nodeamass, I think you need to pull out your science dictionary again. A theory is a plausible explanation for something observed in nature. A law is a theory that has been tested rigorously without the research obtaining results that negate the theory. Since the time required to actually do an experiment that would prove Darwin's theory make such experiments impractical, evolution remains a theory without sufficient experimental evidence to prove its validity. On the other hand, we have the Law of gravity. While it has changed since Newton's time, no experimental results have substantially negated it.