Speaker
Description
We revisit the role of boundary terms in Einstein–Hilbert gravity from the perspective of an initial value variational principle. Instead of imposing boundary conditions at both initial and final times, we employ the Schwinger–Keldysh–Galley (SKG) framework, which naturally implements an initial value formulation by doubling the degrees of freedom and imposing connecting conditions between forward and backward branches.
Within this setup, we show that the Einstein equations arise solely from the bulk part of the action, without the need to introduce additional boundary terms such as the Gibbons–Hawking–York term to ensure a well-posed variational problem. The boundary contributions that appear in the variation are instead directly related to conserved quantities, and we explicitly demonstrate their connection to the Komar current and mass.
Our analysis provides a fresh framework in which the variational principle is well-defined in an initial value setting without any additional boundary terms. This perspective sheds new light on the boundary terms of classical Einstein-Hilbert gravity.
| Research Area | Gravity: Geometric theory |
|---|