Extraterrestrial Life Debate, Antiquity to 1915: A Source Book

12. NEW APPROACHES TO AN ANCIENT QUESTION

NEW APPROACHES TO AN ANCIENT QUESTION This chapter focuses on four authors: Charles Darwin, Richard Proctor, Camille Flammarion, and Alfred Russel Wallace. One of its recurring themes concerns evolution and extraterrestrials. Significant as the publication in 1859 of Darwin’s Origin of Species was, it is important to realize that evolutionary views broadly considered were already widespread before 1859. Earlier readings from Kant as well as consideration of the nebular hypothesis of the origin of the solar system show that in astronomy evolutionary ideas were present long before 1859. Similarly, geologists for more than a century had been coming to see the Earth as evolving in many aspects. Likewise in the life sciences: an array of pre-Darwinian biologists including Buffon, Lamarck, and Chambers had raised a variety of evolutionary issues. Darwin’s impact derived not from his introducing the idea of biological evolution, but rather from his presenting biological evolution in a manner that forced major thinkers to take it seriously. Before we turn directly to Darwin, mention should be made of one crucial development from the period around 1860 in physical science, including astronomy. This development was spectrum analysis. By means of the spectroscope, astronomers could determine in certain cases the chemical compositions of celestial bodies. T T W W E E L L V V E E 369 f r o m 1 8 6 0 t o 1 9 1 5 370 For example, glowing gases in the Sun or stars radiate bright-line spectra, the lines of which reveal the chemical composition of those glowing gases. Similarly, nonradiating, cooler gases such as those in a planetary atmosphere absorb rays of light at particular wavelengths producing dark-line spectra, the lines of which indicate the chemical composition of the gases. Important as spectroscopy was as an astronomical technique, it was also deeply significant in providing the clearest evidence ever obtained of the chemical homogeneity of the universe; it showed that the chemical elements making up the Earth are present throughout the universe, which implies that the laws governing terrestrial chemical reactions hold sovereignty throughout the universe. For these reasons, astronomers, possessing this powerful new technique and aware of its universal message, began to speak of the “New Astronomy ” and to refer to themselves as astrochemists and astrophysicists. And not surprisingly, spectrum analysis intersected at many points with the extraterrestrial life debate. Sir William Huggins (1824–1910) was the leading pioneer of astronomical spectroscopy . Among his achievements in this area was the discovery in the mid-1860s that various nebulous appearing objects exhibit bright-line spectra, indicating that they consist of glowing gases and thereby showing that they cannot be island universes . He also developed spectroscopic methods for measuring radial motion of celestial objects——that is, the motion of the object toward or away from the Earth. Some of Huggins’s early papers were published in collaboration with William Allen Miller. Their “On the Spectra of Some of the Fixed Stars” (1865) contains the following endorsement of the idea of extraterrestrial life: It is remarkable that the elements most widely diffused through the host of stars are some of those most closely connected with the constitution of the living organisms of our globe, including hydrogen, sodium, magnesium, and iron. . . . On the whole we believe that the foregoing spectrum observations on the stars contribute something towards an experimental basis on which a conclusion hitherto but a pure speculation, may rest——viz. that at least the brighter stars are, like our sun, upholding and energising centres of systems of worlds adapted to be the abode of living beings.1 When editing this paper, which became a classic in the history of astronomical spectroscopy, for his Scientific Papers, Huggins added a footnote stating that al1 . William Huggins, The Scientific Papers of Sir William Huggins, ed. Sir William Huggins and Lady Huggins (London: W. Wesley and Son, 1909), 60. though Miller persisted in this belief, he (Huggins) had by 1866 freed himself “from the dogmatic fetters of my early theological education,”2 which had motivated this statement. As the above passage suggests, the involvement of spectrum analysis with ideas of extraterrestrial life was quite substantial.3 Nonetheless, because of the delicacy of many of the observations, astronomers in attempting to determine , for example, whether the Martian atmosphere contains oxygen and water vapor, at times found contradictory results or reported results that were later shown to...