Scientists are rethinking the fundamental principle that scientific theories must make testable predictions. If a theory doesn't make a testable prediction, it isn't science. It's a basic axiom of the scientific method, dubbed “falsifiability” by the 20th century philosopher of science Karl Popper.

Why is it important for a theory to be falsifiable?

For many sciences, the idea of falsifiability is a useful tool for generating theories that are testable and realistic. ... If a falsifiable theory is tested and the results are significant, then it can become accepted as a scientific truth.

What does it mean that a theory is falsifiable?

able to be proven false:All scientific theories are falsifiable: if evidence that contradicts a theory comes to light, the theory itself is either modified or discarded. ...