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Datação por Radiocarbono e Arqueologia
The ice age problem was the first and, until a few decades ago, the only relevant debate on climate change, emerging as a discussion in geology, which was unable to frame it. It remained a mystery in the nineteenth century, being discussed in mathematics and astronomy, and it was a matter of speculation in geophysics and geochemistry without a satisfactory solution. The basic explanation for the occurrence of ice ages was given by Milankovitch, by means of his mathematical theory of insolation in the s. Nevertheless, only the consolidation of paleoclimatology, in the s, provided the necessary evidence to prove it. The refinement of these studies in paleoclimatology, however, brought to light an unexpected phenomenon: the transition between equilibrium state in the climate system took place very quickly in the past. Climate change in the Pleistocene Ice Age was abrupt and radical, contrary to any gradualism. Therefore, the current global warming should be seen as a much more dangerous and unpredictable phenomenon, in comparison with the way it is usually presented. Escrevendo para seu amigo Michelangelo Ricci, Torricelli afirmou: "vivemos submersos no fundo de um oceano de ar" Torricelli apud Walker, , p. Walker, Cox,
Landmarks in the history of radioactivity and current tendencies. The first days of radioactivity, the discoveries of X-rays, radioactivity, of a - and b - particles and g - radiation, of new radioactive elements, of artificial radioactivity, the neutron and positron and nuclear fission are reviewed as well as several adverse historical marks, such as the Manhattan project and some nuclear and radiological accidents. Nuclear energy generation in Brazil and the world, as an alternative to minimize environmental problems, is discussed, as are the medicinal, industrial and food applications of ionizing radiation. The text leads the reader to reflect on the subject and to consider its various aspects with scientific and technological maturity.