[This, and the following two chapters, were the bulk of what I worked on last winter. They are out of sequence with the previous chapter offerings (rearranged…again) but these three go together as a block and can be read on their own. They focus on Earth’s remarkable “fitness” (in the Darwinian sense) for harboring life—a really fascinating topic that most people are unaware of. This chapter sets the table, starting out with a historical overview that ends with a look at the Drake Equation.]
It is almost irresistible for humans to believe that we have some special relation to the universe, that human life is not just a more-or-less farcical outcome of a chain of accidents reaching back to the first three minutes [of the Big Bang], butthat we were somehow built in from the beginning…. It is very hard to realize that this all is just a tiny part of an overwhelmingly hostile universe…. The more the universe seems comprehensible, the more it also seems pointless.
Steven Weinberg,The First Three Minutes
Beginning in the fifth century B.C., Greek philosophers began to muse about Earth’s place in the universe. Thales of Miletus—traditionally considered the father of Western philosophy as well as spurring the development of both theoretical astronomy and geometry—was one of the first to record his thoughts on these weighty matters. He believed the cosmos to be a sort of living organism. One of his students, Anaximander, proposed that Earth resided at its center. Two centuries later, Plato and his student Aristotle ascribed to the same view. Ptolemy’s second century Earth-centered model, based on recorded observations and mathematical computations, was accepted truth through the middle ages. The Ptolemaic universe was envisioned as a suite of nested, transparent orbs encircling Earth and forming the heavens. The most distant of these crystallinecelestial spheresheld the fixed stars and inside it were additional spheres bearing individual planets, all of them linked but turning independently. God—the Unmoved Mover—and his angels resided above the outermost sphere, while Satan ruled at Earth’s very center. Aside from the bothersome retrograde movement of several planets, this model neatly accounted for the movements of heavenly bodies and other astronomical phenomena.
It was not until the sixteenth century that our planet was removed from its lofty position, when Polish astronomer Nicholas Copernicus placed the Sun at the center of the cosmos. His radical proposal was intended as a way to simplify the intricate Ptolemaic system. The Copernican system neatly explained why Mercury and Venus were only seen near the Sun and why the outer planets appeared to reverse course at times. A devoutly religious man, Copernicus was acutely aware that his heliocentric model would be highly controversial and, by design, it was at first known only to a few scholars and fellow astronomers. It took a century for the revolutionary ideas to take hold.
Prior to the invention of the telescope in the first decade of the seventeenth century, Danish naked-eye astronomer Tycho Brahe proposed his own elaborate cosmological model. Brahe’s lasting legacy was in the detailed and accurate observational records kept over many years, by means of a series of increasingly sophisticated sextants and quadrants—instruments that measure angular distances between objects. His observations were far more precise than those made by Ptolemy. (In fact, few accurate systematic astronomic records that improved on Ptolemy’s were made until after the time of Copernicus.) Access to this precious and jealously guarded information allowed German mathematician and astronomer Johannes Kepler, who assisted Brahe during the final year of his life, to correct a number of irregularities in the Copernican model that were the result of those imprecise records. Following Brahe’s premature death in 1601, Kepler gained access to all Brahe’s measurements, which he used to finally explain the mysterious retrograde motions of Mars when he determined that an elliptical, rather than a circular orbit fit the data. Kepler presented his own heliocentric model in one of the most important books in the history of astronomy, Astronomia Nova, the first work referring to planets as independent bodies as opposed to being borne by rotating orbs.[1]
Shortly thereafter, Galileo’s telescopic observations showed that the heavens are filled with stars. This added an unforeseen element of immensity that earlier conceptions of the universe lacked. It was left to Isaac Newton to prove that stars and planets moved according to physical laws in their grand orbital journeys through the heavens—a veritable world of worlds. With the publication in 1687 of his classic work, the Principia.[2]Newton spelled out for the first time, in mathematical terms, the laws of motion. In doing so, he confirmed Kepler’s three principles of planetary motion. In addition, Newton’s law of universal gravitation conclusively accounted for what held the stars and planets in place, provided a basis for explaining planetary motions, what caused the tides, and what prevented objects from falling off a whirling planet.
This is a thumbnail sketch of what has become known as the Copernican revolution—the players and events that led from a provincial Earth-centric depiction of reality to an infinite, expanding universe. Of course, the real story is much more complicated than the familiar popular telling, with those few brave but retiring scientific revolutionaries demoting Earth’s (and by extension mankind’s) central position to their rightful place while singlehandedly battling ignorance and a monolithic church hierarchy. The story of Galileo’s recantation before the Inquisition in 1633, for instance, is far more nuanced than the commonly imparted account. And as for Giordano Bruno, who was burned alive for his sacrilegious beliefs: the Dominican monk’s grisly execution in 1600 was more a result of heretical opinions regarding Church doctrine than for any explicitly Copernican views. But these stories are told and retold, and have been transformed into modern myths in the history of science’s war between the forces of light and darkness. (In truth,an Earth- and human-centered view of the universe was a product of the Renaissance, several centuries in the future.) Most people who knew of such matters in Copernicus’ time would have deemed that the cosmos was centered around God, with mankind being but one—albeit the focal—part of His creation.
Five centuries have passed since Copernicus revealed that Earth does not reside at the center of the universe. Since his time there has been a continuing trend to downgrade and diminish humanity’s place in the cosmos. The principle of terrestrial mediocrity (widely known as theCopernican principle) was a concept first introduced by Harvardastronomer Harlow Shapley.Up until the early 1900s, almost nothing was known about the shape and size of our galaxy, nor our location within it. Shapley’s research proved that the Milky Way was much larger than anyone had expected, and that our solar system was situated in a thoroughly unremarkable region far from its center.
The notion of our place in the cosmos as being unexceptional in any way was later popularized by Carl Sagan, most famously in his eloquent musings about viewing Earth from a distance—Thepale blue dot—and perceiving its utter insignificance within an incalculably vast universe. Since then, the idea has been avidly promoted not only by astronomers but by physicists, philosophers, historians, and those antagonistic to religion (mankind’s centrality in the Creation being a key element of Christian doctrine). Darwin’s theory stripped humans of their status as the pinnacle of creation, proving that we are not only just another species of animal but are chance members of an ancient lineage as well. Then, in 1920, Edwin Hubble demonstrated that long-observed nebulae—colossal clouds of dust and gas—were not part of the Milky Way but were in fact distant galaxies like our own. His findings were widely reported in newspapers and magazines. As word spread, there was a budding public perception (difficult as it all was to grasp) that the universe was far more vast than imagined. And with this dizzying knowledge came the tacit admission of an even further diminished status for humanity; suddenly, our role in the grand scheme was again in question. But it was by way of television that a widespread comprehension of our cosmic insignificance entered popular imagination, largely thanks to the popular series Cosmos, hosted by Carl Sagan.And now, the space telescope named in Hubble’s honor has provided us with breathtaking images of a universe teeming with galaxies.
As if mankind needed further humbling, astrophysicists Fred Adams and Greg Laughlin add another layer of context by introducing the concept of multiple universes:
The seeming coincidence that the universe has the requisite special properties that allow for life suddenly seems much less miraculous if we adopt the point of view that our universe…is but one of countless other universes. In other words, our universe is but one small part of a multiverse,a large ensemble of universes, each with its own variations of physical law. In this case, the entire collection of universes would fully sample the many different possible variations of the laws of physics…. With the concept of the multiverse in place, the next battle of the Copernican revolution is thrust upon us. Just as our planet has no special status within our Solar System, and our Solar System has no special location within the universe, our universe has no special status within the vast cosmic mélange of universes that comprise our multiverse.[3]
And the late Nobel laureate cosmologistSteven Hawking once said in an interview,“The human race is just a chemical scum on a moderate-sized planet, orbiting around a very average star in the outer suburb of one among a hundred billion galaxies. We are so insignificant that I cannot believe the whole universe exists for our benefit.”
Certain individuals find that these words provide a sort of existential solace, a stark reminder of our collective insignificance. Others take such pronouncements as being be a bit too…harsh. (And people who are not offended in the least by being compared to apes might take exception to being written off as chemical scum.) But cosmologists are members of an exclusive tribe whose thoughts dwell far beyond the clouds; their minds inhabit an infinite universe—a vast and frigid cosmic wilderness dotted with galaxies beyond count. For those so inured to eternity, stars are mere grains of sand on the celestial shore. Astrophysicists can thus be excused for relegating humankind’s significance to something of trifling importance in what they perceive as an exclusively material world operating by the dictates of immutable physical law.
Perhaps we have taken all this a bit too far. Some people consider the enthusiastic promotion of the Copernican principle and the current trend of belittling our cosmic status to be a form of psychological over-compensation. They point out that finding delight in the notion of humanity’s utter insignificance (as opposed to a neutral recognition of that aspect of our mortal existence) implies a kind of cultural guilt complex—a reflection of the uncertainty we all experience in not knowing where we stand in relation to the rest of creation.[4]Lost in our existential malaise is the actuality of LIFE’s remarkably successful run on Earth’s stage, with the unlikely rise of conscious beings a remarkable reflection of that achievement.
Putting aside questions of significance, now that the universe’s monstrous enormity is at least dimly sensed, it is commonly assumed that extraterrestrial life surely must be widespread. After all, recent estimates of the number of galaxies are up to around two trillion—a twenty-fold increase from late twentieth century estimates of around a hundred billion. (And this figure, judging by past trends, has nowhere to go but up.[5]) Those of my own generation avidly watched Star Trek, each episode introducing new species of alien life forms, many of them humanlike aside from modified facial features, colorful skin tones, and exotic clothing. After watching endless reruns we know each episode by heart, like children’s fables of times past. Then Star Wars came to our theaters. But even prior to these icons of science fiction entertainment, the alien with vaguely humanoid features was already firmly rooted in our gestalt. Many people believe “they” are out there…somewhere. And these same people feel just as certain that our galaxy is teeming with civilizations (which, as a rule, are more advanced than our own). The Universe is just too immense for there not to be!
The September 1959 issue of the journalNaturecontained a short article entitled “Searching for Interstellar Communications.” Inthe piece, physicists Giuseppe Cocconi and Philip Morrisonargued that radio telescopes had become sensitive enough to detect signaling transmissions from civilizations on planets orbiting other stars in our galaxy. As it turned out, their brief analysis provided the impetus to establish SETI—the Search for Extra-Terrestrial Intelligence program.
Astrophysicist Frank Drake is still known for his early work on pulsars and with the discovery of Jupiter’s ionosphere and magnetosphere. But his name will be forever linked with launching the systematic search for ET life and, perhaps even more so, for devising what later became widely known as the Drake equation—a way to estimate the number of civilizations in the Milky Way with which interstellar communication might be possible. Drake never intended to actually come up with a number. Rather, he came up with the idea of using an equation as a device to stimulate discussion during a small conference being convened at the National Radio Astronomy Observatory near Green Bank, West Virginia, where Drake worked. More thought experiment than mathematical formulation, his approach is considered a classic example of a Fermi problem(a hasty, back-of-the-envelope style estimation for which the physicist was legendary).
This is the original version, written by Drake in 1961, with N being the number of civilizations we could potentially receive communications from:
N = R*xfpxnexflxfixfcxL
where:
R*= average rate of star formation in the Milky Way
fp= fraction of those stars with planets
ne= average number of habitable planets per star with planets
fl = fraction of habitable planets where life actually arises at some point
fi= fraction of these planets that eventually develop intelligent life (civilizations)
fc = fraction of civilizations that develop technologies that choose to release signs of their
existence into space
and,
L = the length of time that such civilizations release detectable signals into space
After much debate, the gathering’s twelve participants tentatively concluded that there could be between a thousand and one hundred million technological civilizations in the Milky Way. Sagan, one of those attending the now-legendary Green Bank meeting, later collaborated with Drake in refining the equation. Again, the Drake equation was intended only to stimulate dialog and help raise pertinent questions.[6]While neither Drake nor Sagan ever claimed that their calculations were anything more than an attempt to gauge possibilities, it is fair to question how anyone could even think to undertake a reckoning so fraught with dubious assumptions. To even guess at factors such as the fraction of these planets that eventually develop technological civilizations(fi) and the fraction of planets that develop sufficient communications technology and choose to use it(fc). Nonetheless, at the Green Bank meetingfl(the fraction of habitable planets where life actually arises)and fiwere given values of one (100%)—the assumption being that life will take hold wherever conditions permit and, once it does, intelligence and civilization and technology will eventually follow. The fraction of planets with civilizations that choose to announce their presence (fc) was given a value of 0.1–0.2 (10–20%).
Each factor in the equation is multiplied together (in the fashion of generating mathematical probabilities) to arrive at a final figure. The original calculations were rudimentary in several regards, containing only a handful of pertinent factors that merit consideration. Plus, each factor can be seen as the product of its own multifaceted probability equation. Later versions added elements previously not taken into account. (Drake reported in 2003 that he personally received suggestions for additional factors on a weekly basis. And he acknowledged one crucial factor that had been overlooked—“the ignorance of politicians.”) But, left out of the mix in 1961 were crucial items such as the frequency of civilization-ending calamities—collisions with asteroids, virulent pandemic disease outbreaks, or extra-solar radiation events—along with the planetary availability of key metal ores, without which advanced technology is a non-starter.
Also, little thought was initially given to the idea that technological civilizations, by their very nature, may be short lived. (Our current trajectory certainly gives the notion credence.) Science writer and self-avowed skeptic Michael Shermer dove into this unsettling question. He looked at the histories of some sixty established civilizations and arrived at a figure of 420 years for their average duration.Focusing on the later, more technologically advanced cultures (post-Roman empire), Shermer ended up with a mean figure of only 305 years. The Green Bank estimate for the duration of technological civilizations (L)was between a thousand and one-hundred million years.But if Shermer’s mean lifetime of three centuries is more in line with a universal reality, the prospect of contact with aliens whose capabilities coincide with our own significantly reduces any solution for N. Bear in mind that any overlap derives from signals whose source may be tens of thousands of light-years away—that is, from the distant past. This being the case, if we were toreceive some sort of electromagnetic calling card, it may have been sent by an intelligent race that vanished thousands of years ago.
Since any factor with a value less than one (100%probability) automatically lowers the final figure, the introduction of additional factors inevitably reduces earlier results. As it became clear that many more considerations needed to be included, for the most part, later outcomes proved not quite as hopeful as the original. To be sure, additional considerations could easily be appended, each of which would further lower future estimates. Not to be overlooked are those alien cultures that simply have no desire to contact others or do not want to risk inviting strangers into their homes. At the same time, a few amendments could increasecertain probabilities. These include the possibility that failed technological civilizations could re-emerge—more than once—to progress even further, and that some alien civilizations might actively colonize other star systems, spreading throughout the galaxy. Five years after the Green Bank meeting, Sagan and Soviet astrophysicist Iosef Shklovsky published a tentative figure of one million technological civilizations existing in our home galaxy alone.
There is an ironic element to the story of early efforts in the search for otherworldly messages. In 1974, at the Arecibo Radio Observatory in Puerto Rico,a transmission was aimed at a globular cluster known as M13, 21,000 light-years from Earth. The reasoning behind this particular selection? There are roughly 300,000 stars in this nearby cluster, upping the number of potential alien astronomers on planets orbiting some of those stars, with the hope that one or more might receive our message.[7]Unfortunately, it was later recognized that globular clusters turn out to be particularly inhospitable environs for life. Though possibly planet-rich, not only would the enormous numbers of densely packed stars generate profuse amounts of deadly radiation, but planetary orbital perturbations were an inevitability. Supernovas in close proximity would result in frequent extinction events.[8]Additionally, stars in globular clusters are generally old—that is, of earlier generations—and thus tend to be deficient in the heavier elements necessary for life. Alas, it is not likely that anyone will be around to take the call when those faint transmissions reach M13 24,000 years hence.
Despite the seeming certainty that life mustexist elsewhere in the observable universe (or undetectable multiverse), we are still faced with the difficult-to-articulate but somehow unsettling possibility that living things are only found on this one tiny island in a boundless cosmic sea. While creationists have no objections whatsoever with this picture—find it validating, in fact—anyone with a scientific bent finds the notion bleak in the extreme. All THIS, just for us?! The immensity of space…all those galaxies and stars and planets… solely for our sake? As unlikely as it might appear, this possibility that we are all alone remains one alternative. Astrophysicist John Gribbin, in his book Alone in the Universe,argues just that. Gribbin makes the case that there are so many fortuitous features, and so many highly unlikely events and conditions involved, many of them dependent on precise timing, that he is forced to conclude that Earth, with its complex life, may be one of a kind. (This estimation will be discussed in more detail in Chapter 27.)
For those who point out how absurd it is to think that an inconceivably vast universe exists as backdrop for a few living planets (even worse if a multiverse): there is another way of looking at this apparent enigma. Life requires time—time for multiple generations of stars to create heavy elements, for solar systems to form, for living things to appear and evolve. The observable portion of our universe is roughly fourteen billion years old, a boundless sphere roughly ninety-three billion light-years in diameter.[9]So: of necessity, living things can onlyexist in a frigid expanse of mostly empty space peppered with inert celestial bodies—another instance of blind necessity. For now, consider the prospect that our universe nonetheless has a built-in predisposition to spawn living matter, even though it might be an exceptionally rare occurrence. While not provable, it may well be true that the multiverse is an actuality and we just happen to live in one expanse that just happens to be convivial to life. And this may be the case even if conditions in the vast majority of bubble-universes make them incapable of producing complex structures. Even though multiverse-based hypotheses can never be verified, they still afford useful models that allow predictions to be made. A multiverse illuminates various cosmic conundrums.
On the other hand, I believe it is more rationally plausible to reason that LIFE is a built-in attribute of the universe and not a chance anomaly. Taking into consideration the history of science—in particular, that of scientific materialism—it is clear why there is resistance to a notion that, in truth, is entirely feasible. Bear in mind that, until recent times many if not most scientists assumed that the origin of life was a highly improbable occurrence that may have happened but once. Many still do. But we now know definitively that, even if the event will forever be shrouded in mystery, it was notthe result of blind chance. As I have repeatedly shown, taken as a whole, the manner in which life “got a grip on Earth with almost indecent haste” (Gribbin) and the wealth of examples of how LIFE came up with marvelous solutions to make ends meet—these things all strongly support the point of view that LIFE will find a way if given a chance. We live in a biophilic—a LIFE-loving—universe.
The next two chapters might convince a few skeptics.
©2018 by Tim Forsell (draft)
[1]Full title: New Astronomy, Based upon Causes, or Celestial Physics, Treated by Means of Commentaries on the Motions of the Star Mars, from the Observations of Tycho Brahe, Gent,published in 1609.
[2]Almost always referred to simply as “the Principia,” Newton’s monumental work is entitled Philosophiæ Naturalis Principia Mathematica(“Mathematical Principles of Natural Philosophy”).
[3]There is no general agreement on precisely what multiverse theory comprises, with a number of different schools of thought and competing versions. Brian Greene has described nine separate hypothetical species of parallel universes. Lee Smolin imagines that massive black holes might give rise to “baby universes.” The various multiple universe theories provide—at best—working models, not legitimate scientific theory. To further complicate matters,a many worlds interpretation of quantum mechanics states that there are an infinite number of co-existent parallel universes in which all possible futures have come to pass, each as real as what we experience in this one.
[4]For instance,Robert Wesson writes, “There is something of self-hate in the materialist approach. It depreciates the life of the mind and works of imagination and character. It demeans the richness and wonder of nature. It seems to make unnecessary further thinking about the mysteries of existence, of life and the universe. If one is gripped by the idea that we were made by chance…and are not intrinsically superior to amoebas…one is not prepared to cope with the responsibility of intelligence and power.”
[5]In 2016, researchers at the University of Nottingham estimated that “the total number of galaxies in the universe is around 2 trillion, almost a factor of 10 higher than would be seen in an all sky survey at Hubble Ultra-Deep Field depth.”
[6]The equation still generates debate, undergoing revision as the values of factors are upgraded to reflect the arrival of new information—particularly with the ongoing discovery of new exoplanets.
[7]There are only about two dozen stars within thirteen light-years of our solar system; a typical globular cluster might contain over a thousand stars in a similar volume. Observers on a planet within a globular cluster would see somewhere in the neighborhood of 120,000 in their night-free sky.
[8]Supernovasare large stars that collapse following the depletion of their nuclear fuel, followed by a massive explosion that blasts away the star’s outer layers. (In contrast, a novais a star, often part of a binary or multiple-star system, that goes through a period of increased luminosity but does not explode.)
[9]This figure takes into account both inflation and the ongoing expansion of spacetime.
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