Editorial: Experimental Predictions in General Relativity: What Now?

Fabiano Feleppa ¹ Elmo Benedetto ^1* Gerardo Iovane ¹ Fabrizio Tamburini ² Ignazio Licata ³

• ¹ University of Salerno, Fisciano, Italy
• ² Rotonium Quantum Computing, Padua, Italy
• ³ Institute for Scientific Methodology (ISEM), Palermo, Italy

data.Finally, in the review article Testing parity symmetry of gravity with gravitational waves, J. Qiao et al. examine the role of parity symmetry in gravitational interactions. While Einstein's general relativity preserves parity, various theories of parity-violating (PV) gravity have recently been proposed across different theoretical frameworks, driven by diverse motivations. In this review, the authors summarize recent advancements in these theories, focusing specifically on the observable effects of PV terms in gravitational waves (GWs), particularly the differences between left-hand and right-hand polarization modes. The authors emphasize the implications of these theories for GWs produced by compact binary coalescences and primordial GWs from the early universe. Deviations in the GW waveforms or the primordial power spectrum can be characterized by the energy scale at which parity violation occurs in each theory. By analyzing current and future observations from laser interferometers and the cosmic microwave background radiation, they present both the existing and potential constraints on the energy scale of PV. These constraints suggest that the parity symmetry of gravity can be tested at high energy scales in the emerging era of gravitational wave research.These four papers collectively provide a broad perspective on active research directions -some focusing on the dark energy and dark matter problem, while others explore potential deviations from general relativity. Strong-field gravitational lensing and gravitational wave physics are among the most promising avenues for detecting such deviations. Hopefully, the ideas presented in these papers will help refine our understanding and enhance our ability to identify these signatures.