Is the Earth too old? The impact of geochronology on cosmology, 1929–1952
Estimates of the Earth’s age have had significant impacts, not only on geology but also on biology, astronomy and biblical creationism. In the 1930s and 1940s, the age of the universe as estimated from the expanding universe was less than 2000 million years, but the age of the Earth as estimated from radiometric dating was perhaps as great as 3000 million years. Astronomers responded to this contradiction in at least three different ways. Some cosmologists favoured Georges Lemaitre’s relativistic model, in which the universe remains about the same size for an indefinite period of time before starting its present stage of expansion. Since theories of the origin of the solar system that were popular in the early 1930s assumed an encounter between the Sun and another star, it seemed plausible that the Earth could have been formed around this epoch of ‘cosmic congestion’. Edwin P. Hubble, generally regarded as the founder of the expanding-universe theory because of his discovery of the redshift-distance law, doubted that redshifts are actually due to velocities, and seemed to prefer a non-expanding model, though he emphasized that the correct interpretation of the redshifts of distant galaxies was still an open question up until the time of his death in 1953. Fred Hoyle, Hermann Bondi and Thomas Gold proposed a ‘steady-state’ cosmology: the universe has always existed, so there is no conflict between its (infinite) age and that of the Earth. The discrepancy was finally resolved in the 1950s when astronomers revised their distance scale and boosted the age of the universe to 10000 million years or more. The current agreement between geologists and astronomers again leaves creationists with no scientific support at all for their claim that both the Earth and universe were created only about 10 000 years ago.
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The Age of the Earth: From 4004 BC to AD 2002
The age of the Earth has long been a subject of great interest to scientists from many disciplines, particularly geologists, biologists, physicists and astronomers. This volume, The Age of the Earth: from 4004 BC to AD 2002, brings together contributors from these different subjects, along with historians, to produce a comprehensive review of how the Earth’s age has been perceived since ancient times. Touching on the works of eminent scholars from the seventeenth to nineteenth centuries, it describes how concepts of the Earth’s history changed as geology slowly separated itself from religious orthodoxy to emerge as a rigorous and self-contained science. Fossils soon became established as useful markers of relative age, while deductions made from geomorphological processes enabled the discussion of time in terms of years. By the end of the nineteenth century biologists and geologists were fiercely debating the issue with physicists who were unwilling to give them the time needed for evolution or uniformitarianism.
With the discovery of radioactivity, attempts to calculate the Earth’s age entered a new era, although these early pioneers in radiometric dating encountered many difficulties, both technical and intellectual, before the enormity of geological time was fully recognized. This effort affected both the theory and practice of geology. Geochronology was largely responsible for it maturing into a professional scientific discipline, as increasingly refined techniques measured not only the age of the rocks, but the rate of processes which now elucidate many aspects of the Earth’s evolution.
Even today the Earth’s chronology remains a contentious topic — particularly for those dating the oldest rocks — and it is implicated in debates surrounding our hominid ancestors, the origins and development of life, and the age of the universe.
The Age of the Earth: from 4004 bc to AD 2002 will be of particular interest to geologists, geochemists, and historians of science, as well as astronomers, archaeologists, biologists and the general reader with an interest in science.