As science progresses we learn more and more. But getting there is an arduous process and one that has been riddled with mistakes. In order for somebody to discover something right, that means other people had to be wrong. This gallery highlights 24 times everyone thought something was crazy, but was later proven to be right. 

Famously, Ernest Hemingway believed that the FBI was watching him. The writer was known to be paranoid, and the majority of people believed that this theory was just an example of that. However, after his death, it was revealed that he was indeed being watched by the FBI under suspicion of connections to communism. But like most similar suspicions of the time, that was incorrect. 

It's incredible how far the medical profession has progressed in the past 100 years, especially in regard to the spread of germs and diseases. Germ theory was laughed at, and doctors routinely moved from one patient and operation to another without washing their hands or cleaning anything. They also then failed to recognize many telltale signs of resulting infection. All I can say is that I'm glad they came to understand the truth.