At the most basic level, the universe is governed by the laws of quantum electrodynamics and general relativity. These theories have been verified experimentally to eleven and twelve decimal places, and they apply over an enormous range of situations. However, these theories become very difficult to apply in situations with many interacting pieces- there is no exact solution in the existing literature for the dynamics of the lithium atom, or for a system of four point masses moving through space. To get around the complexity, we use approximations, and this usually works well- we can still understand that a heavy safe will fall, even if we don’t do out the tensor calculus for how a large, nonuniform object will behave in the warped spacetime of Earth’s atmosphere. But these approximations exist only in our minds, not in reality; there are no objects in our universe with the intrinsic property of liquidity, even if “liquid” exists as a convenient mental category.
Things like art, music, and writing are far too complex to describe in terms of atoms, or even in terms of the biology of human neurons. Normally, this wouldn’t be a very big deal; we would simply invent rules-of-thumb to describe art and music that didn’t require exact analytical solutions, and go on our way. But due to the psychology of our species, we invented art, music, literature, and so forth long before we even knew what the heck an atom was. When we began our studies of how wood burned in oxygen, it wasn’t obvious that the same laws that describe wood burning describe our experience of a nice piece of poetry. Clearly, no matter how much research you do with wood, it can never apply to Art- for are not Art and a piece of wood two entirely separate kinds of thing? And so began the division of the world into genres of study; and lo, this division persisted throughout the ages, for Art and wood felt like two totally unrelated things, and humans are reluctant to abandon a feeling for a fact.
When we finally discovered around eighty years ago that reality was unified at the deepest level, we did not take it well. Some of the saner theologians at least had an excuse- they claimed that God was not part of reality, and so should not have to follow reality’s laws; this is a valid conclusion if you accept the premise. But the social scientists and humanities people continued to claim that their arts were somehow separate from the rest of the universe. The social scientists were eventually outed- they did, after all, claim that they were doing science, and so they could not ignore forever the mountain of experimental results favoring an integrated causal model. And to maintain that what they were doing was separate from science, the humanities people were forced into writing papers with no substance; to make a claim, after all, you need to make a prediction about how the universe will look, which brings in science. This has had the strange effect of negative progress in many humanity-related fields; the Renaissance artists would have laughed at you if you hung random smears of paint in a museum, but modern artists get paid millions for it. And so the time is ripe for the Glorious New Revolution- if the Renaissance men could produce masterpieces from intuition and guesswork, think of what we could do with modern cognitive science and evolutionary psychology.