Neutrinos are one of the most mysterious types of subatomic particles that are known.  Because they interact so weakly with other materials and are nearly massless there are approximately 65 billion neutrinos are passing through every square centimeter of your body per second and you don’t feel a thing!  We need to build detectors which contain 50,000 tons of purified water, or use 3000 billion cubic meters of arctic ice, to have a chance of catching just a few neutrino collisions.  Neutrino physics is about as exotic as it can get!

Besides looking for neutrinos using instruments on the earth, we can use the entire universe as a neutrino detector by looking for ways in which neutrinos have affected the large-scale structures we see in the universe.

The idea that the properties of particles that interact so weakly and which are nearly massless can be detected through observations of the universe as a whole is an expression of one of the reasons why I continue to be so fascinated with cosmology.  It is an example of the spectacular interweaving of the largest and the smallest which occurs frequently as you learn about the physics of the universe.

As a graduate student I came to studying neutrinos through the lens of the universe after reading a paper titled Weighing Neutrinos with Galaxy Surveys– what a great title!  The conclusion of this paper is that in the near future out best chance to determine the mass of the neutrino is through observations of how galaxies cluster together in space.

A few years after reading this paper I worked on a project with Sudeep Das and Oliver Zahn which used observations of the cosmic microwave background to infer properties of neutrinos.  Working with Daniel Grin I am currently extending this original study by using the most up-to-date observations as well as a new way of modeling the ways in which neutrinos affect the evolution of the universe.