«ANCIENT ORIGINS OF A MODERN ANTHROPIC COSMOLOGICAL ARGUMENT MILAN M. CIRKOVIC∗ ´ ´ Astronomical Observatory Belgrade, Volgina 7, 11000 Belgrade, ...»
Astronomical and Astrophysical Transactions
Vol. 22, No. 6, December 2003, pp. 879–886
ANCIENT ORIGINS OF A MODERN ANTHROPIC
MILAN M. CIRKOVIC∗
Astronomical Observatory Belgrade, Volgina 7, 11000 Belgrade, Yugoslavia
(Received 18 November 2002)
Ancient origins of a modern anthropic argument against cosmologies involving inﬁnite series of past events are considered. It is shown that this argument – which in modern times has been put forward by distinguished cosmologists such as Paul C. W. Davies and Frank J. Tipler – originates in pre-Socratic times and is implicitly present in the cyclical cosmology of Empedocles. There are traces of the same line of reasoning throughout the ancient history of ideas, and the case of a provocative statement of Thucydides is brieﬂy analysed. Moreover, the anthropic argument has been fully formulated in the epic of Lucretius, conﬁrming it as the summit of ancient cosmology. This not only is of historical signiﬁcance but also presents an important topic for the philosophy of cosmology provided that some of the contemporary inﬂationary models, particularly Linde’s chaotic inﬂation, turn out to be correct.
Keywords: Anthropic argument; Cosmology; Ancient origins
1 INTRODUCTION: DAVIES–TIPLER ARGUMENT
began with a bang”.1 From the end of the Middle Ages until Hubble’s observational revolution in the third decade of the twentieth century, the stationary world view has been in one way or another dominant. This explains, among other issues, the dramatic reaction of most of the scientiﬁc community, including Lord Kelvin, Holmes, Eddington, Crookes, Jeans and others, to the discoveries of Clausius, Boltzmann and other thermodynamicists, implying a unidirectional ﬂow of time and physical change. Interestingly enough, even during this epoch the idea – today one of most investigated issues in physics – that the thermodynamic arrow of time originates in cosmology, has occasionally surfaced (Steckline, 1983; Price, 1996, and references therein).
The power of a stationary alternative to the evolutionary models of the Universe has been reiterated in particularly colourful form during the great cosmological controversy in the late 1940s, 1950s and early 1960s (Kragh, 1996). Although during this period of conﬂict between the Big Bang and the classical steady-state theories numerous and very heterogeneous arguments appeared on both sides of the controversy, the argument based on the anthropic selection effect was only explicitly formulated a decade after the disagreements ended. As is well known, the debate ceased when empirical arguments persuaded by far the largest part of the cosmological community that a Universe of ﬁnite age is the only empirically acceptable concept.2 However, the argument based on the anthropic principle has been further developed during the 1980s and has gained relevance in a new and developing ﬁeld of quantum cosmology (together with other aspects of anthropic reasoning). This brief note is dedicated to investigation of its origin in the ancient philosophy of nature, while the detailed consideration of its range, scope ´ and various versions will be presented in a forthcoming study (Cirkovi´, 2003).
c The modern version of the anthropic argument against the past inﬁnite series of events (or the past temporal inﬁnity in relationist terms; see the discussion below) has appeared in a short notice by Davies (1978) appearing in Nature. In this succinct critique of the Ellis et al. (1978) static cosmological model Davies pointed out that there is also the curious problem of why, if the Universe is inﬁnitely old and life is concentrated in our particular corner of the cosmos, it is not inhabited by technological communities of unlimited age.
The same idea has been further developed and put on a mathematical footing by Tipler (1982). As claimed by Barrow and Tipler (1986) in their encyclopaedic monograph on anthropic principles, this is historically the ﬁrst instance in which an anthropic argument has been used against cosmology containing the past temporal inﬁnity. As we shall see in the rest of this study, this claim is only partially correct, since the thinkers in antiquity have been aware of a similar argumentation. However, it is indeed fascinating that the same argument had not been considered earlier in the course of the twentieth century. The surprise is strengthened by the fact that cosmologies postulating an inﬁnite past in scientiﬁc or half-scientiﬁc form have existed since the very dawn of science. In addition, since ancient times a belief in the existence of other inhabited worlds has also been present, in one form or another.3 Today, the scepticism sometimes encountered against this mode of thinking is even stranger, when various (and, at least in some cases, not quite inexpensive) search for extraterrestrial intelligence (SETI) projects testify to the reasonable degree of belief in the existence of technological civilizations other than the human one. Their technological nature (the same that produces the problem Davies wrote about) is a conditio sine qua non of any sensible SETI enterprise. In this short
note, we shall try to recall some of the instances this argument has surfaced in the ancient cosmological thought, while leaving the deep tracing of its elements and possibly a wide survey to a subsequent work.
2 EMPEDOCLES’ UNIFORMITARIANISM AND REDUCTIONISMAn ancient echo of this type of argumentation can be recognized in the surviving fragments of some of the most distinguished Hellenic philosophers of nature. From our point of view especially interesting is the cyclic cosmology of Empedocles of Acragas (sixth to ﬁfth century BC), in which the Universe is eternal,4 consisting of the internally immutable four classic elements, as well as two opposing forces (Love and Strife, i.e. attractive and repulsive interactions). The cyclic motion of matter in the Universe is governed by the change in relative intensities of two interactions (see the excellent discussion by O’Brien (1969)). It is interesting to note that Empedocles’ cosmology is uniformitarian, in the sense that all six basic constituents (four elements and two forces between them) are present in each instant of time in accordance with the eternal principles of mutual exchange. In some of the surviving fragments, Empedocles implies that, although this uniformitarianism may seem counterintuitive, as we see things coming into being and vanishing, this is just our special perspective (today we would say anthropocentrism) and not the inherent state of nature.5 This is strikingly similar to the uniformitarian notions present in some of the most authoritative cosmological models of the twentieth century, notably the classical steady-state theory (Balashov, 1994). The connection is strikingly relevant when the fact that the classical steady-state theory entails an inﬁnite past is taken into account.
However, the most interesting aspect of this cosmological picture is what occurs within each individual great cosmic cycle. Probably the most lasting and controversial legacy of Empedoclean cosmology is his assertion that biological and even anthropological evolution are inherent, necessary and inseparable parts of the global cosmological evolution (Guthrie, 1969).
Thus, speaking on the four elements, he states For out of these have sprung all things that were and are and shall be – trees and men and women, beasts and birds and the ﬁshes that dwell in the waters, yea, and the gods that live long lives and are exalted in honor.
For these things are what they are; but, running through one another, they take different shapes – so much does mixture change them.6 However, if we accept this view – which we shall call an ‘Empedoclean picture’ hereafter – that biological evolution and the appearance of consciousness and intelligence are contingent upon cosmological processes, the eternal Universe of Empedocles faces the same kind of problem as that of modern stationary cosmologies such as the classical steadystate theory or that of Ellis et al. criticized by Davies. Why then, in the supposed inﬁnity of time, are ‘men and women, beasts and birds’ of ﬁnite, and relatively small, age? Empedocles may have perceived this himself (his mode of thinking and even his theory of metempsychosis were 4 It seems clear that Empedocles held a sort of absolutist (substantivalist) theory of the nature of time. In particular, the fragment B 16 of the Diels collection reads (according to the translation of Burnet (1908)): ‘For of a truth they (Strife and Love) were aforetime and shall be; nor ever, methinks, will boundless time be emptied of that pair.’ 5 Another pioneering contribution of Empedocles lies exactly in separation (the earliest in Western thought!) of physical nature and artifacts of human cognizance. See, for instance, the Diels fragment B 8, reading (in Burnet’s translation): ‘There is no coming into being of aught that perishes, nor any end for it in baneful death; but only mingling and change of what has been mingled. Coming into being is but a name given to these by men.’ Even more telling along the same lines are fragments B 11 and B 15.
6 Fragment B 21 in Diels (1983), translation by Burnet (1908). Similar content can be found in B 20.
´ ´ 882 M. M. CIRKOVIC closer to the modern anthropic mode of thinking than those of most of the later physicists and philosophers), and he evades the problem in the only natural way that he can: by postulating two singular states in the beginning and in the middle of each of his great cycles. These singular states are moments (in absolute time!) of complete dominance of either Love (an ancient equivalent of the modern initial and/or ﬁnal singularities) or Strife (no true equivalent, but similar to the modern version of heat death in the ever-expanding cosmological models; see for instance Davies (1994)). In these states the life, with its complex organizational structure, is impossible and therefore they serve as termini for the duration of any individual history of life and intelligence. The maximal duration of any form of life and/or intelligence is determined exclusively by cosmological laws. Therefore, there are no arbitrarily old beings, and anthropic argument is inapplicable.
It is worth noting that the Empedoclean reductionist picture of the relationship between biological and psychological processes on the one hand, and physical and cosmological processes on the other, has become quite common in the ancient philosophical thought after Empedocles.
It is also present, for instance, in cosmologies postulating ﬁnite age of the Universe, or at least a ﬁnite duration of world histories, such as in Anaxagoras’ system. According to the testimony of Diodorus (I 7, 7), Euripides has, in his lost tragedy Melanippa, described – clearly under the inﬂuence of his teacher Anaxagoras – the rise of plants, animals and humans as an ultimate consequence of separation of the heavens and the Earth from their primordial unity; which is another suprisingly modern picture. With the rise of Socrates, and subsequently Platonic and Aristotelian philosophy, and in particular during the age of faith, this line of thinking became discontinued; in a sense it has only inherited worthy successors in the modern thought contained in philosophical considerations of both quantum mechanics and cosmology (see for example Schr¨ dinger (1944); Barrow and Tipler (1986) and Smolin (1997)). We cannot treat o these reissues of the Empedoclean picture in the course of this study. However, it is worth noting that the problems facing such contingency of biological upon cosmological processes have also been noted in antiquity by several famous authors.
3 REPETITIONS IN ANTIQUITY
In the very ﬁrst chapter of the immortal history of Thucydides, there is a famous statement that before his time – that is about 450 BC – nothing of importance (σ υ µεγ αλα γ ευεσ θ αι) had happened in history. This startling statement has been correctly called ‘outrageous’ by Spengler (1918) and used to demonstrate the essentially mythological character of ancient Greek historiography (see also Cornford (1965)). It may indeed be outrageous from the modern perspective, but it does motivate a set of deeper questions, ultimately dealing with cosmology.