Is string theory in trouble?
Sunday, May 14, 2006
"Ever since Albert Einstein wondered whether the world might have been different, physicists have been searching for a “theory of everything” to explain why the universe is the way it is. Now string theory, one of today's leading candidates, is in trouble. A growing number of physicists claim it is ill-defined and based on crude assumptions. Something fundamental is missing, they say. The main complaint is that rather than describing one universe, the theory describes 10500, each with different constants of nature, even different laws of physics.
But the inventor of string theory, physicist Leonard Susskind, sees this “landscape” of universes as a solution rather than a problem. He says it could answer the most perplexing question in physics: why the value of the cosmological constant, which describes the expansion rate of the universe, appears improbably fine-tuned for life. A little bigger or smaller and life could not exist. With an infinite number of universes, says Susskind, there is bound to be one with a cosmological constant like ours.
The idea is controversial, because it changes how physics is done, and it means that the basic features of our universe are just a random luck of the draw. He explains to Amanda Gefter why he thinks it's a possibility we cannot ignore."-NewScientist