Star Bound №26: The Truth is In Here
Reading Adam Frank’s The Little Book of Aliens
Adam Frank’s 2023 book The Little Book of Aliens (HarperCollins, 2023) is a congenial and surprisingly thorough introduction to the search for extraterrestrial life. Most thinking on this subject can be broken down into two spheres: (1) Does life exist elsewhere in the universe? And (2) Has that life — in whatever form — visited Earth? Sphere 2 inspires Hollywood hits, flights of fancy, and heated rhetoric about shadowy conspiracies. Sphere 1 is somewhat less entertaining — but it’s also the more promising field of inquiry.
Speculation about whether life exists somewhere out there has an old and distinguished pedigree. Frank, an astrophysics professor at the University of Rochester, traces the discussion back to antiquity. He contrasts the world views of Aristotle (an “alien pessimist”) on the one hand and Epicurus (an “alien optimist”) on the other, and identifies various theorists on the subject of extraterrestrial life over the centuries, including the unfortunate Giordano Bruno, who was burned at the stake in 1600 for various heresies against Catholic orthodoxy. Interest in the subject wasn’t limited to intellectuals. In 1835, for example, a “news” story published in New York’s The Sun about the discovery of life on the Moon set off a brief but lucrative craze for its creators. By the dawn of the 20th Century, though, most serious thinkers considered the possibility of life on other planets to be remote, at least in part because accepted wisdom had it that the existence of planets outside our solar system was rare.
Speculation about aliens — organic beings from elsewhere, as opposed to, say, angels — visiting Earth is of somewhat more recent vintage. The notion got a jump start in 1947, when private pilot Kenneth Arnold reported seeing objects flying at supersonic speed in the skies over Washington State. His claim was picked up by journalists, who managed to misinterpret what Arnold saw, translating his report of flying “C-shaped” structures into stories about “flying saucers.”
Suddenly everyone was seeing discs in the sky. There were hundreds of reports over the course of the next few days. Indeed, flying saucery became so prevalent that the U.S. Air Force set up Project SAUCER, later called Project SIGN, the first of several groups to study the issue of what were, for decades, referred to as unidentified flying objects, or UFOs. Over the course of the seventy-five plus years or so since Arnold’s eventful afternoon, the federal government has studied thousands of reports of mysterious airborne fliers. At least one endeavor in this regard, the Air Force’s long-lived Project Blue Book, was at times openly skeptical of, if not hostile, to UFO sightings.
More recently, NASA entered the discussion. In June of 2022, against the backdrop of Congressional hearings on a number of especially intriguing and puzzling sightings, NASA commissioned a blue-ribbon panel to investigate reports of what the agency now officially calls “unidentified anomalous phenomena.” This was a remarkable development, as NASA has not historically been interested in the subject of UFOs per se — though the agency did for a time in the nineties fund SETI research, and has had an interest in astrobiology for many years. The agency’s panel consisted of sixteen brainiacs including physicists, a journalist, an astrobiologist, and former astronaut Scott Kelly.
In September of 2023, the group reported that it had found no evidence of extraterrestrial visitors. Even so, the NASA panel, like other investigative teams before it, has had to admit that some sightings just can’t be explained — at least not yet, on the basis of the information available.
Official shoulder shrugs seldom bother UFOlogists, who see government denials as the acts of well-meaning dupes at best and at worst further evidence of a vast conspiracy involving important and people in the CIA, the Pentagon, and possibly the White House. “Whistleblower Tells Congress the U.S. is Concealing ‘Multi-Decade’ Program That Captures UFOs,” reads an Associated Press story headline from July of 2023. Frank is open-minded, but skeptical of UFO (or UAP) reports. He quotes the late great Carl Sagan to the effect that extraordinary claims require extraordinary evidence: anecdotes, fuzzy photos, and ambiguous video — however bewildering — just don’t prove anything.
The Little Book of Aliens spends more time on the increasingly mainstream science of exobiology — the study (speculation about, is the better term) of extraterrestrial life OUT THERE. Spoiler alert: We haven’t found any. But the mathematical argument for the possibility of life elsewhere is compelling. Perhaps the most famous expression of this argument is the Drake equation, formulated in 1961 by astronomer Frank Drake. Drake set out to express the odds involved in calculating the number of intelligent civilizations in our galaxy. “N” (for the number), he wrote, involves finding the rate of star formation in the galaxy, then multiplying this figure by a series of possibilities including the percentage of stars that have planets, the number of planets in such star systems that might be able to support life, the percentage of planets on which life actually evolves, the percentage of planets on which intelligent life evolves, and so on, with a total of six multipliers.
The Drake Equation can’t really be “solved,” as several of the variables are wholly speculative. No one knows how many planets harbor or have harbored intelligent life. But what is clear is that the first three variables in our equation, the rate of star formation, the number of stars with planets, and the number of habitable planets, have been reasonably estimated and, once plugged in, lead us to a very large number early on in the equation. Every exobiologist has a stack of digits he can pull out of his or her pocket in this regard. Speaking of the number of possibly life-bearing planets in the universe, Frank says, “Now we can say with confidence that there are roughly ten billion trillion planets in the right place for life to form.” Ten billion trillion is a lot of planets — more, in fact, than the human brain can hold without starting to split at the seams. Moreover, it doesn’t even include the number of moons, like Enceladus and Titan in our own solar system, that might also be habitable.
Given this terrific number of possible habitats, along with the presumed presence on at least some of them of liquid water, plentiful sunlight, and elements like carbon, hydrogen, and nitrogen, the chances that life evolved somewhere other than Earth over the past few billion years are pretty compelling. We think. Since we still don’t know exactly how life sprang, swirled, or was scorched into existence here on Earth, we are simply assuming that given the same set of building blocks, what happened here could happen elsewhere.
On the other hand, if the odds of extraterrestrial life are so great, why haven’t we seen evidence of it? This is the question physicist Enrico Fermi asked in 1950, and it, along with the Drake Equation, form the yin and the yang of the Great E.T. Debate. If the search for extraterrestrial life, or SETI, were a Harry Belafonte song, the Drake Equation would be the call, and Fermi’s question — his “Paradox” — would be the response.
Not content to wait for the answers to Fermi’s inquiry to show up here on Earth, astronomers are spending increasing amounts of time and brainpower in a quest to find life in cosmos. Initial efforts, such as Drake’s Project Ozma, in 1960, attempted to locate radio signals from outer space. Lots of time and effort since has gone into the same sort of search, from the now-defunct Arecibo Observatory in Puerto Rico to China’s FAST (“Five-Hundred Meter Aperture Spherical Telescope”) observatory in the nation’s Guizhou Province. So far, we’ve heard nothing unambiguously alien in origin, though the 72-second Wow! Signal catalogued in August of 1977 by astronomer Jerry Ehman created a remarkable electromagnetic record. Monitoring radio wave transmissions using an Ohio State University instrument, Ehman detected an unusually intense signal — so intense, in fact, that he jotted down the word “Wow!” in reaction to it. The signal seems to have originated from somewhere in the Sagittarius constellation. Unfortunately, it has never been recorded again.
Searching for alien radio transmissions remains one avenue in the search for extraterrestrial life, but there are now other means of inquiry as well. With the aid of powerful new space telescopes, scientists are using spectroscopy to look for biological evidence of alien life on distant planets. If certain wavelengths of light passing through the atmosphere of an exoplanet are “absorbed” by the atmosphere, researchers can conclude that certain chemicals are present in that atmosphere. And the presence on a planet of, say, oxygen or methane, both of which are produced in large quantities here on Earth by organic processes, has been proposed as a good marker, or “signature,” for life on that planet.
Another target for searchers with instruments like the James Webb Space Telescope is technological signatures — the presence of lights, for example, including the reflections from solar panels; the existence of large energy-collection structures, such as Dyson spheres; and the presence in an atmosphere of non-natural substances, like chlorofluorocarbons.
Again, we haven’t found anything. But as Frank points out, we haven’t been looking for very long, and we’ve only examined a tiny portion of the universe. The author cites a study done by SETI researchers at Penn State University, who tried to come up with a sense of how much of the universe has been searched for alien life. The result? If one considers our universe to be the size of all the seas on Earth, we’ve so far sampled only a tiny fraction of it — something like a single hot tub’s worth of water. (This isn’t a great analogy, really, since even a small sampling from most hot tubs would gather the bacterial equivalent of the customers in a Mos Eisley cantina. But you get the idea.) Franks is hopeful that one day our searches will bear fruit — or, um, amoebas, or something, because the chances that we’ll find intelligent life are way lower than that we’ll find blue planet plankton, or lunar lichens, or some other, simpler sort of beings, with limited ability to do us harm but also, unfortunately, far fewer streaming options.
There’s plenty more to learn from The Little Book of Aliens. Franks talks about how we humans might one day venture out of our solar system on a flesh-and-blood journey to meet our distant stellar cousins, whoever or whatever they may turn out to be. The methods — warp drive, “generation ships,” solar sails — are pretty speculative at the moment, but that may change. After all, any sort of space travel was strictly speculative only a century ago. What is clear is that first contact with extraterrestrial life, whenever or however that occurs, is going to be a major, world-shifting event. The Little Book of Aliens is your beginner’s guide. The truth, as they say, is in here.
