Not really Physics this one but...

Iused to believe that living things were made out of cells and non-living things were made out of molecules.

A wonderful theory until you realise that molecules are a LOT smaller than cells!

Bob W.

Once, I believed that if you put an eraser in the microwave, it'd melt into really cool, gooey rubber. I tried it and nearly blew up the microwave.

Jessica Tinch

I used to think what heated the food in the pan was the boiling water, not the heat under it.

Mario

I used to believe that batteries in an appliance (like my old sony walkman) would 'spin' when the item was used.
I spent many hours quickly opening the battery compartment trying to see the batteries turning, but obviously didnt succeed!!

Paul Peej

I used to believe that the boiling water was air passing through the bottom of the pot wich was dilated because of the heat

PonC

I used to believe that each people has their own perception of color, for example: I see color red as red, but when I was a kid I used to think that others may perceive different. I see red but they see other color, and we describe the same color because we are used to it since birth.

Anon

I used to believe that the world was actually flat, and that we were at the bottom of the universe, with the sun and moon, and all the stars floating up above us.

Ben

that red and orange were different shades of the same color

Larry

My sister has an excellent design for a spaceship.

First take a house and tip milk all over it (milk is actually an excellent form of glue), then find out exactly how fast the house is moving, from Heisenburg's Uncertainty Principle, it now follows that the house could be anywhere in the universe.

Note: The reason you have to first tip milk all over the house, is to glue the house up and stop yourself from suffocating if you end up in deep space, rather than on some inhabitable planet.

Anon

I used to believe that because of the damage it does, UV light' was 'ultra violent light' not 'ultra violet'.

Jane

The industrial part of my childhood town had a particular large stormwater runoff drain, at least large enough for one car to drive through, and for many years (I think i was 10 when i started questioning the reality of this gem) i honestly believed that if you stood in the drain you would be cloned. Yes cloned. This was 20 years ago so i guess i must have got the idea from Buck Rogers or some early sci fi crap

Daleen

When I was like 3-4, I wanted a horse shoe shaped magnet. I had seen Tom and Jerry use one to attract everything made of metal. I was wery dissapoitet when i found out that it wasnt true. I also always was dreaming about owning a metal-saw. With one of those i would be able to saw everything!!!

Anon

I had an idea at school to dig a tunnel through the centre of the earth and out to the other side. I would then drop things down it and since the object would be moving faster as it passed through the core, gravity should have less effect and it should shoot out of the tube and into space then other side. It could have been used to dispose of nuclear waste or defend Earth from asteroids but it never materialised.

Jonny

When I was young. One of my friends came up with a way to send signals faster than the speed of light.

It went like this. If you have a pole long enough (i.e. from the earth to the moon) and you jolted the pole on earth. The pole would instantaneously be jolted on the moon, thus sending a signal faster than the speed of light.

Oh How we argued for years over that one :D

Joe

I used to believe that electrons orbiting around a nucleus were a small solar system, with people actually living on the electrons.
The earth was also an electron on an atom in a much larger world.
Time is also relative in all these worlds; say if I were to throw a piece of paper into a fire, the seconds that it will take the paper to fall into the fire are like eons to the inhabitants of the small universe on the paper. Likewise, if someone in the large world tosses the paper we are an atom on into their fire, what seems like a couple seconds in their world will be centuries in ours. So.... suppose the giants have already tossed our piece of paper towards the fire....?

BoB

When I was about 3 ys old I would roll a can (probably a soup can) across the kitchen floor. It would slow down about 8' away and then begin to return roll back to me only to stop again about 3' away and then go forward. Back and forth a few times till it stopped in the middle of the floor. I believed there was some cosmic attachment the can had with the universe, and that the process of rolling would cause it to twist up like a spring in a clock is wound up. It then would return the energy and cause the can to reverse the roll. I accounted for it not making it all the way back each time as energy dissipated by friction. My error was assuming that the floor was level and not concaved downward in the middle of the floor.

Rob McKenzie

I was always scared to walk over bridges, especially wooden ones. I thought that they would collapse on me (probably got this idea from watching too much disaster tv or something). One day, when I refused to walk over a bridge, my mom told me to walk across where the nails were, cause underneath the nails were the beams that held the bridge up, so if the bridge collapsed I would still be standing on the beams and be safe. This made perfect sense to me and I never had a problem again. I guess it never occured to me that the beams would probably fall too. The funny part is, I'm now 20 years old and I still find myself walking on the nails whenever I cross a wooden bridge. :)

Sarah W.

I used to believe that if I threw a paper airplane hard enough, and held on tight enough, that I could fly with it. It only took one failed attempt to realize I couldnt

Ben

My mom told me that the earth was always spinning. This fasinated me, but the next morning when I woke up excited to see my back yard and front yard switched I was very disappointed. My mom had to explain to me that it was the whole earth that moved, not just the yard around the house.

Anon

I use to think that if I laid real still in my bed at night I could feel the earth turn. I would do this all the time. I convinced myself I could feel the earth turn.

just a kid