Theory of everything

"Ever since Newton, and especially since Einstein, the goal of physics has been to find simple mathematical principles of the kind Kepler envisioned, and with them to create a unified theory of everything that would account for every detail of the matter and forces we observe in nature. ...The goal was to find not just a single theory that explains all forces but also one that explains the fundamental numbers... such as the strength of the forces and the masses and charges of the elementary particles. ...A unique theory would be unlikely to have the fine-tuning that allows us to exist. But if... we interpret Einsteins dream to be that of a unique theory that explains this and other universes, with their whole spectrum of different laws, then M-theory could be that theory."

"The clearest expression of this modern "religious" mission can be recognized wherever one encounters the ancient Pythagorean search for natures mathematical symmetry and harmony. This Pythagorean religion was transformed by early mechanists into a search for the mind of the Christian God. That quest has been tempered since the seventeenth century by a concern to find more practical mathematical relationships in nature, but it has not disappeared. ...wherever the religious mission has been retained in its pure form, as, for example, in the quest for a Theory of Everything... fewer women scientists will be found."

"The ideal theory of everything, in the minds of physicists... is a mathematical system of uncommon tidiness and rigor, which may, if all works out correctly, have the ability to accommodate the physical facts... Perhaps physicists will one day find a theory of such compelling beauty that its truth cannot be denied; truth will be beauty... because, in the absence of any means to make practical tests, what is beautiful is declared ipso facto to be the truth. This theory of everything will be... a myth... a story that makes sense within its own terms, offers explanations for everything... but can be neither tested nor disproved... an explanation that everyone agrees on because it is convenient to agree on it, not because its truth can be demonstrated. This... will indeed spell the end of physics... not because physics has at last been able to explain everything... but because physics has reached the end of all things it has the power to explain."

"Do quarks and galaxies play by the same rules? Physicists believe they should, even though they dont quite know why. For decades, physicists have been searching for a "theory of everything"—a comprehensive description of the laws of nature. In particular, they want to bridge the gap between the large and the small with a quantum theory of gravity—a reconciliation of general relativity with quantum mechanics. String theory appears to be the current best bet..."

"I will... argue that... our universe is not just described by mathematics—it is mathematics. ...this hypothesis... should... be useful in narrowing down what an ultimate theory of everything can look like. The foundation of my argument is the assumption that there exists an external physical reality independent of us humans. ...Our most successful theories, such as general relativity and quantum mechanics, describe only parts of this reality... In contrast, the holy grail of theoretical physics is a theory of everything—a complete description of reality."

"[A]greement with observed facts" never singles out one individual theory. There is never only one theory that is in complete agreement with all observed facts, but several theories that are in partial agreement. We have to select the final theory by a compromise. The final theory has to be in fair agreement with observed facts and must also be fairly simple. If we consider this point, it is obvious that such a "final" theory cannot be "The Truth."