What is science?

What a silly question?  Science is ... you know ... "The answer to life, the universe and everything (Douglas Adams)"

It's harder to answer than you would expect.  Most people think it is the search for unassailable truth.  They will often be disappointed. The real, underlying question is: "What do people expect from science?" 

I just completed a book, "Foundations for a Science of Systems".  In order to answer that question, I had to identify the "systems of science" - showing that science is the interaction between 4 "worlds" - the Physical World, the Mental World, a Conceptual World (the three "worlds" of Karl R. Popper), and a relatively recent world, "The Platonic World of Forms" - a world of structure described by the Platonist physicist Roger Penrose, among others.  These four worlds are connected by six "languages" - percepts, schema, forms, cognitions, mathematics, and a complex series of languages that analyze, normalize, and synthesize intermediate results with evaluation and realization (ANSwERs).  Hey, what about natural language? All of these languages start out being described in whatever natural language - words, drawings, music, dance - that the communicator is comfortable with.  Note, too, there are many mathematical languages.  I use Category Theory, but others work too.

It is said, the objective of science "is to separate the demonstrably false from the probably true" (which seems the most correct and complete statement from many points of view). Science is a system - a complex coupled system - with an identifiable "form" (a formal system) that is used to build "valid" knowledge.  You can't tell if something is true, or not, if the process isn't valid. Validity means that the processes are consistent, if not complete.

So, how do you know you've reached "the answer"?  Science only asymptotically approaches the truth. Answers are either sufficient, or not, today.  They get better, or are revised, over time. That's probably the best one can reasonably expect from science.