## Colloquium speaker

### Nima Arkani-Hamed

### Title:Don't modify gravity, understand it!

#### Astronomy Spring Colloquia February 28, 2012 Tuesday, 4:30pm-5:30pm, Peyton Hall auditorium:

Nima will discuss attempts to modify gravity in response to fine tuning arguments about the cosmological constant problem. He will ask the question "Is it possible to modify gravity to de-gravitate the cosmological constant?" He will show that GR is a unique, low-energy theory for interacting massless spin 2 particles, and that attempts to modify gravity are all essentially adding an extra scalar degree of freedom or lead to violent non-locality.