Physics in the Real Universe: Time and Spacetime

The Block Universe idea, representing spacetime as a fixed whole, suggests the flow of time is an illusion: the entire universe just is, with no special meaning attached to the present time. This view is however based on time-reversible microphysical laws and does not represent macro-physical behaviour and the development of emergent complex systems, including life, which do indeed exist in the real universe. When these are taken into account, the unchanging block universe view of spacetime is best replaced by an evolving block universe which extends as time evolves, with the potential of the future continually becoming the certainty of the past. However this time evolution is not related to any preferred surfaces in spacetime; rather it is associated with the evolution of proper time along families of world linesComment: 28 pages, including 9 Figures. Major revision in response to referee comment

Mirror Symmetry and Other Miracles in Superstring Theory

The dominance of string theory in the research landscape of quantum gravity physics (despite any direct experimental evidence) can, I think, be justified in a variety of ways. Here I focus on an argument from mathematical fertility, broadly similar to Hilary Putnam's 'no miracles argument' that, I argue, many string theorists in fact espouse. String theory leads to many surprising, useful, and well-confirmed mathematical 'predictions' - here I focus on mirror symmetry. These predictions are made on the basis of general physical principles entering into string theory. The success of the mathematical predictions are then seen as evidence for framework that generated them. I attempt to defend this argument, but there are nonetheless some serious objections to be faced. These objections can only be evaded at a high (philosophical) price.Comment: For submission to a Foundations of Physics special issue on "Forty Years Of String Theory: Reflecting On the Foundations" (edited by G. `t Hooft, E. Verlinde, D. Dieks and S. de Haro)

BETWEEN SCIENCE AND PHILOSOPHY

xiv, 363 hlm.; 22 c

Social constructionism as cognitive science

Social constructionism is a broad position that emphasizes the importance of human social processes in psychology. These processes are generally associated with language and the ability to construct stories that conform to the emergent rules of 'language games'. This view allows one to espouse a variety of critical postures with regard to realist commitments within the social and behavioural sciences, ranging from outright relativism (language constructs all of our concepts) to a more moderate respect for the 'barrier' that linguistic descriptions can place between us and reality. This paper first outlines some possible social constructionist viewpoints and then goes on to show how each of them conforms to the basic principles of information theory. After establishing this relation the paper then argues that this leads to a deal of commonality between social constructionist positions and the baseline aims of cognitive science. Finally, the paper argues that if information theory is held in common this both suggests future research collaborations and helps to 'mop up' some of the arguments surrounding realist commitments