In addition to concern with the ultimate destiny of humankind people of faith have also frequently inquired about the fate of the universe itself. Convictions about how the world would end had also undergone considerable change by 1800. Since at least the mid-seventeenth century natural philosophers had begun to counter the commonly held assumption that the end times were at hand and that as a consequence nature was deteriorating as the Psalmist had foreseen it would.⁽¹⁾ In its place appeared the idea that nature was a law-bound system. One continued to assume that the cosmos was subject, as Isaac Newton (1642-1727) had observed, to occasional correction by its divine superintendent, but in the main it could be regarded as a stable machine. Some bold minds were even prompted to speculate on ways in which the solar system might have come about by means of God's secondary or indirect supervision as opposed to a direct divine intervention. This tendency blossomed in the eighteenth century into a willingness to consider a natural cosmogony, a creation of the cosmos by natural law.⁽²⁾ It would be left to the nineteenth century to deal with the implications of all this for God's relationship to nature. How, for example, could one resolve the internal tensions between a naturalistic account of creation and development, which involved apparently irreversible processes, and a scientific representation of how nature was preserved as a mechanically reversible machine?

    What was perhaps unexpected as the nineteenth century began was the role that would be played by the physicists specializing in the new science of thermodynamics. The increasing acceptance of the notion of nature bound by natural law implied that in the minds of scientists the future was not threatened by a final physical denouement such as that which was predicted in the Bible to accompany the Battle of Armageddon.⁽³⁾ But if scientists and theologians were coming to regard the world as a perfect machine that would operate forever in accordance with law (law which still for most had been imposed on it by God), how could such a notion square with descriptions of the end times in which "the heavens shall pass away with a great noise and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up"?⁽⁴⁾

    The Laplacian notion of a stable and eternal cosmos therefore ran counter to traditional religious teaching. It also appeared to contradict a scientific conviction of natural philosophers from the seventeenth century onward. Because natural philosophers since Simon Stevin (1548-1620) and Galileo Galilei (1564-1642) had developed numerous arguments against the possibility of a perpetual motion machine⁽⁵⁾ it was inevitable that sooner or later they would have to reconcile this conviction with the alleged eternal stability of the heavens. Recognition of the need for reconciliation was delayed until the middle of the nineteenth century for at least two reasons. First, although the Laplacian cosmos was a system in which observed irreversible physical processes were exposed as merely apparent and not permanent, the impression given by the French scientist's idea of creation by natural law was one of development. Indeed, Laplace's hypothesis went a long way to prepare the ground for later evolutionary claims in biology. Discussions of perpetual motion had been traditionally carried out with respect to a purely mechanical context, not one in which growth or development was involved.⁽⁶⁾ Secondly, Laplace did not eliminate God completely from possessing a supervisory role over nature. He located God's concern with the world not at the level of individual planets, but with the more general laws that governed all the possible specific arrangements planets could assume. Although Laplace himself did not assume that God necessarily intended the solar system would last forever, the impression left by his System of the World was that the planets constituted a stable arrangement.⁽⁷⁾ The notion that God's direct involvement with nature was to be found in the design of the most general laws, in other words, had implications that could work in opposite directions. On the one hand it could reassure scientists that the cosmos was in fact divinely superintended, but it could also postpone for them the question of why the eternal motion of the heavens did not force a concession that perpetual motion was in fact possible.

    As a result of investigations into various transformations of one kind of "force" into another (for example, chemical force into electrical force, electrical force into heat force), numerous figures in the nineteenth century began to consider whether the general capacity to do work was conserved in the universe. In the course of making fundamental contributions to thermodynamics in the 1820s Sadi Carnot (1796-1832) had assumed that heat "force" was conserved when it was used to produce mechanical effect; i.e., no heat force was transformed into mechanical motion. By the 1840s some physicists conjectured that although there was no net loss of nature's total quantity of force, heat was in fact not conserved when mechanical motion was produced; i.e., heat force became mechanical force - there was a mechanical equivalent of heat. Separate from this question, however, was another, one particularly relevant to the eternal working of the heavens: were there physical contexts in which "force" might have to be created?

    During the 1840s, when what later came to be known as the conservation of energy was being formulated, at least one of the contributors to the discovery, Robert Mayer (1814-1878), initially thought that while the destruction of force was impossible, the eternal motion of the heavens indicated force was in fact being created by God. After consensus had emerged that force could be neither created nor destroyed, a property which the physicist William Thomson (1824-1907) associated with God's immutability, there emerged the recognition that what Thomson began calling "energy" was nevertheless subject to what the British scientist called "dissipation." Energy that had been dissipated continued to exist, but was no longer available to do work. Through the work of Rudolf Clausius (1822-1888) and others, physicists realized that since such dissipation unavoidably accompanied the transformation of heat into other forms of energy, the amount of dissipated energy in the universe was gradually increasing. Logic dictated what seemed a tragic conclusion, one enunciated most powerfully by Hermann von Helmholtz (1821-1894) in a public lecture in Königsberg early in 1854: if there was a fixed total of energy in the universe and if portions of that total were increasingly becoming unavailable to do work, then the day would come when all of the energy would be unavailable and no more work could be done.⁽⁸⁾ An argument could be made from physics that there was a final denouement coming, even if it was far in the future and even if it would be a whimper rather than the bang implied by biblical prophecy.

    The theological implications of discoveries being made in thermodynamics ran in the opposite direction from the conclusions that had been drawn by some geologists of the time. From the 1830s on, the noted scientist Charles Lyell (1797-1875) had been teaching that a careful reading of the evidence from geological strata in Europe supported the conclusion not only that the earth's age was enormously old, but that geological processes occurred in the context of steady state rather than of development. In other words, were one to be transported far back in time, one would be able to recognize the geological terrain because it was subject to local and temporary but not universal and permanent change. Lyell's conclusions were later used by Charles Darwin's (1809-1882) supporters to justify the vast time scale that evolution by natural selection required. The geological evidence, while irrelevant to theological issues of eschatology, was enlisted to support a conception of evolutionary development that challenged traditional religious explanations of origin.

Physicists like Thomson resented the claim that geological change was ultimately non-directional because Lyell's view persisted in spite of the theoretical work in thermodynamics that marked the decades around mid-century. Thomson challenged Lyell's view in public, even to the point of opposing the theory of evolution by natural selection. Based on thermodynamical calculations of the rate at which the earth had cooled from an uninhabitable molten mass to the solid crust on which life was thriving, Thomson, who became Lord Kelvin in 1892, concluded that the time which had passed since the earth was cool enough for the earliest life to have survived was insufficient to have permitted evolution by natural selection. From his first estimate of 100 million years, Kelvin kept revising his calculations downwards until in his last public pronouncement on the subject in 1897 he was willing to grant but a scant 24 million years to Darwin and the evolutionists. While his Scottish Protestantism did not require that he reject evolution, he could not accept the dependence on chance required by natural selection. God was in control of Thomson's universe, including the fact that it was running down. Thomson scholar Crosbie Smith has noted that Thomson's understanding of matter and energy "kept constantly in mind the relationship of these concepts to a wider theological dimension throughout the long and difficult construction of this system."⁽⁹⁾

1. Psalm 102:26: "The heavens shall wax old as doth a garment." The function of this interpretation was to oppose the heathenish doctrine of Aristotle, in which the world was regarded as eternal. For an account of the Renaissance notion of the running down of the physical world see "The Decay of Nature," Chapter 2 in Richard Foster Jones, Ancients and Moderns: A Study of the Rise of the Scientific Movement in Seventeenth Century England (Berkeley: University of California Press, 1965).

2. See Ronald L. Numbers, Creation by Natural Law: Laplace's Nebular Hypothesis in American Thought (Seattle: University of Washington Press, 1977).

3. Revelation 16:18,20. Old Testament references to the demise of the original creation are paralleled in the final book of the New testament. Compare Isaiah 65:17 and Revelation 21:1.

4. II Peter 3:10.

5. Cf. Arthur W. J. G. Ord-Hume, Perpetual Motion: The History of an Obsession (New York: St. Martin's Press, 1977), pp. 32ff.

6. This is not to suggest that mechanical explanations of living things were absent at the beginning of the century nor that they would not become central to the eventual resolution of the problem raised by an eternally stable cosmos. Cf. My " 'Nature is an Organized Whole': J.F. Fries's Reformulation of Kant's Philosophy of Organism," in Romanticism in Science (Amsterdam: Kluwer Academic Publishers, 1994), ed. S. Poggi and M. Bossi, pp. 91-101. For the relevance of the understanding of the solar system as an organism to the debate over perpetual motion, see Kenneth Caneva, Robert Mayer and the Conservation of Energy (Princeton: Princeton University Press, 1993), p. 146.

7. "Could not the supreme intelligence, which Newton makes to interfere, make [the arrangement of the planets] to depend on a more general phenomenon? ... Can one even affirm that the preservation of the planetary system entered into the views of the Author of Nature?" Quoted from Laplace's System of the World, by Numbers, Creation by Natural Law, p. 126.

8. Cf. "On the Interaction of Natural Forces," in H. von Helmholtz, Popular Scientific Lectures (New York: Dover Publications, Inc., 1962), pp. 59-90 on pp. 73-74. Tyndall's so-called Belfast address is found in British Association for the Advancement of Science Report, 44 (1874), lxvii-xcvii and was also published separately as Advancement of Science (New York: A. K. Butts and Co., 1874).

9. Crosbie Smith, Natural Philosophy and Thermodynamics: William Thomson and the 'Dynamical Theory of Heat'," British Journal for the History of Science, 9 (1976), 315. Cf. also Joe D. Burchfield, Lord Kelvin and the Age of the Earth (Chicago: University of Chicago Press, 1990), pp. 72-73.