Discovery is seeing what everyone else saw and thinking what no one thought.
On Christmas Eve, 1968, the Apollo 8 astronauts–Frank Borman, James Lovell, and William Anders–became the first human beings to see the far side of the Moon. The moment was as historic as it was perilous: they had been wrested from Earth’s gravity and hurled into space by the massive, barely tested Saturn V rocket. Although one of their primary tasks was to take pictures of the Moon in search of future landing sites–the first lunar landing would take place just seven months later–many associate their mission with a different photograph, commonly know as Earthrise.
Emerging from the Moon’s far side during their fourth orbit, the astronauts were suddenly transfixed by their vision of Earth, a delicate, gleaming swirl of blue and white, contrasting with the monochromatic, barren lunar horizon. Earth had never appeared so small to human eyes, yet was never more the center of attention.
To mark the event’s significance and its occurrence on Christmas Eve the crew had decided, after much deliberation, to read the opening words of Genesis: “In the beginning, God created the heavens and the Earth√?¬Ę√Ę‚??¬¨ ¬¶” The reading, and the reverent silence that followed, went out over a live telecast to an estimated one billion viewers, the largest single audience in television history.
In his recent book about the Apollo 8 mission, Robert Zimmerman notes that the astronauts had not chosen the words as parochial religious expression but rather “to include the feelings and beliefs of as many people as possible.” Indeed, when the majority of Earth’s citizens look out at the wonders of nature or Apollo 8’s awe-inspiring Earthrise image, they see the majesty of a grand design. But a very different opinion holds that our Earthly existence is not only rather ordinary but in fact insignificant and purposeless. In his book Pale Blue Dot, the late astronomer Carl Sagan typifies this view while reflection on another image of Earth, this one taken by Voyager 1 in 1990 from some four billion miles away:
- Because of the reflection of sunlight√?¬Ę√Ę‚??¬¨ ¬¶Earth seems to be sitting in a beam of light, as if there were some special significance to this small world. But it’s just an accident of geometry and optics√?¬Ę√Ę‚??¬¨ ¬¶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. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity, in all this vastness, there is no hint that help will come from elsewhere to save us from ourselves.
But perhaps this melancholy assumption, despite its heroic pretense, is mistaken. Perhaps the unprecedented scientific knowledge acquired in the last century, enabled by equally unprecedented technological achievements, should, when properly interpreted, contribute to a deeper appreciation of our place in the cosmos. In the following pages we hope to substantiate that possibility by means of a striking feature of the natural world, one as widely grounded in the evidence of nature as it is wide-ranging in its implications. Simply stated, the conditions allowing for intelligent life on Earth also make our planet strangely well suited for viewing and analyzing the universe.
The fact that our atmosphere is clear; that our moon is just the right size and distance from Earth, and that its gravity stabilizes Earth’s rotation; that our position in our galaxy is just so; that our sun is its precise mass and composition–all of these and many more are not only necessary for Earth’s habitability, but also have been surprisingly crucial to the discovery and measurement of the universe by scientists. Mankind is unusually well positioned to decipher the cosmos. Were we merely lucky in this regard? Scrutinize the universe with the best tools of modern science, and you’ll find that a place with the proper conditions for intelligent life will also afford its inhabitants an exceptionally clear view of the universe. Such so-called habitable zones are rare in the universe, and even these may be devoid of life. But if there is another civilization out there, it will also enjoy a clear vantage point for searching the cosmos, and maybe even for finding us.
To put it both more technically and more generally, “measurability” seems to correlate with “habitability.” Is this correlation simply a strange coincidence? And even if it had some explanation, is it significant? We think it is, not least because this evidence contradicts a popular idea called the Copernican Principle, or the Principle of Mediocrity. This principle is far more than the simple observation that the cosmos doesn’t literally revolve around Earth. For many, it is a metaphysical extension of that claim. According to this principle, modern science since Copernicus had persistently displaced human beings from the “center” of the cosmos, and demonstrated that life and the conditions required for it are unremarkable and certainly unintended. In short, it requires scientists to assume that our location, both physical and metaphysical, is unexceptional. And it usually expresses what philosophers call naturalism or materialism–the view that the material world is “all that is, or ever was, or ever will be,” as Carl Sagan famously put it.
[Some scientists] argue that although Earth’s complex life and the rare conditions that allow for it are highly improbable, perhaps even unique, these conditions are still nothing more than an unintended fluke. In a lecture after the publication of Rare Earth, Peter Ward remarked, “We are just incredibly lucky. Somebody had to win the big lottery, and we were it.”
We don’t think this is merely coincidental. It cries out for another explanation, an explanation that suggests there’s more to the cosmos than we have been willing to entertain or even imagine.
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