Emergent gravity is a theoretical framework that reinterprets gravity not as a fundamental force but as an emergent phenomenon arising from the thermodynamic properties of spacetime. This concept challenges traditional views by suggesting that gravity results from the statistical behavior of microscopic degrees of freedom encoded on a holographic screen, rather than being a fundamental interaction. The theory has been the subject of extensive research and debate within the scientific community.
In 2009, theoretical physicist Erik Verlinde proposed that gravity is an entropic force caused by changes in the information associated with the positions of material bodies. This idea combines the thermodynamic approach to gravity with the holographic principle, implying that gravity emerges from the statistical behavior of microscopic degrees of freedom encoded on a holographic screen. The paper drew a variety of responses from the scientific community, with some physicists finding it profound and others viewing it as trivial.
Verlinde's theory has been tested in various contexts. In 2016, a team from Leiden Observatory conducted a study using weak gravitational lensing measurements to test Verlinde's predictions. They found that the theory's predictions were in good agreement with the observed galaxy-galaxy lensing profiles, suggesting that emergent gravity could explain phenomena attributed to dark matter. However, the study also noted that further advancements in both the theoretical framework and observational tests are needed before it can be considered a fully developed and solidly tested theory.
Despite these promising results, emergent gravity faces challenges. Some studies have found inconsistencies with observed data, such as discrepancies in the rotation velocities of dwarf galaxies, indicating that the theory may not fully account for all gravitational phenomena.
In summary, emergent gravity offers a novel perspective on gravity and the universe, proposing that gravity is an emergent phenomenon arising from the thermodynamic properties of spacetime. While it has provided alternative explanations for phenomena like dark matter, it continues to be a topic of active research and debate, with ongoing efforts to test and refine the theory.