I used to believe that sunlight coming from windows spontaneously generated dust since that's the only place I ever saw it in the air.
A childhood belief about physics

others believed things like this
- I used to believe Chad Kroeger from Nickelback was computer generated— Indeed
- I believed that Jesus was flying across the sky, it was actually sunlight reflecting off planes.— Patti
- My young daughter thought that night came after the trees ate all the sunlight.— Bruce
- I used to believe that the dust on top of doors was poisonous.— draconid
- What about "Another one buys a Datsun." You know, instead of "Another one bites the dust.— e-man
- I used to believe that the song "Another one bites the dust" was "Another one rides the bus"— Emmy