... ur theory). If the ur hypothesis is correct, the symmetry of urs must play a distinguished role in physics. At this point the second pillar of the ur theoretic structure comes in: the quantum theory ... Weizs¨acker’sobservations, especially in the third part of the book, are of extraordinaryvalue for the history of science. The physical core of the book, the presenta-tion of ur theory in the first part, offers ... about the structure of time, for experience entails applying lessons learned from the facts of the past to the open questions of the future. The use of time as parameter-time—i.e., within the...