A brief review is given of why twistor geometry has taken a central place in the theory of scattering amplitudes for fundamental particles. The emphasis is on the twistor diagram formalism as originally proposed by Penrose, the development of which has now led to the definition by Arkani-Hamed et al. of the 'amplituhedron'.
Keywords: amplituhedron; scattering amplitudes; twistor theory.
© 2015 The Author(s) Published by the Royal Society. All rights reserved.