What is the Beer–Lambert law?

What exactly is a scientific law? What is the absolute definition of a law in science? Can a law change if sufficient evidence nullifies it?

• I'm asking this because a few times I've been told that my understanding of what a law in science is, was wrong. Granted, I'd very much like to know what the definition held by ALL SCIENTIFIC COMMUNITIES is. Not a mere opinion of what a law may or may not be. Also, what is a law dependent upon? Outstanding evidence? I've been told that a law is a mere mathematical expression of a theory, to me, this renders a law (ANY law) to be merely theoretical and only able to hold on if evidence supports it.

• Answer:

  A law is a statement that generalizes a set of observations. That's pretty much it. A law will state that a phenomenon takes place, and will often provide an equation that codifies the phenomenon. E.g. Hubble's law states that the more distant a galaxy is, the greater its recessional velocity (the equation is v=HD, where H is Hubble's constant). Laws do not explain "why" phenomena behave the way they do, however. That's what theories are for. Contrary to what many people think, a theory does "not" become a law when it gathers evidence. They serve different purposes (laws state, theories explain), and both are heavily substantiated. Confusion often arises between the colloquial and scientific meanings of the word theory. A scientific theory is an explanatory framework that may include multiple laws, but a theory is never subordinate to a law. A theory is, in fact, the highest level of support a concept can achieve. If science consisted of nothing but "statements" with no explanations whatsoever, we'd be pretty blind to reality. And yes, laws can be modified (or succeeded by more accurate laws, which is often the case) if evidence arises against them.