Why is the night sky not bright if there are infinite stars?
Image: Brody Wesner, CC0, via Wikimedia Commons
the Olbers' paradox asks
Why is the night sky not bright if there are infinite stars?
Imagine you're walking outside at night, expecting to see a dazzling light from countless stars all around you. Instead, it's mostly dark, with just a few bright stars scattered across the sky.
The universe isn't infinite and static; it's expanding and finite. This expansion stretches light from distant stars, making them appear dimmer and contributing to the darkness of the night sky. The technical term for this phenomenon is the "redshift."
Example
A star 1 million light-years away sends light that stretches and dims as it travels through expanding space, making it appear less bright by the time it reaches Earth.
Remember this
The universe's expansion causes distant starlight to stretch and dim, explaining the dark night sky.
Text adapted from Wikipedia, licensed under CC BY-SA 4.0.
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