Robert Smithson, most notable for the "Spiral Jetty", was also a prolific essayist on contemporary art – "Entropy and the New Monuments" (1966) being one of the most well-known. In it he criticizes a wide swath of sculptors and artists of the time – Donald Judd, Robert Morris, Sol LeWitt, and Dan Flavin. His main beef is that their work – apparently because of their man-made materials – achieves a monumentality that has an "all-encompassing sameness," and as such becomes entropic.
My first issue with this article is one of scientific accuracy. If you're going to reference science in an essay, get the science correct, or you're compromising your point. Smithson makes the mistake of confusing entropy with sameness, and they are quite different. As pointed out in other places, entropy is a state of increased information, which isn't necessarily homogenous.
But let's address his actual point, and not the means by which he analogizes it. The point of the first part of the article, as I understand it, is that by utilizing artificial materials ("plastic, chrome, and electric light"), the artists deny "time as decay or biological evolution", and hence bring about the "destruction of classical time". Smithson summarizes: "this reduction of time all but annihilates the value of the notion of 'action' in art." This point seems immediately dated, considering how contemporary art has progressed in the decades after his writing – the use of plastics, metals, and lights have been replaced by video, data, and relational aesthetics. But I also disagree with his placement of value on a natural sense of time – perhaps because our current culture, through its instantaneous communication, on-demand entertainment, and 24-hour news cycle, has made us all used to, and possibly expectant of, a highly unnatural temporeity. "Classical time" is a quaint artifact. Decay has been replaced with planned obsolescence and disposable items. While he might not like the aesthetic of these modern materials, the prescience of the artists using them at the time can no longer be denied.
The second half of the article ties in crystallography, laughter, and multidimensional math in rather awkward ways, working to a point that at first reading evaded me. While remaining critical of highly polished, reflective "California" surfaces, he seems to begrudgingly grant Donald Judd and other artists a measure of respect, stating:
These artists face the possibility of other dimensions, with a new kind of sight.