Via Radley Balko, a couple of articles in the Daily Telegraph about the prospects for a Theory of Everything — this is a technical term — piqued my interest. The first, a personality-driven piece about a semi-employed surfer who happens to have a Ph.D and has spent years working on a ToE that was inspired by correspondences between the E8 polytope and the workings of nature, is notable for confirming that work done at the apex of theoretical physics looks rather like an artistic project. Take a look at how Garrett Lisi, the theoretician, was moved to his conclusions:
E8 encapsulates the symmetries of a geometric object that is 57-dimensional and is itself is 248-dimensional. Lisi says "I think our universe is this beautiful shape."
What makes E8 so exciting is that Nature also seems to have embedded it at the heart of many bits of physics. One interpretation of why we have such a quirky list of fundamental particles is because they all result from different facets of the strange symmetries of E8.
Lisi's breakthrough came when he noticed that some of the equations describing E8's structure matched his own. "My brain exploded with the implications and the beauty of the thing," he tells New Scientist. "I thought: 'Holy crap, that's it!'"
You can see something similar in The Double Helix: At least if James Watson is to be believed, he and Crick realized, prior to testing, that the double helix had to be the shape of DNA simply by modeling the shape and observing the simple beauty of it. Not to get too sentimental, though, Lisi will need to demonstrate the existence of 20 heretofore unobserved particles to grant his ideas evidential credence.
Second comes this article on the ongoing work of USC physicist Itzhak Bars, who began work on the applicability of gauge symmetries to M-theory as early as 1995 — very, very briefly, a physical symmetry is a system whose features do not undergo observable change in spite of mathematical transformation, such as a circuit whose electric potential is raised uniformly at all points, so that no change in voltage differential occurs and hence no change in the operation of the circuit; and M-theory, according to which there are 10 dimensions of space and one of time, is the current de rigeur theory on the spacetime maniforld — and proposed a two-dimensional (2T) time. Apparently, Bars is not only ready to propose a 2T hypothesis, but to test it. (Subscribers to the New Scientist can read more here.)
What actually caught my eye from the Bars piece is the following:
Changing our picture of time from a line to a plane (one to two dimensions) means that the path between the past and future could loop back on itself, allowing you to travel back and forwards in time and allowing the famous grandfather paradox, where you could go back and kill your grandfather before your mother was born, thereby preventing your own birth.
The idea seems to be that Bars' hypothetical gauge symmetry resolves grandfather paradox-like problems by proposing a manifold of plain old vanilla 3+1 spacetimes, each subsumed within a broader 4+2 framework. Well, here's the thing. There's this temptation that high-powered physicists are often unable to resist, and journalists who write about high-powered physicists are simply incapable of resisting, of going beyond the bounds of data modeling and prediction, and playing around with speculative metaphysics. And the result is usually something that makes philosophers cringe.
So while I have no reason to doubt that Bars' work is a novel and potentially groundbreaking insight into the dimensionality and shape of spacetime, it's sort of laughable that he (and the author of the piece, who doesn't have a byline) seems ingenuously worried that the mathematics of temporal dimensionality could pose insuperable philosophical problems. In fact, no doubt in part because metaphysicians tend to grok science fiction, the problems and paradoxes of multi-dimensional and/or multi-directional time are a fairly well-worn subject in metaphysics, and the current going theories resolve such problems as there are in ways that defuse wild-eyed wonder over Back to the Future scenarios.
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