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Einstein's Biggest Blunder (Lecture #24b of a course on Relativity & Cosmology)
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Part 6 GR & Cosmology (Book Ch 8, and video lectures #21 to #24)
Course textbook: A College Course on Relativity and Cosmology by Ta-Pei Cheng
Description: The feature that the space is dynamic in GR naturally leads to the observed expanding universe. Based on the Cosmological Principle (supported by direct observation) which implies an expanding universe according to Hubble’s law. The spacetime geometry is described by the Robertson-Walker metric. With an ideal cosmic fluid as the source, the resultant Einstein equation is in the form of Friedmann equations. This is the FLRW cosmology. Einstein also discovered that the GR field equation naturally allows for the presence of vacuum energy, called cosmological constant, which gives rise to a gravitational repulsion that increases with distance.
Learning objective: Understanding why general relativity is the natural framework for the study of our universe as a physical system.
Course textbook: A College Course on Relativity and Cosmology by Ta-Pei Cheng
Description: The feature that the space is dynamic in GR naturally leads to the observed expanding universe. Based on the Cosmological Principle (supported by direct observation) which implies an expanding universe according to Hubble’s law. The spacetime geometry is described by the Robertson-Walker metric. With an ideal cosmic fluid as the source, the resultant Einstein equation is in the form of Friedmann equations. This is the FLRW cosmology. Einstein also discovered that the GR field equation naturally allows for the presence of vacuum energy, called cosmological constant, which gives rise to a gravitational repulsion that increases with distance.
Learning objective: Understanding why general relativity is the natural framework for the study of our universe as a physical system.
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