Editor's note: content reprinted from our Scientific American Min article "A Faithful Resemblance"
Twelve years ago today, Photojournalist Mark D. Phillips captured the World Trade Center, engulfed in smoke and flames, seconds after the second plane attack. Unknown to Phillips at the time, the picture, distributed by Associated Press and published on the front pages of several newspapers, contained the face of none other than the Prince of Darkness. A media frenzy ensued, and Phillips, who retired from photojournalism that same day, received more than 30,000 messages related to the “face of evil” in the murky cloud and the feelings it brought forth in the viewers. One year later computer scientists Vladik Kreinovich and Dima Iourinski of the University of Texas at El Paso published a geometric analysis of the face in the photograph, also seen in a different image from CNN. The analysis showed that perturbations in the smoke can consist of horizontal lines (such as the “eyes” and “mouth”) and vertical lines (such as the “nose”) overlaid on a conic surface (the “head”). The scientists concluded that both the background shape (the cone) and the features on the background (horizontal and vertical lines) are naturally explained by the physics and geometry of smoke plumes emanating from fire.