Fatherly in manner, with white hair and a full white beard, Needham had been described to me by a colleague as a “cross between Santa Claus and Eeyore,” an impression that belied his stature as a high wizard in the black art of explosives. With degrees in physics and astrophysics, he is an authority on modeling all variety of blast events and the dynamics of blast reflection, and he spoke with wistful nostalgia of the big “rumble booms” of high-ordnance tests of years past. A glance at his résumé calls attention to the diversity and sheer spookiness of blast-related issues: “modifications to fireball behavior,” “high explosive simulation of nuclear effects,” and “Shock and Vibration symposia.” Needham’s objective was to provide breachers with maps that would show which areas of a given type of structure are safest from reflected pressure. How a blast is reflected is determined not only by whether a space is square or rectangular, and the ceiling high or low, but also by where the wall studs lie, the number and placement of doors and windows, whether there are gaps or holes in the enclosure, whether there is furniture in the room. A shock wave bouncing off a rigid surface, whether of thin plaster or of steel, can be more powerful than the original wave. (Notoriously, the back-blast reflected off the ground at Hiroshima was more powerful than the actual explosion.) The corners of a room, where one might instinctively seek shelter, are particularly dangerous—as is being the third man in a line of breachers carrying protective shields, which, as it turns out, also reflect shock waves. A blast even reflects from within a soldier’s helmet to his head. Every feature in a landscape, every gesture a person makes, shapes a blast event. A terse conclusion of the original 2008 breacher injury study cited “clear evidence” that recommended safe standoff distances required
stickers on uniforms and helmets, may provide an objective measurement of blast exposure. Despite the array of promising strategies, for the time being diagnosis still depends, as it did in WWI, on clinical assessment, which may now involve computer-administered examinations such as the Automated Neuropsychological Assessment Metrics: “Did you experience any of the following: Dazed, confused, saw stars? How much does this word describe how you feel? ‘Shaky.’ ” COMPLEX AS IT MAY BE, a blast event can be created for very little money and with minimal expertise. Explosively formed penetrators, a type of IED used to pierce armored vehicles, can be assembled for a few dollars. Disks that become bullet-shaped and molten hot as they fly through the air, these explosive projectiles can, in the words of one ordnance expert, cut through an armored car “like a hot butter knife.” In this way 25 dollars’ worth of technology can take out a armored vehicle and kill or inflict grievous injury on the soldiers in it. The cost of their medical care—possibly over decades—will add significantly to the economic disparity. Given this cost-effectiveness, explosive force is likely to remain a signature weapon of modern warfare. Today, while researchers strive to figure out what goes on when blast force encounters the human brain, untold numbers of soldiers are struggling with the aftermath of their own encounters. BOOM. On patrol in Iraq in 2009, Robert Anetz felt the immense pressure against his body. Then everything went numb. “Everybody started shouting, ‘Are you good? Are you good?’ You check for blood,” Anetz said. There was no blood, so he thought he was good. But seven