measuring tape
natures clocks how scientists measure the age of almost everything
radioactivity is like a clock that never needs adjusting writes doug macdougall . it would be hard to design a more reliable timekeeper . in natures clocks macdougall tells how scientists who were seeking to understand the past arrived at the ingenious techniques they now use to determine the age of objects and organisms . by examining radiocarbon c 14 dating the best known of these methods and several other techniques that geologists use to decode the distant past macdougall unwraps the last centurys advances explaining how they reveal the age of our fossil ancestors such as lucy the timing of the dinosaurs extinction and the precise ages of tiny mineral grains that date from the beginning of the earths history . in lively and accessible prose he describes how the science of geochronology has developed and flourished . relating these advances through the stories of the scientists themselves james hutton william smith arthur holmes ernest rutherford willard libby and clair patterson macdougall shows how they used ingenuity and inspiration to construct one of modern sciences most significant accomplishments a timescale for the earths evolution and human prehistory .