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PBS
The NEW Crisis in Cosmology
I have good news and bad news. Bad news first: two years ago we reported on the Crisis in Cosmology. Since then, it’s only gotten worse. And actually, the good news is also that the crisis in cosmology has actually gotten worse, which...
Khan Academy
Why Cepheids Pulsate, Stars, Black Holes and Galaxies, Cosmology and Astronomy
Classical Cepheids are supermassive stars that are used to determine distances to galaxies within a local group. Sal explains why Cepheid variables occur, how they are used to determine distances, and the chemistry that creates the...
Khan Academy
Khan Academy: Cepheid Variables: Why Gravity Gets So Strong Near Dense Objects
Find out why gravity gets so strong near dense objects. [8:13]
Khan Academy
Khan Academy: Cepheid Variables: Why Cepheids Pulsate
A video tutorial showing why cepheids pulsate. [7:10]