the atomic nucleus remained rudimentary. Even as the list of so-called elementary particles produced by accelerators grew into the hundreds, theories proliferated, but none were mathematically satisfactory. Neither the aging giants, such as Werner heisenberg, nor the young geniuses, such as Feynman, knew which way to turn. The tantalizing success of QED only added to their frustration. By mid-century the new physics was beginning to pay off in a wide range of applications. Its scope extended vertically, as it were, from the unimaginably small interior of the nucleus up to the incomprehensibly vast stretches of the universe. At the same time, physics also had a powerful horizontal impact on other branches of science, often by way of novel instrumentation, and on technology. For biology, physical methods brought about spectacular results. The discovery of the double helix of the DNA molecule, revealed by X-ray/images of crystallized DNA, triggered a revolution in genetics. Henceforth the mechanisms of heredity could be understood in tangible, material terms, and eventually even manipulated. Medicine a acquired an important technique when Rosalyn Sussman Yalow, an American nuclear physicist, invented a way to use radioactivity for detecting minute amounts of a huge variety of materials, ranging from nicotine to viruses, in the human body. Though its name twists the tongue, her method, called radioimmunoassay, relied on simple principle. If you count six red-eyed fruit flies in a jar and you know that the incidence of red eyes is one in a thousand, you conclude that there are 6000 flies in the jar -- without the tedium of counting them. Radioimmunoassay counts molecules rather than flies, and measures radioactivity, rather than eye color. Chemistry gained a valuable diagnostic tool with nuclear magnetic resonance. Radar research had led to instruments that can identify nuclei by the way they absorb microwaves. For chemists, ...
