In the mid 1980s, Nicolai and Bernard de Wit developed the "N = 8 supergravity theory",[3] which arises from the dimensional reduction of the maximally supersymmetrical eleven-dimensional supergravity to four space-time dimensions (d = 4) and for which, from many plausible viewpoints, a maximal supersymmetry has a supergravity theory with a graviton and no particle with a spin greater than 2.
In the 2000s, Nicolai and colleagues investigated the behavior of gravitational equations close to a gravitational singularity such as the Big Bang;[4] these investigation lead to models with chaotic dynamical billiards, in the case of classical general relativity theory in three dimensions. In the case of eleven-dimensional supergravity, these investigations to ten-dimensional "cosmological billiards", and the infinite-dimensional hyperbolic Kac Moody algebra appears as a symmetry. contains the largest finite-dimensional exceptional semi-simple complex Lie algebra, which has been studied as a candidate for a grand unified theory (GUT].[5] Nicolai proposed a purely algebraic description of the universe in cosmological space-time regions near the singularity (within the Planck time) using the -symmetry, whereby the space-time dimensions result as an emergent phenomenon.[6][7]
Nicolai has also done research on a special role for in M-Theory.
He and de Wit also constructed maximally gauged (N = 16) supergravity theories in three dimensions and their symmetries.[8] Furthermore, Nicolai and colleagues examined generalizations of the variables of loop quantum gravity to supergravity / string theory.
^Nicolai and his colleagues investigated the theoretical implications of the BKL singularity introduced by Belinski, Khalatnikov, and Lifschitz in general relativity
^De Wit, Bernard; Nicolai, H.; Samtleben, H. (2004). "Gauged Supergravities in Three Dimensions: A Panoramic Overview". Proceedings of 27th Johns Hopkins Workshop on Current Problems in Particle Theory: Symmetries and Mysteries of M Theory — PoS(jhw2003). p. 016. doi:10.22323/1.011.0016. S2CID15349626. arXiv.org