Twistor theory and the four-dimensional Quantum Hall effect of Zhang and   Hu
  The construction by Zhang and Hu of a four-dimensional analogue of the Quantum Hall effect is generalized and recast as a purely geometrical theory, using the languages of Lie group theory and twistor theory. It emerges that the Zhang-Hu quantum liquid lies naturally in twistor space and is apparently more primitive than space-time itself, in accordance with twistor philosophy. The quantum liquid is then the glue that holds space-time together. It is argued that the theory is inherently chiral and time asymmetric, consonant with previous conjectures. 
George Sparling