Dear colleagues:
There will be (yet another!) one day mini conference in philosophy of
physics at DAMTP (MR 12), CMS, Cambridge, next Tuesday 19 June, from 10.00
am. Details below, and attached as a Word document. All welcome.
by the way: people interested in time in quantum theory may wish to attend
a one day meeting in Bristol on Thursday 21 June: details at:
http://www.bristol.ac.uk/ias/diary/2018/tompashbyworkshop.html
Best wishes,
Jeremy Butterfield
----
Location: 10.00 till 17.00 in MR 12.
10.00 M Farr (Cambridge): The C Theory of Time.
Does time have a direction? Intuitively, it does. After all, our
experiences, our thoughts, even our scientific explanations of phenomena
are time-directed; things evolve from earlier to later, and it would seem
unnecessary and indeed odd to try to expunge such talk from our
philosophical lexicon. Nevertheless, in this talk I will make the case for
what I call the C theory of time: in short, the thesis that time does not
have a direction. I will do so by making the theory as palatable as
possible, and this will involve giving an account of why it is permissible
and indeed useful to talk in time-directed terms, what role time-directed
explanations play in science, and why neither of these should commit us to
the claim that reality is fundamentally directed in time. On the positive
side, I will make the case that the C theory's deflationism about the
direction of time offers a superior account of time asymmetries in physics
than rival time-direction-realist accounts.
11.00 Coffee
11.30: B Pitts (Cambridge): What Are Observables in Hamiltonian
Einstein-Maxwell Theory?
Is change missing in Hamiltonian General Relativity with Maxwellian
electromagnetic fields? This question requires an adequate definition of
observables, the finding and testing of which is a multi-step process.
Pitts has proposed bifurcation of observables to require invariance under
internal gauge symmetries but only covariance (a *4*-dimensional Lie
derivative) under external gauge (coordinate) symmetries. This definition
implies that the electromagnetic field strength is observable for Maxwell
and the metric and its concomitants are observable for Einstein, considered
in isolation. But does the definition yield plausible results when applied
to Einstein-Maxwell theory, which exhibits a combined internal-external
gauge symmetry?"
12.30 Lunch
2.00: J Butterfield (Cambridge): On dualities and equivalences between
physical theories
The main aim of this paper is to make a remark about the relation between:
(i) dualities between theories, as 'duality' is understood in physics and
(ii) equivalence of theories, as 'equivalence' is understood in logic and
philosophy. The remark is that in physics, two theories can be dual, and
accordingly get called 'the same theory', though we interpret them as
disagreeing-so that they are certainly not equivalent, as 'equivalent' is
normally understood. So the remark is simple: but, I shall argue, worth
stressing-since often neglected. My argument for this is based on the
account of duality developed by De Haro: which is illustrated here with
several examples, from both elementary physics and string theory. Thus I
argue that in some examples, including in string theory, two dual theories
disagree in their claims about the world. I also spell out how this remark
implies a limitation of proposals (both traditional and recent) to
understand theoretical equivalence as either logical equivalence or a
weakening of it. This talk corresponds to arxiv: 1806.01505
15.00: Tea
15.30: J Read (Oxford): Geometry and conspiracy in relativity theory
Abstract: I discuss the debate between advocates of dynamical versus
geometrical approaches to spacetime theories, in the context of both
special and general relativity. By distinguishing between what I call
'individual' versus 'modal' explanations, I argue that there is a perfectly
viable form of the geometrical approach.
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