In 1953 I was inducted into the Army. Since I had studied physics at college and worked for a short time in private industry, I was assigned to the Enlisted Scientific and Professional Personnel (SPP) Program and sent to the Army Chemical Center, in Edgewood, Maryland. There were more than two thousand SPPs at the center when I arrived, many of them recent graduates. We lived in a dormitory, and at times it felt almost as if we were still at school. That is, for a while.

My job was to design and develop instruments to assess the yield of nuclear devices. Much of my work was stimulating, but other people were less fortunate. One evening at Drago’s Pizza & Bar, a group of us decided to stave off boredom by organizing a physics seminar, with each of us presenting a paper in his area of expertise. We asked Colonel Delmar, the laboratory commander, for permission, and he granted it, provided the seminar wouldn’t interfere with our assigned duties.

We met weekly, giving papers that, considering our circumstances, were quite professional. But inevitably we began to run out of topics, and rather than disband we decided to seek outside speakers. Dan Smith, an audacious Texan, came up with the outrageous suggestion that we invite Robert Oppenheimer, the principal scientist responsible for the Manhattan Project.

Since none of us knew Oppenheimer, this was akin to law students inviting the Chief Justice of the United States to participate in a moot court. Nevertheless, Smith and I agreed to write him at Princeton, where he worked. Several weeks later we received a letter accepting our invitation. Shock set in.

We now faced an awkward situation. The Army Chemical Center was a secure installation, and after the well-publicized hearings questioning his loyalty, Dr. Oppenheimer’s security clearance had been revoked. When we presented our problem to Colonel Delmar, he was appalled. Our reckless act had put the Army in an impossible position, he pointed out, and we risked humiliating Dr. Oppenheimer. The colonel recommended that we write a letter postponing the visit “due to pressing Army duties.” Dr. Oppenheimer graciously wrote back that he would be happy to address us at a more convenient time.

A few years later, separated from active service, I attended the annual conference of the American Physical Society in New York. The scheduled speaker was the eminent theoretical physicist Wolfgang Pauli, and as I entered the hotel lobby, I ran into my old friend Dan Smith. Suddenly there was a stir in the room, and I heard someone say, “Oppenheimer’s here.” We spotted him standing all alone in a corner of the room. This was surprising, given his celebrity, and Dan and I decided to go to him to explain