Professor Sir Michael Berry, Bristol University, will talk about emergence and limits in physics. In physics, each deeper level of description (e.g. quantum mechanics) 'reduces' to a less general level (e.g. Newtonian mechanics) in the limit when a characteristic quantity (e.g. Planck's constant) is negligibly small. Such limits are usually singular; this explains why the different levels can involve very different concepts ('incommensurability'), and also leads to predictions of qualitatively
new phenomena inhabiting the borderlands between theories. Thus the philosophical problem of theory reduction can itself be reduced - in physics at least - to technical problems in mathematics.
Coffee will be available from 19:00, and the talk will begin 19:30.