The Copernican principle states that there's nothing special or unique or privileged about our local frame of reference: we're not at the center of the solar system, we're not at the center of the galaxy, this is not the only galaxy, and the next logical step would be to posit that this is not the only universe.
I do not believe in reincarnation of any sort. I believe this is my only life.
It has been believed that the Earth was flat. I'm sure at least someone had considered the implication that the Earth goes on forever. This has turned out to be false. The Earth has positive curvature, and thus only finite surface area.
Quite a few people have considered the idea that atoms are little solar systems, which could have their own life. It turns out that electrons are almost certainly fundamental particles. And even if they're not, the way physics works on a small scal...
As per a recent comment this thread is meant to voice contrarian opinions, that is anything this community tends not to agree with. Thus I ask you to post your contrarian views and upvote anything you do not agree with based on personal beliefs. Spam and trolling still needs to be downvoted.