Everything is art. But the human determination of such is a matter of physics and economics.
I disagree. What about a nuclear blast? Not a photo or video of the event, but the blast itself? Lots of physics and economics involved in that, but were either Hiroshima's or Nagasaki's blasts art?
Nature can be art, as perceived by one observing. A tree is art. The leaves on the ground are art (wind is the painter). A human didn't necessarily intervene (what if you planted the tree?), but it's our perception of beauty and emotion.
A photograph of a tree or vista can be art (Ansel Adams anyone?)...
Nature can be beautiful, but not art. Nearly anyone with the gift of sight has seen beauty in a sunset, but did the sun, earth, and atmosphere intend to create the view? Is it art or natural beauty? We would all agree that a photo or painting of the same vista is art; the artist took action to create a representation of what they experienced. But is the sunset itself art? Can it be caused? Can it be sold?
...whether taken by a human or a Google car autonomously (the driver isn't the artist, is the person who programmed the timing of the photos?).
Art implies an artist and an intent. For something to be art, it must not have "been" and then must "be" by the artist's conception and action. Ultimately, an item must be observed by a second party and experienced before it is art, or is it art without being
Anything can be art.
So a computer making art isn't a surprise, it should be expected. It might not be born of human emotion, but that isn't necessary.
Art doesn't require a specific act to create it. Accidents can be art. Mistakes can be art.
Regarding economics, is it worth money? Then it's art...
In nearly all debatable cases (e.g. "Artist's Shit", pornography, graffiti, etc.), the debate centers on what beauty or meaning (i.e. value) could the viewer ascribe to the item in question. Questionable performance pieces may not fit the classic definition of beauty, but do evoke reaction and experience and memory in the viewer thereby satisfying the artist's intent. There's usually some understanding that a consensus or plurality of observers who individually find beauty/meaning in a piece would agree "yes, this is art".
In this case, the debate is more on the definition of art itself as opposed to the substance or interpretation thereof. Can something created without intent be called "art"? The AI didn't choose to make the piece -- it was instructed to make something according to a set of rules made by a programmer. Sure, there may have been a fair amount of learning, training or genetic pruning to get the result...and someone may be willing to pay for the beauty/meaning/novelty they see in a copy of the product...but the AI did not intend for a viewer to derive anything from viewing/experiencing the product.
The one day you'd sell your soul for something, souls are a glut.