Holger Bech Nielsen is a Danish theoretical physicist and professor emeritus at the Niels Bohr Institute, at the University of Copenhagen, where he started studying physics in 1961.
Prof. Holger Bech Nielsen
In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries the gravitational force. Thus, string theory is a theory of quantum gravity.
A cross section of a quintic Calabi–Yau manifold
A magnet levitating above a high-temperature superconductor. Today some physicists are working to understand high-temperature superconductivity using the AdS/CFT correspondence.
A graph of the j-function in the complex plane
Leonard Susskind