Joint cosmology seminar at Tufts:

Tuesday, May 2, 2017, 2:30 pm

574 Boston Ave, Room 310

Tufts University

Refreshments at 2:00 outside room 304

**An Information-Theoretic Lower Bound on the Energy Density**

Aron Wall

Institute for Advanced Study

Abstract:

A physical system is stable if its Hamiltonian is bounded below, so that we can define a positive notion of "energy" relative to the ground state. But what about the local energy density - can that be negative? I will provide an elegant derivation that a positive energy density always exists, in (discrete or continuous) classical systems with one spatial dimension. When we try to apply the same argument to quantum systems, we will obtain a surprising result linking the energy to information theory.