Astro Night

Thu, August 01, 2019

Astro Night 2019_August


Josh Dillon received his Ph.D. in physics in 2015 from the Massachusetts Institute of Technology, working with Professor Max Tegmark. He is now an NSF Astronomy and Astrophysics Postdoctoral Fellow at the University of California, Berkeley, working with Professor Aaron Parsons on the Hydrogen Epoch of Reionization Array (HERA) project. Josh’s research focuses on the theory and practice of data analysis for 21 cm Cosmology, a new way to map neutral hydrogen throughout cosmic time with low-frequency radio telescopes. Josh grew up outside Chicago and got a B.S. in physics from Stanford University.  In his spare time, Josh works on Cards Against Humanity and chairs the Science Ambassador Scholarship.


The last century has seen a revolution in our understanding of the universe and our place in it. We now know that the universe is about 13.8 billion years old and only about 5% normal matter–the stuff we’re made up of like protons, neutrons, electrons. Uncovering the nature of the other 95%, the mysterious dark matter and even more mysterious dark energy, is one of the most important questions in fundamental physics today.

I will talk about a new technique we’re developing at Berkeley with collaborators around the world to use radio telescopes to make huge 3D maps of hydrogen, the most abundant element in the universe, to test our cosmological theories. I will explain the observational challenges we’re facing and the reason why we’re building a giant array of 350 dishes–each one almost 50 feet across–in the middle of the South African desert. Along the way, he will discuss how we know what we know about cosmology today and how we use radio telescopes to map out that ancient hydrogen and see the impact that the very first stars, galaxies, black holes, and maybe even dark matter had on it.