Question

Weeks 5, 6: How is Olber's paradox solved? Does the Universe have a center or an edge? What is the cosmological principle? The Universe expands: why, how, and how do we know? What is cosmological redshift? What is the Big Bang? How old/big/fast is the Universe? How do Hubble's constant, the critical density of the flat universe, and the density parameter help us understand those properties of the Universe? What is the cosmic light horizon and why is it the limit to which we can see out in space? What is the Planck time? What is the Cosmic Microwave Background Radiation? What happened in the Universe when it was about 380,000 years old? Why, at that time, did it change from opaque to transparent? What happens to temperature and density, matter and radiation in the Universe during its evolution? What is the shape of space and how is it determined? Know about spherical (closed), flat, hyperbolic (open) and accelerating universes and their properties. How do their sizes change with time? What is dark energy? Is it the same as dark matter? What percentage of the Universe is dark energy? What percentage is matter?

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