Everything—even you—is made of little strings
Physicists may have a knack for mind-boggling theories, complicated equations, and utterly confounding jargon, but they actually love simplicity. They assume reality is simple at its foundation. That's why they aren't comfortable with their own standard model of particle physics. This model describes the characteristics and interactions of 57 (at last count) different particles—from electrons to quarks to muons—that make up everything in the universe. (When the muon was discovered, a physicist famously asked, "Who ordered that?")
Joe Lykken, a physicist at Fermilab near Chicago, points out: "It seems absurd that the most elementary piece of the universe should come in 57 varieties." It's as though Heinz is running the show.
The search for an underlying reality has led many physicists to embrace string theory. This theory imagines that every substance in the universe is made of just one thing: tiny vibrating strings. At different resonances these strings create the 57 different particles—and everything else.
The theory also has the unusual feature (some might call it a drawback) of requiring at least nine spatial dimensions, six of which are not noticeable to those of us living in a three-dimensional world.
At the moment the theory has no experimental support. No one has seen strings. They'd be way too small, by a factor of many trillions. As for the hidden dimensions, they're wherever you left the car keys.
But physicists are desperate to scrape up evidence of strings because they would, says Lykken, "reduce extremely complicated physics down to fairly simple equations that you can write on a single piece of paper." Signs of extra dimensions might emerge when physicists collide particles in giant accelerators and tally up the energy at the end. If any is missing, it might have leaked into another dimension.
Brian Greene, author of the best-selling book The Fabric of the Cosmos, thinks it might be possible to discover evidence of strings in the cosmic microwave background (CMB)—radiation visible everywhere in the sky. (The CMB is the cooled, diluted afterglow that scientists consider the imprint of the big bang that formed the universe.)
The expansion of the universe has stretched out the CMB, and in it we might see slight variations of temperatures in space that would be consistent with string theory. "We just need to learn how to read the message that strings have left for us," Greene says.
Not easily done, to be sure. Merely finding something consistent with string theory is not the same thing as proving it's true, and skeptics will need a lot of convincing. But Greene points out that string theory is still in its youth. He says, "Had you gone up to Mr. Stradivarius when he had a block of wood on the table and said, 'Play that violin,' he would have said you were a little early."
At the very least string theory is a great intellectual achievement. If someone told you to create a universe from scratch, these strings would come in mighty handy.
—Joel Achenbach
Washington Post staff writer
