In the end, I keep coming back to the question of how you know a weapon works if you cannot test it. (Or, for that matter, how testing ever established reliability since it destroyed the object whose reliability it demonstrated.) Who am I to question the judgment of the physicists who have spent decades honing their expert knowledge of this arcane field? Still, I keep thinking of a conversation I had in 1995 with a senior weapons designer, now retired, who told me that an inexperienced designer with a code is like a drunk driver, wrongly convinced of their excellent judgment. And I cannot help but notice a 2012 Department of Energy report complaining that National Ignition Facility shots were not producing the energy levels predicted by simulation codes. Nor, in 2015, has the National Ignition Facility met its former director’s prediction of reaching ignition—getting more energy out than was put in—by late 2012.