Stringbewegung

Stringbewegung, literally "string motion," refers to the dynamical behavior of fundamental string excitations within string theory. It describes how strings, which are one–dimensional objects, propagate and oscillate in spacetime, giving rise to the particle spectrum observed in nature.

In the theoretical framework, the string’s motion is governed by the Nambu–Goto action or, more conveniently, by the Polyakov action, which leads to equations of motion analogous to those of a vibrating membrane. Quantization of these equations yields a tower of vibrational modes, each corresponding to a distinct particle state, with mass squared proportional to the mode number. The lowest‑lying modes reproduce the known bosons and fermions of the Standard Model, while higher modes represent heavier excitations beyond current experimental reach.

Stringbewegung also encodes the propagation of massless modes such as the graviton, thereby bridging quantum mechanics and general relativity. In dualities like T‑duality, the same physical situation can exhibit different string motions, illustrating the deep symmetry structures of the theory.

Historically, investigations of stringbewegung began in the 1960s with the dual resonance model and evolved into modern superstring theory. Contemporary research examines how deformations of the background spacetime alter string dynamics, with implications for cosmology, black hole physics, and holographic dualities. The study of stringbewegung remains central to efforts to formulate a consistent quantum theory of gravity.