PBS NOVA: The Elegant Universe: Welcome to the 11th dimension

from Nova's The Elegant Universe

with Brian Greene

October 2003


"Program Three, 'The Elegant Universe: Welcome to the 11th Dimension,' shows how in 1995 Edward Witten of Princeton's Institute for Advanced Study, aided by others, revolutionized string theory by successfully uniting the five different versions into a single theory that is cryptically named 'M-theory,' a development which required a total of eleven dimensions.

"Ten . . . eleven . . . who's counting? But the new eleventh dimension is different from all the others, since it implies that strings can come in higher dimensional shapes called membranes, or 'branes' for short. These have truly science-fiction-like qualities, since in principle they can be as large as the universe. A brane can even be a universe--a parallel universe--and we may be living on one right now.

"Branes might also explain why gravity is the weakest force, requiring all the matter in the Earth to produce a measly one g. According to this idea, gravity may be far more potent, but most of its strength is leaking into a parallel universe.

"Witten has described string theory as 'a part of 21st-century physics that fell by chance into the 20th century.' In fact, the theory is so far ahead of experimental technique that there is as yet no way to verify whether strings are real or a figment of some very creative imaginations.

"But scientists at the CERN atom-smasher on the French-Swiss border are working to test of one of the predictions of string theory. Scheduled to run later in this decade, this experiment may take an important step in showing that string theory is not just a crazy idea, but crazy reality. "



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