Science · 6 pages · 12 min
Why the night sky is dark
The night is dark because the universe is not an endless, ageless room of stars.
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From the opening
The night sky is dark because a line of sight does not end on a star that has been shining forever. Stars and galaxies are plentiful, yet their light still does not brighten every direction the way an eternal static cosmos would. The opening covers what Olbers paradox is asking, why a finite age matters, and what the microwave glow is.
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Inside
- What Olbers paradox is asking
- Why a finite age matters
- What the microwave glow is
- What city lamps do instead
- Where the idea stops applying
- A distinction worth keeping
Sources
- Olbers paradox of the dark night sky
- The finite age and expansion of the observable universe