First Contact (22 page)

His explanation of occulters and the Webb gambit finished, Soummer pointed to a photo on his office wall. It was of a large dark globe with flickers of light around its edges. “That,” he said, “is the ultimate occulter.” The photo was of the moon passing in front of the sun in a total eclipse. It turned out that Soummer's interest in the field of occulters and other sun blockers, and his sense that the Webb team just might provide the needed filter upgrade, were tied up with events related to that photo.

He had taken the picture, and others that he eagerly brought out, back in 1999 when the total eclipse occurred in France. He was twenty-seven then and an astronomy graduate student in the southern French city of Nice. But he had done his homework and found that the area several hundred miles north of Paris would be the best place to view the eclipse. And so he and his brother headed up north and started to set up and calibrate their telescope at 3:30
A.M
. for the noontime event.

Dawn came and it was cloudy. At 9
A.M
. it was still cloudy, and the eclipse was looking more and more like a bust. But a while later Soummer saw a patch of blue in the sky some miles away and, with his brother, jumped into the car and raced toward the open sky. They went through small villages and past wheat and corn fields, speeding ahead in a way that Soummer now looks back on and cringes. When they finally reached the patch of blue, the eclipse was about to start. The two had about five minutes to frantically set up the telescope, to make sure it was pointing at exactly the right spot and was at the right angle. They were just finishing when the sun began to go behind the otherwise unseen moon.

“It was magic, the most beautiful thing I've ever seen,” Soummer remembered. “It looked like dusk and then like night—a night with a full moon out—but it was in the middle of the day. I was looking and taking photos through the telescope and was always smiling.” The eclipse, he said, lasted about fifteen minutes and he had a clear shot at it the entire time.

As he soon after learned, virtually nobody else in France had found their patch of blue sky, and so virtually nobody else had photos. He learned this when he took in his negatives to be printed, and a photographer friend told him he should try to sell them. The friend went to some of the big publications in France for Soummer, and ultimately found a buyer at
Science et Vie
, a French equivalent to
Scientific American
. They ran eight pages of Soummer's pictures, and he came away from the experience high as a kite. He also came away with a wonderful connection to the ultimate solar system occulter, and a sense that even very small odds of success can sometimes pan out.

Three months later, Soummer, Cash, and the Webb team were still deciding whether to switch filters to enable a future occulter mission. But the future for the occulter, or something like the occulter, looked bright. That's because the astronomy panel of the National Academy of Sciences, in its ten-year review of future priorities, placed exoplanets and their atmospheres at the very top of its influential list of scientific targets for the next decade. Writing that exoplanets are “one of the fastest-growing and most exciting fields in astrophysics,” the report said that the goal of NASA and the National Science Foundation should be to “image rocky planets that lie in the habitable zone—at a distance from their central star where water can exist in liquid form—and to characterize their atmospheres.” Many technical and bureaucratic and especially financial challenges remained, but the occulter plan now had a little blue sky. Searching for signs of biology on distant exoplanets might not have to wait a generation after all.

We have learned a lot about how the universe came to be what it is now, but we know very little about why the 13.8-billion-year process played out in the entirely improbable way that it did. Astrobiology has happily moved into this vacuum, and not only asks the question “Are we alone?” but also the question “How are we here at all?” This is the kind of question that is generally considered outside the realm of science. But in this case, where the whole astrobiology effort is anchored in the expectation that a universe that led to our existence is likely to give rise to other forms of life, that nonscientific question of “why?” is impossible to entirely disentangle from the traditional scientific question of “how?”

To think through this question, astrobiologists, like scientists in other areas, have had to consider why the universe we know is so exquisitely fine-tuned. The concept refers to the well-established fact that life could never have started and evolved if the laws of physics were not almost precisely what they are. The more scientists learn about the cosmos, the greater the fine-tuning appears to be. Fine-tuning can be dismissed as a tautology (of course life arises only under conditions conducive to life), it can be embraced as an argument for a Creator, it can be seen as a series of signposts directing scientists to the deepest, least understood logic of the universe. But however it is interpreted, fine-tuning is a significant reality of the universe.

Here are some prominent examples:

• At the level of the cosmos, gravity is the organizing force. Yet gravity is extraordinarily weak compared with the electrical forces that hold together electrons, protons, and neutrons in an atom. That weakness, physicists have determined, is absolutely essential to the existence of our universe. A strong gravity universe would not only keep life from growing larger than a small insect, but would also pack stars closer together and with that proximity most likely keep stable solar systems from ever forming. Here's where the fine-tuning comes in: The ratio of the strength of the electrical forces in an atom compared with the force of gravity is 10 to the 26th. That's 1,000,000,000,000,000,000,000,000,000,000,000,000. As Lord Martin Rees, England's Astronomer Royal, described it, nothing as complex as humankind could have emerged if that number were even slightly smaller.

• The mass of a neutron in the center of an atom is 1.0013784 times heavier than the mass of a proton—in other words, they're virtually the same. This ratio allows atoms to remain stable and for chemistry to occur between elements. But if the proton were the same 0.1 percent heavier than the neutron, then the whole system would fall apart and life (and chemistry) as we know it would be impossible.

• British astronomer Fred Hoyle found in 1952 that the processes that form carbon, the indispensable element of Earthly life, depend on an improbable coincidence. His calculations, which have subsequently been confirmed many times, led him to conclude that very little carbon would be produced in the stellar furnaces unless the carbon nucleus vibrated at the same frequency as the nucleus of another element involved in the reaction, beryllium. Nobody even knew when Hoyle made his prediction that carbon nuclei could vibrate at that kind of frequency, but they soon confirmed that it did. And carbon, it turns out, is not only essential for life as we know it, but its presence in interstellar space is needed to cool down clouds of gases created by the dying explosions of large stars. Without that cooling, far fewer new stars would be formed.

The standard model of particle physics, which explains how atoms work, has about twenty constants that, if changed to any even minute degree, would make matter, stars, and galaxies very different and life, to a greater or lesser extent, impossible. Another ten cosmic constants order the universe. Some of these forces overlap, and not all require precise fine-tuning. But several do, and must be fine-tuned to an accuracy of greater than 99 percent to make a universe capable of forming and supporting life. It all sounds quite far-fetched, but it nonetheless is reality.

Fine-tuning has been hotly debated by physicists and cosmologists in recent decades, but without any real resolution. Since the descriptions of these physical relationships and interactions are demonstrably true, then the issue is not to prove or disprove them, but rather to make sense of them. Somehow our universe formed with physical laws, chemistry, and cosmic forces that allow for life on Earth and, quite possibly, elsewhere. How did that happen? Why did it happen? The Canadian philosopher John Leslie perhaps best conveyed the dilemma posed by fine-tuning with this parable: A man is facing a firing squad and fifty expert marksmen are preparing to end his life. The word is given and many shots are fired. To his amazement, the target opens his eyes after the fusillade and discovers he is still alive. What happened? Either he was stupendously lucky and everyone missed, or the marksmen intentionally missed their mark. As biological creatures in a finely tuned universe, we are that man.

In the search for other explanations, the theory of the “multiverse” emerged in the 1980s as a seriously studied alternative, although it was proposed as far back as 1895 by philosopher William James. Many variations on the theory exist, but all posit that we live in one of many, perhaps an infinite number of universes. Just as the earth is minuscule in comparison to our sun, so too would our universe be a speck in the enormous collection of universes that exist beyond our ability to detect them. Under the multiverse theory, countless universes exist where the necessary forces did not combine in a way to allow for life, while leaving room for the possible formation of a universe like ours where they did. The theoretical logic is strong, but
some scientists argue the multiverse idea is not actual science since it can't be either verified or falsified now, and perhaps never will be. Since the multiverse presupposes universes in many different dimensions, at distances farther than the speed of light could travel in the 13.8 billion years of our universe, the ability to tease out the reflected presence of a second or third or billionth universe is absent. Until some way is found to detect another universe, the multiverse can only remain a plausible if unproven theory or, even worse, speculation—even though the number of physicists and cosmologists who embrace some variation of the theory grows ever larger.

Multiverse thinking—the attempt to address fine-tuning and other questions of theoretical and cosmological physics—proposes many different kinds of universes and dimensions. There's the bubble universe theory, which assumes that our universe as well as numerous other universes were formed from a “bubble” of a “parent universe.” The many-worlds interpretation posits only one universe, but it splits into “many worlds” based on the logic of quantum mechanics. These worlds, however, cannot interact with each other. The so-called strong anthropic principle, in one of its interpretations, says that a range of different universes is necessary for the existence of our own. It also says, however, that the universe exists because we are here to observe its existence. None of these approaches has attracted anything close to a scientific consensus.

Theoretical physicist Lee Smolin, a founding professor of the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, has sought to reconcile the concept of fine-tuning with science by using the idea of a cosmic natural selection. His best-known work,
The Life of the Cosmos
, makes the case that many of the seemingly fine-tuned aspects of the universe can be explained by a kind of cosmic Darwinism—one in which differing laws of physics in effect compete and change over time, allowing them to evolve in a way that leads to a finely tuned world. (I liked Smolin even better when I saw a video of a lecture he gave at his institute on the physics of the universe. The pointer he used was a clunky wooden hockey stick.)

Since the mid-1980s, when he studied biology as well as theoretical
physics, Smolin's pathway into understanding and working to resolve the fine-tuning problem has focused on the parallels he intuited between the two fields. Those perceived parallels led to his theory that the universe, like the Darwinian world of life on Earth, evolves under the pressure of natural selection. The rise of life and ultimately humans is not the goal of that cosmic process—any more than humans are the goal of Darwinian evolution—but it is a predictable offshoot. As Smolin explains it, the key is star creation. Not a new idea, but he adds a twist: that the very same processes that lead to the existence of long-lived stars happen to support the almost infinitely lengthy trail of processes essential to make biology possible. That mutuality of results is, he says, “an important clue for fundamental physics.” So too is the abundance of carbon dioxide and oxygen in the universe—not because it has anything to do with life per se, but because it helps accelerate or increase the formation of massive stars that then give rise to much greater molecular complexity, which in turn makes life possible far down the road. “So the universe,” he argues, “evolves in ways hospitable to life as part of natural selection, the movement towards a more complex universe.” Fine-tuning, in this interpretation, is the process by which more powerful, more fit laws of physics triumph over others, and life follows in the wake. Smolin said that he has tried to apply his cosmic natural selection theory to a single-universe model, but so far “couldn't find an approach that didn't yield predictions that disagree with experiment.”

This is a very short version of a long scientific story that includes a universe where the laws of physics can be different in disparate regions, where the existence of other universes is mathematically essential, and where black holes may be the key to the formation of those other universes. The idea that black holes, where the laws of physics fall apart under the pressure of concentrated gravity, might play a central role in the formation of new universes cannot be proven and has many detractors. But Smolin argues that black holes are nurseries for Big Bangs, that the collapsing in of matter into black holes leads directly to the formation of new universes on the
other side. Each universe will have a different set of laws of physics that either can or cannot evolve into a structure that supports life.