In the fall of 2017, something extraordinary happened. An object entered our solar system, headed toward the Sun, then rounded the Sun and headed back out of the solar system. The path it took, its apparent luminosity, and the speed at which it traveled, make it unlikely to be a random piece of space junk. Indeed, a reasonable hypothesis, perhaps the most reasonable hypothesis, is that the item was evidence of extraterrestrial life.
So writes Avi Loeb in a riveting new book, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth. Read the subtitle again, and let it sink in: “Intelligent life beyond Earth.”
What can that possibly mean?
Loeb is not your cranky Uncle Bob spinning yarns over dessert at Thanksgiving. He’s a professor of astronomy at Harvard University, where he chaired the department from 2011 to 2020, and he is current director of the Black Hole Initiative and the Institute for Theory and Computation at Harvard. He’s a fellow of the American Academy of Arts and Sciences, the American Physical Society, and the International Academy of Astronautics. He advises investors on space exploration.
And – and this is important – he writes well.
Here’s what he has to say.
An object, scientists named it oumuamua (pronounced “oh-moo-ah-moo-ah”), a Hawaiian term meaning, more or less, “scout,” in honor of its discovery by Robert Weryk at a Hawaiian observatory, was spotted in the night sky on October 19, 2017. It moved too quickly to be bounded by the Sun’s gravity. It rounded the Sun, then sped out of our solar system. Scientists quicky concluded it was an object entering our solar system from beyond the system itself. As it rounded the Sun, its path was not the expected course; it seemed to accelerate, but not in the manner expected as a result of traveling around the Sun. It left no tell-tale sign of its mechanism of acceleration.
Oumuamua was gone before we even realized it was here, detected as a stream of light by telescopes capturing events after they have occurred. Indeed, the most difficult part of this fine little book – it is but 200 pages – is reconstruction of the circumstantial evidence about oumuamua’s size, shape and method of propulsion. As best as Loeb can tell, it was likely an enormous light-sail, a thin membrane propelled to move at near the speed of light by radiation, enjoying a boost in speed from the Sun’s radiation. (Another hypothesis is that it was giant, tumbling cigar-shaped projectile.) It may well have been debris from advanced technological equipment originating from a source other than Earth.
Advancing this hypothesis has earned Loeb the scorn and skepticism of many of his colleagues. Considering the possibility of intelligent life from a source outside our solar system is too much for some folk.
But why?
Poetic metaphors do not do justice to the vastness of space or the reach of time. We aren’t just an improbable speck in an infinite sea; we are the briefest flicker in a darkness so immense as to be inconceivable. Indeed, I suspect, Loeb would counsel against the too ready resort to metaphor to cast us in our cosmological place. We possess life; the conditions that make that possible almost certainly exist elsewhere in space and time. It is hubris to believe otherwise.
Something like vertiginous dizziness overcame me at various points as a I read this breathtaking book. I kept thinking of Michaelangelo’s painting on the ceiling of the Cistine Chapel in Rome, of God’s reaching out to transmit the spark of life. As between creation ex nihilo and the chance appearance of life, I am not sure which I find more miraculous, or more improbable. Perhaps there is no need to choose between religion and science. That there is a world at all is a fact so astounding, so breath-taking as to reduce an observer to speechless awe.
Loeb writes about wonder, humility and being open to drawing the best and most reasonable inferences from the evidence we can detect. A good part of this book chastises the scientific establishment for becoming too comfortable with its hard-earned orthodoxy. Loeb would have us all remember that we are pilgrims in a place we did not create. “Science at its core demands humility,” he writes, “an understanding that humanity’s imagination is incapable of mapping out the full richness and diversity of nature. But the proper response to humility is wonder and, with it, a desire to open ourselves to a greater range of possibilities.”
Amen, a thousand times, amen.
Loeb urges us to accept Oumuamua’s Wager, the scientific version of Pascal’s Wager. Pascal urged a leap of faith because the risk of error was eternal damnation. Oumuamua’s wager is simply being open to the possibility of life beyond our own. This yields a sense of wonder and humility sufficient to meet the challenges required for our species to survive. Of course, that requires what appears to be the impossible: a unity of purpose and collective effort on behalf of the nearly 8 billion people currently alive.
Why is there a world rather than not? That is one of the greatest questions of all. Religious doctrine yields answers. Perhaps science can as well. It appears there is more to the heavens than we can easily imagine. Loeb persuaded me to keep an open mind, to cultivate wonder, to become child-like in by apprehension of the evidence before me.
What a wonderful book this is. What a wonderful universe. Loeb helped me peak beyond the blinders I so gladly don. This simple book should inspire greater desire to know more about this home of ours, a place so tiny, yet so brimming with significance.
I want to know more.