Foundations of Physics Seminar Wednesday the 13th of October
Hans Westman Scale invariance, Weyl Gravity, and Einstein's Three Objections In the standard model the only two terms breaking scale invariance is the Higg's mass term and the Einstein Hilbert term. We give a simple introduction to Weyl's 1918 scale invariant gravity based on basic epistemology and discuss the three main objections put forth by Einstein: 1) the hydrogen spectrum depends on their previous history of the atom something which is empirically ruled out to a high precision, 2) there is no account for proper time measurement 3) field equations are 4th order leading to Ostrogradsky type instabilities. We show that the first two objections can be readily answered. In particular the second object is answered by developing a physical model of ideal clocks from which proper time is identified as the readings of the clocks. We also show how this proper time (first discovered by Perlick) can be used in a variational principle to determine the geodesic motion of test particles. We then outline how one can tackle the third objection by breaking foliation invariance and so introduce a preferred simultaneity. Last we put forth a variant of Einstein's first objection which cannot so easily be answered: if there is no fundamental scale in nature how come all hydrogen atoms have the same size? Philosophy Common Room, S413, Main Quad, 11:30–1:00. All welcome. Please see <http://bit.ly/SydFop> http://bit.ly/SydFop for the latest program.
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