Determining whether string theory or general relativity governs our universe is a complex question that currently remains unanswered. Here's a brief overview of these theories and how their validity is assessed:
General Relativity: General relativity, proposed by Albert Einstein in 1915, is a theory of gravity that describes the large-scale behavior of objects in the presence of matter and energy. It has been extensively tested and has successfully explained a wide range of gravitational phenomena, including the precession of Mercury's orbit, gravitational lensing, and the bending of starlight around massive objects. General relativity has been verified through numerous experiments and observations, supporting its validity on macroscopic scales.
String Theory: String theory is a theoretical framework that seeks to unify all the fundamental forces of nature, including gravity, within a single consistent theory. According to string theory, the fundamental constituents of the universe are tiny, vibrating one-dimensional strings of energy. String theory goes beyond the concept of point-like particles in quantum field theory and attempts to provide a quantum mechanical description of gravity.
However, string theory is still a work in progress, and there is currently no definitive experimental evidence to confirm its validity. Due to the extremely high energies required to probe the scales at which stringy effects become significant, testing string theory predictions is challenging with current experimental capabilities. As a result, string theory remains largely theoretical and is an active area of research.
Determining which theory governs our universe is a significant challenge because both general relativity and string theory are successful in their respective domains of applicability. Researchers are actively exploring various approaches, such as studying the behavior of black holes, cosmological observations, and mathematical consistency checks, to understand the interplay between these theories and potentially uncover experimental evidence that can differentiate between them.
It's worth noting that there are also alternative theories of gravity and other frameworks beyond general relativity and string theory, such as loop quantum gravity and modified gravity theories, which aim to provide alternative explanations for the behavior of the universe.
Ultimately, the question of which theory governs our universe requires further advances in both theoretical understanding and experimental capabilities to reach a conclusive answer.