LMR-102 · Cosmology
Olbers' Paradox
Why is the night sky dark? The answer is the entire history of the universe.
§ A first look
§ Depths
Six ways into the same idea — from bedtime story to chalkboard. No order required.
L1 · Crayon
Told like a bedtime story.
For a curious 10-year-old. No jargon. Just a picture in your head.
Imagine a forest. If there's a tree in every direction, no matter where you look you'll eventually see trunk. Now imagine the universe was infinite and old and stars existed everywhere, forever. Every line your eye could draw out from your face would eventually land on a star. The sky should be as bright as the Sun, in every direction, all night. But it isn't. The sky is dark. That darkness is telling you something gigantic: the universe is not infinite-and-forever the way it looks. The dark is the loudest piece of evidence we have.
§ Strange but true
- 01The universe is stranger than your intuition. This is a rule, not an exception.
- 02Every fact in physics was once an outrageous guess. Most still feel like one.
- 03If it doesn't bend your brain a little, you haven't read it carefully enough.
§ From the field journal
Olbers' Paradox
"Why is the night sky dark? The answer is the entire history of the universe."
— observed, sketched, not yet fully understood.
§ Nearby
Constellations near Olbers' Paradox
→
Big Bang
Not an explosion in space. An expansion of space.
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CMB
The afterglow of the Big Bang, still arriving 13.8 billion years later.
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Redshift
The universe is stretching, and dragging every wavelength of light with it.
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Light
You're reading messages that left stars before humans existed.
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Cosmic Web
Galaxies don't drift randomly. They live on filaments around vast empty voids.