Oscar Wilde once said, “We are all in the gutter, but some of us are looking at the stars.”
The political season lately ended in the United States has left many with a “gutter” kind of feeling, but as the year 2016 wanes a Harvard astrophysicist is reminding people that there is reason to look up — and cheer up.
“All the observations so far… are consistent with the idea that humanity is not mediocre at all,” Howard A. Smith said in an op-ed in the Washington Post recently. “It seems we might even serve some cosmic role. So this season let us be grateful for the amazing gifts of life and awareness, and acknowledge the compelling evidence to date that humanity and our home planet, Earth, are rare and cosmically precious. And may we act accordingly.”
Smith is a lecturer in the Harvard University Department of Astronomy and a senior astrophysicist at the Harvard-Smithsonian Center for Astrophysics. He writes that the cosmological pendulum has swung from the view that Earth is the center of the universe and humans were “special” to believing we are “cosmically inconsequential,” after the Copernican revolution, and back again to understanding our uniqueness in the universe.
How did that happen? Big bang cosmology and the discovery of exoplanets — planets around other stars, Smith says. “The universe, far from being a collection of random accidents, appears to be stupendously perfect and fine-tuned for life,” he writes. “The strengths of the four forces that operate in the universe — gravity, electromagnetism, and the strong and weak nuclear interactions (the latter two dominate only at the level of atoms) — for example, have values critically suited for life, and were they even a few percent different, we would not be here.”
The most extreme example is the big bang creation: Even an infinitesimal change to its explosive expansion value would preclude life. The frequent response from physicists offers a speculative solution: an infinite number of universes — we are just living in the one with the right value. But modern philosophers such as Thomas Nagel and pioneering quantum physicists such as John Wheeler have argued instead that intelligent beings must somehow be the directed goal of such a curiously fine-tuned cosmos.
Recent discoveries of water on Mars and other places “out there” lead to tantalizing discussions of finding extraterrestrial life. But the chances of finding anything approaching “intelligent life” are infinitesimally slim, Smith argues. Quite simply, intelligence is difficult to “produce:”
Paleontologist Peter Ward and astronomer Donald Brownlee summarize the many constraints in their book “Rare Earth: Why Complex Life is Uncommon in the Universe” and show why it takes vastly more than liquid water and a pleasant environment to give birth even to simple (much less complex) life. At a minimum, it takes an environment stable for billions of years of evolution, plus all the right ingredients. Biologists from Jacques Monod to Stephen Jay Gould have emphasized the extraordinary circumstances that led to intelligence on Earth, while geneticists have found that DNA probably resulted from many accidents. So although the same processes operate everywhere, some sequences could be unlikely, even astronomically unlikely. The evolution of intelligence could certainly be such a sequence.
If it’s even possible for life to get started on exoplanets, it’s easy for it to run into trouble, Smith explains. “Many such planets have highly elliptical orbits around unstable stars, making evolution over billions of years difficult if not impossible,” he writes. “Other systems contain giant planets that may have drifted inward, disrupting orbits; and there are many other unanticipated properties. These unexpected discoveries are helping scientists unravel Earth’s complex history.”
Bottom line? For Smith, the sentiments of popular scientists like Stephen Hawking, who once said “The human race is just a chemical scum on a moderate-sized planet,” are unnecessarily dismal. The stars tell a different story, and it’s a bright one.