The one and only major problem to be solved is how to assemble into an efficient H-bomb the materials we already have at hand or will have in a few months. Here, too, we are much farther advanced than we were at the time we decided to build the A-bomb, as we are not called upon to start from scratch. For whereas in the early days of the A-bomb development scientists were doubtful whether it could be made at all and were actually hoping that their investigations would prove that it was impossible, for the Nazis as well as for us, no such doubts seem to exist in the minds of those most intimately associated with the problem. On this score we have had more than hints from a number of those in the know, among them Senator McMahon. “The scientists,” he said in a historic address to the United States Senate on February 2, 1950, “feel more confident that this most horrible of armaments [the hydrogen bomb] can be developed successfully than they felt in 1940 when the original bomb was under consideration. The hydrogen development will be cheaper than its uranium forerunner. Theoretically, it is without limit in destructive capacity. A weapon made of such material would destroy any military or other target, including the largest city on earth.” What is this confidence based on? Scientists are a very conservative lot, not given to jumping to conclusions without experimental evidence on which to base them. I remember well the agonizing hours preceding the test of the first A-bomb in New Mexico, when everyone present, particularly the intellectual hierarchy that was most responsible, was beset by grave doubts whether the A-bomb would go off at all, and if it did, whether it would live up to expectations or turn out to be no more than an improved blockbuster. Very few, if any, felt confident that it would be as good as it finally turned out to be. For example, in a pool in which everyone bet a dollar to guess the ultimate power of the bomb in terms of TNT, Dr. Oppenheimer placed his bet on 300 tons. This makes it evident that the scientists were not very confident even as late as 1945, up to the very last minute, when “the brain child of many minds came forth in physical shape and performed as it was supposed to do.”