Crop circles: real or hoax? (Physical/Earth News).

They"--or "it"--flatten sprawling mysterious circular patterns in fields of barley, oats, or wheat, leaving surrounding plants untouched. But how?

Explanations range from freak weather conditions to alien visitors. But as actor Mel Gibson discovered in Disney's recent movie Signs, crop circles pose one strange puzzle. They first appeared in England in the 1970s--but some historians claim crop circles existed as far back as the 1800s. In the early 1990s, artists began claiming responsibility--one group, the Circlemakers, even explains the process on their Web site.

But if crop circles are mere artistic pranks, why have some British and American scientists spent decades studying cereology, the crop-circle phenomenon?

"Some formations bear no trace of a human hand," says cereologist and electrical engineer Colin Andrews, who's studied thousands of circles: Eighty percent are human-made, he claims. The rest? "Possibly by an energy we've never met," he says.

Biophysicist W.C. Levengood of the BLT Research Team in Cambridge, Mass., has compared hundreds of plants inside and outside crop circles. In crop-circle specimens he documented oddities like microscopic holes perforating the thin barriers, or membranes, that surround plant cells, and unusually swollen stem nodes, joints from which plant leaves and branches originate. These changes could result from bombardment by invisible energy waves called microwaves or low-frequency sound waves (infrasound) generated by objects in space, like meteors, he claims. But why such waves would concentrate in such bizarre, circular patterns baffles Levengood.

Another possible cause? Magnetic fields, or naturally occurring lines of attractive or repulsive force that radiate between Earth's north and south poles. Andrews measured magnetic force fields inside and outside the circles. In some circles, Andrews says, the magnetic field is tilted 10 degrees from the norm, which could create a forceful energy that flattens a crop. "Maybe," he muses, "someone is trying to tell us something."