the.com/theory of everything

means A hypothetical master framework in physics that would unify gravity with quantum mechanics and explain all fundamental forces and particles under one coherent set of laws.

from The phrase is modern physics' own plain-spoken coinage — not derived from Greek roots or ancient myth, but assembled straightforwardly from 'theory' (from Greek theoria, 'contemplation, viewing') and 'everything,' gaining currency in the 20th century as physicists chased Einstein's unfinished dream of unifying general relativity with quantum mechanics. Einstein himself spent his later decades hunting a 'unified field theory'; the grander, more sweeping label 'Theory of Everything' caught on afterward, popularized through physics writing and later candidates like string theory, as shorthand for the ultimate, all-forces-included equation still being searched for.