Just wanted to offer a heads-up on an excellent interview with Edward Witten, considered by many to be the greatest string theorist of our time, which I encourage you to go watch before reading further.
On the whole, it’s fascinating to observe Witten’s combination of, on one side, extreme humbleness and open-mindedness, and on the other, quiet grandiosity and certitude. Unlike many scientists who have frozen into a kind of triumphalist zeal whereby all matters mental or physical will eventually be conquered by reductionism and mechanism–a doth-protest-too-much optimism–Witten, refreshingly, almost seems intrigued by contemplating what he does not know, or even what may never be known to science.
While he seems like most mathematicians and physicists to be in the Platonist camp, speaking of the “existence” of theories and theorems as something “out there” to be discovered, he also has some moments reminiscent of late Wittgenstein, in observing the way that people are often curiously “on the same page” about very complex aspects of life and feeling. To paraphrase, he says the things that are hopeless to explain and will likely remain so, like happiness or consciousness, everybody else somehow already knows about; while the things that you have a chance at explaining, like theories in physics, almost nobody knows. In this vein of mysterian humbleness, Witten also sounds not so far off from Chomsky, who freely admits that “we are not angels” and are likely to remain in ignorance regarding certain problems, to learn more about human nature from novels than from psychology, and so on.
Yet for anyone who works on something variously known as the “Theory of Everything” or the “final theory”, the grandiosity cannot help but be there as well; in Witten’s case, though, I admit even these grandiose moments are hard to dismiss out of hand, for he presents even his more sweeping and speculative notions with a clarity that speaks well even to the non-initiated.
Among these notions is that time and space are not truly separate entities or fundamental categories. All current physical theories preserve some kind of core functional distinction between time and space dimensions–even special and general relativity. While formulated in a four-dimensional spacetime, special relativity’s Minkowski metric, for example, takes the time coordinate as positive in sign and the space coordinates as negative in sign.
In Witten’s grand conception, time and space may be but human concepts that approximate reality at long timescales; at the Big Bang, he supposes, they would in fact blend together into some more fundamental, as-yet unknown entity. In this way, the conundrum of what “caused” the Big Bang itself can be avoided: there is no “boundary condition” to be set.
Another grandiose discussion revolves on Witten’s explication of how representing fundamental particles as strings makes it possible to include their properties and interactions “naturally” in their very structure. Whereas with electrons or other particles as currently understood, there are numerous variables whose values have to be experimentally determined and then “plugged in” to the theory, the innate mathematics of the string and its vibrations can itself encode all the information needed to tell how it will interact. (That this approach so far has led, where at all empirically testable, to a mixture of successful postdictions and failed predictions, is graciously passed over.)
Witten also envisions a final theory as not a completion of scientific inquiry, but as ultimately revealing itself as an intellectual object of such complexity and fertility that its ramifications can be explored indefinitely, much like number theory. He is at pains to express the compelling beauty of string theory for those who can appreciate its mathematics, which he compares with the beauty other people find in music.
This sounds to me a hair too much like an excuse for physics to end up as a combination between what I call a “pocket infinity” (a system of finite elements that can be creatively composed to create an endless succession of fascinating or useful products, but that does not itself have reality or solidity) and what John Horgan has called “ironic science” (science-like theorizing which does not converge on truth or useful applications, but inspires our awe and reflection). But from the lips of a wizard of Witten’s calibre, it sounds curiously appealing nonetheless.
(Here I’d point out another perspective on the “pocket infinity” concept, which is that a “pocket” is something one may become trapped in. The pocket infinity can be a way of using infinity, of rendering it articulate to thought using finite mortal means, or it may be a kind of delusion where one imagines limitless possibility while really being “in the pocket” all along. To Witten’s view, string theory is a straight and true road to the infinite; to an increasing number of critics, it is an unfalsifiable pocket in which physics has become trapped.)
Throughout, Witten appears remarkably thoughtful, genial, and surprisingly human, even admitting he would choose a happy family life above unlocking the final theory. The close of the interview, though, is most touching of all. By that point, Witten has discussed, at length and with obvious relish, the impressions of awe and wonder unlocked by physical theories and their curious ways of fitting together; he has considered the paradoxes and mental “discomfort” evoked by the quantum mechanical framework; he has reflected on the fate of all life in a universe that collapses or freezes, and seized upon Dyson’s concept never-ending evolution of new life forms in an infinitely cooling universe as the preferable option by far; he has wryly batted away questions about God with a call for everyone to interpret the wonderments of the universe as they see fit. “It is an amazing universe we live in,” he has just finished saying, when the interviewer turns to another subject entirely. It is a surprising one: he asks Witten for his thoughts about the Holocaust, which claimed much of his mothers’ family in Poland.
A deep silence falls, stretches on and on. The face grows distant, strained.
“I might know one or two things about physics which might be novel for your audience,” he says at length. “But the Holocaust–” another pause. “It’s not something I can offer any insight about: how such a thing can happen”. A longer silence. Small tics of pain, or bewilderment, flit across his face as the seconds roll on. Fade-out.
It’s a telling finish. Faced with the visceral reality of evil, a great mind that minutes before seemed so triumphant, happily constructing a wondrous cathedral of physical and mathematical logic at home in the midst of mystery, paradox, and awe, finds itself at a total loss.
At the risk over-psychologizing, it is as though all this theory, all this abstract beauty in another realm no one can prove to exist, is in some way this brilliant and quite sensitive man’s gambit to escape one all-too-obvious fact about the universe: that just as much as it is a logically interlocking wonder, it is also opaque, incomprehensible, even horrible.
Maybe the “cathedral” of physical and mathematical regularities has become Witten’s way (and perhaps many other physicists’ way, and perhaps our whole civilization’s way), of projecting some kind of optimism onto the sobering facts that science has discovered–the staggering vastness of the universe, its seeming indifference to our fate, and the shortness of our time in it–and, via the idea of progress, onto the equally sobering facts that history has long taught.
Perhaps this is the key sign that a science has begun to shoulder too much of our all-too-human need for paradise, grace or escape, and instead crept too far into the religious realm: that it begins to find itself, however disguisedly, grappling with theodicy. This is an idea that bears a closer look in the future.