There are many things in science that didn't have concrete evidence to the contrary before they were researched; where do you think concrete evidence comes from

There are many things in science that didn't have concrete evidence to the contrary before they were researched; where do you think concrete evidence comes from if not starting to research? It's ironic that you criticize propaganda on one hand while suggesting that we just believe whatever we're told is true without question on the other hand. What is that if not propaganda?