Chapter 19: Life in the Universe

Buckminster Fuller, 1972-3 tour at UC Santa Barbara.

One of the most intriguing questions in astronomy is whether or not the Earth alone harbors intelligent life. Either extraterrestrial life exists or it does not. Both possibilities have striking consequences. As American architect and designer Buckminster Fuller (1895-1983) said, "Sometimes I think we're alone. Sometimes I think we're not. In either case, the thought is staggering." The universe is a large and bountiful place. There are an enormous number of potential sites for life, and the chemical constituents of life are distributed widely across space. At first sight, it appears unlikely that we should be alone. If intelligent life exists beyond the solar system, our world might well be influenced by it, for better or worse. At the very least, as anthropologist D.K. Stern has pointed out, the discovery of alien life "would irreversibly destroy our self-image as the pinnacle of creation." The alternative is equally profound. If we are the only intelligent creatures in the universe, it would imply a universe of incredible grandeur with us as the only, and quite temporary, spectators.

Enrico Fermi, Italian-American physicist, received the 1938 Nobel Prize in physics for identifying new elements and discovering nuclear reactions by his method of nuclear irradiation and bombardment

In the 1940s, the physicist Enrico Fermi took a back-of-the-envelope approach to this problem. He was heavily persuaded by the argument that the vast number of stars in the universe must imply that some of them must host planets with intelligent life. This line of reasoning led Fermi to ask the question "Where are they?" He estimated an advanced society could populate the entire Milky Way in just 5 to 50 million years. If there is intelligent life out there, why have we not been contacted? He considered how radio astronomers have listened for radio messages and heard none and how our skies are not filled with alien visitors observing us or trying to contact us. Looking around, all he saw was a lack of evidence for aliens in a galaxy that potentially could be as fully colonized as the land masses of our own planet Earth. Even looking at history, there is no concrete evidence of "ancient astronauts" or alien visitations in earlier Earth history.

An artist's concept of a possible Moon colony. Just a few kilometers from the Apollo 17 Taurus Littrow landing site, a lunar mining facility harvests oxygen from the resource-rich volcanic soil of the eastern Mare Serenitatis. Here a marketing executive describes the high iron, aluminum, magnesium, and titanium content in the processed tailings, which could be used as raw material for a lunar metals production plant. This image produced for NASA by Pat Rawlings, (SAIC). Technical concepts for NASA's Exploration Office, Johnson Space Center (JSC).

Fermi and others have postulated that an advanced race could colonize the Milky Way on a timescale that is short compared to the age of the galaxy. Such a civilization could feasibly even explore the galaxy without biological colonization by sending unmanned (unaliened?) spacecraft to other planetary systems. These probes could then use local materials to replicate themselves and they could rapidly propagate through the galaxy, carrying out technological colonization while sending information back at light speed to the originators. If this sounds far-fetched, remember that such a scenario requires only a modest extrapolation of our current technology; we are probably less than 100 years from robots that can construct other robots and propulsion systems that can accelerate a small payload to a tenth the speed of light in space. Already, the Japanese are looking to build a fully robotic base on the Moon.

These aren't answers that satisfy everyone. Polls in the

A poll on how many people believe that aliens exist.

An artist's conception of the NASA Spitzer Space Telescope.

Despite our fears, we do continue to look. The search for alien life is a new scientific adventure in the making. Astronomers continue to study the possibilities of life beyond the Earth as a direct way of questioning our role in the universe. Admittedly, discussions of the existence, intelligence, psychology, or appearance of higher alien life forms are almost highly speculative. But an interdisciplinary group of researchers has begun to take these issues very seriously. Astronomers have detected planets in orbit around nearby stars, and modern observatories like Spitzer can actually measure the chemical composition of some of these planets' atmospheres. While we haven't yet discovered any habitable worlds, they have also found complex, carbon-based molecules in interstellar space and in meteorites. This confirms that complex chemistry is active beyond our own solar system. Chemists have studied the pathways by which replicating molecules and simple life forms can be synthesized from simple constituents. Evolutionary biologists have considered how life might evolve in complexity starting with single-celled organisms. Physicists have even calculated the rates at which interstellar cultures might populate the galaxy. Together, all these scientists have worked to predict what atmospheric clues life might create. It just may be that intelligent life is found first by how it pollutes chemically rather than how it transmits radio signals!

Freeman Dyson at Harvard University in 2004

Optimists in the search for extraterrestrial intelligence have one additional, hopeful, answer for the bleak scenario that intelligent life is rare in the galaxy. Rather than use signals for communication from point to point, alien civilizations might use signals to store information in a vast, cosmic internet. If one civilization succeeded in sending probes across the galaxy, they could use these probes to set up a communication network across the galaxy. These artificial stations could beam information at planets, collect information from planets with intelligent life forms, and store the information in a growing database. Each newly intelligent civilization would not have to wait thousands of years of light travel time to communicate across the galaxy; they would only have to wait the much shorter time to tap into the nearest node of the network. The information in this cosmic internet would survive the death of any civilization and act as a kind of galactic consciousness.