No, not the great song from the even greater musical, Wicked. I’m referring to another act of science in this case. Colarado-based land artist Michael Grab patiently stacks pieces of rocks in his free time to create a whole bunch of gravity-defying rock structures. Not exactly sure how he manages these, but his series “Gravity Glue” is quite the feat I’d say. "If not observed carefully, one small . . .