Today, an old inquiry into life on other planets. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.
Long ago a Jehovah's Witness came by selling the Watchtower. When my wife found she could get it in German, she signed up so she could practice reading German. When the Watchtower arrived, the lead article asked, Gibt es Leben im Weltraum? -- Is there Other Life in the Universe?
Jehovah's Witnesses believe the Genesis creation was unique, and there's no other life in the universe. Modern scientists divide on the question. Carl Sagan believed he could find alien life. But the question is much older. It took shape in the 17th century as modern cosmology formed out of conflicting theories of the heavens.
Christiaan Huygens was an early believer in alien life. Born in 1629, Huygens worked in math, optics, astronomy. He built the first practical pendulum clock. He spent time in France before the French Catholic Church turned conservative in 1684. Then, since he was a devout Protestant, he had to leave France for good.
Late in life, Huygens finished his Cosmotheoros, a book of careful conjectures about life on other worlds. By then, he'd talked with Newton about Newton's new theories. Huygens loved the new calculus, but he was skeptical of Newton's gravitational theory.
Huygens argued that God's wisdom and providence is clearest in the creation of life, and Earth holds no privileged position in the heavens. Since the same natural laws operate everywhere, life must be universal, and it cannot differ much from life on earth.
But as he looks at the solar system, the weakness of his case becomes evident. Anything resembling a human would be squashed like a bug by Saturn's gravity. (Without accepting Newton's gravitational laws he couldn't see that.) Also missing was the late-19th-century molecular theory of gases. On earth, gas molecules move much slower than the escape velocity. That's why we keep our atmosphere. The moon with, its much lower escape velocity, loses its atmosphere. Mars is in between, and its atmosphere is very thin.
Worse yet, Huygens had no knowledge of oxygen and its role in sustaining life. He had no way of knowing that other gases surround other planets. For many reasons, unknown to Huygens, the planets offer vastly different environments to any life they might harbor.
Huygens also argued that cultures will be similar. Take music: Our scales are dictated by laws of physics. All music must have elements in common . (That really is true on planet Earth.)
But as we search for extra-terrestrial life, it retreats from us. It's now clear that if there is other life in the solar system, it's minimal. Our listening posts have heard no signals from outer space yet. Still, the universe is vast and full of surprises. Huygens might yet be vindicated. Meanwhile, that argumentative question in the Watchtower, Gibt es Leben im Weltraum?, remains as open as it was when Huygens wrote about it, three hundred years ago.
I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.
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Huygens, C., Cosmotheoros, Sive de Terris Coelestibus, Earumque Ornatu, Conjecturae. The Hague: 1698 (Oeuvres XXI). (Huygens's work appears in many later versions and in various languages. I am grateful to Toni Blackwell, UH Library, for drawing my attention to one of these sources.)
Bos, H. J. M., Huygens, Christiaan. The Dictionary of Scientific Biography, New York: Charles Scribner's Sons, 1973.
I find it interesting to note Huygens's remark about the origins of the planets. He doesn't believe that either science or religion will be served by chasing this question. He says,
I shall be very well contented ... if I can but [know] how things are now, never troubling myself about their beginning ... knowing that to be out of reach of human knowledge or even conjecture.
Huygens's Pendulum Clock
From the 1832 Edinburgh Encyclopaedia