Lecture 32: Space, Time, & Gravity: General Relativity
What is gravity? Newton left that question unanswered when he formulated\nhis inverse square law of the gravitational force, framing no hypothesis\nfor what agency transmits gravity, only asserting it was an action\nat a distance. Einstein brought gravity into relativity by answering\nNewton's unanswered question with his General Relativity, our modern\ntheory of gravity. In Einstein's formulation, Matter tells spacetime how\nto curve, and curved spacetime tells matter how to move. This lecture\npresents the basic picture of General Relativity, and introduces some\nof its observational consequences. The surprising conclusion is that\ninstead of space and time being a backdrop for physics in Newton's view,\nunited into spacetime by Relativity they are understood to be physical\nand dynamic. This is important for understanding how the Universe as\na whole works.\nRecorded 2006 February 21 in 1008 Evans Laboratory on the Columbus campus\nof The Ohio State University.