One pair of scientists thought they’d discovered a new antiviral protein buried inside skin cells. Another research team saw early hints suggesting that the flu virus might cooperate to boost infections in humans. And a nationwide team of clinicians thought that high doses of certain vitamins might prevent cancer.
These studies don’t have much to do with each other, except that the researchers had all based their hypotheses on convincing earlier data.
And those hypotheses were all wrong.
The hypothesis is a central tenet to scientific research. Scientists ask questions, but a question on its own is often not sufficient to outline the experiments needed to answer it (nor to garner the funding needed to support those experiments).
So researchers construct a hypothesis, their best educated guess as to the answer to that question.