About ten years ago, doing research for a book, I asked Freeman Dyson about a study he’d helped do about whether we would have lost the war in Vietnam a little less if we’d used tactical nuclear weapons. Dyson and two colleagues, all members of a scientific advisory group called Jason, were doing this study back in the mid-1960’s, more or less on their own hook; no one had asked either them or Jason to do it. They did it anyway because they’d overheard a Pentagon power honcho remark off-hand that it might be a good idea to throw in a nuke once in a while just to keep the North Vietnamese guessing. The remark reflected loose talk at the time that the few nukes dropped on mountain passes might block the passes and stop the enemy army from coming south. “You can do that wonderfully well with a few bombs,” Dyson said. “You blow down all the trees.” And I thought, “How does he know that?”
It turns out that while tactical (i.e., little) nuclear bombs do blow down trees wonderfully well, the large enemy army only has to clear a path through the blown-down trees and keep moving south. “It’s only bought you a couple of months,” Dyson said. “And you can’t blow down the same trees twice. After you’ve blown them down, that’s it.” He was snickering. I didn’t bother asking him how he knew this and didn’t think about it again until a couple of weeks ago.
I was interviewing another scientist who started digressing into the old nuclear bomb tests out in Nevada. “Tree blowdown was experimental,” he said, meaning they knew how nuclear bombs blew down trees because they’d done it. Continue reading
I did a big run on Saturday morning. On Saturday afternoon, I stuffed my face, had a welcome beer after a 
