As you say, the way string theory requires all these extra dimensions and this comes from certain consistency requirements about how string should behave and so on.

Works
Techniques of Differential Topology in Relativity (1972 ISBN 0-89871-005-7)
Spinors and Space-Time: Volume 1 Two-Spinor Calculus and Relativistic Fields (with Wolfgang Rindler 1987) ISBN 0-521-33707-0 (paperback)
Spinors and Space-Time: Volume 2 Spinor and Twistor Methods in Space-Time Geometry (with Wolfgang Rindler 1988) (reprint) ISBN 0-521-34786-6 (paperback)
The Emperor's New Mind: Concerning Computers Minds and The Laws of Physics (1989 ISBN 0-14-014534-6 (paperback); it received the Rhone-Poulenc science book prize in 1990)
Shadows of the Mind: A Search for the Missing Science of Consciousness (1994 ISBN 0-19-853978-9 (hardback))
The Nature of Space and Time (with Stephen Hawking 1996 ISBN 0-691-03791-4 (hardback) ISBN 0-691-05084-8 (paperback))
The Large the Small and the Human Mind (with Abner Shimony Nancy Cartwright and Stephen Hawking 1997 ISBN 0-521-56330-5 (hardback) ISBN 0-521-65538-2 (paperback) Canto edition: ISBN 0-521-78572-3)
White Mars or The Mind Set Free (with Brian W. Penrose earned his Ph. Further to this there was a suggestion that the microtubules could be pumped into a coherent state by biochemical energy.

He has received a number of prizes and awards including the 1988 Wolf Prize for physics which he shared with Stephen Hawking for their contribution to our understanding of the universe. He is the Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute of the University of Oxford as well as an Emeritus Fellow of Wadham College.