Title: On the calculating power of Laplace's demon: 
         physics, metaphysics and domain theory

John Longley (Edinburgh)

Abstract:

In 1819, Laplace famously claimed that a sufficiently powerful
`intelligence' that could comprehend the entire instantaneous state of
the universe would be able to predict the future (and retrodict the
past) with complete certainty.  But - regardless of whether he was
right or not - what precisely might one mean by such a claim? For
example, how exactly is the state of the universe supposed to be
presented to the demon, and what kinds of (e.g. infinitary) deductions
or computations is it deemed able to perform on this data?

Even in the simplest Newtonian situation, these questions lead to a
surprising number of delicate issues, involving ideas from
constructivity, computability and domain theory. In particular, an
attempt to develop portions of physics from minimal metaphysical
assumptions seems to lead one naturally to a physical ontology based
on an "interval" view of the continuum and of functions on it. The
mathematical ideas involved are now fairly familiar within the domain
theory community, but what they imply in the context of physics is
perhaps surprising.