ANTHROPIC UNIVERSE—the conviction or clearly defined position that states that the universe in its global dimensions has properties that allow life to come into existence and develop within it, especially conscious human life (hence the term “anthropic”). If it did not possess these properties, the universe could not produce conditions favorable to life and consequently life would not have come into existence or develop in it.
To speak of an anthropic universe is to indicate that the universe in a special way is open to life and to emphasize that the universe is organized to a human measure. This conviction is drawn from the evident fact that life exists in the universe. In the form known to us, life could not exist in an arbitrary world but has rigorous requirements as to conditions. Depending on the cognitive level at which these conditions, and life itself, are defined, the statement that the universe has an anthropic character may have the validity of a scientific, philosophical, or even a theological and religious thesis.
Significant progress in the natural sciences has given the idea of the anthropic universe an explicitly scientific character. The achievements of the mathematico-physical sciences has enabled us to complete the idea of the anthropic universe with specific details. The conception of the anthropic universe is sometimes called the “anthropic system” (in the broad sense of the word), for in distinction from the explicitly epistemological character of the anthropic principle, the idea of the anthropic universe concentrates mainly upon the ontological aspects of the universe. The universe, and in particular those of its properties and processes that make it open to life, are the main contents of the idea. In the case of the anthropic principle, on the other hand, the argumentation starts from the fact that life exists, and this fact determines how we know the universe, the range of our knowledge, and how we explain its properties. In both approaches life is conceived in the form in which it is known on earth, carbon-based life of which man is the most highly evolved form. The possibility of other forms of life such as silicon-based or nitrogen-based life is not rejected. Of course, the conditions in the universe favorable to such a form of life would have to differ greatly from natural present conditions. This would not change the basic meaning of the idea of the anthropic universe which states that the cosmos is clearly disposed and open to some form of life.
Survey of positions. The idea of the anthropic universe is as old as philosophy; questions about man’s position in the universe, his role, and how he is related to the reality around him, are basic questions about the meaning of human existence and as such cannot be disregarded by any religion or philosophy. It is difficult, however, to determine where and when the full contemporary understanding of the idea of the anthropic universe first appeared.
It is generally held that certain details associated with the idea of the anthropic universe may be found among the ancient Greeks, especially their conviction that the universe is ordered, without which it would be difficult to treat the universe as favorable to life and man. Over centuries this conviction was articulated in various ways and was never explicitly and seriously called into question. For the Ionian philosophers, the idea of the anthropic universe took the form of a search for a primordial principle of the world which would explain the raw material of the world, how the world arose, and how everything in the world acts. In the centuries that followed the idea appeared with an accent upon the universal harmony of the cosmos. The idea of the universal cosmic harmony lay at the foundations of the Aristotelian and Ptolemaic picture of the world. Modern science made the description and explanation of his harmony one of the main purposes in its investigations.
One manifestation of the anthropic character of the universe was the emphasis upon its teleological aspect. While this teleology did not always exhibit an anthropocentric character, that is, it was not always directed to man and in itself it did not exhaust the contemporary understanding of the idea of the anthropic universe, it is still today an important object of study.
The idea of the anthropic universe found expression in the perennial question whether other universes exist and whether we are alone among all the universes. The atomists’ doctrine of many worlds was an important element of their philosophy. At present this view, in connection with the possibility of explain cosmic coincidences (fine tuning) has found many adherents.
Socrates’ remarks as reported by Xenophon are closest to the present understanding of the idea of the anthropic universe. Socrates noted that the world is noticeably open to man. An example of this is the way the heavenly bodies act. They seem to serve man, giving him light in the day and the night to rest, etc.. This image of the universe was not shared by all the schools of ancient philosophy. According to Epicurean atomism there is an infinite number of worlds subject to the same laws that direct the behavior of atoms; man and the gods are parts of the world and are not exempt from these laws, and therefore they cannot influence the face of the cosmos.
In modern times the development of the mechanistic image of the world was an important limitation for the theory of the anthropic universe. In this vast mechanism governed by principles entirely unconnected with the intentional and normative structure of human thought, there was no special place for man. In cosmology this attitude took the form of the so-called cosmological principle which states that all the regions of the universe are completely equal under the laws of nature, and so the existence of life and man were not treated as exceptional or unique in the history of the cosmos.
Although the mechanistic approach to the world and the appearance of new theories in natural science brought important discoveries, scientists began to see more clearly the limitations of this approach. In many cases new theories indicated the important role in knowledge of the existence of life in the universe. One of the first such theories was static thermodynamics. Its author, L. Boltzmann, saw that from the point of view of this theory, man’s existence requires the universe to have a particular thermodynamic state, because life performs an energy exchange with its environment, and a very improbable state of thermodynamic imbalance is necessary for life to exist and evolve. This means that a universe that possesses life cannot be an arbitrary universe but must meet specific conditions.
The idea of the anthropic universe was revived much more widely in the cosmological and quantum theories that developed in the twentieth century. A. S. Eddington and P. A. M. Dirac presented the problem of large numbers. This problem had an immediate anthropic dimension for their successors. The fact that man exists as an observer in the universe played for J. B. S. Haldane the role of a selective factor; i.e., it selected from the whole class of cosmological models the model in which the existence of life is possible. For G. J. Whitrow this fact was an answer to the question of why our universe is three-dimensional. The basic development of the idea of the anthropic universe occurred in connection with the so-called standard cosmological model. On the one hand, Whitrow pointed to many subtle tunings in the behavior and properties of the present universe without which life, especially in its human form, could not have appeared at all. On the other hand, this model could not explain many of the properties of the universe that it predicted. This started an extensive discussion that spilled over to the scientific plane led by B. Carter, J. D. Barrow, F. J. Tippler, and others.
The theory of Subtle Tunings. The biochemical and physical characteristics of life and the description of the expansion and evolution of the universe have enabled scientists to understand many subtle connections between the phenomenon of life and cosmic processes. By the same token, biological evolution was linked with the universal cosmic process of transformations of matter. In effect certain particular behaviors and properties of the universe were singled out which directly or indirectly condition the appearance and development of life in the familiar form of protein. Thus our universe, which possesses properties favorable to life in general and man in particular, was with full right called an “anthropic universe”, and so a universe explicitly tuned to the requirements posed by the existence of the familiar form of life within it. The universe is therefore a place of a particular kind full of peculiar structures and complex action, the presence of which is at least a necessary condition for life to come into existence. Without these properties, man could not have appeared or continue to exist in the cosmos. The coming-into-existence in the universe of properties necessary for life is, however, conditioned—as physics, astrophysics, and cosmology show—by an assortment of laws of nature, initial conditions, and the numeric values of the fundamental physical constants and of the more important cosmological parameters. In view of the narrow divisions of these values or their univocal definitions they were called “subtle tunings” or “astonishing coincidences”. If therefore such coincidences had not occurred, and so if the values of the physical constants and cosmological parameters had been different, the universe also would have been different. It might not have had galaxies, stars, or planets. Its evolution might have been too fast in comparison with biological evolution. The biogenic elements, stable and slowly burning stars, etc., might not have been present. It is therefore highly improbable that life as we know it could have appeared in such theoretical universes. Since, however, our universe exists, it must produce in itself at least the initial conditions favorable to life and to man, and so it became an anthropic universe.
There are long lists of such conditions. Most often mentioned are the presence of large-scale structures, especially stars and planets, the presence of chemical elements in general and biogenic elements in particular, a stable supply of energy from outside of the living organism, the proper range of temperature, the presence of the atmosphere which has protects, acts like a store-house, and has a communicative function, the proper mass of planets to ensure the transformation of the atmosphere and prevent it from escaping into outer space, etc..
At the same time, many factors must coincide to meet all these conditions. Among these factors, appropriate values of cosmological parameters and the basic physical constants play a basic role. The most important cosmological parameters include the cosmological constant (λ), the three-dimensional nature of space (the so-called baryon assymmetry, the relation of the number of photons (Nγ) to the number of baryons (NB), which determines the entropy of the universe), and parameters that are conditions for the appearance of large-scale structures, such as the relation of the speed of expansion (ve) to the speed of the escape (vu) of the expanding universe, the value of the so-called parameter of density (Ω), the very narrow range of primitive fluctuations in the density of matter, and other conditions. The basic physical constants are Planck’s constant (h), the Newtonian gravitational constant (G), the speed of light (c), the elementary electrical charge (e), the mass of the electron (me), and the mass of the proton (mp). The combinations of these constants are also interesting. The combinations provide in effect various unmeasured constants among which the so-called constants of subtle structure play a special role in the process of the appearance of chemical elements.
All these subtle tunings of the values of physical constants and cosmological parameters reveal very characteristic relations of interdependence among the physical, astrophysical, and cosmological properties of the universe and the presence of life in the universe. They also clearly indicate the anthropic character of the universe in which we live.
A separate question is how to explain such subtle tunings, and so how to explain the existence of the right laws of nature, initial conditions, and values of physical constants and cosmological parameters. At their present stage of development, the natural sciences cannot provide completely satisfying answers to these questions, and so it is understandable to resort to philosophical answers. Most often this points either to the so-called hypothesis of many universes which in a purely naturalistic way explains the perceived coincidences, or to God in who in the act of creation gave the universe all the necessary and sufficient conditions for the existence of life. It should be emphasized, however, that these answers are not the result of deductive inference from scientific data, but are an attempt at a reductive explanation of the findings of the natural science on a philosophical level. As such, then, they are not infallible, but the degree of this infallibility depends also upon the degree of justification of the philosophical thesis itself.
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