Light of the Stars: Alien Worlds and the Fate of the Earth (2018)
Adam Frank (1962)
262 pages
When I was a boy living on a dirt road in farmland outside a medium-sized city in central Michigan, my sister and I and a few other children would be recruited each summer by my godmother, who we all called Aunt Betty, to walk with her along the nearby roads with trash bags to collect the many bottles and cans – and other accompanying pieces of garbage – littering the ditches. Then, in 1976, Michigan passed a bottle deposit law, and our clean-up walks immediately became a thing of the past, as the littering largely stopped.
Would that the understanding of, and solution to, all our environmental problems was so straight-forward.
Instead, we face an array of complex environmental challenges – most principally from global warming – arising out of an inability to evolve our civilization to the point of achieving a sustainable presence on Earth. That human activity impacts and, in fact, fundamentally alters the planet has become broadly accepted by scientists, leading some to embrace a new name for our current era, as described by astrophysicist Adam Frank, in his book Light of the Stars:
Ten thousand years ago, our project of civilization was born after the beginning of what geologists call the Holocene, a planetary epoch of warm, wet conditions following the end of the ice ages. But, in driving climate change, we’re now pushing the Earth out of the Holocene into a new era in which human impacts dominate the planet’s long-term behavior. The new era is called the Anthropocene. (12)
Because we have so far been unable to come to a common understanding about the extent of our impact on the biosphere, we have consequently failed to find the political and social will to address it. Frank claims that this “failure is rooted in the mistaken view that we, and our project [of civilization], are a one-time story” (12); to correct this he proposes, as described in the subtitle of his book, that we consider the connection between Alien Worlds and the Fate of The Earth. In engaging and accessible prose he summarizes the history of our scientific understanding of other planets, and the possibility of alien civilizations, as a means toward helping us better comprehend the existential threat our civilization now faces, and the possibilities for maintaining Earth’s habitability for our project of civilization.He pursues his goal by marshaling what has been learned about other worlds – from the planets in our own solar system to the planets now understood to be circling distant stars – in order to tie our understanding of the evolution of the biosphere on Earth to that of other planets, and of the implications of human impact on the biosphere to the challenges technologically advanced life on other planets, so-called exo-civilizations, might similarly face. Through such an understanding he believes, we can better grasp the deeply intertwined nature and fate of our civilization and Earth’s biosphere.
Frank begins with the story of perhaps the most well-known question about technologically advanced life beyond Earth: in 1950, during a conversation with colleagues about the possibility of such alien civilizations, Enrico Fermi suddenly asked: “But where are they?” Known as Fermi’s Paradox, his question arose from his consideration that, if exo-civilizations are common, then given the age of the universe relative to that of our own civilization, they would have had plenty of time to spread through the galaxy, and so we should see evidence of them.
Noting that the actual search for life beyond Earth has had a checkered history of wild claims, resulting in many scientists having had fairly dismissive attitudes to any of their colleagues taking such study seriously, Frank then introduces Frank Drake, an astrophysicist who in the 1950’s became one of the first scientists to methodically search for signs of alien civilizations. In 1961, having been asked to host a small conference on the topic – effectively, to address Fermi’s paradox – Drake sought a structure around which to organize the meetings, and ended up developing now the most famous equation related to the search for exo-civilizations.
With the goal of estimating the number of exo-civilizations in the galaxy that could currently be detectable, he wrote an equation with seven factors, each of which could be individually investigated by scientists. Specifically, he postulated that the number of detectable civilizations, N, could be estimated by the equation N=N* fp np fl fi fc L where N* is the rate of star formation in the galaxy per year; fp is the fraction of stars with planets; np is the number of planets in “the Goldilocks Zone” in which life is possible as we understand it; fl is the fraction of planets with life; fi is the fraction of planets with life that develop intelligent life; fc is the fraction of planets with intelligent life that develop a technological civilization (defined as capable of broadcasting radio signals); and, L is the average lifetime in years of a technological civilization.
Frank notes that when Drake proposed this equation as a guide for focusing the conference discussions, little, if any, concrete evidence existed for knowing what values to assign to any of its constituent terms. In the mid-twentieth century, even the formation process of stars was just being worked out, and the formation of planets was still thought to be a rare event, with the leading theory being that they occurred when two stars passed close to one another, something known to be extremely unlikely. Over the past half century, however, there has been a revolution in the understanding of several of these terms, and Drake’s equation becomes the foundation for Frank’s further analysis.
But before looking to alien worlds for keys to the fate of the earth, Frank first explores the question as to whether the planetary processes observed on Earth apply on other planets. After covering the rather wild history of expectations about our neighboring planets, he reviews what has been learned over the past several decades from numerous probes launched to planets throughout the solar system. Focusing in particular on the missions to Venus and Mars, he describes how scientists have determined from analysis of data sent back from probes that the physics of Earth’s climate processes generalize to other planets, and so are not unique to Earth. As a consequence, not only have models developed for Earth’s climate aided in the understanding of the climate evolution on our neighboring planets, but what has been learned from past and present conditions on these other planets has enabled scientists to improve models of Earth’s climate evolution, including into the future.
These learnings become a key element in Frank’s framework for understanding and addressing the dangers we face in the Anthropocene. Improved understanding of the evolution of Earth’s climate over the 4.5 billion years of our planet’s existence provides bracing cautions for our actions today. In particular, Frank notes, we now understand from this history that life can dramatically transform the planet – the Anthropocene will not be the first time. As with Copernicus moving Earth from the center of the universe, it’s now also understood that man is not the only form of life with the power to alter its climate.
Frank describes a previous such event from the distant past, pointing out that 2.7 billion years ago, “[the Earth’s] “air” was composed almost entirely of nitrogen and CO2.” (99) But then, some 2.5 billion years ago, “the concentration of atmospheric oxygen increased by a factor of a million” (116), completely transforming the biosphere, in what is referred to as the Great Oxidation Event (GOE). And, in a consequence that has ominous implications for our current climate crisis, Frank points out that
changing the planet may not work out well for the specific forms of life that caused the change. The oxygen-producing (but non-oxygen-breathing) bacteria were forced off the Earth’s surface by their own activity in the GOE. (118)
This past fundamental transformation of our planet has made clear that there is a coevolution of Earth’s biosphere and life. Combined with the understanding that the physics of the biosphere are universal, it has become clear that any “planet could be deeply transformed by the life it births, including when that life goes on to create its own globe-spanning civilization.” (130)
But before this understanding of the coevolution of a planet’s biosphere and life could be engaged to understand what planets outside our solar system can tell us about the possibility of exo-civilizations, it had first to be understood whether there are such planets. Frank summarizes the fascinating history of the search for planets around other stars, describing some of the more charismatic and sometimes eccentric personalities that have led the way over the past couple of hundred years. Success came only in the present century, however, as the obsessive dedication and work of a few key scientists laid the necessary groundwork for the Kepler Mission, a telescope sent into space in 2009 specifically to search for planets around other stars. With planets being discovered from already the first moments of the mission, within a few years the accepted value for the fraction of stars with planets went from “very low … [to] about 1” (150).
With astronomers having thus provided solid estimates to the first there terms in Drake’s equation – the rate of star formation in the galaxy (~1/year), the fraction of stars with planets (~1), and the number of habitable planets (~0.2) – attention shifted to the final terms, the domains of biology, sociology and anthropology: the fraction of planets with life; the fraction that develop intelligent life; the fraction that develop a technological civilization; and, the average lifetime such civilizations.
Given the challenges to determining estimates for these final terms, Frank and several of his colleagues considered a bounding question: could they define a value that estimates how many civilization have ever existed in the universe. To do so, they created a simplified version of Drake’s equation, which lumps together the original seven factors into two – one for the first three terms describing the likelihood of habitable planets, and a second for the likelihood of technological civilizations developing; for their purpose, L, the length of time a technological civilization lasts is not germane.
Using this equation, they calculated what they refer to as a “pessimism line,” which defined, given what is known now about the likelihood of habitable planets existing, “how bad the probability of a civilization forming would have to be in order for ours to be [the] only one that has ever existed.” (155) They determined this probability to be “one in ten billion trillion,” (155) which is to say that, if one identified in the universe ten billion trillion planets in the habitable region around stars, then only on Earth would there be civilization. Though Frank brings up skeptics of his team’s work, and addresses their positions, from his point of view one would indeed have to be fairly extremely pessimistic about the chances of life occurring and civilization developing to not be convinced that there has been somewhere, at some time, other civilizations in the universe than only on Earth.
Having established values for the existence of habitable planes, and developed a numerical framework demonstrating the likelihood that at least some exo-civilizations have existed, Frank turns to the final factor in the Drake equation, noting that it has garnered the most debate and discussion: the anthropological question of how long (radio capable) civilizations tend to last.
Hard-set on avoiding the rabbit hole of hand-waving arguments, Frank grounds his exploration of this question on the history of how the development of the predator-prey model in the early 20th century led to a shift in the work of biologists to the use of models to analyze and understand biological phenomena. Based on that approach, Frank and his team developed a model that allows them to evaluate how a planetary civilization might evolve once it reaches its Anthropocene moment, their base assumptions being that the development of technology requires energy and in fact leads to an inevitable increase in energy demand, and that any civilization exploiting that energy will at some point not only impact, but ultimately alter, their planet’s biosphere. (As Frank points out: “even [energy generation from] wind … has a planetary cost (though far lower than fossil fuels).” (191))
When he and his team ran their model under different scenarios – different reactions of a civilization upon reaching the Anthropocene – the results were not encouraging. Most scenarios lead to either a die-off, or a complete collapse of civilization. Frank makes the concept of civilizational collapse concrete by referencing the example of Easter Island made famous by Jared Diamond in his book Collapse, which demonstrated the devastating results when a “civilization overshot the carrying capacity of its environment.” (182)
The knowledge that life has the ability to completely transform the planet – as happened in the GOE some 2.5 billion years ago; the recognition that human civilization – entering the Anthropocene – has initiated a shift in the climate that may already have passed the point of being reversible; and the modeling that indicates dire outcomes if our civilization fails to take active steps to counter its impact on the planet’s biosphere. Taken together, Frank argues, the threat that these understandings make clear demands immediate action, at a civilization level, before it becomes too late.
To better clarify the situation we find ourselves in, Frank explores ways of classifying the level of impact of a planet’s biosphere from processes that transform energy. He first recalls a scale developed by the Soviet astronomer Nikolai Karadashev in 1964 to describe a civilization’s level of technological development, based on how much energy it harvests for use: Type 1, all on the planet; Type 2, all in its stellar system; and, Type 3, all in its home galaxy. He points out, however, that this scale fails to recognize the impact of a civilization on its planet, a connection fundamental to a civilization’s ability to survive long-term.
To address this, Frank and his colleagues propose a new scale based on the level of energy transformation on a planet: Class 1, no atmosphere, so none; Class 2, atmosphere present, but no life present to alter it; Class 3, “life has gotten started [and] it’s affecting the rest of [the planet’s] coupled systems, but does not yet dominate these systems.” (218); Class 4, a planet that has “been hijacked by life” (218), which creates a coupled system with the planet; and, Class 5, have “agency-dominated biospheres [with] the civilization … deliberately working with the rest of the natural systems to increase the flourishing and productivity of both itself and the biosphere as a whole.” (219) Frank argues that human civilization, having entered the Anthropocene, has moved beyond Class 4, but “is not yet, and may never be, a Class 5 planet,” (220) – depending on what we do next.
In Light of the Stars, Frank looks to move the discussion around the existential threat of climate change beyond the simplistic calls to save the planet – “the Earth will happily move on without us” (223), or particular solutions. Instead, by exploiting the knowledge that’s been gained over particularly the past 70 years or so through the dedicated work of astronomers, biologists and others, he wants us to understand that the challenges we face are fundamental to any other civilizations that may have arisen or may yet arise in the universe as we understand it.
Engaging these challenges requires that our human civilization not simply consider itself to be using the planet. Instead, Frank argues, in order to develop a sustainable civilization humanity must acknowledge its transformational impact on the planet’s biosphere, and develop processes of energy use with an understanding of the coupled nature of civilization’s systems and the planet’s processes. We must recognize that our civilization must co-evolve with the planet, understanding how our actions impact the planet and, crucially, whether our transformed planet will be able to support us. Failure to do so, he argues, condemns us to a possibly irrecoverable collapse.
At a time when humanity seems to be splitting apart at the seams, with populations in many advanced nations bifurcating into seemingly hopelessly divided factions, it seems a tall order that Frank asks of us. But by a least understanding the full scope of what is required, and the universal nature of the challenges we face, we can perhaps take the necessary steps to summoning the will to ensure the continuation of our “project of civilization.
Other reviews / information:
A nice video graphic from NASA/SYSTEM sounds of the exoplanets that have been discovered highlights the accelerated pace of discovery after 2010.
Have you read this book, others by this author, or even similar ones by other authors? I’d enjoy hearing your thoughts.
Other of my book reviews: FICTION Bookshelf and NON-FICTION Bookshelf
