Sections of this chapter
The Expanding Universe
The Big Bang Theory
The Steady State Model
The Evolutionary Perspective
The Evolution of Planets
Proteins and Nucleic Acids
The evolution of humanity is part of the evolution of the universe. The universe is an interconnected whole whose individual parts cannot be fully understood in isolation from one another. You can best understand human evolution and your own creativity by first understanding the physicochemical process which led to you.
The observable universe is by the best current estimates between 15 and 20 billion (1.5 to 2.0 X 1010) years old . The sun, the earth and the planets are about 5 billion (5 X 109) years old . The first question that comes to mind is, "What existed before the observable universe?"
The most amazing aspect of this question is that it can be answered at all. We can answer this question because we can actually look back in time and see what the universe was like billions of years ago. Light travels at a finite speed of about 300,000 kilometers per second. When we look at the most distant parts of the universe, we are seeing the universe as it appeared when light from that part of the universe began traveling toward us. Among the most distant parts of the universe which can be observed today is a quasar discovered in 1986, estimated at over 13.5 billion light-years away, which is to say that the light reaching us from there today began traveling toward us over 13.5 billion years ago. In 1988, a galaxy which appeared to be 15 billion light-years away was discovered. The most notable observable fact about the distant parts of the universe is that, with two possible exceptions, they are very much like the closer, visually older, parts. The two exceptions are that (1) matter in the universe seems to be receding from us and itself (i.e., distant clumps of matter all recede from one another) at ever greater speeds in direct proportion to its distance from us and itself respectively, and (2) there are some peculiar objects called quasars which seem to be more numerous at greater distances, i.e., quasars seem to have been more numerous when the universe was younger.
The Expanding Universe
The units of matter in the universe seem to be receding from each other. What constitutes a unit of matter is quite arbitrary. For cosmological purposes it is currently convenient to consider a galaxy as the elementary unit of matter. What galaxies are and how they are formed we will consider later. For now we merely consider them as semi-autonomous particles of matter of roughly the same size.
The Newtonian model of universal gravitation would predict that if a system of particles existed, the particles would tend to cluster together by mutual gravitational attraction unless there was an outside force applied to this system. Since the galaxies are receding from one another, there must be an outside force. Depending on what we assume to be the nature of the outside force, we deduce different cosmologies.
The Big Bang Theory
Under this theory, it is assumed that all matter in the universe was once concentrated in a mass at a single point, possibly a sphere of zero diameter. This super-dense mass is sometimes called "the primordial atom" or the "cosmic egg." More technically, it is sometimes called the "cosmological singularity." This super-dense mass caused an enormous explosion similar in quality to a hydrogen bomb, but vastly more powerful. This in turn caused all matter and space to explode out from a common center, which is the reason for the observed expansion of the universe, i.e., it is a continuation of the original explosion. Time, matter, space and all physical laws all came into being within the first few instants of the Big Bang. Actually it is space that is expanding and taking matter along with it.
This very simple model of the universe makes reasonably good predictions about many observed natural phenomena, such as the age of the universe and the observed background energy of the universe, i.e., the residual background black-body radiation from the Big Bang. It is clearly too soon to say if the Big Bang model is correct. It is merely one of many reasonable cosmological models. Its major immediate difficulty is philosophical: The questions which immediately come to mind are, (1) Where did the cosmic egg come from? and (2) What will become of the universe in the future? According to the Big Bang theory there may be one common answer to both questions.
If the total mass of the universe is sufficiently large and the original explosion was not too powerful, then the universe will eventually begin to collapse again by mutual gravitational attraction (the "Big Crunch") until it again becomes a superdense plasma and explodes. This process goes on forever and we have an oscillating universe which periodically expands and evolves and periodically contracts and disintegrates. This universe is finite and closed in space but cyclically infinite in time.
An oscillating universe is quite compatible with certain Eastern philosophies, such as Hinduism, which believe that because nature is a cyclic process, there is no true progress. To Western philosophies, which take the view of continual progress starting from a more primitive state, the oscillating universe is an inherently unsatisfying model. Judaeo-Christian and Marxist belief, as well as Darwinism, imply a continuous progress from a single starting point. Furthermore, some empirical evidence, such as the residual black-body radiation, imply that there was only one Big Bang and not an infinite series. The residual black-body radiation is the average temperature to which the universe was heated by the original Big Bang. This temperature, which is about 3° Kelvin (-270°C), is consistent with a single Big Bang, but it would probably be higher if there were a series of Big Bangs. Actually all the cosmological theories are incorrect in the precise radiation predicted. Therefore, they all probably have serious errors. All paradigms are false or incomplete.
A Big Bang model without oscillation is inherently more satisfying to those who subscribe literally or intuitively to Judaeo-Christian belief because it implies the notion of a first cause--God being the creator of the Big Bang. "History" plays the role of "God" for Marxists. We note that one of the originators of the Big Bang theory was a Catholic priest, the Abbe LeMaitre. Another major contributor was George Gamow, a refugee from Soviet communism in the early 1930s. Few persons can separate their scientific ideas from their ideology. The problem is that there are even more philosophical difficulties with a single-event universe than with an oscillating universe. The "God," or "history," hypothesis may be a scientifically inadequate way of describing what existed before the Big Bang. If every time we encountered a hard-to-explain event we merely said "God caused it," then there would be no scientific, technical or intellectual progress. This is not to imply, however, that God or gods in some sense do not exist. We must try to seek explanations which are consistent with observed or derivable facts and not introduce any unnecessary conjectures to our scientific models. A good alternative to the Big Bang is the steady state model.
The Steady State Model
This model, first proposed in the late 1940s by Gold, Bondi, and Hoyle , represents a radical departure from orthodox cosmology, because in order to explain all the observed facts it assumes an unobserved fact. The fundamental assumption is that matter is continuously being created within the universe. The creation of matter was at first assumed to be a very slow and modest process, producing only one atom of hydrogen for every cubic centimeter of space every thousand years. This is a phenomenon which is not yet measurable under laboratory conditions on earth. Therefore, the assumption does not contradict any existing facts; but it does violate the first law of thermodynamics, which says that energy, and therefore matter, can be neither created nor destroyed. Matter and energy may interchange forms, but their sum remains a constant. However, this "law" is based on the fact that no one has ever actually observed the creation or destruction of energy and not on some more fundamental premise. Furthermore, the single Big Bang implies a one-time, instantaneous creation of all matter and energy. Therefore, the hypothesis of continuous creation may be scientifically valid and it is not really assuming more than the Big Bang theory.
The important thing to keep in mind is that all scientific models are only approximations to reality. In science no model is ever held to be absolutely true and beyond doubt or improvement. We simply tend to tentatively accept as "true" the model which makes the best predictions until another model comes along which makes better predictions. Then this model in turn becomes the "true" model. If two or more models are equally good at predicting, we tend to accept the simplest model which makes the fewest assumptions and/or is easiest to use. Science is therefore a pragmatic process which seeks only to improve humanity's ability to predict its total environment. The upholding of some specific philosophical or ideological premise at the cost of simplicity and/or predictability is contrary to the scientific spirit. In science only what can be shown to work is regarded as tentatively true. At best, the scientific paradigm is true but incomplete.
The steady state model is therefore contrary to neither the spirit nor the facts of science. We have introduced one unobserved fact into the cosmological process in order to explain all the observed facts. If the steady state model is correct, then we can make many predictions about the nature of the universe that are contrary to the simple Big Bang models. If observation verifies these predictions, then we tend to accept the steady state model. If observation contradicts the predictions, then we look for a better model.
Hoyle's latest version of the steady state model  explains the expansion of the universe as a result of the pressure being created by the unexplained generation of new matter; the unit of creation is not now a single hydrogen atom, but rather a galaxy - a mini-Big Bang, if you will. Galaxies begin as white holes similar to quasars. The old galaxies move out to make room for the new galaxies and this process goes on forever. The universe is infinite in space and time. Although the universe is dynamic and in constant progress, one part of the universe looks very much like any other part, and from each part the universe appears the same. That is to say there is no privileged position in space or time from which the universe as a whole looks different.
All these features of the steady state model have intuitive appeal forthose who have difficulty accepting either (1) a finite universe which started from nothing and is becoming nothing by spreading out into infinity, thereby becoming increasingly diffused until all matter exists in total isolation (i.e., all the particles of matter are 20 billion or more light-years apart and can no longer be observed one from the other), or (2) a finite oscillating universe which is constantly expanding and contracting in an endless cycle which leads nowhere--a cosmic treadmill without progress.
But intuitive appeal and satisfaction have little to do with scientific validity. Scientifically, we can accept the steady state model only if it makes correct predictions.
The steady state model seems to make correct predictions about everything that is observable in the universe except possibly (1) excess helium, (2) quasars being concentrated at cosmological distances, and (3) elementary particle physics. Fred Hoyle is currently adjusting the theory to compensate for these discrepancies . Even the residual black-body radiation can be made compatible with this model. The structure and distribution of galaxies seems better predicted by the steady state model than by the Big Bang model. However, there is more helium in the universe than is predicted by the steady state model - about 25% of the total universe; and this is precisely the amount of helium predicted by the latest version of the Big Bang model, which assumes an infinitely condensed, very hot initial cosmic singularity. This is in complete agreement with particle physics, which predicts a 25% helium universe.
Quasars seem to be the most amazing and difficult-to-explain objects ever discovered. The answer to "What is a quasar?" will determine in part whether the steady state model is accepted in some form or is rejected. Right now the major argument for the Big Bang theory is that it is the simplest model which makes the best predictions except for the structure of galaxies. It also unifies cosmology and particle physics. However, all current cosmological models will probably eventually be replaced by a more elegant model. In order to discuss quasars, we must first understand the nature of galaxies.
A galaxy is an interacting system of up to several hundred billion stars. Our own galaxy, the Milky Way, has a mass of about 2.8 X 1044 gms or about 1.4 X 1011 times the mass of our closest star - the Sun . If all of this mass represented stars, then our galaxy might have well over 200 billion stars. However, many stars are much more massive than the sun and some of the mass of the galaxy is contained not in the stars but in the clouds of interstellar dust from which new stars may eventually condense . The mass contained in the planets is negligible. More will be said of stellar evolution later. For now we consider stars as particles of matter which makeup the systems called galaxies, just as galaxies were considered particles in the system of the observable universe.
Galaxies are of four major types: spirals, barred spirals, ellipticals, and irregular galaxies that are neither spirals nor ellipticals, and may range from exploding galaxies to ring-shaped galaxies having almost any shape. Our own galaxy seems to be a spiral of over 100,000 light-years in diameter, very similar to Andromeda, which is the closest major galaxy at about two million light-years distance. Like Andromeda, our galaxy has two smaller satellite galaxies called the "Magellanic Clouds," which are about 163,000 light-years away.
As was mentioned earlier, observational evidence from several independent sources indicates that the galaxies are, in general, all receding from each other. Andromeda and our own galaxy are among the few exceptions and are approaching each other. Galaxies occur in clusters and the clusters in superclusters. Within any given cluster, the galaxies are gravitationally bound and may be approaching each other. The latest evidence is that galaxies cluster along the surface of spheres and may not be on the average uniformly distributed within the universe, at any scale - another possible argument against the steady-state model, as well as against the Big Bang model. It has also been observed that the speed of recession is in direct proportion to the distance between the galaxies. This relationship may not be quite linear at the extreme distances; but out to several billion light-years, a linear approximation to the recessional speeds of the galaxies applies. The recession speed itself is measured indirectly by means of the galactic red shift.
The red shift of the closer galaxies can be independently shown to be due to the Doppler effect of the speed of recession. The greater the speed of recession, the greater the red shift. This is analogous to the decrease in pitch of a sound such as a train whistle which is moving away from us. The faster it moves away the lower the pitch. Hence, the faster a galaxy is moving away from us, the further its spectrum will be shifted toward the red.
Independently of their red shifts, older stars tend to be reddish and young stars tend to be bluish. Irregular galaxies consist mostly of young, blue stars. Spiral and barred galaxies tend to have old, red stars near their nuclei and young, blue stars in their spiral arms. Elliptical galaxies tend to consist mostly of old, red stars. From this one might conclude, speculatively, that as galaxies condense from hydrogen gas and interstellar dustinto an irregular cloud, stars begin to condense and glow blue. As the galaxy ages, it increases its speed of rotation and the older stars remain near the center while new stars continue to be condensed in the spiral arms. As the galaxy grows still older it loses its energy through radiation and begins to slow down, losing its spiral or barred arms to become elliptical, until it ends as a dense globular cluster of old stars collapsing upon itself. Elliptical and irregular galaxies may also come from collisons between spiral galaxies.
Some globular clusters are estimated to be over 13 billion years old. An old globular cluster which heats up as it collapses upon itself might undergo a mini Big Bang and spew out its material into the universe, where it will eventually end up as part of other younger galaxies, or it might collapse into a massive black hole which produces the effect of a quasar while all the matter is collapsing. The Big Bang theory does not predict the structure of galaxies. In order to see whether these hypothetical mini Big Bangs are an explanation for the quasars, we must go into some detail about how stars evolve.
As we indicated earlier, a basic building block for the evolution of the universe is hydrogen, which is the simplest and by far the most abundant element in the universe. Since according to the steady state theory it is hydrogen and not other elements which are being created by a field effect of time, space, and matter, it is natural that hydrogen should be the most abundant element. The first question which comes to mind is, "Where do the other elements come from?" This is one cosmological question that has been thoroughly explored and adequately explained. All the elements other than hydrogen and some helium are synthesized from hydrogen and helium in the centers of the stars or are created in the process of the disintegration of a star in a supernova. There are other astrophysical evolutionary processes, such as slow neutron capture in the envelopes of the red giants.
Consider a universe of pure disassociated hydrogen with zero momentum. The hydrogen atoms will condense into clouds by gravitational attraction. As a cloud grows it attracts still more hydrogen and begins to contract into a spherical shape. As it contracts it begins to heat up from the increasing number of collisions between the ever denser hydrogen atoms. Eventually the hydrogen nuclei at the center of the cloud are so energetic, at about 10 million degrees, that they fuse and become helium nuclei. This causes an enormous release of energy, as in a hydrogen bomb, which causes the cloud to explode outward and overcome the gravitational collapse. There is a balance established between the gravity making the star collapse and the nuclear explosions making the star expand. The more collapsed the star becomes, the more energetic are the nuclear explosions making the star expand. Therefore, the star, if it is not too big, becomes a homeostatic, self-regulating system that will burn for billions of years until almost all of its hydrogen has been dissipated. Our own sun is an average star estimated to have an expected lifetime of about 10 billion years, half of which is over. The larger the star, the sooner it will disintegrate and the hotter it will burn. Very small stars that never quite catch fire are called "brown dwarfs."
Eventually much of the hydrogen at the core of stars larger than a brown dwarf will be converted to helium. Then the star is made of a large percentage of helium. There is then less energy available to keep the star from collapsing and it begins to undergo gravitational collapse again, becoming even hotter until it reaches a temperature of about 100 million degrees at its center. At this point the helium nuclei themselves begin to fuse and release even more energy than from the fusion of hydrogen nuclei. The hydrogen nuclei continue to fuse in the upper regions of the star. The star now becomes extremely hot with a helium core and a more diffused hydrogen atmosphere. This type of star is called a "red giant." When the sun becomes a red giant in about two or three billion years, it will extend out beyond the orbit of the earth. The earth and all the inner planets will be destroyed while the outer giants, Jupiter, Saturn, Uranus and Neptune, together with their moons, may become more hospitable.
When helium fuses it undergoes a series of complex nuclear reactions which eventually lead to carbon and oxygen. When the helium is exhausted in the star, the star can go two ways; it can become a supernova or a white dwarf made mostly of carbon. Stars between the size of a brown dwarf and about four times the size of the sun become white dwarfs with a density of 10 gms/cm. Stars much larger than this become supernovae. In these large stars carbon and oxygen undergo fusion through a gravitational collapse leading eventually to the formation of iron and all the intermediate elements such as neon, sodium, magnesium, aluminum, silicon, and sulfur. Supernovae collapse into a neutron star or totally disintegrate soon after fusion occurs in the carbon core. A neutron star is made up of collapsed matter in which no atoms but only neutrons exist. A teaspoonful of matter from such a star would have a mass of over 60 tons. A neutron star may have as much mass as the sun but be only 10 miles in diameter. The smaller stars produce very few elements heavier than carbon. Stars that are much more massive than the sun are the ones which produce most of the elements between carbon and iron. Elements heavier than iron are not produced by fusion in the core of the stars, since the fusion of elements heavier than iron consumes instead of produces energy; rather, the heavier elements are formed primarily by slow neutron capture in the envelopes of the red giants and by fast neutron capture just outside the core of the giant stars as they are exploding into supernovae.
The supernovae themselves produce various remnants, such as neutron stars, which are probably the source of the pulsating radio stars, planetary nebulae, and possibly black holes.
Black holes are amazing objects which are predicted by the general theory of relativity. In these objects a collapsed star, after undergoing a supernova explosion, is so massive and its gravity so strong that nothing can escape from it - not radio waves, light, or particles. It is the deadend of matter. We can detect black holes primarily by their gravitational effects. If elliptical galaxies collapse into black holes they might produce an effect similar to a quasar.
As matter falls into a black hole it emits massive amounts of radiation in a type of death scream until gravity overcomes it. It is believed that at the center of each galaxy is a massive black hole. Stephen Hawking has shown that it is also likely that small grain-sized black holes were created during the first few instants of the Big Bang. He has also shown that inthe long run black holes are stable in proportion to their size. Some of thesmall black holes may be exploding while the large black holes will last tens of billions of years. The nature of black holes may help us understand quasars.
There are objects in the sky which by their red shifts are estimated to be at extreme cosmological distances. Some have been detected at well over 13.5 billion light-years - or so it seems. However, these objects emit energy in such massive amounts that if they were truly at the distances which their red shift indicates, then they are entire galaxies in which all the matter is being converted to energy at a rate which cannot be explained by the nuclear fusion processes which go on in stars. Furthermore, these Quasi Stellar Objects (QSO's), or "quasars" as they are called, sometimes vary in intensity periodically with some periods as short as a day. (The first QSO's discovered were radio emitters and were called Quasi Stellar Active Radio Sources or "Quasars." QSO's which did not emit radio waves were found later, but "quasar" stuck.) This implies that some quasars are probably not more than a light-day in diameter or about the size of the Solar System, yet they emit much more energy than an entire galaxy.
The size limitation is due to the fact that if an object is undergoing periodic changes over the entire object, then these changes cannot propagate over the object faster than the speed of light. The special theory of relativity states, and experiment confirms, that matter and energy cannot transcend the speed of light within the observable universe, at least not by known means. Observational data indicate that quasars are starlike in visual appearance, since they have no observable shape as do the galaxies and appear as points of light as do the stars. Very distant galaxies also appear as points of light.
In summary, the preponderance of evidence indicates that quasars are very distant objects with masses at least as great as a galaxy, sizes often not much greater than a solar system, and energy outputs so enormous that no known physical process - except possibly the collapse of a galaxy into a black hole at its nucleus - can explain them. If the mass of a galaxy were being converted to energy at the same rate as it is in a quasar, it would only last about 100,000 years; yet all the observed galaxies seem to be many billions of years old. But perhaps the destiny of all galaxies is to collapse into black holes.
The first theory that some cosmologists developed in order to explain quasars was to hypothesize that they were not at the distances indicated by their red shift but were giant stars within or near our own galaxy. A quasarlike red shift can occur if the object emitting light is extremely massive or receding at a very high velocity. Then relativity predicts a red shift. Actually all light is shifted at least slightly to the red by gravity. When an object is extremely massive, then the red shift is so great that no light at all escapes as in the case of a black hole. However, stars sufficiently massive to produce a red shift of this dimension can easily be shown to be unstable. Such a star would quickly explode, and what remained either would become a black hole and/or condense into separate new stars. By studying old astronomical photographs we know that some quasars have had the same average brightness for at least 85 years, although in the past it was not known that these objects were quasars (they were thought to be ordinary stars). Furthermore, no known energy source or process could accelerate a nearby star to a velocity approaching the speed of light. Therefore, we are left with the inescapable conclusion that quasars are at extreme cosmological distances and/or all the models of the universe are in serious error. The latter case is not improbable.
One possibility for error which is currently being studied is that the physical constants of the universe, such as the gravitational constant, the electromagnetic constant, and the speed of light, are indeed variables which change very slowly with time. This theory was first propounded by Dirac in the 1930s . Fred Hoyle has done some modeling with a universe in which the gravitational constant decreases one part in 10 per year . This could not be detected in a laboratory, but it would have enormous consequences for all cosmological models, often reversing predictions. In short, cosmology can currently be said to be in a state of rapid change with no clearly superior model, although the Big Bang is by far the most popular model among scientists. Yet there is still much which can be said of the evolution of the universe. Consider the speculations in the following section.
The universe is infinite in temporal and spatial extension. A steady state model describes the universe as a whole. Throughout the universe there are Big Bangs (or mini-Big Bangs, if you prefer), occurring. Each Big Bang creates a mini-universe of its own, a bubble within the larger universe. Within each mini-universe the laws of physics including the nature of space, time, and matter, vary as a function of the size, mass, and age of the bubble and the conditions under which it was created. The bubbles themselves are unstable. As a mini-universe ages, it expands and the gravitational constant becomes weaker. Eventually the bubble bursts and the laws of the mini-universe become the laws of the universe within which it is contained. Each universe hatches another universe. Within the larger universe the laws of the mini-universe do not apply, but it has laws of its own. Each universe has its own space, time, matter, and set of physical laws. There is perhaps an infinite hierarchy of universes, each one contained within another, each one with laws of its own. Bubbles within bubbles within bubbles.
The gravitational constant is inversely proportional to the size, mass, and age of the bubble. Planck's constant varies from universe to universe. We note that some bubbles may contain infinite mass, i.e. infinitely many bubbles, but each bubble must be of a smaller order of infinity than the bubble which contains it. The mathematical concept of a hierarchy of nested infinities applies here [556, 652]. In our universe, as galaxies reach the speed of light relative to one another, they undergo a relativistic contraction and become increasingly thin, so that it is possible to pack an infinite number of galaxies in a finite volume. The mass itself is merely an area of curvature within the bubble as is indicated by the general theory of relativity. When the curvature becomes sufficiently great in the positive direction, we have a black hole, which is a direct exit from the mini-universe into the larger universe which contains it - a bursting of the bubble. When the curvature is sufficiently great in the negative direction, we have an entrance from the larger universe into the smaller universe. This area of high negative curvature is a quasar, or a "white hole." The quasars are more probable at the periphery of the bubble and represent a puncturing of the bubble from without. They produce more energy than is possible within the smaller universe because they represent a streaming of energy from the larger more energetic universe into the smaller, less energetic one. Eventually all the matter in a universe consists entirely of quasars and black holes and the universe is completely open to and from the larger universe. It has ceased to exist.
Although the quasars and the black holes are both unstable, within the larger universe the quasars play the role of protons and the black holes play the role of electrons, or they are some other analogue of elementary particles. No elementary particles in any universe are ever stable; they are always collapsing from within and from without. The bubbles become open from without and from within and merge with other bubbles to create an infinite variety of universes.
Within any given bubble there are new bubbles being formed. The frequency of bubble formation changes with time because the relationships between the physical constants are changing as their values change. The mini-Big Bangs within our own universe are not the supernovae but the creation of quasars. Protons and electrons are being generated in our universe from the quasars. Quantum phenomena result from the random punching of portals from and to the universes, within and without. These phenomena are random because they are partially determined by forces outside our universe which we can neither predict nor control. These forces are "hidden variables" outside of our time and space. Within any universe there is a smallest possible bubble. Within our universe that smallest possible bubble is one quantum of energy.
The preceding is, of course, all speculation and may contain logical or factual inconsistencies which either could be analytically evident or could manifest themselves by the inability of this cosmological model to make correct predictions. If the model is correct, a unified field theory may be derivable from it. However, the main reason for this cosmological speculation was not necessarily to derive a correct model but to show the kinds of thought processes one must go through in creating new models, which are always necessary to make all the existing facts consistent and then to be able to predict new facts. This model, for example, predicts that quasars are truly at cosmological distances and must be more common at these distances. Indeed, as we observe ever farther out we should find ever more quasars. The fact that observed quasar density begins to fall off at about 8 billion light-years is due to the red shift, which makes the quasars increasingly difficult to observe until they become invisible at about 15 billion light-years. The quasars are the major points, but not the only points, where matter is being created. This is why they are so energetic. At the time of our local Big Bang, our universe was one giant quasar. The energy for this Big Bang came from the larger universe in which we are contained. It was a puncturing of the fabric of space-time which created our own universe with our own peculiar laws. The bubble began to expand from within by our own laws and from without through subsequent smaller quasars. Eventually our universe will be entirely made up of quasars and black holes in dynamic interaction governed by the laws of the larger universe which contains our mini-universe. We will have become as we always were, matter within the larger universe.
As was mentioned, the outstanding cosmologist Stephen Hawking has estimated that black holes are unstable and will eventually explode after periods much longer than the current age of the universe. Even protons and neutrons seem to be unstable. In the long run nothing remains the same. Everything is eventually transformed into something else. At the cosmological level, therefore, we see a pattern of galaxies, quasars, and black holes, joining in a system to form an integral part of vastly larger and more complex systems. At the micro-level we see the same pattern where quarks, electrons, and protons join together in a system to form our local mini-universe. In between there is a whole spectrum of physical, chemical, biological, and psychosocial evolution. Since there is no bubble less massive than a single quantum of energy, our universe may be near the bottom of a cosmological evolutionary ladder that extends up to infinity. In order to see humanity's place in the cosmic scheme of things and better understand the total process of general evolution, we begin to trace the process which led from matter to us. Eventually this process will lead us again to cosmological considerations in Chapter 5, where we consider another cosmological model based on the deeper aspects of quantum mechanics. The macro and the micro are intertwined in a coherent whole within the infinite hierarchy of all the universes that have ever existed and ever will exist.
The Evolutionary Perspective
All cosmological models are highly speculative. If we look at these models, starting from Genesis in the Bible and ending with the steady state model of Hannes Alfven , which assumes a universe permeated by plasmas, we see that all of these models had to be radically altered as new facts were discovered. Yet each of the models has a certain level of truth and meaning, and makes unique predictions. Genesis still has relevance if we interpret the Biblical account figuratively and not literally. Many modern theologians, including some within the Catholic Church, use this figurative interpretation. Remember that the Bible, by its own account, is an ancient narrative of reality written by imperfect men, not by a perfect God. Since then, many distortions may have been introduced by imperfect copying and even more imperfect translations. The chronological sequence in Genesis is in close agreement with the best scientific estimates, and the six days of creation can be considered as six epochs. Man being made from mud and the Garden of Eden account can be interpreted as man evolving from matter and becoming animal and finally human (an ethical being). Leaving the Garden of Eden was not a "fall," but an ascent to assuming ethical responsibility for our own evolution rather than being the obedient pet of a despotic God.
Later we will show that humanity has an intuitive, unconscious grasp of evolution because it is an integral part of it. The universe seems to have a holographic structure in which each part reflects the whole. We can perceive evolution directly because we can perceive our own existence directly. This direct perception of self in an evolutionary context expresses itself in religion and art. These are ways in which we integrate dimly perceived unconscious knowledge in a conscious symbolic synthesis. All this we will show within the context of psychosocial evolution. At this point it is only necessary to indicate that evolutionary modeling is an essential part of being human. We all either speculate on evolution or accept others' speculations, as in the case of religious adherents.
As was indicated earlier, models about the evolution of stars are much less speculative and are on firmer ground than models about cosmological evolution. We can observe our own star, the sun, at close hand and do laboratory experiments, as in the case of nuclear fusion, which can test our hypotheses about stellar evolution. Knowing how stars evolve, it is easy to explain how planets evolve.
The Evolution of Planets
As was stated earlier, stars evolve from the gravitational collapse of a cloud of hydrogen, helium, and other matter. Recently there has been a unification between particle physics and Big Bang cosmology. This unification predicts that at the time of the Big Bang, 25% of all the matter was converted into helium from the primordial hydrogen, and 75% remained hydrogen. This agrees with observation. It is further evidence in favor of Big Bang cosmology, although the same result can be obtained by assuming that each galaxy begins as a mini-Big Bang from a white hole, and part of the hydrogen is converted into helium.
As the sun was condensing by gravity into a dense cloud it began to spin. This resulted from the conservation of angular momentum. The dynamics of a gas cloud condensing under gravity are fairly well understood, and the results are predictable.
As the cloud condenses it spins ever faster. The centrifugal force causes it to become disc-shaped, similar to a galaxy. Then rings begin to form in the outer parts of the disc, and a spinning spherical nucleus is formed in the center by transferring angular momentum to the planets, as predicted by Hannes Alfven, through electromagnetic fields - again, as with a galaxy. We see an analogy of this today in the planet Saturn. (Note that Jupiter, Uranus, and Neptune also have rings.) The rings themselves are unstable and break up into new spherical shapes, many of which crash into one another, e.g., planets and comets. If these spheres have sufficient mass, they will become stars themselves, and we will have a multiple star system, such as abounds in the universe. If the spheres are smaller than the critical size, they will become comets, asteroids, planets or satellites of planets like the moon.
The larger planets, such as Jupiter, Saturn, Uranus, and Neptune, will have enough of a gravitational field to retain part of their hydrogen and helium atmosphere, although, except for Jupiter, most of this atmosphere will be lost to outer space. In the smaller planets the atmospheric hydrogen and helium will be almost completely lost to outer space. However, chemically bonded hydrogen is retained as in H2O. In the smaller planets, such as Mars, even H2O in its disassociated form is eventually lost because of weak gravity. If Mars had been a little larger, it would have been an earth-like planet, since it is within the ecosphere of the sun .
The largest planet, Jupiter, is actually a star which did not quite make it. It radiates more energy than it receives from the sun, but it does not have enough mass to engender a nuclear reaction even at its center. The radiant energy of Jupiter is probably due to a slow gravitational collapse. But Jupiter is too small to even be a brown dwarf. Jupiter has an atmosphere and surface of fairly complex molecules. Sagan has estimated that Jupiter probably has a higher probability of engendering life within its atmosphere (not its surface) than any planet of the Solar System other than earth .
While hypothesizing about life evolving on non-earthlike planets is a highly interesting, speculative exercise, it is not central to our problem of developing a generalized model of the evolutionary process. We need only assume that evolution can occur on any earthlike planet, and note that in our galaxy alone the expected number of earthlike planets is enormous, since there are at least 100 million sunlike stars [676, 705]. On any earthlike planet around a sunlike star, chemical evolution is, up to a point, a natural consequence of the laws of chemistry.
All the basic elements given in the periodic table evolve from the nucleons making up hydrogen. The nucleons themselves either (1) are being continuously created as a function of time, space, and matter (steady state model), (2) were created at a single point in time and space (the Big Bang), or (3) always existed and always will exist in either an infinite or a finite universe (e.g., Hannes Alfven's steady state model ). Given that a sufficient mass of elements exists to create the solar system, the rest of the evolutionary process follows directly and inexorably. We may speculate about cosmic evolution or simply say we do not know and may never know about the origin and destiny of time, space, matter, and natural laws; we merely take them as a given for now and will get back to them later within the context of humanity's evolutionary future.
Cosmic evolution involves elementary particles becoming organized into atoms and eventually into galaxies, stars, and planets. This process seems predictable and seems determined by the existence of energy and current natural laws. Chemical evolution involves atoms becoming organized into molecules.
Molecules are formed by the interactions of the electrons surrounding the nucleus of the atoms. This process is primarily electromagnetic and seems to be almost completely independent of nuclear forces and gravity. Chemical evolution is a characteristic of planets, but it is not confined to planets. The basic organic molecules of life may have been formed, or have already existed, in the cosmic cloud from which the sun and the planets condensed. These molecules have been detected in the interstellar clouds as well as in the atmosphere of the sun , and they may still be synthesized there [359, 360]. However, the early earth provided an adequate environment for all aspects of chemical evolution.
As the earth was condensing, the iron, nickel, and cobalt sank toward the center of the cloud, forming the molten core of the earth; then the nextheaviest elements, such as silicon, aluminum, sulfur, etc., condensed to form the crust of the earth. In this stage, elements were highly reactive and combined with some oxygen, hydrogen, and nitrogen in the still-hot atmosphere to form chemical compounds such as the aluminum silicates and the pyrites, which form most of the surface of the earth. Then, as the atmosphere cooled to about 1,000°C, water molecules in the form of steam began to condense from oxygen and hydrogen in the cooler, upper atmosphere and eventually precipitate as rain; but they would be gassified into steam as soon as the rain came in contact with the hot earth. There is also an accretion model, stating that the oceans were due mainly to watery comets crashing into the earth. As the comets are used up, the crashes become less frequent, but are still going on today.
In any case, there were convection currents set up between the hot, solidifying crust and the turbulent atmosphere which contained the elementary gases and the rapidly forming gaseous molecules such as H2O, HCN, CO2, CH4, NH3, etc. As the earth cooled these molecules stabilized and did not become so easily disassociated into their elements by the hot crust. The heavier molecules began to concentrate near the surface and to dissolve in the oceans which began to form once the crust had a temperature below 100°C. The lighter molecules of H2 and He were lost to outer space. The oceans were much smaller than at present, as much of the water was still in the hot atmosphere. The heavy organic molecules and the isolated pools of water began to form into a concentrated soup about 25,000 years after the solidification of the earth.
Within the atmosphere the simpler organic molecules began to react under the influence of ultraviolet radiation and lightning to form more complex and heavier molecules, which would concentrate by sinking to the soup. The process was abetted by the catalytic action of inorganic clays. The oxygen molecules, highly reactive, were almost entirely incorporated into chemical compounds with other elements so that there was very little free oxygen and consequently no ozone, O3, to shield the earth from ultraviolet radiation. The earth had a reducing atmosphere. Most of the surface would remain relatively unoxidized for hundreds of millions of years. These conditions can be repeated in the laboratory today.
If we simply put H2O, O2, C, and N in an environment approximating that of the primitive earth, we obtain the simple molecules CO2, H2, CH4, NH3 and HCN and, of course, some residual amounts of the original elements. We note that these molecules are gases at the temperature of the primitive earth, but that they are much heavier than H2 and He. Therefore, they will be retained and concentrated by the earth while the H2 and He are being lost. After the earth had cooled sufficiently, still more complex molecules would begin to form in the atmosphere from these simple molecules. If today we put these molecules into a container in which the conditions of the earth a few thousand years after its formation are duplicated, and passelectrical discharges through it, equivalent to lightning, and bombard it with ultraviolet rays, equivalent to unshielded sunlight, then spontaneously we have the amino acids formed [527, 528].
Here we see another step in complexity of structure which occurs automatically by chemical laws under the conditions of the primitive earth. The amino acids are basic building blocks leading to the proteins determining the physical structure of all known living systems.
Chemical evolution can only go so far by the same process by which amino acids are created. Eventually molecules must become self-reproducing in order to sustain increasing complexity. This is the case because the extremely complex molecules represent unlikely and unstable events. The complex molecules will spontaneously decay into simpler molecules at room temperature unless some mechanism is making the reaction go in the other way. This process is what Darwin called "natural selection."
Relatively simple molecules such as RNA have autocatalyzing properties. This means that these molecules serve as templates by means of which simpler molecules are induced to organize themselves into complementary replicas of the original molecule. Recent evidence indicates that the inorganic clays contribute to this process. This is not reproduction in the normal sense of the word since the original molecule has not split into two or more copies of itself but has merely caused the creation of complementary copies of itself. There must be at least two complementary copies. With RNA we have four complementary copies and a slight variant, uracil, which is used in T-RNA. However, once autocatalyzing molecules exist it is possible to begin the process of natural selection.
Given that there are several species of autocatalyzing molecules spontaneously created through deterministic chemical reactions, then those molecules which can most effectively catalyze copies of themselves will take up more of the supply of available simple molecules to make copies of themselves while the other molecules are eventually disassociated into their constituents, which in turn are catalyzed into copies by the more effective molecules before they themselves disassociate. Eventually any given environment will contain only one species of competitive autocatalyzing molecules - the most effective at catalyzing copies of itself - all the other species having become extinct. However, the molecules are themselves constantly changing.
Through random bombardments of energy by radioactive elements, volcanic action, lightning, ultraviolet light, meteors, etc., the self-catalyzing molecules are constantly having their chemical structure changed. Most of these random changes will cause the molecule to become disassociated and less effective in catalyzing copies of itself, and those mutations will become extinct. However, very infrequently a change will increase the autocatalyzing efficacy of the molecule; this mutation will quickly replace all its brothers. Therefore, here we have an example of chemical evolution by natural selection. This type of chemical evolution has been very elegantly modeled by Manfred Eigen and his associates [217, 218, 219, 608].
Evolution by natural selection involves three essential factors - reproduction, mutation, and death. Death simply means a disorganization of an entity into its more elementary component parts, as happens with all complex molecules which become disorganized into simpler molecules. If there were no death, eventually all the chemical compounds necessary for forming new molecules would be tied up in the older molecules and no new molecules could form. If there were no mutation, there would be no change, and new, more effective molecules would not be formed. If there were no reproduction, then there would be no mechanism for giving advantage to one molecule over another and the relative proportion of different molecules would depend only on the probability of any molecule being formed from its constituent parts. Therefore, all three components must be present for the system to evolve by natural selection.
We note that evolution, by whatever means, involves simpler structures organizing into more complex structures. This process is highly predictable and determined strictly by the laws of physics and chemistry up to the existence of autocatalyzing molecules. Once autocatalyzing molecules come into being, then highly unpredictable random factors determined by quantum mechanical laws begin to operate. The causes and results of any mutation are uncertain. The mutations which increase the reproductive efficiency of any molecule may be among the least probable. It is somewhat like randomly jumbling the letters and symbols in a blueprint and reproducing a better design. Evolution by natural selection is therefore a process by which highly unlikely events consolidate themselves and outlive much more likely events. It represents a monotonic decrease in the entropy of a system.
The concept of entropy was first proposed by Clausius in the nineteenth century to refer to a property of all closed systems by which they lose their capacity for performing useful work. Another way of saying the same thing is to say that they are gradually transformed into their most probable state. This latter statement of the concept of entropy was formulated by Boltzman. A third way to describe entropy is in terms of a decrease in the coherent information in a system. The greater the coherent information in a system, the lower its entropy. The more chaotic and disorganized a system, the higher its entropy. This view was derived by Claude Shannon in the late 1940s and is mathematically equivalent to the other formulations of entropy. The most probable state for any system which evolves by natural selection is death, i.e., a disorganization of the system into its component parts. In the case of the autocatalyzing molecules this means a breakdown of those systems into the simpler compounds which compose them. Experimentally we observe that in a closed system, say a glass flask which has been exposed to high temperatures, most of the molecules will be in the disassociated state. All entities are exposed to random disruptive energy from earthquakes, solar bursts, cosmic rays, meteors, natural radioactivity, volcanos, and many other natural but not precisely predictable, i.e., random, events which disrupt them and increase their entropy.
The second law of thermodynamics states that the total entropy in any closed system can never decrease. Intuitively we can look at the concept of entropy as (1) the non-availability of energy in a system for doing useful work or (2) the total disorder and randomness of a system. Therefore, the second law of thermodynamics apparently states that evolution cannot occur in a closed system. Yet evolution is an objective, directly observable reality. Only the mechanisms by which evolution occurs are disputed.
Evolution refers to (1) the increase in the ability of a system to predict and control its total environment, i.e., to do useful work, (2) an increase in the complexity and order of a system, or (3) simply a decrease in the entropy of a system, sometimes expressed as an increase in negentropy. The autocatalyzing molecules clearly increase their capability to predict and control, which in their case is limited to producing progeny. In the process they increase their complexity and decrease their entropy, as is indicated in the studies by Manfred Eigen et al and by Lila Gatlin . The concept of complexity is not usually treated precisely. For our purposes, we will regard the complexity of a system to be a direct function of (1) the total number of components of a system, (2) the number of different connections and relationships between the components, (3) the number of differences between all the components and connectors, and (4) all other information in the system. This is clearly a simplification of the concept of complexity.
The sun has approximately 1059 components, i.e. hydrogen atoms, but there are relatively few relations and connections between them in the form of helium and heavier elements. The largest living cells have no more than 1012 atoms. However, the connections between the atoms in the cell are much more numerous than in the sun, so that the cell seems much more complex than the sun. The information content of a cell may be greater than the sun's. By the time we come to a system of cells such as a human being, we have information and complexity greatly exceeding that of the sun. Therefore, if we consider the solar system as a closed system, although the entropy of the sun is clearly increasing, it is not clear that the entropy of the total solar system is increasing, because of the enormous increasein complexity of the biomass in general and of the human species in particular.
If the second law of thermodynamics is to continue to hold, this means that the solar system is not closed, as indeed our section on cosmology indicates, but that organizing energy and, more importantly, information are being drawn from other parts of the universe and that this information is contributing to the evolutionary process. The nature of this extrasolar organizing information will be discussed later. For now we merely note that although natural selection may explain much of the evolutionary process it does not necessarily explain all of it. Darwinism in all its forms may be an incomplete description of the evolutionary process. We shall see that there is evidence that information can increase faster than physical entropy, although there is a one-to-one mathematical correspondence between the information theoretic and the thermodynamic concepts of entropy.
Given that a system has autocatalyzing properties - i.e., reproduction, mutation, and death - then evolution will proceed as long as there is an adequate supply of energy plus information and as long as the energy is not so disruptive as to produce an overwhelming rate of deleterious mutations or deaths. (See Lila Gatlin's work .)
A mutation is deleterious when it decreases the probability of the autocatalyzing system to reproduce itself, i.e., increases its entropy. The death rate becomes overwhelming if it exceeds the birth rate until the species undergoes extinction. Life and indeed chemical evolution cannot occur on the sun or the inner planets (Venus and Mercury) because the energy is too disruptive to allow complex molecules to form for a significant length of time. On the outer planets and their moons there may not be proper energy or appropriate conditions to push evolution against the force of entropy. As indicated earlier, Jupiter and possibly Mars may be exceptions . Evolution by natural selection requires a very delicate balance in mutation rates, death rates, and reproduction rates, or it will not take place . An essential condition also seems to be the existence of liquid water. Around any given star there is only a relatively narrow shell, "the ecosphere," within which the conditions for evolution are adequate and the balance is achieved. (Our sun's ecosphere extends from just inside the orbit of earth to just outside the orbit of Mars .) When this balance is achieved, then entropy is overcome step by step.
"... and behold a ladder was set up on earth, and the top of it reached to heaven." (Genesis 28:12)
The counterentropic climb up the evolutionary ladder begins with the autocatalyzing molecules. Once the first such molecule was formed in at least one complementary pair by unlikely but not impossible chance from the physicochemical forces prevalent in the primitive earth, it began to reproduce, mutate, and die. The overwhelming majority of the mutations would increase their entropy and leave fewer progeny, but for every few billion mutations, one was, again by unlikely but not impossible chance, decreasing its entropy and becoming more effective in organizing and concentrating simple molecules into copies of itself. Every time that this happened its descendants would replace the descendants of its less effective siblings and one more step would be taken up the ladder of evolution. The second law of thermodynamics was still operating but in such a way that the less efficient, more entropic autocatalyzing systems were becoming extinct while the more efficient, less entropic ones were multiplying. At the same time the conditions which produced the mutations and gave advantage to one molecule over another were themselves changing. Therefore, the ladder of evolution is one in which the lower rungs are continuously being disassembled and used to build the upper ones. It is possible to climb up, but one cannot climb down without falling off into irreversible entropy.
It is estimated that the sun is 60% hotter now than when the earth was first formed. However, as the organic molecules and the CO2 in the earth's atmosphere became fixed in living forms and dissolved in the oceans, the greenhouse effect decreased, so that earth could maintain a steady temperature with a hotter sun. Amazingly, the ecology of the earth changes to maintain an almost steady temperature. There is clear evidence that the earth's temperature has been remarkably constant for the last four billion years. (See James Lovelock's work .)
In time, the autocatalyzing molecules which were most efficient at one stage could not survive or reproduce at another stage. Their elements had been used to create the next rung on the ladder of evolution which their progeny continued to climb. Eventually so many of the organic molecules essential to reproduction were tied up in the increasingly stable and efficient autocatalyzing molecules that a new type of reproduction becamenecessary.
So long as there were simple organic molecules, i.e., nutrients, plentiful in the environment, reproduction by catalyzing complementary copies through template action was an efficient form of reproduction. However, as the number of self-reproducing systems increased and the nutrient concentration decreased, this type of reproduction became increasingly difficult to perform, and it became necessary for the self-reproducing systems to concentrate nutrients. This was done by growth.
Although there may not be a sufficient concentration of nutrients at some particular point in space and time for an autocatalyzing molecule to reproduce itself, if it can absorb these nutrients and store them, then eventually it can have enough nutrients for two copies of itself. The way molecules can grow, almost without limit, is by polymerization. Therefore, in a system which is evolving by natural selection, the autocatalyzing property is used by the molecule to extend itself at both ends in a single system which eventually splits into two and only two parts. Then these parts in turn extend themselves, split, and repeat the cycle. These systems which reproduce by polymerization growth and splitting are by and large less stable than the more simple autocatalyzing molecules. Therefore, they will have higher death and mutation rates. They are less likely to exist early in the evolutionary process in competition with the simpler autocatalyzing molecules. However, they have a much higher reproductive efficiency in an environment which is becoming dilute in nutrients. Today we know of two major types of molecules which have some of the properties of these early self-reproducing polymers; they are the proteins and the nucleic acids.
Proteins and Nucleic Acids
Proteins are polymers formed from amino acids, which, as we have seen, were spontaneously synthesized and concentrated in the conditions of the primitive earth. The proteins form fairly stable polymers and they are very effective catalysts. But they require more idealized conditions to reproduce copies of themselves than the nucleic acids and they have a lower mutation rate.
The nucleic acids tend to form relatively unstable polymers, but they are very efficient reproducers and easily mutable. The fact that proteins and nucleic acid polymers primarily use different nutrients means that they could coexist and evolve in parallel. They were noncompetitive. More importantly, it is possible for them to form symbiotic systems.
Symbiosis is a process by which two distinct, self-reproducing systems organize into a compound system such that the net reproductive effectiveness for both is increased. An evolutionary process based solely on proteins or solely on nucleic acids is less thermodynamically effective than one based on the symbiosis of both proteins and nucleic acids, as is shown in the work of Manfred Eigen . Therefore, it is likely that once chemical evolution by growth and splitting began it was soon based on symbiotic systems of proteins and nucleic acids.
These might have been formed by the spontaneous capture of nucleic acids within protein spheres. Many proteins in water spontaneously form into hollow spheres under conditions which probably existed on the early earth. Most of these spheres would have been nonviable. However, once the right proteins and the right nucleic acids formed, then a symbiotic process began. This is the closest point to the actual beginning of life. These processes would, in fact, have begun spontaneously if the right proteins andnucleic acids came together in any given region. However, this would be highly unlikely because conditions for their synthesis are different. Once they began interacting symbiotically, their concentrations would increase, and there would be a higher probability of a protein sphere capturing the right nucleic acid and forming what amounted to a protocell. The symbiotic interaction of proteins and nucleic acids to create one another, and thereby to create life as an epiphenomenon, is known as "autopoiesis" (self-creation) , after Chilean scientists Varela and Maturana .
In living cells the functions of the proteins and the nucleic acids are clearly divided. The nucleic acids are in charge of all information storage, transfer, and reproduction, while proteins are in charge of forming structures and catalyzing chemical reactions. The nucleic acids (RNA) are organized into DNA. The DNA molecules within each cell contain all the information for structuring each given living creature whether it be an amoeba or a human being. This division of function could not have survived under the pressure of natural selection if they were each evolving in isolation from one another. And, as we have seen, this isolated evolution might have preceded the symbiotic evolution. Therefore, these complex self-reproducing polymers, the protocells, which were the precursors of living cells, must have been quite different from existing proteins, DNA, or living cells.
We can imagine but not yet create a polymer which has properties of both proteins and nucleic acids. If such a molecule were subjected to natural selection, it would be more thermodynamically efficient for the functions of the nucleic acids and the proteins to differentiate. Therefore, it might be that the protocell was a generalized molecule with properties of both proteins and nucleic acids to start. Later this molecule became differentiated into a system of distinct molecules working symbiotically (complementary pairs) to become a living cell. However, for reasons to be given in Chapter 5, this does not seem to be the case. The entire pattern of the evolution of the universe seems to be based on autopoiesis between complementary pairs of entities such as protons and electrons, proteins and nucleic acids, or males and females. When this autopoietic interaction occurs then a whole new dimension is added to evolution. The new dimension that was added to matter by autopoiesis we call "life."
© John David Garcia, 1991, All rights Reserved.