As a child, I believed in the law of balance. I don't even know where I got the idea. I believed if there were two options or two ideas, one had to be one way, and the other had to be the opposite.
Like winding an old clock, you had to let it wind down or you'd break the spring if you kept winding it. We had a bathroom with two light switches, one of them not connected to anything. So when I flipped the switch for the light up, the unused switch had to go down, and vice-versa.
Or if I had to turn around to the right to do something, I'd then have to turn back around to the left, as if there was some invisible string attached to me that would get wound around me oddly and somehow make my life more difficult if I didn't unwind it the other way.
I also believed that if I was walking with someone closely, like a friend or parent, there was some sort of invisible connection between us, and if I let something pass between us, like me walking on one side of a pole and the friend walking on the other, we'd break the connection and our relationship might start to fall apart. So I always scooted to be sure we walked on the same side of things together, eve if we had to go single-file.
That's pretty much the oddest thing I believed.
A childhood belief about physics

others believed things like this
- i used to think the song "walking in a winter wonderland" was "walking in a womens underwear"— stephen s
- I used to believe that jay walking was walking naked on the street. — Kendra
- I once told a friend of mine that if you held in a smelly burp, it'd turn into a fart. She believed me.Anon
- I used to belive that if we could find the light switch that controlled the sun, we could control the world. Anon
- Yesterday I realised that invisible ink doesn`t make me invisible.— Jonathan Eleven years old
- I believed if I let my dog lick my face and didn't wipe off the slobber, that I would turn into a dog myself.— robyn