The Canon (47 page)

No they can't. And yet, they do. The good news, such as it is, and I warn you it isn't much, is that the great majority of astronomers I interviewed believe there is life on other planets. Some think that life is common, that the universe is flooded with star stuff stuffed into self-replicating organisms of more or less cellularly based structures. Others say that life is likely to be rare, but that nonetheless it's probably not limited to Earth. Their conviction comes down to sheer statistics, and the rule of large numbers. "Are we alone?" said Neta Bahcall of Princeton University. "To me the answer is easy and obvious. Our sun is one star out of hundreds of billions of stars in our galaxy, and the Milky Way is just one out of billions and billions of galaxies. It's just impossible that we are the only life in the universe."

"I'm inclined to think that life is very common in the universe," said David Stevenson of Caltech. "I may turn out to be wrong, of course, but that's my working hypothesis."

In an interview conducted not long before his death, John Bahcall of Princeton said, "I am absolutely certain there is more life out there. It's one of the very few things for which I don't have any proof but on which I would bet a lot of money. The odds are so overwhelmingly in my favor."

Not only are there billions of stars, astronomers say, billions of solar ovens radiating photonic comestibles that practically beg to be eaten, but there are likely to be billions of planets circling those stars, billions of possible tables where one might find organisms that take in nutrients, excrete waste, replicate, and actually use the fondue set they got as a wedding present. Planetary formation, it seems, is a frequent byproduct of stellar condensation, the planetary disk forming as a result of the angular momentum of a collapsing, spinning star; anywhere from 10 to 50 percent of stars may have their share of circumstantial circumnavigators. Many astronomers are now searching for signs of extrasolar planets by checking for wobbles or irregularities in a star's motions, which may signal that it has gravitational companions, or the intermittent dimming of a star's light that would result whenever an orbiting planet passed between the star and us. And though for a while the only extrasolar planets astronomers could find were of the uninhabitable gas-giant category, more recently they have detected signs of smaller and possibly earthier worlds, tracing orbits at sensibly temperate distances from their parent suns.

Astronomers also find comfort in how relatively quickly life arose on Earth after the crust had cooled, and the unshakable conviction with which life has stood its ground ever since. They point to recent work in the field of nanotechnology, the chemistry of materials constructed on extremely small scales, showing that carbon molecules spontaneously form rings, tubes, and spheres, the very sort of skeletal structures on which life is draped. Carbon is a common constituent of supernova shrapnel, they say, and if carbon so readily self-assembles into the precursors of biomolecules, the rise of life may be virtually inevitable if carbon finds itself self-assembling in certain settings—for example, on a planet with liquid water to its credit. Again, not an outrageous demand. Water, like carbon, is commonplace, and though most of the cosmic quotient of water looks to be in gaseous or frozen form, there are sure to be other liquid oases in the vast sample space that is outer space. "Here on Earth, anywhere you find liquid water, you find life," said Andy Ingersoll of Caltech. "Life is remarkably robust when it comes to adapting to extremely cold or hot water, or very acidic water. It's hard to imagine, given the robustness of microbial life, that if there's liquid water somewhere else, life hasn't found a way to take advantage of it."

On the question of how complex any of that extraterrestrial life may be, and whether there are other technologically sophisticated civilizations with whom we in theory could communicate, astronomers become far more reserved. "When you start asking, what is the probability that life, once it has developed, will evolve something sufficiently intelligent that it tries to communicate and travel around, well, I don't think we're in a position to make a useful estimate of that," said Dave Stevenson of Caltech.

Nevertheless, a few resilient souls have sought to do exactly that.
Most famously, Frank Drake, then a Cornell astronomer and a founder of the Search for Extra-Terrestrial Intelligence initiative, or SETI, in the 1960s offered his methodical approach to calculating how many "communicative societies" may be out there in the Milky Way, a formulation now known as the Drake equation. Drake's take consists of seven variables to consider, proceeding from such comparatively straightforward factors as the rate of new star formation and the number of stars likely to have planets, and progressing into ever softer and more subjective terrain, including: the odds that a particular life-bearing locale will give rise to intelligent life; that the intelligence will be of a tinkering, toolmaking type; and, finally, that the technologically adroit civilization, having reached the point where it is capable of sending its halloos our way, will persist long enough to hear our reply.

Stevenson observes that the most uncertain and potentially deflating parameter of the Drake equation is the last one. "If the life span of an advanced civilization is only a few thousand years, then the probability of another intelligent civilization coexisting with us becomes low," said Stevenson. "Other civilizations might have come and gone before us, and new ones may be in the process of forming, but by the time they do we'll have destroyed ourselves. Either way, we could well be the only one in the galaxy at present."

But take heart! Remember that, while our naked night vision is limited mostly to the Milky Way, our sample space is not. Even if there were only one communicative society per galaxy, that still leaves us with billions of hypothetical entries on the Rolodex of hope. Admittedly, the terrible distances between galaxies could well preclude any communication beyond the science fictional, but it's good to think they're out there, those probabilistic star-flecked partners in space-time. And who knows? They may be better off than we are and have found the perfect intergalactic wormhole and are steadily heading our way. Please, please, stop by, any time, any stardate. We can't promise, but we will try, with all our heart and hemoglobin and every one of our 90 trillion body cells and our bacterial symbionts, too, to hang on, and dodge our own bullets, and be here when you arrive.

REFERENCES

ACKNOWLEDGMENTS

INDEX

l. Thinking Scientifically: An Out-of-Body Experience

Altschuler, Daniel R.
Children of the Stars: Our Origin, Evolution and Destiny.
Cambridge and New York: Cambridge University Press, 2002.

Atkins, Peter.
Galileo's Finger.
Oxford: Oxford University Press, 2003.

Ben-Shahar, Y., A. Robichon, M. B. Sokolowski, and G. E. Robinson. "Influence of Gene Action Across Different Time Scales on Behavior."
Science
296 (2002): 741–44.

Bryson, Bill.
A Short History of Nearly Everything.
New York: Broadway Books, 2003.

Donald, Janet.
Learning to Think.
San Francisco: Jossey-Bass, 2002.

Eisner, Thomas. "Making the Microscope Loom Large in a Child's Life"
New York Times,
August 10, 2004. June 23, 2006

.

Emiliani, Cesare.
The Scientific Companion.
New York: Wiley, 1995.

Hazen, Robert M., and James Trefil.
Achieving Science Literacy.
New York: Doubleday, 1990.

Krauss, Lawrence M.
Fear of Physics.
New York: Basic Books, 1993.

Lustig, Cindy, Alex Konkel, and Larry L. Jacoby. "Which Route to Recovery?"
Psychological Science
15 (2004): 729–35.

National Science Foundation. "Science and Engineering Labor Force."
Science and Engineering Indicators 2006.
September 6, 2006

.

Piel, Gerard.
The Age of Science.
New York: Basic Books, 2001.

Pollack, Henry N.
Uncertain Science ... Uncertain World.
Cambridge: Cambridge University Press, 2003.

Remnick, David, ed.
Life Stories: Profiles from
The New Yorker. New York: Modern Library, 2001.

"Science Dull and Hard, Students Say."
BBC News.
September 6, 2006

.

Tallack, Peter, ed.
The Science Book.
London: Cassell, 2001.

Trefil, James.
The Nature of Science.
Boston: Houghton Mifflin, 2003.

Trefil, James, and Robert M. Hazen.
The Sciences: An Integrated Approach.
New York: Wiley, 2001.

Weinberg, Steven. "Can Science Explain Everything? Anything?"
The New York Review of Books.
May 31, 2001. January 31, 2002

.

2. Probabilities: For Whom the Bell Curves

American Academy of Dermatology. "Melanoma Fact Sheet."
AAD Public Resource Center.
September 6, 2006

.

Belkin, Lisa. "The Odds of That"
New York Times.
August 11, 2002.

Cohen, Jack, and Ian Stewart. "That's Amazing, Isn't It?"
New Scientist.
January 17, 1998.

Cohn, Victor.
News and Numbers.
Ames: Iowa State University Press, 1989.

Gonick, Larry, and Woollcott Smith.
The Cartoon Guide to Statistics.
New York: Harper Perennial, 1993.

"HIV Infection and AIDS."
National Institute of Allergy and Infectious Diseases.
September 6, 2006

.

Huff, Darrell.
How to Lie with Statistics.
New York: W. W. Norton, 1954.

Koehler, Jonathan J. "One in Millions, Billions, and Trillions."
Journal of Legal Education
47 (1997): 214–23.

Kolata, Gina. "1-in-a-Trillion Coincidence, You Say? Not Really, Experts Find."
New York Times.
February 27, 1990.

Lee, Jennifer 8. "Who Needs Giacomo? Bet on the Fortune Cookie."
New York Times.
May 11, 2005.

Muller, Richard A.
Physics for Future Presidents.
Berkeley: University of California Press, 2004.

Palo Alto Medical Foundation. "The Darker Side of the Sun: Facts about Skin Cancer." September 6, 2006

.

Paulos, John Allen.
Innumeracy.
New York: Vintage, 1990.

———.
A Mathematician Reads the Newspaper.
New York: Anchor, 1996.

Phillips, John L.
How to Think about Statistics.
New York: W. H. Freeman, 2000.

Pollack, Henry N.
Uncertain Science
...
Uncertain World.
Cambridge: Cambridge University Press, 2003.

Salsburg, David.
The Lady Tasting Tea: How Statistics Revolutionized Science in the Twentieth Century.
New York: W. H. Freeman, 2001.

Slovic, Paul. "Perception of Risk Posed by Extreme Events."
Risk Management Strategies in an Uncertain World.
Palisades, N.Y. April 12, 2002.

Taleb, Nassim N. "Learning to Expect the Unexpected."
Edge.
June 23, 2006

.

U.S. Department of Health and Human Services. "Results from the 2004 National Survey on Drug Use and Health: National Findings."
Office of Applied Studies.

.

Weiss, Rick. "Dazzled by 'Tortured Data.'"
Washington Post.
November 23, 1993. June 23, 2006

.

Willett, Martin. "Bell Curves."
Debate Unlimited.
June 23, 2006

.

3. Calibration: Playing with Scales

American Society for Microbiology. "Monsters Among the Microbes."
Microbes.
September 1, 2005.

Ash, Russell.
The Top Ten of Everything 2004.
London and New York: Dorling Kindersley, 2003.

Calder, Nigel.
TimeScale.
New York: Viking, 1983.

Carpi, Anthony. "The Cell."
The Natural Sciences.
City University of New York. June 23, 2006

.

"Day."
Wikipedia.
September 6, 2006

.

Ford, Kenneth W.
The Quantum World.
Cambridge, Mass.: Harvard University Press, 2004.

Haldane, J.B.S.
On Being the Right Size.
Oxford: Oxford University Press, 1985.

Jaffe, Robert L.
The Time of Your Life—and Other Times.
Manuscript. 2005.

Lieberman, Abraham N. "What You Should Know about the Cell, DNA, and Genes" National Parkinson Foundation. October 6, 2005

.

Morrison, Philip, and Phylis Morrison.
Powers of Ten.
San Francisco: Scientific American Library, 1982.

NASA. "Solar History Timeline"
Solar-B.
September 6, 2006

.

"The Nervous System"
ThinkQuest.
September 6, 2006

.

Pollock, Steven.
Particle Physics for Non-Physicists.
Chantilly, Va.: The Teaching Company, 2003.

Rensberger, Boyce.
Instant Biology.
New York: Fawcett Columbine, 1996.

Rigden, John S.
Hydrogen: The Essential Element.
Cambridge, Mass.: Harvard University Press, 2002.

Sandow, Stuart A., Chrissie Bamber, and J. W. Rioux.
Durations: The Encyclopedia of How Long Things Take.
New York: Times Books, 1977.