12:00–1:00 pm ERC 501
Host: Vikram Dwarkadas
Hayden Lee "Building gravitational waves from gluons"
One of the remarkable properties of scattering amplitudes is a double copy relation, which expresses gravity amplitudes as two copies of gauge theory amplitudes. I will present a cosmology version of this relation in de Sitter space, which expresses graviton correlations (primordial gravitational waves) as the “square" of gluon correlations.
Michael Zhang "What are exoplanet atmospheres made of anyhow?"
To study an exoplanet's atmosphere, we take a spectrum and look at the molecular features. But if it's so easy, why do exoplanet scientists disagree on the most basic facts about entire classes of exoplanets? Why do we not even know whether hydrogen makes up 80% of most exoplanets' atmospheres, or 0%? Why, after hundreds of hours of observations by the world's best telescopes--telescopes such as Keck, Hubble, and James Webb—are many of the most observationally favorable planets still shrouded in mystery? In this talk, I'll explain from first principles how to extract information from an observed spectrum. I'll describe why the spectrum is sensitive to some atmospheric properties but insensitive to others, including the ones we most want to know about. Finally, I'll talk about why second-order effects mean the situation may not be hopeless after all.
