• Physics and Astronomy Colloquium

October 23, 2026 3:30 PM - October 23, 2026 4:30 PM
PAIS 1100

Host:

Carl Caves

Presenter:

Niayesh Afshordi

General relativity describes the Universe with extraordinary success, yet black holes, the Big Bang, and cosmic acceleration all point toward regimes where its classical description may be incomplete. Can observations turn quantum gravity into an empirical science?

I will explore this question through several interconnected examples. I will first discuss quadratic gravity, where quantum corrections that are normally viewed as problematic may instead point toward a UV-complete theory of gravity. The running of its couplings can dynamically generate inflation in the early Universe, connecting physics at extremely high energies to observable predictions for the cosmic microwave background. I will then turn to black holes, where the same interplay between quantum gravity and horizons may leave observable signatures in their multipole structure and in delayed gravitational-wave “echoes.” Finally, I will discuss whether hints of evolving dark energy could instead reflect a small “cosmic glitch” in gravity—a mismatch between its strength on local and cosmological scales.

Together, these examples illustrate how black holes and cosmology may provide surprisingly accessible laboratories for physics far beyond the reach of conventional particle accelerators.