Harry Lehmann and the analyticity unitarity programme

I try to describe the extremely fruitful interaction I had with Harry Lehmann and the results which came out of the analyticity unitarity programme, especially the proof of the Froissart bound, which, with recent and future measurements of total cross-sections and real parts, remains topical.Comment: (10 pages, latex

History of Spin and Statistics

These lectures were given in the framework of the ``Dixi\`eme s\'eminaire rhodanien de physique'' entitled ``Le spin en physique'', given at Villa Gualino, Turin, March 2002. We have shown how the difficulties of interpretation of atomic spectra led to the Pauli exclusion principle and to the notion of spin, and then described the following steps: the Pauli spin with 2$\times$2 matrices after the birth of "new" quantum mechanics, the Dirac equation and the magnetic moment of the electron, the spins and magnetic moments of other particles, proton, neutron and hyperons. Finally, we show the crucial role of statistics in the stability of the world.Comment: latex file, 7 figures, 3 table

Liturgy at Ground Level

(Excerpt) On the back yard of our parish lot is a patch of ground I drive by every day. It is the place where we have a bonfire of trees and greens on the Twelfth Night of Christmas. Each Ash Wednesday, if it is not covered by snow, it is a blackened smudge on the face of the lawn. By Easter, however, that patch seems the most alive. For there the green blade rises, unhindered by dead overgrowth, looking even greener against the charred earth

A Passage Theory of Time

This paper proposes a view of time that takes passage to be the most basic temporal notion, instead of the usual A-theoretic and B-theoretic notions, and explores how we should think of a world that exhibits such a genuine temporal passage. It will be argued that an objective passage of time can only be made sense of from an atemporal point of view and only when it is able to constitute a genuine change of objects across time. This requires that passage can flip one fact into a contrary fact, even though neither side of the temporal passage is privileged over the other. We can make sense of this if the world is inherently perspectival. Such an inherently perspectival world is characterized by fragmentalism, a view that has been introduced by Fine in his ‘Tense and Reality’ (2005). Unlike Fine's tense-theoretic fragmentalism though, the proposed view will be a fragmentalist view based in a primitive notion of passage