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The Intriguing, Seductive and Ultimately Unsatisfying Anthropic Principle
Credit: ESA and the Plank Collaboration
Some believers in a traditional deity deny, or at least are skeptical about, certain claims of science. The issue may be the origin of the universe in a Big Bang, the age of the universe, the nature of the evolution of life on Earth or some other proposition. In these instances, the believers see science as inconsistent with, even in opposition to, a sacred truth revealed in some literature such as the Torah, the Christian Bible or the Qur’an, and therefore should be rejected.
On other occasions, though, believers will embrace science. They will hear that the initial conditions of the universe, certain laws of nature or the location and chemistry of our planet are set within a limited range that allows for human existence — a proposition sometimes called the Anthropic Principle (i.e., relating to humankind) — and take those conditions and characteristics as proof of a personal god. They will understand a “fine-tuned” universe as demonstrating, or at least strongly implying, the existence of a Fine-Tuner, a Devine Designer.
Drawing a conclusion about the existence of God from certain natural phenomena is not, of course, a new idea. Well over two thousand years ago, the author of Psalm 19 wrote that “the heavens declare the glory of God” and “His handiwork is proclaimed by the firmament.” (Psalm 19:1.)
Centuries later, we find an early Jewish version of the Watchmaker argument. Responding to a heretic who asked him who made the universe, Rabbi Akiba reportedly said: “Just as a house attests to its builder, a garment to its weaver or a door to its carpenter, so too does the world attest to the Holy One who created it.” (See Midrash Temurah 5.)
Even twentieth century theological rationalists, like Mordecai Kaplan, can be attracted to the argument from nature. Kaplan found evidence for God in “the oneness that spans the fathomless deeps of space” and “the elemental substance of stars and planets, of this our earthly abode and of all it holds.” (See Scult, The Radical American Judaism of Mordecai M. Kaplan (Indiana U. Press 2014 ) at 150-51.)
Science has advanced considerably since the day of the psalmists and Akiba, and since Kaplan’s time, too. And the argument based on the observation and understanding of natural phenomena has been refined accordingly.
In his popular book, Just Six Numbers (Basic Books 2000), British cosmologist Martin Rees described six constant numbers that “constitute a ‘recipe’ for a universe.” (Id. at 4.) One is the ratio of the strength of the electrical forces which hold atoms together to the force of gravity between them. It is huge, 1036. Were it smaller, however, only a miniature universe could exist and then not for long enough for evolution to take hold. Another number is small, 0.007. While not meant to invoke James Bond, ironically it “defines how firmly atomic nuclei bind together, . . . (and) how stars transmute hydrogen into all of the atoms of the periodic table.” If this number were a thousandth larger or smaller, you would not be reading this post. You would not exist. (See Id. at 2.)
Two other numbers relate to the size and texture of the universe. One “measures the amount of material in our universe” and the relationship of gravity and “the expansion energy in the universe.” The fourth number “controls the expansion of our universe.” Were there even slight deviations in either number, cosmic evolution would not have occurred. (See Id. at 2-3.)
The final two numbers “fix the property of space itself . . . .” One “represents the ratio of two fundamental energies and is about 1/100,000 in value.” A smaller number would have meant an inert universe while a larger one would evidence a violent one. The final number is 3, the number of spatial dimensions in the universe. With only two or with four dimensions, life would not exist. (See Id. at 2-3.)
Others have produced different and longer lists. Some years ago, astronomer and devout Christian Dr. Hugh Ross generated a list of over two dozen “parameters” that he contended set the boundaries for life on Earth. Some of these factors relate to the universe as we know it. They include, in addition to the factors discussed by Rees, the age and entropy level of the universe, the energy levels of beryllium, carbon and oxygen, and the distance between and luminosity of stars.
Other parameters apply to the Earth’s capacity to be a fit habitat. Some of these concern the Earth’s parent star, including the Sun being the only star companion for the Earth, the birth date and age of the Sun, the Sun’s distance from the center of the galaxy, as well as the Sun’s mass, color and surface gravity. Still others are more Earth specific, including the Earth’s period of rotation, gravitational interaction with the Moon, magnetic field, axial tilt and seismic activity, plus the carbon dioxide, water vapor and ozone levels and the oxygen to nitrogen ratio in the atmosphere. According to Ross, each and every condition identified operates within a relatively narrow range beyond which human life would not be possible. Ross updated his list in 2006 to include over ninety values.
The Anthropic Principle has been adopted on occasion by orthodox Jewish scientists such as Gerald Schroeder and Nathan Aviezer, each of whom seeks to promote the notion of a close and harmonic relationship between the Torah and modern science. Schroeder, a physicist now residing in Israel, is best known perhaps for his attempt to conflate the six days of Biblical creation and the fourteen billion years of cosmological evolution into the same time period. (See generally, The Science of God (“TSOG”) (Free Press 1997), discussed here, here and here.) After briefly reviewing the eons of evolution, Schroeder writes that we “live on a planet within a galaxy of a universe made for life,” a planet he calls a “just-right Earth.” (Id. at 191-92; see also, here.)
Rather than review fourteen billion years of cosmological evolution, Aviezer, a physics professor at Bar-Ilan University in Israel, offers a few examples of the Anthropic Principle. He refers to the strength of “the nuclear force” in thermonuclear reactions in the Sun, the presence of water on Earth and the delicate balance of Earth’s atmosphere. In addition to these often discussed factors, Aviezer adds that human life would not have been possible except for the highly improbable event of the sudden destruction of all dinosaurs due to a meteor impacting the planet with a force strong enough to cause the extinction of the then dominant life form and yet not so strong as to kill all life on the planet.
Both Schroeder and Aviezer conclude their arguments by discussing the probability that human life would ever arise. Schroeder refers to the work of British mathematician Roger Penrose who, in The Emperor’s New Mind (Oxford 1989), calculated the likelihood that we would find ourselves in an environment suited for life at “less than one chance out of ten to the power of ten to the power of 123” (TSOG, at 192-93), that is, “1” followed by 10123 “0”s. One in a billion (109) would seem to be exceptionally small (except perhaps to a university mathematician), but this number is so many zillion times smaller it literally cannot be written out, much less be expressed or understood with any precision.
Aviezer also devotes some space to the issue of calculating probabilities, but instead of revealing a particular number, merely concludes that the events leading to human life on Earth were “extremely unlikely.” He adds that the “extreme rarity of the events . . . is well established.” Consequently, he claims that “the anthropic principle has become a scientifically established fact.”
Well, not quite. There are problems with the Anthropic Principle, some definitional, some philosophical, some empirical.
The first problem with the Anthropic Principle is that there is no agreement on what it is. The term itself was invented relatively recently, apparently by British cosmologist Brendan Carter around 1974. In contrast to the Copernican revolution, which denied that humankind was at the center of the universe, the purpose of the Anthropic Principle (the “AP”) is to “portray the cosmos less as an impersonal machine and more as . . . a ‘home to Man.’” (Ferris, The Whole Shebang (Simon & Schuster 1997) at 292.)
In the last forty years, others have proposed variations on the theme. For instance, some claim that there is a Weak Anthropic Principle (“WAP”) and a Strong Anthropic Principle (“SAP”) among other APs. WAP asserts that the laws of nature must be such as to “permit the emergence of life” while SAP asserts that the universe must also allow for “’the creation of observers in it.’” (See Id. at 299.)
In addition, some writers have discussed PAP, the Participatory Anthropic Principle, and FAP, the Final Anthropic Principle. The late, great science writer Martin Gardner called the last of these the Completely Ridiculous Anthropic Principle, or CRAP. (See generally, “WAP, SAP, PAP, and FAP” in The Night is Large (St. Martin’s 1996), at 40-49.)
Like Schroeder and Aviezer, most writers do not seem overly concerned with the definitional dilemma. Even well regarded scientists like Hayden Planetarium Director Neil DeGrasse Tyson and University of Michigan Prof. Fred Adams tend to define the Anthropic Principle in a cursory and general manner. According to Tyson and co-author Donald Goldsmith, the argument is that “(b)ecause we exist . . . the parameters that describe the cosmos, and in particular the value of the cosmological constant, must have the values that allow us to exist.” (See Origins (Norton 2004), at 102.) Prof. Adams describes the basic idea as restricting the laws of nature in order to “allow for the appearance of living beings capable of studying the laws of nature.” (See Origins of Existence (Free Press 2002), at 209.) That is, “our universe had to take its observed form for us to be here to argue about these issues.” (Id. at 218.)
Albert Einstein formulated the relationship of energy and matter, a fundamental feature of the entire universe, in a simple and elegant formula, E=mc2. The precision of his formulation has allowed his theory of special relativity to be tested thoroughly over the course of a century leading to greater understanding and new technologies. By contrast, articulation of the AP is neither simple, nor elegant, nor even agreed. Far from being “a scientifically established fact,” the Anthropic Principle is confusing and flawed.
For starters, the AP is misnamed. It is not even a principle as that word is commonly understood, that is, a rule or a basic truth, an explanatory fact or law of nature. Tyson and Goldsmith call it an “approach,” rather than a principle (see Origins, above, at 104), but even that may be generous. The AP does not really prove anything, nor does it predict anything. Indeed, to assert that the universe must be fine-tuned for life because we are here is simply to make a circular argument. The old children’s song “We’re here because we’re here because we’re here because we’re here. Etc.” makes as much or as little sense.
Nor is it clear that the underlying theme of the AP is, or ought to be, anthropic, that is, of or related to humanity. The argument that the universe was made for humans because we are here could be made with regard to other organisms that have found their niche, like Darwin’s finches, or which are long time survivors like turtles or ubiquitous like cockroaches. Under this approach, one might even argue that a hole in a street was designed for the puddle that fills it perfectly.
Physicist Timothy Ferris asserts that the AP “is less scientific than philosophical.” (See Ferris, above, at 300.) Even so, the AP fails. Martin Gardner considered himself a philosophical theist, but he had a “dim view” of the AP, and thought that the fine-tuning argument for God was “logically fragile.” (See “Proofs of God,” in The Night is Large, above, at 539-540, 546.) As Gardner recognized, if the AP is read as proclaiming that “because we exist the universe must be constructed as to allow us to have evolved,” then it is nothing more than a “trivial tautology.” (See “WAP, SAP, PAP, and FAP,” above, at 41.)
More formally, the AP contends that because B (humankind) chronologically follows A (the original conditions for the universe), that A caused B, or in the phrasing of the AP, that A was fine-tuned for B. This backward reasoning is a form of “retrograde analysis” in which observations about the present are the basis for speculation about the past. (See “Proofs of God,” above, at 539-41.) The fallacy is known as the post-hoc fallacy. (See Ferris, above, at 300.) What is more accurate is that through a natural process of cosmological and then organic evolution, including natural selection and adaptation, over a long period of time human life emerged. Rather than the universe being suited for humankind, humankind and its predecessors adapted to the universe that was available.
The AP also fails to conform to reality. To assert as a principle that our universe is fine-tuned for life is contrary to some rather obvious facts. Only about four percent (4%) of the universe is made up of conventional (baryonic) matter, with almost all of the balance being composed of dark energy (~70%) and dark matter (~25%), about both of which we know precious little. (See Adams, above, at 55.) What we do know is that almost all of the universe is empty and frigid, and, because of accelerating expansion, getting visually emptier and colder. (See Id. at 60, 62-63, 219-20.) So, it is not surprising that to date we have no evidence of any life, much less intelligent or human-like life, on other planets.
Even on our planet, life flourishes in a limited number of locations. And where it does is often a scene of harsh and bitter struggle. If the universe really were fine-tuned for life, especially human life, then why isn’t it flourishing and visible? And why would a Fine-Tuner create such vast amounts of wasted space and a system dependent on conflict? Conversely, if our search for extraterrestrial life is successful, what does that mean for the AP? Does that confirm that the universe is fine-tuned for life or does it suggest that life is not as unique as we once thought? And what if that life is not human?
The AP is also premature. The universe is just shy of fourteen billion years old. Our genus emerged about two million years ago, with our species, Homo sapiens, arriving about 300,000 years ago. (See Coyne, Why Evolution is True (Penguin 2009) at 203, 206.) So, we have been around for just two ten thousandths of one percent of the life of the universe. For the other 99.9+% of the time, it would not have been at all obvious or perhaps even plausible that humankind would arise.
Similarly, the complete story of human existence on the home planet has not yet been written. If, in the next one thousand or one hundred thousand years, another massive meteor struck the earth triggering extinctions, including of us, would that mean the Anthropic Principle was false? Or just a temporary principle?
But what about the long odds on us being here, of each cosmological constant and ratio being just right to allow for the universe to form and evolve sufficiently for heavy elements to be formed in stellar nuclear reactions, spewed into space, and collected in a solar system which includes a planet at just the right distance from a correctly sized and aged single star and with just the right chemistry to allow for life to emerge?
Let’s start by considering the probability that any human now alive would be alive today. Each of us is the product of some twelve thousand generations of human evolution over the last 300,000 years. Each of those generations is the product of the fertilization of a reasonably random egg by an even more random sperm. Change the egg or the sperm in any one of those encounters and the current beneficiary of the process would not be here. The retrograde analysis of the AP would argue that we should not be here, but we all are – despite the odds. To paraphrase lyricist Oscar Hammerstein, improbable things are happening every day.
Still, what of Penrose’s calculations? Recall that Gerald Schroeder relied on certain calculations of Roger Penrose in The Emperor’s New Mind to buttress his argument for the AP. Schroeder, however, failed to note that in that same book Penrose also stated that the improbabilities of the AP do not fully explain the improbabilities of our universe. (See Penrose, The Emperor’s New Mind, above, at 354.) More recently, Penrose has characterized the AP as a “highly contentious set of ideas,” upon which “too much reliance is frequently placed” to support “implausible-sounding themes.” (See Penrose, Cycles of Time (Knopf 2010) at 171.)
Perhaps we can put the math aside. Physicist Victor Stenger argues, essentially, that the probability question is misplaced. He contends that there is, in fact, nothing unusual about the processes that preceded our existence or the situation in which we find ourselves. He argues, in short, that the values identified by Rees or Ross are within the range one would expect from “established physics.” (See generally, The Fallacy of Fine Tuning (Prometheus Books 2011).)
Now, if you are having problems with the Schroeder/Aviezer claim that the universe is as God designed it, and you don’t like Stenger’s view that the universe is what it naturally is, there is another option. Martin Rees, among others, finds “compellingly attractive” the admittedly speculative theory that ours is but one of many universes. (See Rees, above, at 166.) Postulating a theoretical multiverse naturally improves the odds that a universe like ours would be among other universes, and Rees is, therefore, not surprised our number came up. (See also, Carroll, “Welcome to the Multiverse” (2011).)
But is it necessary to imagine a multiverse in order to explain our existence? Doesn’t that just substitute one mystery for another? Moreover, doesn’t a multiverse violate a principle of problem solving known as Occam’s Razor which favors, among competing theories, the one with the fewest assumptions. Rabbi Jonathan Sacks thinks so, which is one reason why he favors “a single unprovable God over an infinity of unprovable universes.” (See Sacks, The Great Partnership (Schocken 2011), at 269; but see also, Stenger, above, at 292.).)
In sum, the Anthropic Principle is an intriguing and seductive but ultimately unsatisfying concept for believers and non-believers alike. Its adoption by believers in support of a supernatural god is understandable, but it does not really advance their claim, does not provide proof. Nor is it even necessary for a believer to rely on, or even refer to, the AP. As Rabbi Sacks teaches, “faith is the defeat of probability by the power of possibility.” (Id. at 283.)
Non-believers, too, are attracted to the AP for its purported non-theistic explanation of the seeming miracle of our existence. Some, conscious of the apparent overwhelming improbability of that existence, seek to improve the odds by changing the number of universes under discussion. But, based, on the available data, there is no reason to think that what we observe is anything other than what one would have expected from the normal operation of physics and chemistry, over time, and adding new universes, for which there is no current observable evidence, does not make the argument stronger or resolve the logical fallacies inherent in the AP.
At its core, the AP represents a return to pre-Copernican thinking, placing humanity, if not at the physical center of the universe, certainly as the reason for the origin and evolution of the universe. But we do not need to regress. The fact of our existence, even if not at the center of our universe but just on a speck of rock at the outer spiral of a conventional galaxy in an obscure region of space, is in and of itself reason enough for wonder and joy. And the truths of our emergence from stardust and our historic relationship to each other, to all of life, to all matter and all energy are truths to be cherished and nurtured with humility and gratitude.
Amen or Q.E.D., as you prefer.