Meetings 2026 To find out more about the group, email Mike Witt: mike (at) physicscafe (dot) org Upcoming [June 14th]: Spacetime (and maybe Geodesics) (Collier 7.3, maybe 7.4) Past [June 7th]: Three key principles of GR, ̶a̶n̶d̶ ̶S̶p̶a̶c̶e̶t̶i̶m̶e̶ (Collier 7.1 – 7.2) [May 31st]: The Ricci tensor and Ricci scalar [May 17th]: Riemann curvature tensor for a spherical surface [May 10th]: Geodesic Problems Review [May 3rd]: Review Collier chapter 6 [April 26th]: Open Meeting [April 19th]: Proposition 9 (the Force Law for an Equiangular Spiral) [April 12th]: Proposition 7 (Finding the Force Law for a Circle, with Off-center Sun) [April 5th]: NO MEETING [March 29th]: Continue Collier chapter 6 [March 22nd]: Continue Collier chapter 6 [March 15th]: Start on Collier chapter 6 [March 8th]: Tensor review, start on curvature [March 1st]: GR Continues [Feb 22nd]: GR Continues [Feb 15th]: GR Continues [Feb 8th]: GR Continues – Flowchart and planning session [Feb 1st]: GR Continues – More on Vectors and One-Forms [January 25th]: Tensor Homework Discussion – Tensor Homework #1 [January 18th]: Tensor Intro Review – Preparing for derivatives of Tensors [January 11th]: Principia: Proposition 6 – Finding the Centripetal Force for Any Orbit [January 4th] New Year Social 2025 Meetings