Are We Alone?
RICHARDS, JAY W. & GONZALEZ, GUILLERMO
reason to think otherwise—and reason to ponder what makes the Earth unique. MERICAN TAXPAYERS RECENTLY FOOTED THE BILL FOR A RISKY $800 MILLION NASA MISSION. The good news? It worked. In January,...
...We have access to a striking diversity of nearby stars and other galactic structures, as well as a clear view of distant galaxies and the unique cosmic microwave background radiation, both essential for discovering the astonishing facts that the universe is expanding and finite in age...
...This makes our solar eclipses more valuable scientifically...
...Guillermo Gonzalez is assistant professor of astronomy and physics at Iowa State University...
...JAY W. RICHARDS & GUILLERMO GONZALEZ Sagittarius and Perseus spiral arms...
...And the first evidence is in...
...T HESE EXAMPLES ARE MERELY illustrative...
...While we can't yet say how wide it is, the Galactic Habitable Zone seems to be a fuzzy ring in the thin disk at roughly the Sun's location, a ring whose habitability is itself compromised at several points where it intersects the spiral arms...
...Measurability refers to those features of the universe as a whole, and especially to our particular location in it—both in space and time—that allow us to detect, observe, discover, and determine the size, age, history, laws, and other properties of the physical universe...
...It's what makes scientific discovery possible...
...Our Milky Way is a spiral galaxy...
...In fact, of Lne more than 65 major moons in our Solar System, ours best matches the Sun as viewed from its planet's surface, and this is only possible during a fairly narrow window of Earth's history encompassing the present...
...Quite simply, it's because most astrobiologists now realize that such water is necessary not just for Earthly life, but for life anywhere...
...There's no law of physics or celestial mechanics that requires the right configuration...
...That's the most important but almost overlooked lesson of our study of Mars...
...Is there any way we could tell...
...Astronomers have noted this odd coincidence for centuries...
...But this is only one example of the correlation between habitability and measurability...
...that our position in our large spiral galaxy is just so...
...The Moon also contributes to Earth's ocean tides, which increase the vital mixing of nutrients from the land to the oceans...
...Mars, as long suspected, probably once had some liquid water on its surface...
...The tests led to the general acceptance of Einstein's theory, which is the foundation of modern cosmology...
...Surely no question in science is more interesting and more controversial...
...But here's the part that suggests conspiracy rather than quirky coincidence...
...We're now learning how much must go right to get a habitable planet...
...Even as late as the 1950s, some scientists thought Mars was home to intelligent life...
...a large, well-placed moon to contribute to tides and stabilize the tilt of the planet's axis...
...But why all the fuss and expense in search of this humble substance...
...The two moons around Mars are much too small to stabilize its rotation axis...
...In addition, it's only in the socalled Circumstellar Habitable Zone of our Sun—that cozy life-friendly ring where water can stay liquid on a planet's surface—that the Sun appears to be about the same size as the Moon from Earth's surface...
...JAY W. RICHARDS & GUILLERMO GONZALEZ (This is to say nothing of having a universe with a fine-tuned set of physical laws to make stars, planets, and people possible in the first place...
...We argue that there is...
...Mars has more in common with Earth than does any other known body in the universe...
...The Moon is about 400 times smaller than the Sun...
...But only in the 19th century did astronomers observe solar eclipses with spectroscopes, which use prisms...
...1908, H.G...
...We reside between the A moon large enough to cover the Sun stabilizes the tilt of the rotation axis of its host planet, yielding a more stable climate, which is necessary for complex life...
...h Jay W. Richards is vice president and senior fellow of the Discovery Institute in Seattle...
...We are now reduced to looking not even for microbial Martians, but for the existence of one of life's necessary conditions sometime in the distant past...
...they also have been surprising-ly crucial for scientists to discover the universe...
...Why this pervasive opinion among scientists, the media, and the public at large...
...They are co-authors of the recently released book The Privileged Planet: How Our Place in the Cosmos Is Designed for Discovery (Regnery, 2004...
...So, the Moon's apparent size on the sky matches the Sun's...
...And they have taught us an important, if unadvertised lesson...
...If habitability depends on proximity to the so-called co-rotation circle—that region in which stars orbit at about the same speed as the spiral arms—then this thin and often broken ring could be narrower still...
...F IRST, THESE OBSERVATIONS HELPED disclose the nature of stars...
...ET THE EXPECTATION THAT LIFE is everywhere lives on...
...Our planet is a lonely speck in the great enveloping cosmic dark...
...And the life Earth sent there clearly didn't "terraform" the planet...
...In January, two NASA landers bounced to their destinations and released their rovers Spirit and Opportunity to prowl the Martian landscape...
...In fact, mounting evidence suggests that the conditions needed for complex life are exceedingly rare, the probability of them all occurring at the same place and time, minuscule...
...In 16 THE AMERICAN SPECTATOR MAY 2004 Alone...
...This knowledge enabled astronomers to interpret the spectra of the distant stars...
...Second, in 1919, perfect solar eclipses allowed two teams of astronomers, one led by Sir Arthur Eddington, to confirm a prediction of Einstein's General Theory of Relativity—that gravity bends light...
...The combination of the man-made spectroscope with the natural experiment provided by 20 THE AMERICAN SPECTATOR MAY 2004eclipses gave astronomers the tools they needed to discover not only how the Sun's spectrum is produced, but the nature of the Sun itself...
...Properly framed and developed, however, we think the evidence for the correlation between life and discovery forms a pervasive and telling pattern, a pattern that not only contradicts the Copernican Principle, but also suggests that the universe, whatever else it is, is designed for discovery...
...Intuitively, you might think that such a precise configuration of life-friendly factors suggests that Earth is part of some cosmic design...
...Following the Copernican Principle, most scientists have supposed that our Solar System is typical and that the origin and evolution of life must be quite likely, given the vast size and great age of the universe...
...At the moment, we're learning about habitability mostly as a spinoff of the increasingly quixotic search for extraterrestrial life, because many astronomers are still in the grip of the Copernican Principle...
...That planet needs to be just the right distance from the right kind of single star, in a nearly circular orbit, to maintain liquid water on its surface...
...Accordingly, most have assumed that the universe is probably teeming not just with life, but complex, intelligent life...
...Planetary systems are not all alike...
...ARE WE ALONE...
...Such a test was most feasible during a perfect solar eclipse...
...The two small potato-shaped Martian moons, Deimos and Phobos, appear much too small to cover the Sun's disk, and they zip across it in less than a minute...
...It turns out that the precise configuration of Earth, Moon, and Sun are also vital to sustaining life on Earth...
...In contrast, the inner ghetto of the Milky Way suffers from greater radiation threats and comet collisions, and an Earth-size planet is less apt to form there in a stable circular orbit...
...Martian life enthusiast Percival Lowell summed up the basic idea in 1895: "That we are the sum and substance of the capabilities of the cosmos is something so preposterous as to be exquisitely comic....[Man] merely typifies in an imperfect way what is going on elsewhere, and what, to a mathematical certainty, is in some corners of the cosmos indefinitely excelled...
...In his book Pale Blue Dot, Sagan reflected on a famous image of Earth taken by a Voyager satellite from some four billion miles away...
...But it's just an accident of geometry and optics....Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light...
...So argued Peter Ward and Donald Brownlee in their best-selling book Rare Earth: Why Complex Life is Uncommon in the Universe...
...It's intriguing that the best place to view total solar eclipses in our Solar System is the one time and place where there are observers to see them...
...S INCE THE MID-19905, astronomers have been able to detect planets around other Sun-like stars...
...MAY 2004 THE AMERICAN SPECTATOR 19 ARE WE ALONE...
...This, in turn, allows us to put ancient calendars precisely on our modern calendar system...
...The recent pictures of solar eclipses sent back from the Opportunity rover on Mars nicely illustrate how much better our solar eclipses are...
...To put it more technically, "measurability" seems to correlate with habitability...
...That planetary system must be nestled in a safe neighborhood in the right kind of galaxy, with enough heavy elements to build terrestrial planets...
...Even though we're near the mid-plane, there's very little in the way of dust in our neighborhood to absorb light from nearby stars and distant galaxies...
...It's not as if life has only one instruction in its recipe: "Just add water...
...But that's another long and complicated story...
...According to Carl Sagan, Lowell's enthusiasm "turned on all the eight-year olds who came after him, and who eventually turned into the present generation of astronomers...
...But what if we're not merely the winners of a blind cosmic lottery...
...So, in a sense, perfect eclipses were a key that unlocked the field of astrophysics...
...These remarkable little robots were not searching for archaeological ruins or strange, black monoliths but something much less exotic—the fingerprints of water in liquid form...
...This is strange because there's no obvious reason to assume that the very same rare properties that allow for observers would also provide the best overall setting for observing the world around them...
...Design...
...The universe, after all, is a big place, with some 1022 stars in the part we can see...
...Any remaining life would be the microscopic vestiges of a dying world...
...Wells published a non-fiction article in Cosmopolitan magazine about the civilization that he thought inhabited the planet...
...T HOUGH THE VISIBLE UNIVERSE contains perhaps a hundred billion galaxies, astronomers group them into just three basic types: ellipticals, irregulars, and spirals...
...And finally, perfect eclipses give us unique access to ancient history...
...Our ability to observe perfect solar eclipses has figured prominently in several important scientific discoveries, discoveries that would have been difficult if not impossible on the much more common planets that don't enjoy such eclipses...
...And that planet will need to form during the narrow habitable window of cosmic history...
...Galaxies are filled with dangerous radiation hazards, and many regions are either so low in heavy elements as to prohibit terrestrial planets from forming, or so high that planetary systems will be hostile to life...
...In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves...
...Moreover, even the relatively rare, large spiral galaxies like the Milky Way, which are likely optimal for life, probably contain only a few locations within a "Galactic Habitable Zone" compatible with complex life...
...Life doesn't just spring up spontaneously out of water...
...Galaxies are filled with dangerous radiation hazards, and many regions are either so low in heavy elements as to prohibit terrestrial planets from forming, or so high that planetary systems will be hostile to life...
...that our Sun is its precise mass and composition: all of these and many more are not only necessary for Earth's habitability...
...If we're right, research dollars would be better spent exploring what other factors, still undiscovered, also contribute to a planet's habitability (and capacity for discovery...
...Contrary to popular impression, not all galaxies are equally habitable, since habitability depends on a galaxy's mass, type, age, and allotment of heavy elements...
...It turns out that the same rare, finely tuned conditions that allow for intelligent life on Earth also make it strangely well suited for viewing, analyzing, and discovering the universe around us...
...By consulting historical records of past solar eclipses, astronomers can calculate the change in Earth's rotation over the past several thousand years...
...Consider how our expectations for Mars have diminished in the last century...
...In fact, what is striking is not that Mars once had lots of liquid water on its surface, but that, although it was probably bathed by Earthly microbes during the same time, there's no evidence that life prospered on the Red Planet...
...And, since the Sun appears larger from the Earth than from any other planet with a moon, an Earth-bound observer can discern finer details in Planetary systems are not all alike...
...We are now reduced to looking not even for microbial Martians, but for the existence of one of life's necessary conditions sometime in the distant past...
...We live in the disk, very close to its midplane, about half way between the dangerous Galactic nucleus and its visible edge...
...Among scientists, at least, it comes not so much from scientific discovery as from an assumption called the Copernican Principle or Principle of Mediocrity...
...The outer regions are safer, but stars there will be accompanied by only fairly small terrestrial planets, planets too small to retain an atmosphere or sustain plate tectonics...
...With so many opportunities, maybe at least one habitable planet will turn up just by chance...
...The fact that we inhabit a terrestrial planet with a clear atmosphere and water on its surface...
...That alone seems fishy...
...Liquid water is a necessary condition for life, but not nearly a sufficient one...
...OPENING PHOTO: ASTROGEOLOGY.USGS.GOV MAY 2004 THE AMERICAN SPECTATOR 21...
...These are just three ways in which perfect solar eclipses, produced by conditions that help create a habitable planet, have fostered scientific discovery...
...To be persuasive, the argument needs more detail, more evidence, and more rigor...
...Yet, so far as we know, it still doesn't harbor life...
...the Sun's chromosphere and corona than from any other planet...
...As a result, we enjoy perfect solar eclipses...
...But in science, as in life, things can change...
...And the spiral arms are much more hostile to planetary systems aspiring to habitability than is our location between spiral arms...
...But our argument has more mundane implications...
...A rare convergence of events allows Earthlings to witness not just solar eclipses, but perfect solar eclipses, where the Moon just barely covers the Sun's bright photosphere...
...It also needs a home within a stable planetary system that includes some outlying giant planets to protect the inner system from too many deadly comet impacts...
...Around the same time, Percival Lowell built an observatory to gather evidence of that civilization—canals built by Martian engineers...
...Ward and Brownlee obviously challenge the letter of the Copernican Principle...
...But they don't challenge its spirit...
...Another unfortunate result of that principle is that few are inclined to ask if the universe could be designed for a purpose, let alone to seek evidence for such a possibility...
...Spiral galaxies like the Milky Way derive their popular name from the beautiful spiral pattern formed by their young stars and bright nebulae...
...This dampened considerably enthusiasm for Martian civilizations...
...F COURSE, justifying such a O claim requires a lot of evidence...
...In the decades that followed, the Mariner, Viking, and Sojourner missions to Mars revealed a barren and hostile environment...
...The list gets longer all the time...
...that our moon is just the right size and distance from Earth to stabilize the tilt of Earth's rotation axis...
...Most of its stars are located in its flattened disk, its thickness is only about one percent its diameter...
...Complex life in particular probably needs many of the things that we Earthlings enjoy: a rocky terrestrial planet similar in size and composition to the Earth, with plate tectonics to recycle nutrients, and the right kind of atmosphere...
...Ward and Brownlee, however, argue that although the conditions that allow for complex life are highly improbable, perhaps even unique, these conditions are still nothing more than an unintended fluke...
...But the scientific evidence has stubbornly pointed in the opposite direction...
...At the same time, our location within the Galactic Habitable Zone offers the best overall location to be a successful astronomer and cosmologist...
...What if our existence is the result of a conspiracy rather than a coincidence...
...We're far enough from the galactic center and the disk is flat enough that it doesn't excessivelyobscure our view of the distant universe...
...The "canals" turned out to be the result of optical illusions and an active imagination...
...They're the best places for scientific discovery...
...Such eclipses depend on the precise sizes, shapes, and relative distances of the Sun, Moon, and Earth...
...At the much larger, galactic, scale, we again find that the most habitable place is also the best overall location for making a diverse range of scientific discoveries...
...But unbridled enthusiasm for ETs has obscured the obvious...
...A moon large enough to cover the Sun stabilizes the tilt of the rotation axis of its host planet, yielding a more stable climate, which is necessary for complex life...
...He made clear that the Copernican Principle is no mere scientific 18 THE AMERICAN SPECTATOR MAY 2004 hypothesis, but an offshoot of the materialistic worldview: Because of the reflection of sunlight...the Earth seems to be sitting in a beam of light, as if there were some special significance to this small world...
...Perennial questions, even when officially ignored, have a way of bubbling up...
...But a couple of examples should be enough to illustrate what we mean by a "correlation between habitability and measurability...
...Scientists since Isaac Newton (1666) had known that sunlight splits into all the colors of the rainbow when passed through a prism...
...But right now, the Moon is about 400 times closer to the Earth than is the Sun...
...They succeeded in measuring the changes in the positions of starlight passing near the Sun's edge compared to their positions months later...
...Those rare pockets of habitability in our universe, as it happens, also allow for the most measurement...
...This Zone is an exclusive piece of real estate...
...In fact, mounting evidence suggests that the conditions needed for complex life are exceedingly rare...
Vol. 37 • May 2004 • No. 4
