M

In the late 1960s, government-subsidized physicists were trying to explain the mysterious force that binds together certain particles at the center of the atom called protons. Fragmentary evidence indicated that the protons might themselves result from the movement of infinitesimally small, stringlike objects: little loops of energy that vibrate through 25 dimensions of space. Oops, said the scientists. We can't deal with the four dimensions we already have -- three of space and one of time -- so forget these strange string things.

But a few bold and stringy souls persisted, despite the ridicule of their peers and their assignment to relatively menial jobs. In 1984, John Schwarz, a research associate at the California Institute of Technology, and Michael Green of Cambridge University made crucial discoveries in "superstring" theory.

Advancing the eclectic mathematics that fuels string theory, these intrepid pioneers discerned that what had been perceived as fatal flaws in the theory were actually blessings. To the astonishment of the physics world, a theory of "quantum gravity" was shown to be possible. Creating the unified field theory Einstein had failed to find -- uniting gravity and quantum mechanics -- seemed to be an equation or two away.

Now, Available in Only 10 Dimensions ...
It turns out (at least according to string theory) that when physicists write equations describing reality in the four "normal" dimensions, they only "see" shallow aspects of the vibrating string. But when the universe is mentally modeled in 10 dimensions, more complexity is revealed.

The six "extra" dimensions are minuscule measurements: not much bigger than a string itself. So why are they important?

In each dimension, the vibration of the string emits what may be metaphorized as a musical note. Physically stuck inside four dimensions, we humans experience each harmonically connected note as a different type of elementary particle. For instance, certain vibrations of a string create quarks, which stick together to form the protons at the center of the atom. Other vibrations make photons, the elementary packets of energy that we see as light. To date, physicists can only wet-dream of finding evidence of a graviton, the force-carrying particle of gravity slung off by a string.

String theory continued to evolve during the '80s and early '90s. For a while, science writers hyped it as a Theory of Everything. But millennial expectations of the theory abruptly died when five different -- and incompatible -- string theories appeared.

An embarrassing surfeit of theory had been produced; and nobody knew how to make five inconsistent postulations fit into one elegant theory. The string theorists had uncovered a wealth of circumstantial evidence that could not be accurately backtracked to basic scientific principles. It was as if a crime detective had discovered a gun, blood, and a spent bullet, but could not say what crime had been committed.

Yet another attempt to invent a theory of quantum gravity had flopped, because nobody could tie up all the loose string theories. Disappointed stringies wandered off to plow other fields, until universal hell broke loose in 1995.

M Is For ...
Steve Shenker's colleagues describe him as one of the top five or six string theorists in the world. Shenker talks more modestly about the role he has played in string theory.

In the early years of his career, he studied something called phase transitions, which is what happens when, say, water changes into steam or ice. Study of physical change led directly to string theory, because anything that changes must be made up of smaller things that change. And there are rules governing all change.

"Physics is like chess," says Shenker. "There are rules, and then there are the consequences of using the rules. We study strings to discover what the rules of the game are, the basic principles governing how the universe is allowed to move."

Discovery, for Shenker, occurs as a flash of intuition. He lives and breathes string theory, and every few years a big idea occurs to him, usually in a group setting. But mostly, theorizing is a game of trial and error. Shenker floats his speculations like balloons, and his $200,000-a-year peers shoot at them.

With eyes constantly cocked on the Nobel Prize, physicists have developed an elaborate system of credit apportionment. But more than personal glory is at stake -- program funding, after all, is based on lists of professional accomplishments. Technical papers are full of exact acknowledgements of the slightest remark of one person that inspired even a mildly important thought by another. And although string theory may be the most collective thinking endeavor since the Manhattan Project, each scientist jealousy guards his individual thought-turf. String etiquette frowns on those who would appropriate even a shred of another's intuition without crediting the fount.