When a was a kid – not quite a teenager, but close enough – I fell big-time into the UFO craze, reading book after book about ancient aliens visiting us (just what else explains those biblical angels “floating in mid-heaven”?), and swallowing all their claims pretty much whole. How, for example, could ancient cultures have created giant figures on the ground, such as giant stylized hummingbirds, without alien overseers hovering in spacecraft to guide them? And how else to explain the perfect symmetry of crop circles, unless they were caused by flaying saucers landing on rural fields and crops? Then I read one account that, at age 12, pretty much made me go, “Oh.” Giant figures in perfect scale? Math. Perfectly round crop circles? Put a stake in the middle of a field, tie a length of rope to it, and walk around in a perfect circle, mowing everything inside. “Oh.” And yet, these TV specials keep appearing…