A complex variable used in some descriptions of space–time.
 Example sentencesExamples
-  One of Penrose's major breakthroughs was his introduction of twistor theory in an attempt to unite relativity and quantum theory.
 -  Right at the end the reader becomes aware of elaborate setups put in place hundreds of pages back, in anticipation of the spectacular climax - the unveiling of Penrose's best shot at promoting further research into his twistor theory.
 -  The space arises naturally (as the fiber) in twistor space.