Wednesday, 3 September 2014

Olbers' Paradox

Why isn't the night sky uniformly at least as bright as the surface of the Sun? 

If the Universe has infinitely many stars, then presumably it should be. 

After all, if you move the Sun twice as far away from us, we will intercept one quarter as many photons, but the Sun's angular area against the sky background will also have now dropped to a quarter of what it was.  So its areal intensity remains constant. 

With infinitely many stars, every element of the sky background should have a star, and the entire heavens should be at least as bright as an average star like the Sun.

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