In short, Star Trek.
Once when I was very young I remember being scared to go into space because I thought I might fall into a black hole. (Come to think of it, it might have been after seeing Voyager's
second episode, which was itself a goldmine of hilarious misconceptions) At the time I thought things like stars and galaxies just floated around inside the solar system and posed real threats to the space shuttle.
Later on, I'd read books like The Science of Star Wars or A Brief History of Time and come up with crazy theories for warp drives and weapons, etc; such as shooting a bullet close enough to the speed of light that it would become small and massive enough to collapse into a singularity and swallow enemy ships; or using the
GUT to basically make anything you wanted (such as gravitons for warp drive or strange matter to hold open a wormhole) out of poo by heating it up enough. (God particle from the machine?)