The physical limitations, due to quantum mechanics, on the functioning of computers are analyzed.

Recent developments in quantum theory have focused attention on fundamental questions, in particular on whether it might be necessary to modify quantum mechanics to reconcile quantum gravity and general relativity. This book is based on a conference held in Oxford in the spring of 1984 to discuss quantum gravity. It brings together contributors who examine different aspects of the problem, including the experimental support for quantum mechanics, its strange and apparently paradoxical features, its underlying philosophy, and possible modifications to the (...) theory. (shrink)

In this paper I put forward a new micro realistic, fundamentally probabilistic, propensiton version of quantum theory. According to this theory, the entities of the quantum domain - electrons, photons, atoms - are neither particles nor fields, but a new kind of fundamentally probabilistic entity, the propensiton - entities which interact with one another probabilistically. This version of quantum theory leaves the Schroedinger equation unchanged, but reinterprets it to specify how propensitons evolve when no probabilistic transitions occur. Probabilisitic transitions occur (...) when new "particles" are created as a result of inelastic interactions. All measurements are just special cases of this. This propensiton version of quantum theory, I argue, solves the wave/particle dilemma, is free of conceptual problems that plague orthodox quantum theory, recovers all the empirical success of orthodox quantum theory, and at the same time yields as yet untested predictions that differ from those of orthodox quantum theory. (shrink)

Winner of the Wolf Prize for his contribution to our understanding of the universe, Penrose takes on the question of whether artificial intelligence will ever ...

Physical and chemical processes may act upon the mind; and when we are writing a difficult letter, our mind acts upon our body and, through a chain of physical...

A Quantum-Mechanical automation, equipped with mechanisms for the measurement and the recording and the prediction of certain physical properties of the world, is described. It is inquired what sort of empirical description such an automation would produce of itself. It turns out that this description would be a very novel one, one such as was never imagined in the conventional discussions of measurement.

In the never-ending debate about the scope and limits of science, the hottest argument now centres on the scientific study of man himself. Can there be a science of man at all, in any comprehensive sense? Or is the idea in some way ultimately self-defeating, like that of pulling oneself up by one's own shoelaces? My purpose in this paper is not to venture a direct answer to this ticklish question, but rather to highlight one or two desirable characteristics of (...) a science which I think must inevitably be lacking in any attempt to turn the scientific spotlight upon ourselves. Whether we call the attainable residue by the name of ‘science’ is less important than that we see clearly what not to expect of it. (shrink)