String theory

String theory, or superstring theory, is a class of models in theoretical physics which replace zero-dimensional points (particles) with one-dimensional strings as the fundamental building block of physics. The hope is resolve conflicts between gravity and quantum mechanics in existing models of physics. The elusive goal is to develop a set of equations that unify all known natural forces (gravitational, electromagnetic, weak and strong). A leading proponent of string theory has been Edward Witten of the Institute for Advanced Study.

There is much debate on whether string theory is truly scientific. Under the positivist philosophy, models must be falsifiable (i.e. it must be possible to define an experiment which will prove or disprove the theory) for them to qualify as science, and then they must survive these tests. In more general terms, a model is not scientific unless we can use it to make predictions about the world we observe, and it is consistent with those predictions. Due to the sheer complexity of the models, string theory has yet to yield a particular definitive test, although variables involved in the theory have had bounds placed upon them. However it is not yet demonstrated that the theory is insoluble (see the Incompleteness theorem): that is, while string theory is not yet provable, it has not been shown to be unprovable. As an analogy, it can be suggested that all objects become green when they are not being observed: this is a model which is unprovable in principle, and therefore unscientific.