Present at the Future by Ira Flatow

problematic. “Why the ideas which seemed at first so beautiful, so natural, were not getting us where we expected to get twenty years ago.”
    Smolin points out that just about every 25 to 30 years, new ideas in physics come along to replace the old ones. If you look back over the last 200, he says, it’s very unusual for three decades to pass without a scientific revolution. For example, he writes that “from 1830–1855 Michael Faraday introduced the notion that forces are conveyed by fields, an idea he used to greatly further our understanding of electricity and magnetism.”
    In the 25 years that followed, James Clerk Maxwell expanded those ideas into “our modern theory of electromagnetism.” He explained how light was also like radio waves and unlocked other secrets of our natural world. Then came the next dramatic period, 1880 to 1905, in which electrons and X-rays were discovered. In that 25-year period, Smolin continues, Max Planck’s work would “spark the quantum revolution.” Einstein’s era would arrive in 1905, and understanding the impact of relativity would occupy the next two and a half decades. By Einstein’s death in 1955, we would know all about a whole new world of subatomic particles and organize the forces of nature into a family of four.
    The next 25 years and the 25 after that would see the creation of a “standard model” of the elementary particles in the universe, and on a larger scale, we’d see Stephen Hawking and other luminaries enlighten our understanding of black holes, the big bang, and dark energy and matter.
    But since the 1980s, says Smolin, we have been stymied. String theory is now more than 20 years old and doesn’t seem to be yielding the answers that have been expected of it. “History seems to show that when there’s a good idea about unifying different parts of physics, it works fast if it’s going to work.” Scientists should be able to conduct experiments that either bolster or bat down that new idea. But the problem with string theory is that so far, there are no experiments thatcan solidify it. Or, as Smolin puts it, “string theory is not making experimental predictions. There are certainly very beautiful things about it,” but a theory that can’t be tested is nothing more than a theory. In science, you can’t hang on to an idea too long; if it can’t be tested and proven, it’s on to the next big thing.
    Krauss agrees. He says string theory has been a failure. “There isn’t a shred of empirical evidence, not only for extra dimensions but essentially also for string theory. They [scientists] haven’t made any predictions that have been tested. And moreover, in fact, to some extent, we’re still just learning what the theories are.”
    Greene agrees that the evidence, so far, has been lacking. But as one of string theory’s greatest proponents, he says we have to give the experimentalists a bit more time to find the evidence.
    “How long will it take for those experiments to happen? I don’t know. We could get lucky. It could be that the Large Hadron Collider, which will turn on in 2007 or 2008,” will show some evidence for string theory. “We might see some of the fingerprints of string theories through something called supersymmetry, certain particles that the theories suggest should be there but nobody has yet seen.”
    Astronomers, looking into space, might also find evidence of string theory. “That’s what I spend my time on these days, trying to see where these strings might leave some imprint in the microwave background radiation, the heat left over from the big bang. All of these are long shots. But we’re doing exactly what Lee is saying one should do in science—namely, work toward experimental verification. How long? I can’t predict. Nobody can predict.”
    Greene says it could be years, even decades, before experiments can determine the validity of string theory. And should that happen, interest in the theory would drop off