Up Next
Back to Show
It's Okay to Be Smart
Traffic Lights Are So Much Weirder Than You Realize
Why are stop lights red? The common explanation about red light traveling farther through fog is actually wrong. The real story involves early railroads, deadly accidents, an exploding gas traffic light, forgotten inventors, and even the evolution of primate color vision. Here’s how history and biology accidentally created the nearly perfect traffic signal.
Support Provided By
12:37
Think traits like eye color or tongue-rolling are simple genetics? Think again.
11:08
Why is the Martian sky red by day… but blue at sunset?
14:51
Seedless fruits are delicious, convenient… and completely unnatural.
21:13
What does randomness really mean? And why your digital life depend on it?
16:20
Why do we have different blood types? And why do we have blood at all?
16:18
How did dinosaurs become birds—and what good is half a wing?
16:00
Just how big would a telescope need to be to actually see an alien world in detail?
16:53
The key enzyme behind photosynthesis isn’t actually all that great at its job.
16:40
The oldest rocks on Earth are more than just ancient—they’re time machines!
17:11
This is one of the weirdest mysteries of human evolution: Why do we have grandmas?