It is said of Jackson Pollock's paintings that one must experience them in person to "get" them, that the in person experience is a completely different thing. This is true, my experience of Pollock's paintings in person was eye-opening. They're very big, it turns out. Enormous.
Abstract art in general is a fine fine theory. Art is about communication. We have a rich collection of visual symbols we can use to express emotions and ideas. It is the (or at any rate a) role of art to combine these symbols in evocative or thought provoking ways. Arguably, in appealing ways as well.
When we shoot in black and white, we deliberately reduce our available vocabulary, in exchange for a connection to other work and access to certain powerful idioms. By reducing our vocabulary, perhaps we tighten up our communication, make our ideas clearer and sharper. Frankly, we make the job easier, as well. Photography itself works in a reduced vocabulary, being two dimensional and static, as opposed to sculpture or film, say.
Abstract art merely removes another part of the vocabulary, that of identifiable representations of things. Surely an mysterious shape can look terrifyingly, or swoon with emotion, or whatever?
It turns out this is really hard.
Alfred Stieglitz took a bunch of photographs of the sky, wispy clouds on a dark background, which he called "Equivalents". The idea seems to have been to evoke emotional response with these essentially abstract pieces. The work was evidently well received in the 1920s, and were pretty much ground-breaking as the first important work of abstract art with a camera. They were probably significant in getting photography accepted as "art" by the art community.
They do pretty much nothing for me. Too much of the vocabulary I can understand is stripped away. I think they're superb for what they are, I can feel them almost working, and they probably work very well for some people. Some work for me better than others, but I am pretty sure that's because they're evoking specific objects and shapes, rather than operating at a visceral, emotional, level.
If you haven't seen these things, go look at them. Whether they work as art or not for you, they will certainly open your mind to possibilities.
I "get" what the Equivalents photographs are trying to do. I think I even "get" what Pollock was going for. Christo? I dunno, that guy's just nuts. It just doesn't work for me.