I study the large scale structure of the universe to learn about the birth and evolution of galaxies and to extract information about fundamental physics and our cosmic origins. I am particularly interested in the high-redshift universe and using the clustering and cross-correlations of Lyman-break Galaxies (LBGs) and CMB lensing to constrain cosmology in the matter-dominated era. I created and lead the LBG Topical Team of the Dark Energy Science Collaboration (DESC) of the Vera C. Rubin Observatory's Legacy Survey of Space and Time (LSST). I use a variety of machine learning tools in my research, including normalizing flows, convolutional neural networks, and variational autoencoders.
I also work on developing algorithms for and commissioning the Rubin Observatory's active optics system. This system applies real-time corrections to the optical alignment and mirror figures to ensure optimal image quality for precision science. I lead the development of the wavefront estimation algorithms, i.e., algorithms that infer the presence of optical aberrations from Rubin images, and have spent many nights on the summit observing with and commissioning our systems on the Rubin telescope.
In August 2025 I will begin as a Rubin Fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) at Stanford University and SLAC National Accelerator Laboratory. I am currently finishing my PhD at the DIRAC Institute of the University of Washington, where I work with Prof. Andy Connolly. I received a bachelor's in physics from Duke University, where I was a Duke Faculty Scholar working with Prof. Kate Scholberg in the Duke Neutrino and Cosmology Group.
In my free time I enjoy alpine climbing, backcountry skiing, and watching way too many movies.
Note that I have a double name, and go by "John Franklin" or "JF", not just "John".