Peter Breitenlohner

Peter Breitenlohner was a theoretical physicist whose work with Daniel Z. Freedman established the Breitenlohner-Freedman bound for fields in Anti-de Sitter spacetime.

For a scalar field in $(d+1)$-dimensional Anti-de Sitter spacetime with curvature radius $L$, the familiar form is $m^2{L}^2\ge -d^2/4$, with stability also requiring suitable boundary conditions. The negative right-hand side explains the surprising feature: a negative mass-squared parameter alone does not establish instability in this curved background. Their result links field dynamics to the geometry and boundary conditions of spacetime.^[ref]