In conventional cosmology we comprehend the universe by extrapolating
Einstein's general theory of relativity from the Solar System (where
it is well tested) to many different length scales and gravity regimes.
General relativity succeeds in explaining many observations of galaxies
and cosmology, but only if we postulate that the universe is filled
with exotic dark matter and dark energy. Some have questioned the
supposition that we know so much about gravity but so little about
the substance of the universe. Various modifications to Einstein's
theory have been proposed, either to build a cosmology without dark
matter and/or dark energy, or to incorporate ideas from the search
for a quantum theory of gravity. In my research I use the gravitational
deflection of light as a unique tool for examining the dark universe
paradigm, and testing general relativity and alternate theories of
gravity.
I also maintain a public-domain software package for gravitational
lensing calculations and lens modeling applications.
I am teaching a two-semester, junior-level survey of astrophysics.
Our goal is to use gravity, electromagnetism, gas physics, and
atomic and nuclear physics to understand a wide range of
astronomical systems.
Gravity is the dominant force in many systems; in the fall
semester (Physics 341) we use it to analyze planetary motion,
extrasolar planets, supermassive black holes, galaxies and dark
matter, and cosmology.
In the spring semester (Physics 342) we draw on the rest of
physics to understand the atmospheres of planets and stars,
the nuclear furnaces inside stars, stellar life cycles, and
the formation of the elements. The course is organized around
the question: How did we come to be here?
