By Carlo Rovelli
By Joseph Silk (, Savilian Professor of Astronomy, University of Oxford)
By Adam Becker
By Christophe Galfard
By John Archibald Wheeler
By Sean Carroll
By Brian Greene
By Professor Pedro G. Ferreira
By Janna Levin
By Marcia Bartusiak
By Pirani, Felix
By Hawking, Stephen William, Stephen Hawking
By Moore, Patrick
By Tennyson, Jonathan
By Galfard, Christophe
By G. E. Chrisitanson
By Tayler, Roger
By Gregory, Stephen, Zeilik, Michael
By Prialnik, Dina
By Beaton, Roderick
By Lawrence, Richard
By Professor Brian Cox., Brian Cox, Andrew Cohen
By Giles Sparrow, Matthew Taylor
By Allday, Jonathan
By Musser, George
By Suplee, Curt
By Croswell, Ken
By Stephen Hawking, Hawking, Stephen