I was convinced that hot air sinks. Why else are mountain tops cold, and Death Vally is so hot?

Not-my-wife

I used to believe that the tiny flashes you sometimes see when you have your eyes closed were neutrinos passing through your eyes.

Anon

I used to watch the clouds blowing across the sky and think I was seeing evidence of the earth's rotation.

Dave T

When I was kid, I read a lot of physics books, and then, this one time, I saw a program on the big bang, and I thought there was no way the whole universe was made with one big bang. The universe was too big. There must have been a lot of big bangs all over the place to account for the size.

mcp

I used to think that if a spaceship went through "hyper space", it would take a temporary toll on the crews' brains, thus making then scream, panic, go into hysterics, and slam against things. When hyper space was over, everything was fine.

Hyper space sounded pretty fun.

Jessica Tinch

It was back in 1994, I was 7 yo and when summer vacation was, every morning I watched educational cartoon for kids. One of episodes explained had does electricity works. I took their explanation of running electrons too literally, and for next few years I believed that when you switch on the trigger on the wall, line of little guys starts running through the inside of wire and gets crashed within the bulb, emiting lot of warm and making light!

Ruda Śląska 4ever

I always thought that Marie Curie was so called because she invented the Cure for Cancer. It never crossed my mind that she would have always had that name, and only later in life would have started finding cures for things.

Katie Watie

when i was little i always wondered why hot food would get cold if you left it out too long, and cold food would get hot. when i was about 12 i realized it was food turning to room temperature.

Flow

I spent many frustrating hours believing that if i tried hard enough I could lift myself off the ground with no means of support. I also thought if a lift was plummeting down a shaft you would be perfectly alright if you gave a little jump just before it hit the floor.

Chris

I used to believe that the sun moved up and down in space and that's how we got seasons... then I discovered the tilt of the earth. I also believed that the North and South poles of the earth were due to a giant bar magnet with hte red end sticking out of the North pole and the blue end sticking out of the South pole.

Russ

When I was smaller I always thought that instead of the water filling the glass from the bottom up, it would fill from the top down.

Emily

My older brother told me when I was 3 or 4 that the reason ships float is because they are so light. In fact, they are so light I could lift an ocean liner with my little finger. I figured out the truth by the time I became an adult.

M.A. Stolz

I used to lay on the ground looking up at the sky, watching the clouds go by. I thought that was evidence that the world was turning, as if the clouds were stationary, and the world moved beneath them.

Zen_Sorcere

My parents are religious fanatics, so of course they did not properly explain the "big bang" to me. I am now an atheist, but back then (when I was 7 or so) I thought the "big bang" theory was idiotic. Why? Well, because I thought that the BIG BANG meant that something went *kaboom* and *poof* there was the earth as I knew it! My parents also told me that the theory of evolution meant that humans evolved from monkeys! But then, many uninformed people make that mistake...

Rose

I used to believe that the front of our green family van was the direction north. Whichever way the van was facing was how direction was determined.

Troy

After spinning around in a chair or just self-propelled, I thought the spinning environment was the earth rotating. I used to do it a lot cuz i thought it was the only way i could see the earth spinning.

tree

As a bit of backstory, my Dad, as a child, skipped Kindergarten. Until around 46, my dad thought that the primary colors were just a myth, and you could mix something like green and orange to get red. We still tease him about this.

Anon

It doesn't fit the vehicle categories, but I think this one's pretty good:
When we were kids a friend of mine thought a ten centimeter long propeller driven ship I had in my bathtub was exactly as fast as the ferrys from Norway to Denmark, because it was a copy of one of them. I disagreed even though I was two years younger. We got into a really long and tiresome argument about it, and I don't think we ever managed to agree. It's been years since I saw him, but if I run into him maybe I should ask if he still thinks it could be the case. He's 34 now.

Christer

When I was embarrassingly old--9 or so, I think--I used to believe that if you had half a glass of water and stuffed a washcloth into it, and the water rose to the top of the glass, you now had a full glass of water. My mother was unable to explain displacement in a way that satisfied me, so I held on to my belief persistently.

Ward Webber

I knew that the earth was spherical for as long as I can remember... but I do remember a time (until I was 4 or 5) that I believed that people on the other side had to hold on to these rungs when they moved from building to building to keep from falling out into space. I thought the houses were made so that the people walked on what we think of as the ceiling... with their feet facing the sky.

Rose