Exploring Energy-Momentum Squared Gravity and Its Cosmological Implications

Recent research has introduced a review of Energy-Momentum Squared Gravity (EMSG), specifically focusing on the theory denoted as $f(R,T_{\mu

u}T^{\mu

u})$ gravity. This framework incorporates quadratic contributions from the energy-momentum tensor, which has significant implications for cosmology, particularly during the early epochs of the Universe.

The authors, Ricardo A. C. Cipriano, Nailya Ganiyeva, Tiberiu Harko, Francisco S. N. Lobo, Miguel A. S. Pinto, and João Luís Rosa, highlight that the inclusion of these quadratic terms can address unresolved issues within General Relativity (GR), such as the initial singularity and aspects of big-bang nucleosynthesis. The research suggests that under high-energy conditions, EMSG may provide insights into phenomena that GR struggles to explain.

One of the key findings is that the non-minimal coupling between matter and geometry leads to the non-conservation of the energy-momentum tensor. This prompts a reevaluation of cosmological scenarios through the lens of irreversible thermodynamics, interpreting energy-balance equations as descriptions of irreversible matter creation processes.

The study emphasizes that while EMSG converges to GR in vacuum conditions, the differences become pronounced in regions of high curvature, such as the dense cores of compact objects. This could lead to new understandings of gravitational behavior in extreme environments.

The full paper can be accessed for further details and insights into the implications of EMSG for modern cosmology and gravitational theory. For those interested, the article is titled "Energy-Momentum Squared Gravity: A Brief Overview" and is available on arXiv with the identifier arXiv:2408.14106.