Magic works by tricking the universe into thinking something is there when it isn't, or thinking something isn't there when it is. At least, in essence, that's the current theory. As a result, mages can levitate objects, make objects seem heavier, cause fires, make things much colder, and cause buildups of electrical charge where, ordinarily, there wouldn't be - and cause small lightning storms. Of course, there is something there: magic, which has, over the centuries, been observed and studied as much as electromagnetism and gravity. It follows an understandable set of laws which can be used to enhance inherent magical talent and advance technology.
In an effort to better understand magic, mages have become scientists like alchemists became chemists. At this point in time, their analogue of Neil DeGrasse Tyson could probably take on Dumbledore, but otherwise their science looks roughly the same as ours (although they have a slight technological edge in some areas). But because magic has been studied in such detail, I'm starting to question whether scientists would even call it "magic." It's an explainable, natural, recurring phenomenon which has been dissected and tested via the scientific method for centuries now.
If magic existed, would scientists call it "magic"? Or would they dismiss the word as mere superstition from a less civilized area and insist that it be called something else, with fewer supernatural connotations? Or would "magic" be nothing more than a word that high school students dread to hear, like "chemistry" and "physics"?