61pages, 4 public lectures with Sir Roger Penrose, PDF: 1994
Abstract:
"The Nature of Space and Time."
A clear explanation of physical space and time, general relativity, black holes, the big-bang, astrophysics and more, in simple, introductory terms for everyone. Public lectures and academic arguments with Sir Roger Penrose who presents a different, more mathematically-based (but also less physically intuitive) approach to Quantum Gravity and space-time. Professor Stephen Hawking's concise summing up of these lectures and public, academic, Agora-style, arguments is as follows: "That general relativity soon acquired a much better reputation, and more interest, is in a considerable measure because of Roger's work. Up to then, general relativity had been formulated as a messy set of partial differential equations in a single coordinate system. People were so pleased when they found a solution that they didn't care that it probably had no physical significance. However, Roger brought in modern concepts like spinors and global methods. He was the first to show that one could discover general properties without solving the equations exactly. It was his first singularity theorem that introduced me to the study of causal structure and inspired my classical work on singularities and black holes. I think Roger and I pretty much agree on the classical work. However, we differ in our approach to quantum gravity and indeed to quantum theory itself." The very first exposition to read before embarking on any precise mathematical descriptions of general Relativity, Cosmology and Big-bang theories. http://hawking.org.uk/old-site/pdf/time.pdf
Rights:
Open access:
http://hawking.org.uk/old-site/pdf/time.pdf
