i believe that would be string theory/supergravity. General relativity is pretty well understood and is quite flawed if we use it at small scale. this is why we prefer using quantum mechanics at small scale and general relativity at large scale. String theory is the magic theory supposed to bind those 2 theory togethers by fusing the 3 known universe principles: electromagnetism, nuclear and gravity. The conecept of string theory is genious, but our mathematics aren't developped enough to calculate their equations. they end up with too many negative abs/square roots, divisions by zero and infinite variables.
My uncle.. I created the formula for him initially. He got lucky when he found out the formula from me.