2020/11/19 by Zhi-Wei Wang, Samuel L. Braunstein, Wang, Zhi-Wei +1 · 1 citation
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc)
paper · pdf · doi:10.48550/arxiv.2011.09923
openalex publication_date 2020/11/19 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We construct the gravitating mass of an isolated composite system on asymptotically-flat spacetimes within conventional general relativity and investigate when this quantity is well defined. For stationary spacetimes, this quantity is known to exactly equal the physical (ADM) mass. However, it remains an open question whether these two masses are equal in the absence of a timelike Killing vector. This is especially apropos since our universe has an `origin' and hence no such Killing vector. Further, if these masses failed to agree then composite systems could behave as if they had a `dark component,' whose gravitating mass would not equal the physical mass-energy present. The existence of such an apparent discrepancy is indeed ubiquitous in galaxies and galaxy clusters, though currently it is attributed to the presence of dark matter. We conclude that the theoretical question of the relation between these masses for dynamical spacetimes is ripe for attention.