A question no longer: what is the Theory of Every Thing?
My colleagues in the fashionable fields of string theory and quantum gravity advertise themselves as searching desperately for the 'Theory of Everything", while their experimental colleagues are gravid with the "God Particle", the marvelous Higgson which is the somewhat misattributed source of all mass. (They are also after an understanding of the earliest few microseconds of the Big Bang.) As Bill Clinton might remark, it depends on what the meaning of "everything" is. To these savants, "everything" means a list of some two dozen numbers which are the parameters of the Standard Model. This is a set of equations which already exists and does describe very well what you and I would be willing to settle for as "everything". This is why, following Bob Laughlin, I make the distinction between "everything" and "every thing". Every thing that you and I have encountered in our real lives, or are likely to interact with in the future, is no longer outside of the realm of a physics which is transparent to us: relativity, special and general; electromagnetism; the quantum theory of ordinary, usually condensed, matter; and, for a few remote phenomena, hopefully rare here on earth, our almost equally cut-and-dried understanding of nuclear physics. [Two parenthetic remarks: 1) I don't mention statistical mechanics only because it is a powerful technique, not a body of facts; 2) our colleagues have done only a sloppy job so far of deriving nuclear physics from the Standard Model, but no one really doubts that they can.]
I am not arguing that the search for the meaning of those two dozen parameters isn't exciting, interesting, and worthwhile: yes, it's not boring to wonder why the electron is so much lighter than the proton, or why the proton is stable at least for another 35 powers of ten years, or whether quintessence exists. But learning why can have no real effect on our lives, spiritually inspiring as it would indeed be, even to a hardened old atheist like myself.
When I was learning physics, half a century ago, the motivation for much of what was being done was still "is quantum theory really right?" Not just QED, though the solution of that was important, but there were still great mysteries in the behavior of ordinary matter--like superconductivity, for instance. It was only some twenty years later that I woke up to the fact that the battle had been won, probably long before, and that my motivation was no longer to test the underlying equations and ideas, but to understand what is going on. Within the same few years , the molecular biology pioneers convinced us we needed no mysterious "life force" to bring all of life under the same umbrella. Revolutions in geology, in astrophysics, and the remarkable success of the Standard Model in sorting out the fundamental forces and fields, leave us in the enviable position I described above: given any problematic phenomenon, we know where to start, at least. And nothing uncovered in string theory or quantum gravity will make any difference to that starting point.
Is this Horgan's End of Science? Absolutely not. It's just that the most exciting frontier of science no longer lies at the somewhat sophomoric — or quasi-religious — level of the most "fundamental" questions of "what are we made of?" and the like; what needs to be asked is "how did all this delightful complexity arise from the stark simplicity of the fundamental theory?" We have the theory of every thing in any field of science you care to name, and that's about as far as it gets us. If you like, science is now almost universally at the "software" level; the fundamental physicists have given us all the hardware we need, but that doesn't solve the problem, in physics as in every other field. It's a different game, probably a much harder one in fact, as it has often been in the past; but the game is only begun.
PHILIP W. ANDERSON is a Nobel laureate physicist at Princeton and one of the leading theorists on superconductivity. He is the author of A Career in Theoretical Physics, and Economy as a Complex Evolving System.
