physics logo final

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


November 10
Ved Lekic, University of Maryland

Imaging the Earth's Deep Interior Using Seismic Waves

November 17
John Harte, University of California, Berkeley
Hosted by: Victor Yakovenko

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


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


December 8


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



Upcoming Events


Tue, Oct 13, 2015 10:00 am - 1:00 pm


Tue, Oct 13, 2015 4:00 pm - 5:00 pm


Wed, Oct 14, 2015 10:00 am - 1:00 pm


Wed, Oct 14, 2015 12:30 pm - 3:00 pm


Wed, Oct 14, 2015 3:30 pm - 4:30 pm


Thu, Oct 15, 2015 10:00 am - 1:00 pm


Thu, Oct 15, 2015 12:30 pm - 1:30 pm


Thu, Oct 15, 2015 1:00 pm - 2:00 pm


Thu, Oct 15, 2015 2:00 pm - 3:30 pm