AST 111 Lecture Notes - Lecture 30: Cosmological Constant, Accelerating Expansion Of The Universe, Vacuum Energy
6 Jun 2020
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Document Summary
In 1998, two teams of scientists (one led by anu astronomer brian schmidt) announced that the expansion of the universe was accelerating. They did this by measuring the expansion rate from distant galaxies compared with that of nearby galaxies. In 1916, einstein tried to model the universe using this new general theory of relativity. Could only come up with models that expanded or contracted not static models. Einstein heard about hubble"s discovery of the expanding universe. He rejected the cosmological constant, calling it the biggest blunder of his career. Gravity provides a force of attraction that pulls galaxies together, and would cause expansion of the universe to slow down. Cosmological constant is effectively an opposite force that pushes the galaxies apart. It is a pressure associated with empty space. Quantum field theories predict a vacuum energy associated with empty space due to quantum fluctuations. Predicted effect is much bigger than the observed cosmological constant.
