The Johns Hopkins Cosmology Discovery Group (CDG) brings together particle physicists and astrophysicists from the particle theory group and the Center for Astrophysical Sciences to attack problems at the interface of cosmology and fundamental physics.  These include the nature of the dark matter required to hold individual galaxies together, the dark energy that drives different galaxies apart, and the early-Universe mechanism that set the wheels in motion to produce the Universe we see today.  The CDG consists of experimental physicists and observational cosmologists, and theorists who work with pencil and paper and with powerful computational resources.

Nima Arkani-Hamed


A professor at the Institute for Advance Study,   Arkani-Hamed is also a Visiting Professor in the Department of Physics and Astronomy at Johns Hopkins. Arkani-Hamed is a particle theorist with broad interests, among them the physics behind inflation and the nature of dark matter. Arkani-Hamed is also currently pursuing fundamental new paradigms that may ultimately supplant our notions of space and time.

Charles Bennett


Bennett is an experimental cosmologist perhaps best known for his role as Principal Investigator of NASA’s Wilkinson Microwave Anisotropy Probe (WMAP), the satellite experiment that transformed our view of the Universe and the nature of its contents. Bennett is now co-leading (with Prof. Toby Marriage) the CLASS (Cosmology Large-Angular-Scale Surveyor) experiment which provides a unique avenue toward extracting information about inflation from the polarization of the cosmic microwave background. He is also building up to study the properties of the dark Universe as a member of the Euclid science consortium and of the Subaru Prime Focus Spectrograph (SPFS).

Marc Kamionkowski


Kamionkowski is a theoretical cosmologist with interests in inflation, dark energy, dark matter, and beyond. He is known largely for his work on dark matter and for the development of ideas that have motivated several generations of cosmic microwave background experiments. He is currently exploring new ideas for dark energy, dark matter, and inflation and news ways to test these ideas with a variety of astronomical observations and laboratory tests.

David Kaplan


David Kaplan is a particle theorist whose wide interests include several subjects in cosmology. He is responsible for some of the most inventive and influential recent ideas for dark matter, including several that relate the origin of dark matter to that of the ordinary atomic matter of which we are composed. Kaplan is also known for his role as producer (and co-star) of “Particle Fever,” a feature-length documentary that follows the discovery of the Higgs boson at the Large Hadron Collider. Kaplan is currently exploring several new ideas for dark matter and new strategies for dark-matter detection.

Jared Kaplan


Jared Kaplan is a particle theorist of remarkably broad interests that extend from condensed-matter theory to the early Universe.  He is known in the world of cosmology as co-creator of the effective field theory of inflation, a novel and powerful way to look at inflation, and for his work on dark matter.  His current work on black-hole physics in unusual spacetimes holds promise to elucidate the fundamental physics that may underlie inflation.

Toby Marriage


Marriage is an experimental cosmologist who before arriving at Johns Hopkins played a central role in the development, fielding, analysis pipeline, and science results from the Atacama Cosmology Telescope.  Chief among the results that he contributed to are measurements of cosmological parameters and studies of galaxy clusters.  He is currently co-leading (with Chuck Bennett) the CLASS (Cosmology Large-Angular-Scale Surveyor) experiment which provides a unique avenue toward extracting information about inflation from the polarization of the cosmic microwave background.

Brice Ménard


Ménard is an observational cosmologist who specializes in distilling novel and important science results from large astronomical data sets.  This work has led to major advances in our ability to determine the distribution of dark matter in the Universe and the discovery of vast reservoirs of interstellar dust in galactic halos.  Ménard is currently developing a new approach to determine cosmic distances, a technique that is likely to considerably augment how science is done with future cosmic surveys.  He will also study the properties of the dark Universe as a member of the Euclid science consortium and of the Subaru Prime Focus Spectrograph (SPFS).

Adam Riess


Riess is an observational cosmologist interested in measurements of the cosmic expansion history.  He was one of the key players in the 1998 discovery of accelerated cosmic expansion, which suggests that the Universe is filled with some negative-pressure “dark energy” that drives galaxies away from each other.  His work since then has placed important constraints on the nature of this dark energy.  He has also been leading an array of projects that provide the most stringent constraints to the Hubble constant, the parameter that measures the expansion rate of the Universe today.

Joseph Silk


Silk, who splits his time between Johns Hopkins, Oxford University, and the Institut d’Astrophysique in Paris, is one of the grey eminences of cosmology, with nearly half a century of contributions to a stunning variety of subjects in cosmology, physics, and astronomy.  This includes pioneering work on the cosmic microwave background and ideas that have motivated a variety of the most significant current experimental efforts to detect dark matter.  Silk currently works on a broad array of subjects, including dark matter, the physics of black holes, inflation, and galaxy formation.

Alex Szalay


Szalay’s career has spanned an enormous range, beginning with important early theoretical contributions to particle astrophysics and cosmic statistics.  He was the chief architect of the Sloan Digital Sky Survey Data Archive and has become known as one of the chief pioneers of big-data astronomy.  His interests in big data have evolved into an array of subjects within computational astrophysics and to areas of science well beyond astrophysics.  His current research includes work on the large-scale structure of the Universe, data-archiving and data-mining techniques, and the mechanisms for doing science with future cosmology surveys.