys on their way out of the solar system.  Another of the many space instruments built by the Space Physics Group was carried on the Cassini spacecraft, which was launched in 1997 and went into orbit about Saturn in 2004.  That mission is scheduled to end on Sept. 15, 2017, with a dive into Saturn’s atmosphere after a “Grand Finale” during which Cassini will zip between Saturn and its innermost ring 22 times.  I will discuss some of the Voyager and Cassini discoveries at Saturn and in the outer heliosphere and what might be expected during the final years of these missions  (possibly another 10 years for the Voyagers).

November 3
Immanuel Bloch, Max Planck Institute of Quantum Optics & Ludwig Maximilian University of Munich
Hosted by: Alexey Gorshkov

Probing and Controlling Quantum Matter at the Single Atom Level

More than 30 years ago, Richard Feynman outlined the visionary concept of a quantum simulator for carrying out complex physics calculations. Today, his dream has become a reality in laboratories around the world. In my talk I will focus on the remarkable opportunities offered by ultracold quantum gases trapped in optical lattices to address fundamental physics questions ranging from condensed matter physics over statistical physics to high energy physics with table-top experiment.

Specifically, I will show how the realization of quantum gas microscopes for bosonic and fermionic quantum matter has revolutionized our way of probing and controlling quantum matter and how it offers outstanding opportunities for future experiments down to the level of revealing individual quantum fluctuations in a many-body systems. I will also show, how recent experiments with cold gases in optical lattices have enabled to realise and probe artificial magnetic fields that lie at the heart of topological energy bands in a solid. Using a novel ‘Aharonov-Bohm’ type interferometer that acts within the momentum space, we are now able to determine experimentally the geometric structure of an energy band. Finally, I will show how the unique control over ultracold quantum gases has enabled the creation of negative temperature states of matter and thereby the realization of Bose-Einstein condensation at absolute negative temperatures.

November 10
Ved Lekic, University of Maryland

Imaging the Earth's Deep Interior Using Seismic Waves

Deep beneath our feet, in the inaccessible depths of the Earth’s interior, lie structures and processes responsible for the break-up of continents, the creation of oceanic islands, and the pattern of circulation driving plate tectonics. Earthquakes emit elastic waves that illuminate the interior and can be recorded by arrays of seismometers capable of recording miniscule ground motions across different frequencies. The wealth of information contained in seismic waveforms can transform our understanding of the Earth. Yet, the transformative potential of these datasets is stymied by routine analysis and modeling techniques that discard much of the information contained in complete seismic waveforms, and inadequately quantify uncertainty of our inferences. I will present techniques that help address these limitations and illustrate their promise with concrete examples of imaging deep Earth structures.

November 17
John Harte, University of California, Berkeley
Hosted by: Victor Yakovenko. Joint colloquium with UMD Biology. This talk will be held in room 1410 of the John S. Toll Physics building.

Maximum Entropy and the Inference of Pattern and Dynamics in Ecology

Constrained maximization of information entropy yields least biased probability distributions. From physics to economics, from forensics to medicine, this powerful inference method has enriched science. Here we apply this method to ecology, using constraints derived from ratios of ecological state variables, and infer functional forms for the ecological metrics describing patterns in the abundance, distribution, and energetics of species. I show that a static version of the theory describes remarkably well essentially all observed patterns in quasi-steady-state systems but fails for systems undergoing rapid change. A promising stochastic-dynamic extension of the theory will also be discussed.

About the Speaker: 

John Harte is Professor of Ecosystem Sciences at the University of California, Berkeley. His degrees in physics, are from Harvard and U. Wisconsin. He was formerly a physics professor at Yale and is currently an External Faculty Member of the Santa Fe Institute and a senior researcher at the Rocky Mountain Biological Laboratory. His research includes experimental field investigations of ecosystem-climate feedbacks and theoretical studies in macroecology. He is a Fellow of the American Physical Society and the AAAS, and in 1990 was awarded a Pew Scholars Prize in Conservation and the Environment. In 1993 he was awarded a Guggenheim Fellowship and in 1998 he was appointed a Phi Beta Kappa Distinguished Lecturer. He is the 2001 recipient of the Leo Szilard prize from the American Physical Society, a recipient of a George Polk award in journalism, and has served on six National Academy of Sciences Committees. He has authored 220 scientific publications, including eight books.

November 24
Jun Ye, JILA-Boulder
Hosted by: Alexey Gorshkov

Ultracold Molecules – a New Frontier for Quantum Physics and Chemistry

Molecules cooled to ultralow temperatures provide fundamental new insights to strongly correlated quantum systems, molecular interactions and chemistry in the quantum regime, and precision measurement. Complete control of molecular interactions by producing a molecular gas at very low entropy and near absolute zero has long been hindered by their complex energy level structure. Recently, a range of scientific tools have been developed to enable the production of molecules in the quantum regime, where molecular collisions and chemical reactions are controlled via quantum statistics of the molecules at the lowest collision partial waves, along with dipolar effects. Further, molecules can be confined in reduced spatial dimensions and their interactions precisely manipulated via external electromagnetic fields. For example, by encoding a spin-1/2 system in rotational states, we realize a spin lattice system where many-body spin dynamics are directly controlled by long-range and anisotropic dipolar interactions. These new capabilities promise further explorations of strongly interacting and collective quantum effects in exotic quantum matter.

December 1
Michael S. Turner, University of Chicago
Hosted by: Drew Baden

Cosmology at the Crossroads

ΛCDM, the consensus cosmological model, is consistent with an enormous body of laboratory and cosmological data and describes the Universe from a very early burst of cosmic expansion and quantum fluctuations (inflation) to its present state of stars, galaxies and clusters and accelerated expansion. ΛCDM has enabled stunning progress in our understanding of the “astrophysical history of the Universe”, but it has also raised fundamental theoretical issues, from dark matter and dark energy to inflation and the multiverse. These issues offer both opportunities for advances as well as challenges to the basic cosmological framework.

About the Speaker:

Michael S. Turner is a theoretical astrophysicist and the Bruce V. and Diana M. Rauner Distinguished Service Professor at the University of Chicago. He is also Director of the Kavli Institute for Cosmological Physics at Chicago, which he helped to establish, and the past-President of the American Physical Society, the 50,000 member organization of physicists.

Turner was born in Los Angeles, CA, and attended public schools there; he received his B.S. from Caltech (1971), his M.S. (1973) and Ph.D. (1978) from Stanford (all in physics). He holds an honorary D.Sc. (2005) from Michigan State University and was awarded a Distinguished Alumnus Award from Caltech in 2006. Turner helped to pioneer the interdisciplinary field of particle astrophysics and cosmology, and with Edward Kolb initiated the Fermilab astrophysics program which today accounts for about 10% of the lab’s activities. He led the National Academy study Quarks to the Cosmos that laid out the strategic vision for the field. Turner’s scholarly contributions include predicting cosmic acceleration and coining the term dark energy, showing how quantum fluctuations evolved into the seed perturbations for galaxies during cosmic inflation, and several key ideas that led to the cold dark matter theory of structure formation. His honors include Warner Prize of the American Astronomical Society, the Lilienfeld Prize of the American Physical Society (APS), the Klopsted Award of the American Association of Physics Teachers, the Heineman Prize (with Kolb) of the AAS and American Institute of Physics, the 2011 Darwin Lecture of the Royal Astronomical Society and 2013 Ryerson Lecture at the University of Chicago.

Turner’s twenty-plus former Ph.D. students hold faculty positions at leading universities around the country (e.g., Chicago, Caltech and University of Michigan), at national laboratories (Fermilab, JPL, and Argonne) and on Wall Street. He has served as Chief Scientist at Argonne National Laboratory (2006 to 2008), Assistant Director for the Mathematical and Physical Sciences at the National Science Foundation (2003 to 2006), Chair of the Department of Astronomy and Astrophysics (1997 to 2003), and President (1989 to 1994) and Chairman of the Board (2009 to 2012) of the Aspen Center for Physics.

Turner’s current national service includes membership on the NRC’s Committee on Science, Engineering and Public Policy (COSEPUP) and on the Senior Editorial Board of Science Magazine, Chairmanship of the OECD Global Science Forum’s Astroparticle Physics International Forum, a member of the Board of Directors of the Fermi Research Alliance, the Secretary of Class I of the National Academy of Sciences, and the founding Chair of ScienceCounts, a brand new 501(c)3 organization that promotes the awareness and support of science.

December 8


Rush Holt, American Association for the Advancement of Science
Hosted by: Bill Dorland



Upcoming Events


Wed, Dec 2, 2015 11:00 am - 12:00 pm


Wed, Dec 2, 2015 2:00 pm - 4:00 pm


Wed, Dec 2, 2015 3:00 pm - 4:00 pm


Thu, Dec 3, 2015 12:30 pm - 1:30 pm


Thu, Dec 3, 2015 2:00 pm - 3:00 pm


Thu, Dec 3, 2015 3:00 pm - 4:30 pm


Thu, Dec 3, 2015 3:30 pm - 5:00 pm


Fri, Dec 4, 2015 12:00 pm - 1:00 pm


Mon, Dec 7, 2015 11:00 am - 12:00 pm