[PhilPhys] Phil Physics Seminar this week: Wallace on Gravitational Entropy

[Chris Timpson]

Dear All,

 

(Apologies for cross-postings)

 

This week's Oxford Philosophy of Physics Seminar  (Thursday, 4.30pm, Lecture
Room, 10 Merton St) features our very own David Wallace arguing for: 

 

"The irrelevance of gravitational entropy in cosmological thermodynamics"

 

Abstract:

 

There is a widespread view that (i) in the presence of gravity, highly
concentrated systems are actually higher-entropy than more dispersed
systems, and (ii) that - because it makes the early universe low- rather
than high-entropy - this is the ultimate explanation of the second law of
thermodynamics. This view has recently been sharply criticised by Earman,
who argues that (iii) gravitational entropy is too ill-defined to play a
foundational role of this kind. I will review this discussion and argue that
(i)-(iii) are all either flat wrong or at any rate often understood in a
confused fashion. I will argue that (a) we have a perfectly satisfactory
understanding of the consequences of gravity for entropy at the energy
scales relevant to classical cosmology; (b) that understanding does lead to
the conclusion that uniform dispersed systems are relatively low-entropy,
but this is not really because squeezing those systems into smaller spaces
increases their entropy; (c) that spatial uniformity is not, as far as
thermodynamics is concerned, the real explanation for the lowness of the
entropy of the early universe and hence for the 2nd law in our present
epoch.

 

All welcome!

We'll probably go for a drink after the seminar, before dinner. Could those
who'd like to join the speaker for dinner let me know so I have a sense of
numbers.

 

Best wishes,

Chris Timpson

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