Research Interests

In recent years it has become possible with novel astrophysical measurements to address such fundamental, almost philosophical, physics questions as the composition, extent, and fate of the Universe. My research has centered on the use of supernova explosion measurements to answer these questions by measuring the expansion history of the Universe. We developed techniques to discover, study, and calibrate significant samples of extremely distant Type Ia supernovae. Their peak brightnesses indicate their distances-and hence how far back in time each supernova explosion occurred. The redshift of each supernova's spectrum tells us how much the Universe has stretched since that time in history. It was expected that the Universe would be found to be expanding faster in the past, since the gravitational effect of mass in the Universe would slow it. Instead, supernova measurements indicate that the Universe is accelerating. Apparently some previously unrecognized energy dominates the Universe, overwhelming the deceleration due to mass. My more recent work is developing techniques to explore this mysterious dark energy. In particular, we are pursuing a new wide-field space telescope experiment designed to extend the supernova measurements of the expansion history farther back in time with significantly better precision.

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Primary Section

Section 13: Physics

Secondary Section

Section 12: Astronomy