As long as it’s been around, string theory has contended with criticisms. Some of string theory’s critics are among the most respected members of the physics community, including Nobel laureates such as Sheldon Glashow and the late Richard Feynman, both of whom were critical as far back as the first superstring revolution in the mid-1980s. Still, string theory has steadily grown in popularity for decades.
Recently, the rise in criticisms against string theory has spilled into the popular media, making the front pages of science magazines and even large articles in more mainstream publications. The debate rages across radio waves, the Internet, academic conferences, the blogosphere, and anywhere else that debates are allowed to rage.
Though the debate sounds passionate, none of the critics are really advocating that physicists completely abandon string theory. Instead, they tend to view string theory as an effective theory (a useful approximation) rather than a truly fundamental theory, which describes the most basic level of reality itself. They are critical of string theorists’ attempts to continue to promote the theory as a fundamental theory of reality.
Here are some of the most significant criticisms levied against string theory (or the string theorists who practice it):
String theory is unable to make any useful prediction about how the physical world behaves, so it can’t be falsified or verified.
String theory is so vaguely defined and lacking in basic physical principles that any idea can be incorporated into it.
String theorists put too much weight on the opinions of leaders and authorities within their own ranks, as opposed to seeking experimental verification.
String theorists present their work in ways that falsely demonstrate that they’ve achieved more success than they actually have. (This isn’t necessarily an accusation of lying, but may be a fundamental flaw in how success is measured by string theorists and the scientific community at large.)
String theory gets more funding and academic support than other theoretical approaches (in large part because of the aforementioned reported progress).
String theory doesn’t describe our universe, but contradicts known facts of physical reality in a number of ways, requiring elaborate hypothetical constructions that have never been successfully demonstrated.
Behind many of these criticisms is the assumption that string theory, which has been around for 30 years, should be a bit more fully developed than it actually is. None of the critics are arguing to abandon the study of string theory; they just want alternative theories to be pursued with greater intensity, because of the belief that string theory is falling short of the mark.
To explore the validity of these claims and determine whether string theory is in fact unraveling, it’s necessary to lay out the frame of the debate by looking at where string theory has been and where it is today.