Einstein's theory of general relativity is often considered elegant and simple by some people due to several reasons:
Conceptual Framework: General relativity provides a comprehensive and intuitive conceptual framework for understanding gravity. It describes gravity as the curvature of spacetime caused by the presence of mass and energy. This idea of spacetime curvature simplifies the understanding of how objects move in the presence of gravity.
Mathematical Formulation: General relativity is formulated using tensor calculus and differential geometry. While the mathematical tools involved may be complex, the final equations themselves are concise and elegant. The key equation, known as the Einstein field equations, relates the curvature of spacetime to the distribution of matter and energy. This equation beautifully encapsulates the relationship between gravity and the geometry of the universe.
Universality: General relativity is a theory that applies universally. It provides a unified description of gravity, encompassing both the motion of everyday objects and the behavior of massive celestial bodies, such as stars and black holes. The theory's ability to explain a wide range of phenomena under a single framework is often seen as elegant and simple.
Empirical Confirmation: General relativity has been extensively tested and verified through various experiments and observations. For example, the precise predictions of general relativity regarding the bending of light around massive objects have been confirmed during solar eclipses. The detection of gravitational waves, ripples in spacetime caused by violent cosmic events, further supports the validity of the theory. The fact that general relativity consistently matches observations adds to its perceived simplicity.
It's important to note that while general relativity can be conceptually and mathematically elegant, mastering the theory and applying it to complex scenarios can be challenging. The simplicity often lies in the underlying principles and equations, but their practical application and understanding can require a deep level of study and expertise.