The anthropic principle, which was first introduced into the academic communities back in 1961 by Robert H. Dicke of Princeton University, actually had its origins in the so-called “big numbers” in cosmology discussed as early as 1931 by the British theoretical astrophysicist Sir Arthur S. Eddington and by the British quantum theorist Paul Adrien Maurice Dirac in 1937. Both Eddington and Dirac were intrigued by certain numbers that could be obtained by combining other numbers important to physics and astrophysics, such as the charge of the electron q, the speed of light c and the universal constant of gravitation G. In Dirac’s own words as they appeared in the article The Cosmological Constants published in Nature:
“The fundamental constants of physics, such as c the velocity of light, h Planck’s constant, e the charge and m mass of the electron, and so on, provide for us a set of absolute units for measurement of distance, time, mass etc. There are, however, more of these constants than are necessary for this purpose, with the result that certain dimensionless numbers [a dimensionless number is one that remains the same regardless of the system of units used to measure it or evaluate it. For example, the square root of two will have the same value under any system of measurement, whereas the ambient temperature will have a different numerical value depending on whether the temperature is measured in degrees Fahrenheit or degrees Centigrade] can be constructed from them. The significance of these numbers has excited much interest in recent times, and Eddington has set up a theory for calculating each of them purely deductively. Eddington’s arguments are not always rigorous, and, while they give one the feeling that they are probably substantially correct in the case of the smaller numbers (the reciprocal fine-structure constant hc/e² and the ratio of the mass of the proton to that of the electron), the larger numbers, namely the ratio of the electric to the gravitational force between electron and proton, which is about 1039, and the ratio of the mass of the universe to the mass of the proton, which is about 1078, are so enormous as to make one think that some entirely different type of explanation is needed for them. According to current cosmological theories, the universe had a beginning about 2•109 years ago, when all the spiral nebulae were shot out from a small region of space, or perhaps from a point. If we express this time, 2•109 years, in units provided by atomic constants, say the unit e²/mc3, we obtain a number about 1039. This suggests that the above-mentioned large numbers are to be regarded, not as constants, but as simple functions of our present epoch, expressed in atomic units. We may take it as a general principle that all large numbers of the order 1039, 1078 … turning up in general physics theory are, apart from simple numerical coefficient, just equal to t, t² …, where t is the present epoch in atomic units. The simple numerical coefficients occurring here should be determinable theoretically when we have a comprehensive theory of cosmology and atomicity.”
Thus, considering only the order of magnitude rather than using exact values, some physicists at the time pointed to the fact that there were several cases where the order of magnitude was an integral power of the large number 1039, as can be seen from the following list:
- 1080: Estimated number of particles in the known Universe (at the time). [In a rather extraordinary coincidence, two thousand years before Arthur Eddington obtained this famous estimate of 1080 particles in the known universe at the time, the Greek mathematician Archimedes obtained this same estimate as described in a letter from him to king Gelon entitled "The Sand Reckoner", treated in more detail in the article "The Cosmic Numbers" that appeared in the December 1972 issue of the magazine Physics Today.]
- 1040 :Ratio of the estimated size of the universe at maximum expansion to the “size” of an elementary particle.
- 1040 : Ratio of electric forces to gravitational forces.
- 1020 : Ratio of the “size” of an elementary particle to Planck’s length.
- 1020 : Ratio of the estimated number of photons to the estimated number of baryons in the universe.
As the reader may have noticed, there does appear to be a relationship among these “big numbers”, raising some suspicions among prominent scientists, although skepticism remains. Charles Misner, Kip Thorne and John Archibald Wheeler reflect this attitude in the book Gravitation, where they jot down the following comments:
“Some understanding in the relationships between these numbers has been won. Never has any explanation appeared for their enormous magnitude, nor will there ever, if the view is correct that reprocessing the universe reprocesses also the physical constants. These constants on that view are not part of the laws of physics. They are part of the initial –value data (initial conditions!). Such numbers are freshly given for each fresh cycle of expansion of the universe. To look for a physical explanation for ‘big numbers’ would thus seem to be looking for the right answer to the wrong question … A per cent or so change one way in one of the ‘constants’, hc/q², will cause all stars to be red stars; and a comparable change the other way will make all stars be blue stars, according to (Brandon) Carter. In neither case will any star like the sun be possible. He raises the question whether life could have developed if the determinants of the physical constants had differed substantially from those that characterize this cycle of the universe … Dicke (1961) has pointed out that the right order of ideas may not be, here is the universe, so what must man be, but here is man, so what must the universe be? In other words: (1) What good is a universe without awareness of that universe? But (2) Awareness demands life. (3) Life demands the presence of elements heavier than hydrogen. (4) The production of heavy elements demands thermonuclear combustion. (5) Thermonuclear combustion normally requires 109 years of cooking time in a star. (6) Several 109 years of time will not and cannot be available in a closed universe, according to general relativity, unless the radius-at-maximum-expansion of that universe is 109 light years or more. So why on this view is the universe as big as it is? Because only so man can be here! … In brief, the considerations of Carter and Dicke would seem to raise the idea of the ‘biological selection of physical constants’ … However, how to select is impossible unless there are options to select between.”
In an article entitled “The Anthropic Principle” by George Gale, published in the December 1981 issue of Scientific American, Gale introduces us to the subject in the following manner:
“The earth is an exceptionally hospitable place for mankind, with abundant water and average temperature that happens to lie in the narrow range where water is a liquid. In view of the evolutionary origin of life, these facts are hardly surprising; if the earth were as cold as Mars, or if it had a steamy, caustic atmosphere like that of Venus, intelligent beings would not have evolved to remark on the hostility of their surroundings. It seems decidedly odd, however, to argue that the presence of life on the earth might ‘explain’ why the planet has a temperature between the freezing point and the boiling point of water. The usual practice has been to argue the opposite proposition, namely that life evolved on the earth because circumstances were conductive to its existence … Although the reasoning may at first seem backward, the idea that the mere presence of intelligent life can have can have some explanatory power has recently been introduced into cosmology, where the task is to understand the history not of a single planet but of the entire universe. It is easy to imagine a universe quite different from the observed one. For example, changing the values of certain physical constants might give rise to a universe where the chemical elements heavier than helium are never formed or where all stars are large, hot and short-lived. In most such imaginary reconstructions of the universe it is unlikely that an intelligent form of life would ever appear. The fact that the real universe does harbor intelligent observers therefore places certain constraints on the diversity of ways the universe could have begun and on the physical laws that could have governed its development. In other words, the universe has the properties we observe today because if its earlier properties had been much different, we would not be here as observers now. The principle underlying this method of cosmological analysis has been named the anthropic principle, from the Greek anthropos man … The mode of reasoning embodied in the anthropic principle is quite different from the deductive mode that has long been characteristic of much scientific thought. A deductive theory begins by specifying the initial conditions of a physical system and the laws of nature that apply to it; the theory then predicts the subsequent state of the system. For example, one might deduce the present conditions on the earth by specifying the initial size, mass and chemical composition of the nebula from which the solar system condensed, then tracing the evolution of the sun and the planets under the influence of physical laws that describe gravitational forces, nuclear reactions and so on. The anthropic principle has been invoked in cosmology precisely because the deductive method cannot readily be employed there. The initial conditions of the universe are not known, and the physical laws that operated early in its history are also uncertain; the laws may even depend on the initial conditions. Indeed, perhaps the only constraint that can be imposed on a theory reconstructing the initial conditions of the universe and the corresponding laws of nature is the requirement that those conditions and laws give rise to an inhabited universe … At the least the anthropic principle suggests connections between the existence of man and aspects of physics that one might have thought would have little bearing on biology. In its strongest form the principle might reveal that the universe we live in is the only conceivable universe in which intelligent life could exist.”
The anthropic principle, appealing as it may sound, has a lot of critics (besides a lot of supporters) in the academic communities. The most important weakness of the anthropic principle is that to date it is only a principle. Currently, it provides no specific formulas that can enable us to go back in time and make a prediction amenable to verification in our own time with known current data or put that prediction to the test in a laboratory (at least not yet, although it is possible that some day it may be given such capabilities by some bright young scientist!)
Nevertheless, in spite of some of the sharp criticisms it has received, logic alone tells us that its basic tenet must be fully valid. Our presence in this Universe must be taken as full proof that, as far as this Universe is concerned, at the very moment of its creation the initial conditions were there such that they would allow the life form known as Man to come into being and flourish, even if for a very short time when compared to the life span of the Universe itself. Even if we draw quantum mechanics into the picture with all of its built-in uncertainties, out of the many possible sets of initial conditions allowable by quantum mechanics at the very moment of creation at least one had to be available in the set in order to allow for our appearance in this Universe, for otherwise we simply would not exist, unless of course all that you have seen, experienced or read in your entire life (including this book you are reading) may be just a dream from which you have not yet waken up!
In its mildest form (the so-called weak version), the anthropic principle demands that the Universe be built in such a way that, at some point in time after the moment of creation, all of the necessary parameters required to enable the appearance of an intelligent life form such as Man will converge precisely just as they are required. Anything less will just not do. For example, several billions of years after the Universe was born, at a time when everywhere along the Universe the stars at the center of planetary systems are beginning to cool down just enough to allow the emergence of life forms in the planets that circle around them, it is almost a mandatory requirement that the mean lifetime of many radioactive elements besides plutonium and uranium must be short enough so that most of those elements will have decayed into more stable non-radioactive forms by the time life begins to appear, for if not any emerging life forms will be killed by the radioactivity, and it is extremely hard to envision how any new life form could adapt to lethal doses of radioactivity when the radiation will be constantly striking hard at the very core of the genetic material necessary for the life forms to reproduce and pass its genes to the next generations. A counterargument might reply by pointing to the long-lasting presence of radioactive radon in many homes around the world, a gas seeping from beneath the crevices of the land upon which many homes around the world are built, which is thought to be a major contributor to certain types of cancer, and whose presence should be monitored in order to determine if a home can be considered safe for inhabiting. However, we must take note on the fact that the radon gas, however plentiful it may be around the world, it is not plentiful enough to make life unbearable. Yes, perhaps some cases of fatal illness will develop each year that can be attributable directly to the presence of radon. But these cases are the exception rather than the rule. Radon is not abundant enough at present to make any significant dent against the statistics of reproduction and life-support. If it were much more abundant, then perhaps Earth would be a desolate planet devoid of any signs of life.
Most life forms as we know them can only survive in a very limited temperature range. Few will argue that below the freezing point of water, zero degrees centigrade, there can be no life that will move around, since everything will be “solid” ice not allowing anything to move around. And the vast majority of life forms (save for a few elementary organisms that have been found to thrive near volcanoes) will break down at the boiling temperature of water, one hundred degrees centigrade. Man himself is not capable of withstanding those extremes even for brief periods of time without very serious consequences. If Man is to be the yardstick, the temperature range that will allow him to survive and reproduce in this planet cannot be beyond some five to fifty degrees centigrade for sustained periods of time unless he adapts rather quickly by either building suitable shelters and wrapping himself in warm protective clothing, or by migrating to more hospitable regions. A temperature range of some fifty degrees centigrade might seem to be a wide range, but if we consider that the temperature of the Universe about a second after the Big Bang took place was about ten billion degrees centigrade, and since then it has cooled down rather quickly throughout some ten billion years to about minus two hundred and seventy degrees centigrade (this is the temperature outside Earth, the temperature of the “cosmos”), then we can appreciate that the temperature range that has allowed us to survive is but a very small barely noticeable insignificant dot along the measurement scale.
We can extend the anthropic principle even further, and argue that since life on Earth in order to evolve requires a reliable sustained energy source that will last hundreds of millions of years, this requirement demands that the source of energy be of thermonuclear origin, in our case the Sun. Any other source will just not do (in days of yore, some ancients who thought that the Sun kept on shining and warming us by burning some fuel like coal were actually quite afraid of the moment the Sun would run out of coal). In order to have a thermonuclear source like the Sun, some nuclear reactions between light elements such as hydrogen and helium are required, and these nuclear reactions demand extremely high temperatures in order for a process known as fusion to take place (the difficulty in replicating artificially those temperatures here on Earth is the main obstacle that is keeping us from harnessing the power of the Sun in our own backyards in spite of the fact that hydrogen is quite abundant in this planet), and the material must follow a very delicate balancing act between the extremely hot and violent nuclear reactions which are fusing the hydrogen atoms into heavier elements and the gravitational forces that keep the very hot energetic materials from flying off into space.
As mentioned before in the quotation taken from the book Gravitation, Brandon Carter of Cambridge was one of the first serious investigators who appealed to the anthropic principle in trying to find out possible constraints upon the early Universe. Taking the gravitational coupling constant as a starting point, Carter has noticed that if the constant had been just an order of magnitude larger, then our Sun would have quickly evolved into a type of star commonly known as a “blue giant”, and it is an accepted fact that these type of stars are incapable of sustaining life because these stars don’t last long, they die too soon. On the other hand, if the gravitational coupling constant had been just an order of magnitude smaller, then our Sun would have evolved rather quickly into another type of star commonly known as a “red dwarf”, a very stable star that can last a very long time but that radiates very little energy, and thus it is also incapable of sustaining life. The only star capable of supporting life is a star that lies precisely at the very narrow margin that divides blue giants and red dwarfs. It is an extremely narrow margin, and the gravitational coupling constant has precisely the value required to allow the appearance in the Universe of stars positioned in the “main sequence” such as our Sun. Anything else will just not do, as far as allowing the appearance of Man on Earth later on. Carter has applied the anthropic principle in other areas, and one of them lies in the realm of subatomic physics. Carter has shown that if the coupling constant associated with the “strong” (or nuclear) force that is only marginally strong to bind together protons and neutrons into the nuclei of atoms had been just a little bit weaker, then hydrogen would have been the only element that would have formed in the Universe, again making the appearance on Man in the Universe an impossible event. On these two counts alone, the existence of Man demands that two widely different and very important physical constants, the gravitational coupling constant and the coupling constant that binds together the nuclei of atoms, have precisely the values they have today.
Earlier in this Chapter we saw in the quotation from the book Gravitation a mention regarding the fine structure constant (though not by name), a pure number that is obtained by dividing the square of the electric charge of a single electron by the product of the speed of light and Planck’s constant, or q²/hc. Let us see what John D. Barrow has to say about this physical constant in his book Theories of Everything:
“Its peculiar value of 1/137.036 … is obtained by combining the measured values of the three constants that comprise it. We do not know why these two numbers take the precise values that they do. Where they different, our Universe would be different, perhaps unimaginably different. The fact that so many of Nature’s most important creations owe their gross size and structure to the mysterious values of the constants of Nature places our own existence in a new and illuminating perspective. We can see how the conditions necessary for our own existence are contingent upon the values taken by the constants. At first one might imagine that a change in the value of a constant would simply shift the size of everything a little, but that there would still exist stars and atoms. However, this turns out to be too naïve a view. It transpires that there exist a number of very unusual coincidences regarding the values and particular combinations of the constants of Nature which are necessary conditions for our own existence. Were the fine-structure constant to differ by roughly one per cent from its actual value, then the structure of stars would be dramatically different. Indeed, there is every reason to suspect that we would not be here to discuss the matter. For the biological elements like carbon, nitrogen, oxygen, and phosphorous are produced during the final explosive death throes of the stars. They are blown out into space where they become incorporated into planets and, ultimately, into people. But, carbon, the crucial biological element which we believe to be essential for the spontaneous evolution of life, should really only exist as the minutest trace element in the Universe instead of in the healthy abundance that we find. This is because the explosive nuclear reactions that make the carbon in the late stages of stellar evolution are typically rather slow at producing it. However, there exists a remarkable coincidence of Nature that allows carbon to be produced in unexpected abundance. Carbon originates in the Universe via a two-step process from nuclei of helium, or alpha particles as we usually call them. Two alpha particles combine under stellar conditions to make a nucleus of the element beryllium. The addition of a further alpha particle is necessary to transform this into a carbon nucleus. One would have expected this two-step process to be extremely improbable, but remarkably the last step happens to possess a rare property called ‘resonance’ which enables it to proceed at a rate far in excess of our naïve expectation. In effect, the energies of the participating particles plus the ambient heat energy in the star add to a value that lies just above a natural energy level of the carbon nucleus and so the product of the nuclear reaction finds a natural state to drop into. It amounts to something akin to the astronomical equivalent of a hole-in-one. But this is not all. While it is doubly striking enough for there to exist not only a carbon resonance level but one positioned just below the incoming energy total within the interior of the star, it is well-nigh miraculous to discover that there exists a further resonance level in the oxygen nucleus that would be made in the next step of the nuclear reaction chain when a carbon nucleus interacts with a further alpha particle. But this resonance level lies just above the total energy of the alpha particle, the carbon nucleus, and the ambient environment of the star. Hence, the precious carbon fails to be totally destroyed by a further resonant nuclear reaction. This multiple coincidence of the resonance levels is a necessary condition for our own existence. The carbon atoms in our bodies which are responsible for the marvellous flexibility of the DNA molecules at the heart of our complexity have all originated in the stars as a result of these coincidences. The positioning of the resonance levels are determined in a complicated way by the precise numerical values of the constants of physics … There are many other examples of this ilk. At almost every turn, the conditions necessary for the evolution of any form of complexity in the Universe exploit the occurrence of crucial coincidences between the values of the constants of physics … if the constants of Nature were not within one per cent or so of their observed values, then the basic building blocks of life would not exist in sufficient profusion in the Universe. Moreover, changes like this would affect the very stability of the elements and prevent the existence of the required elements rather than merely suppress their abundance.”
The crucial role played by carbon in the development of life forms cannot be overemphasized, in spite of the fact that many modern science philosophers have given serious consideration to the possibility that life may be evolving right now in other corners of the Universe using other elements as primary building blocks instead of carbon. However, these expectations could be too optimistic. For example, silicon has been raised as a candidate to replace carbon in creating a silicon-based chemistry instead of a carbon-based organic chemistry, taking into account its position in the periodic table of elements which gives silicon the same chemical valence as carbon –four. Unfortunately, silicon is a metalloid, and metals are generally unable to bind together with other elements such as hydrogen, oxygen and nitrogen and at the same time bind together with other silicon atoms to form rings and long chains in the way that carbon is able to do, and the longest such molecule only has three silicon atoms. Thus, silicon may be unable to compete with carbon. Sulfur has also been considered as a worthwhile candidate because it is able to form large molecules in the shape of rings and chains. Unfortunately, such molecules usually are made out mostly of sulfur, and we cannot get from sulfur the enormous variety of compounds that can be obtained from carbon. Thus, it appears that sulfur also may be unable to compete with carbon. The other elements are even less likely candidates to replace carbon. Fortunately, there is an abundant supply of carbon in the Universe thanks again to an extraordinarily series of very “lucky” coincidences as demanded by the anthropic principle.
Let us now study another case, the case of the cosmic asymmetry between matter and antimatter. The existence of antimatter, ever since it was predicted by Paul Adrien Maurice Dirac and confirmed with the discovery of the “positive electron” or positron (the first antiparticle to be discovered), has come to be an accepted scientific fact that has been confirmed many times over with the discovery of many other subatomic particles and their corresponding antiparticles. One salient characteristic of antimatter is that whenever it comes together with its counterpart they both annihilate each other, and their masses are converted into pure energy. Appealing to aesthetic grounds, many physicists theorize that when the Universe was created there was supposed to be exactly as much matter as antimatter, for there is no obvious reason of why there should be more matter than antimatter and vice versa. At least that would be the basic assumption. But if the Universe was created with exactly as much matter as antimatter, then this poses a very serious dilemma, since then exactly one-half of all the material “stuff” contained in the Universe should have annihilated with the other half, leaving nothing behind. But the presence of Man in the Universe –a material being- demands that there should be enough matter left after the massive mutual annihilation so as to make it possible at least for the Solar system to exist enabling Man to appear later. Therefore, if the antimatter that should have annihilated long ago all the atoms that make us up has not gone elsewhere, then in order to make it possible for Man to appear is it required that since the beginning of time there should have been an asymmetry built into the Universe, with more matter being created than antimatter, in such a way that we would be the “leftovers” resulting from that asymmetry. It makes no difference whether the asymmetry was there before the Big Bang took place or whether the asymmetry was scheduled to show up after the moment of creation; the requirement is still the same, there needs to be more matter than antimatter. The anthropic principle demands it. In the article “The Structure of the Early Universe” cited on Chapter Three, John Barrow and Joseph Silk write the following:
“The cosmological principle is the powerful concept that the universe is homogeneous and isotropic, regular to within one part in 1,000. There is evidence that it has been that way since 10-35 second after the big bang. Cosmologists have traced the origin of the universe to a singularity: a state of apparently infinite density. The singularity represents the origin of space and time perhaps 10 billion years ago. Before that time, the laws of physics known today did not apply … It seems that just before the universe was a millisecond old there was a minute imbalance between matter and antimatter: 1.00000001 particles per antiparticles. Until recently the origin of this peculiar imbalance was a complete mystery because of a principle having to do with baryons: heavy particles, including nucleons, that feel the strong force. Physicists believed the number of baryons in a system minus the number of antibaryons was absolutely fixed for all time. No interactions or transformations could ever change this quantity. If this were true for the universe as a whole, the asymmetry of one part in 108 of matter over antimatter must have been built into the initial structure of the big bang.”
Renowned physicist Stephen Hawking has also appealed to the anthropic principle on several occasions in order to make ends meet, and one of them has to do with the observed isotropy of the Universe (by this we mean the rather uniform distribution of galaxies throughout the Universe). In particular, it has been found under several theoretical models and computer simulations that the Universe would not have been what it is today if the recessional velocity of matter in the Universe [this is the velocity at which galaxies and interstellar matter in the Universe are being spread apart due to the expansion of the Universe. It still has not dawned upon many people that three-dimensional space has been created since the birth of the Universe and is still being created at this very moment. The creation of space between galaxies may give the illusion that the galaxies that surround us are "moving" away, while in fact they are really "standing still". It is this creation of space everywhere that "carries along" every galaxy further and further apart, giving the appearance of "motion" at a speed which is dubbed the "recessional velocity"] after the Big Bang had not been equal to the escape velocity of matter needed to counteract the overall gravitational attraction. If the recessional velocity is greater than the escape velocity, then the Universe would have been completely homogeneous; no galaxies would have formed and all matter and energy would have been spread out equally on all parts of the Universe. On the other hand, if the recessional velocity had been smaller than the escape velocity, the Universe would have collapsed again into a “big crunch” before any galaxies could have had any chance to form. We quote the following from the article by George Gale that appeared on Scientific American:
“C. B. Collins and Steven W. Hawking of the University of Cambridge have found that in the current models of the universe only a few sets of initial conditions out of the many conditions possible could give rise to the observed isotropy. Any theory in which the isotropy is deduced or predicted must begin by postulating such highly arbitrary initial conditions. Collins and Hawking find this result unsatisfying, because it offers no compelling reason for the universe’s having turned out the way it has and not otherwise. What is needed is some prior constraint that would explain why the initial conditions had to be among those few that lead to isotropy; a prior constraint on the initial conditions of the universe, however, is almost inconceivable. Investigators have therefore resorted to the anthropic principle, which limits the class of possible initial conditions not by a prior constraint but by a subsequent one.”
In considering the possibility of the existence of other dimensions under which life may be able to flourish, Stephen Hawking makes the following comment in his book A Brief History of Time where he mentions directly the anthropic principle by name:
“It seems clear that life at least as we know it, can exist only in regions of space-time in which one time and three space dimensions are not curled up small. This would mean that one could appeal to the weak anthropic principle, provided one could show that string theory [according to string theory in its most general version, assumed to be one of the most fundamental physical theories of Nature, the Universe is made from tiny, vibrating, stringlike particles, which can be closed loops like rubber bands or open-ended like bits of twine, and multidimensional membranes. So far, the biggest barrier to its acceptance is that it provides no compelling predictions that can be verified with an experiment] does at least allow there to be such regions of the universe –and it seems that indeed string theory does. There may well be other regions of the universe or other universes (whatever that may mean), in which all the dimensions are curled up small or in which more than four dimensions are nearly flat, but there would be no intelligent beings in such regions to observe the different number of effective dimensions.”
It is possible that life may be able to evolve under different conditions other than the ones we are used to. Perhaps if the Universe had been built with other physical constants, it still might have been possible for life to evolve in such alternate universe. But for our discussion and for the time being, this will be irrelevant, since we have no way at present of detecting or reaching other alternate universes even if they do exist at all, and our main concern is the Universe we live in, the only Universe we have ever known (nevertheless, we will explore again later in this book the possibility of creating alternate universes under different physical laws).
Thus, the demands placed by the existence of Man upon the possible design variations the Universe may itself exhibit go much farther than requiring an adequate temperature range, the existence of liquid water, an abundant energy supply powered by a safe long-lasting source of thermonuclear energy such as the Sun, and many other obvious things. Indeed, the constraints placed by the anthropic principle are so strenuous that even Heinz Pagels, a sworn enemy of the anthropic principle, could not help himself from invoking this principle in spirit though not in name, as can be seen in the following quotation taken from his book Perfect Symmetry:
“The present state of our universe depends critically upon certain physical quantities lying within a delicate range of values. I have already mentioned one such physical quantity, the specific entropy of 400 million photons per one nuclear particle. If that quantity was very different from its present value, then the universe as we observe it would not exist … Other examples of such critical physical quantities are the values of the quark masses. For example, the down quark has a heavier mass than the up quark, and for this reason the neutron, which contains more down quarks than the proton, is heavier than the proton. This implies that a free neutron might decay into a proton, thus releasing energy. But if instead the up quark were heavier than the down quark, the neutron rather than the proton would be the stable nucleon. But then the hydrogen atom could not exist, because its nucleus is a single proton and that could now decay into a neutron. About 75 percent of the visible universe is hydrogen, and we would conclude that it would not exist if the value of the quark masses were just slightly different. There are many examples of such physical quantities which cannot lie outside a narrow range of values or the universe would not be as it is; stars, galaxies and life might not exist.”
In a way, trying to figure out the possible constraints placed in the very early past upon the creation of the Universe because of our presence here today is not that much different from trying to determine the hidden lineage of a cellular automaton given the existence of a certain highly evolved pattern. At first, it would appear that the task of attempting to determine the hidden lineage of the cellular automaton would be easier than trying to get as close as we possible can to the initial conditions that gave rise to the Universe because of the fact that we can always “run” the cellular automaton forward several generations into its future and figure out by observing the changes that have taken place what the rules that make the cellular automaton work may be, a luxury beyond our purview in the case of the Universe since we cannot make the “cosmic clock” run forward by several billions of years to see what happens, nor is it practical to sit down and wait for the passage of those billions of years while recording any changes we might see. However, we have an enormous advantage on our side: the finite speed of light. Light does not travel instantaneously from one place to the other (although in our ordinary lives we live under the illusion it does so). It takes light a very definite time to move from one site to the other, and by the time an image reaches our eyes what we are witnessing is really an image from the past, depending on how far away the object under surveillance is from us, whether it be a minute before, a second, an hour or a year. Everything, and that means absolutely everything, including the images of the people to whom we talk to each day, are images from the past; we never see any images from the “present”, since this would be a theoretical impossibility. On something as big as the Universe, where the distances are measured in light-years –with a light-year being the distance it takes for light in empty space to travel during a year- we can be most sure that the images from far-away galaxies we are now seeing are in fact images from a very distant past, when those galaxies were very young, and the farther we look the closer we get to witnessing the actual moment of creation. And we are now getting very close either to witnessing how the Universe looked like just a few million years after the Big Bang event or to overhauling all of our theoretical estimates for the current age of the Universe. To make this point clearer, let us take a galaxy named 0140+326RD1. Astronomers working at the W. M. Keck Observatory on Mauna Kea in Hawaii discovered this galaxy on March 12th 1998 in the constellation Triangulum, and until recently it was considered to be the most distant object ever sighted by Man. This galaxy was about 90 millions light-years away from the previous farthest known galaxy that was discovered in 1997. According to the estimates from the available data, the light detected from this galaxy left the galaxy some 12.2 billion years ago. If we assume that the creation of the Universe from the Big Bang explosion took place about 13 billion years ago, then it can be estimated that the image we have of such galaxy was emitted from the galaxy about 820 million years after the instant the Universe was created, when the Universe had only 6% of the age it is now estimated to have. If our theoretical models had told us that the Universe was about ten trillion years old, then seeing a galaxy such as 0140+326RD1 would be just a very small drop in the bucket in our attempts to reach towards the origins of our Universe. But with a Universe estimated to have an age between ten and fifteen years billion years old, the galaxies we are now able to reach are taking us closer and closer to the moment of creation. And even more powerful astronomical tools are on the way. This is the reason behind all the excitement surrounding astronomers at the start of the third millennium. And in trying to peer into our origins, there is an added bonus: as we gaze farther and farther thus going deeper and deeper into the past, we can study the shape of millions and millions of galaxies on the way, witnessing how those galaxies came into being, discovering how our own Milky Way galaxy might have looked ten million, fifty million, one billion, two billion, five billion and more years ago. It is like running a videotape backwards at very high speed.
The anthropic principle can be extended even further making it extremely plausible for life to evolve in other planets and galaxies besides Earth. Indeed, once the existence of Man on Earth has placed very tight limitations on the acceptable range of values that many physical constants can have, since those physical constants are assumed to be universal constants having exactly the same values elsewhere in the Universe then everywhere else in the Universe we may expect to find conditions very similar to those that can be found on the Solar system. Indeed, the gravitational coupling constant whose value was so crucial in making it possible for our Sun not to turn out to be either a blue giant or a red dwarf has exactly the same value in any other planets in any other galaxies as the value it has on the Solar system on the Milky Way. The same can be said for the coupling constant associated with the “strong” force that makes it possible for many other elements besides hydrogen to exist. The same can be said for the fine structure constant. At least from the astronomical point of view, if the presence of Man on Earth has required all the important universal physical constants to have very specific values, and this convergence of values is not unique to planet Earth but can also be found anywhere else in the cosmos, then there is no reason of why we should not expect many other regions inside the Universe to harbor Solar systems like our own, ready to be populated by that ubiquitous drive for survival that many modern day philosophers call biological life force, a force whose desire to endure forever has made it possible for its progeny to adapt to some of the most adverse conditions we can think of. Thus, the possibility for extraterrestrial life can be deduced as a consequence of the presence of Man in this Universe.
However, on their treatise Rare Earth, both paleontologist Peter Ward and astronomer Donald Brownlee, noted authorities in their own fields, seem to carry the anthropic principle even further by suggesting that complex life is uncommon in the Universe, even more uncommon than noted scientists such as the late Carl Sagan once thought. In their basic arguments, they believe that bacterial life forms may be present in many galaxies, but complex life forms, such as those that have evolved here on Earth, are extremely rare in the Universe. According to them, there are a lot of additional requirements to the anthropic principle needed to sustain the evolution of life into complex beings such as us like the following: an optimal distance from the Sun of the planetary system (planets close to the Sun are extremely hot, and planets far away from the Sun are extremely cold, only a few planets in the middle lie in what we could call the “comfortable zone”), the positive effects of the moon’s gravity on our own climate, plate tectonics and continental drift on our own planet Earth, the right types of metals and elements, ample liquid water, maintenance of the correct amount of internal heat to keep surface temperatures within a habitable range, and a gaseous planet the size of Jupiter to shield Earth from catastrophic meteoric bombardment. Indeed, they are so pessimistic that their answer to the age old question:
Are we alone in the Universe?
comes very close to being YES, although they stop short of making such a chilling statement. Oddly enough, the search for intelligent life outside the confines of our solar system has become the real life equivalent of those so far unsolvable mathematical problems such as Goldbach’s conjecture in which it takes just a single example or counterexample to prove or disprove the conjecture, in the absence of a formal mathematical proof capable of accomplishing the task in a limited number of steps, but finding that single example or counterexample could require an infinitely powerful computer trying all of the possibilities available until it hits pay dirt, a physical impossibility since we cannot hope to build now or ever an infinite computer with our limited resources. Likewise, it only takes finding just a single planet outside our solar system with intelligent life to prove that we are not alone in the Universe, but it may be beyond our means to build spacecraft capable of travelling through the entire observable Universe (which we assume to be infinite in extent) in order to start exhausting all possibilities, hoping we get lucky and find an intelligent life form before visiting ten trillion planets in some ten billion years. And such a quest would only provide an answer to the basic question of whether we are alone in the Universe or not. Once that question has been resolved, if it can be answered at all, if we can confirm the existence of another planet similar to ours with an intelligent life form with which we could try to communicate in some manner, the next logical question would be: How many more planets are out there in the entire Universe harboring intelligent life forms? However, a definitive answer to this last question in impossible, even if it is as simple as the number five, because it would require us to visit every single habitable planet in the entire Universe, a task we cannot expect to accomplish, not even in principle, not even with Nirvana or mystic revelations. Only a being capable of looking at infinity itself straight in the eye, capable of comprehending it fully, operating outside our physical limitations, could provide us with such an answer, which leaves us with all of our Science and our foreseeable Science yet to come in no better shape than those ancient Greeks who sought the wisdom of the Delphic oracle. However, if we as intelligent beings are indeed alone in the Universe, then our preordained ignorance may be a blessing in disguise, for such a blunt answer could prove too much to digest for some philosophers and even for many common ordinary people.
If we take a pessimistic stand and agree with the concept expounded on Rare Earth that intelligent complex life forms come very close to being an impossibility outside planet Earth, then with such overwhelming odds stacked against the possibility of finding little green men out there it should be cause for amazement that many if not most of the scientists who reject altogether any possibility of any kind of intelligent force taking part in the pre-design of our Universe going all the way back to those mysterious initial conditions, are the same ones who truly believe in the possibility of the existence of intelligent life beyond the solar system in spite of the absence of hard evidence, to the point of actually getting big government to invest millions of dollars in programs such as the SETI (Search for Extraterrestrial Intelligence) project and spending their lives in the buildup of sophisticated astronomical equipment to prove their point. To justify themselves, they resort to semantics arguing that their quest is not science based on faith, but is science based on hope. Try to figure this out!
Besides the “weak” and the “strong” versions of the anthropic principle that we have discussed so far, there is an even stronger version that Brian Appleyard discusses in his book Understanding the Present:
“This is the formal statement of the weak (anthropic) principle: ‘The observed values of all physical and cosmological quantities are not equally probable, but they take on values restricted by the requirement that there exist sites where carbon-based life can evolve and by the requirement that the Universe be old enough for life to have already done so.’ … So, perhaps, from the initial conditions a whole range of universes sprang up in which every permutation of physical development took place. Very few, perhaps only ours, would attain the alignment of qualities that would produce life. And yet ours in the only one we can study. The fact of our existence must, therefore, condition the entire history of the universe; it is precisely our presence that distinguishes it from other possible universes … This leads to the Strong Anthropic Principle: ‘The Universe must have those properties which allow life to develop within it at some stage in its history.’ … And, as if that were not enough, there is the Final Anthropic Principle. This suggests that not only must conscious life come into existence in this universe, but also that, once it has done so, it can never die. The argument is utterly speculative and hugely complex … ‘At the instant the Omega point is reached,’ explain John Barrow and Frank Tipler, ‘life will have gained control of all matter and forces not only in a single universe, but in all universes whose existence in logically possible; life will have spread into all spatial regions in all universes which could logically exist, and will have stored an infinite amount of information including all bits of knowledge which is logically possible to know. And this is the end.’ One can say little about the validity of such speculations except that they are and they do much to demonstrate the new style of the scientific imagination. Both the idea of Total Symmetry and the Omega Point suggest a visionary unity and completion springing from within the confines of science itself. These things are not being discussed by theologians or philosophers, they are being discussed by scientists.”
Without going to such extremes, in light of all that we have discussed, we cannot help but reach the conclusion that any scientific theory we may devise to try to explain the origin of our Universe must be amenable to restriction within very narrow confines, so as to make it possible for us to appear at some point in time, since anything less will just not do. Such a scientific theory must be able to make the Universe follow a certain path, the path we have already traveled, almost as if, … as if, … as if the Universe had been designed specifically on purpose with the appearance of Man in mind. This may not be so, but as far as we are concerned, the effect is the same. Regardless of the criticisms that the anthropic principle may receive, this is the one thing we can be most certain of: any successful theoretical model capable of accurately describing the origin of our Universe must be able to predict that somewhere at some point in time after the moment of creation, all of the necessary conditions will be there together in order to allow the appearance of Man. In other words, the theoretical model must be formulated in such a way as if the Universe had been created so as to satisfy all of the requirements needed for Man to appear. If the theoretical model is incapable of predicting such scenario, if it cannot predict in due time the meeting together of all the conditions required by Man to show up, the model will crumble immediately and will have to be discarded away without further considerations, since it would be in direct contradiction with the most solid argument that can be posed against any such model: our own existence.
