No Proof

In his article, Where's the Proof in Science? There is none, Geraint Lewis compares science to a courtroom:

So, science is like an ongoing courtroom drama, with a continual stream of evidence being presented to the jury. But there is no single suspect and new suspects regularly wheeled in. In light of the growing evidence, the jury is constantly updating its view of who is responsible for the data.

Sure, there's evidence, but that is not the same as proof. As the statistical probability grows, we grow more confident in our beliefs, but we never reach that magical 100% certainty that we all desire. 

The one person who was sure that he had reached this state of 100% certainty was Rene Descartes. He is famous for saying, "I think, therefore I am." And yet, his certainty is today an easy target even for Intro to Philosophy students. Descartes sought a sure foundation on which he could built the whole edifice of knowledge. If you build your structure on such shaky ground it's sure to come falling down. 

If you want 100 Proof, you'll probably have to turn to Vodka, not science.