 In 1951, his book "The Hell Bomb" warned about the use of a cobalt bomb – a form of hydrogen bomb (still an untested device at the time he wrote it) engineered to produce a maximum amount of nuclear fallout.In 1956, he was present at the testing of a hydrogen bomb at the Pacific Proving Grounds.That same year, he was appointed science editor of the "Times", succeeding Waldemar Kaempffert.