String theory

A string theory is a physical model whose fundamental building blocks are extended objects (strings, membranes and higher-dimensional objects) rather than points. String theories are able to avoid problems, such as infinite energy density, associated with the presence of mathematical points in a physical theory.

The term 'string theory' properly refers to both the 26 dimensional bosonic string theories and to the 10 dimensional superstring theories discovered by adding supersymmetry to bosonic string theory. Nowadays, 'string theory' usually refers to the supersymmetric variant while the earlier is given its full name 'bosonic string theory'. The different superstring theories were discovered to be the same theory in the 1990s.

Discovery of bosonic string theory

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