Alladi Ramakrishnan Hall

Action Principle for Gravity, Null Surfaces and Thermodynamic Consequences

S Chakraborty

IACS, Kolkota

In the first part of my talk I will discuss the variational
principle for general relativity and some associated subtle facts. In
particular, I will try to arrive at the correct action principle for
general relativity in presence of null boundaries. Possible generalization
to Lovelock theories will also be presented. In the second part of my talk,
I will discuss the thermodynamics of null surfaces. In particular, I will
show that three different projections of gravitational momentum related to
an arbitrary null surface in the space time leads to three different
equations, all of which have thermodynamic interpretations.