Only the Best
Science does not provide absolute certainty. It provides scientific theories. Scientists often announce the level of certainty or uncertainty they have in their results from testing a theory. This helps us weigh up their evidence for the theory.
Established scientific theory, such as atomic theory or evolutionary theory, make predictions. These predictions are testable.
For example, evolutionary theory predicts that nobody will ever find fossils of mice in layers of rock that are hundreds of millions years old. If the fossil mice were found, that would show that there is something very wrong with evolutionary theory. A lot of people have looked at a lot of rocks but have not found the one fossil mouse (or bat or human) in the wrong kind of rock that would show that ideas about evolution are wrong.
It is good practice for scientific theory to be set up so that predictions using it can be shown to be false by new observations. This is known as falsification.