Great Book: The Possibility of Life, by Jaime Green

“There are relatively few paths that will lead where you want to go, and the sooner you understand that, the sooner you can start putting yourself on those paths."

“But the question most often - too often - asked about extraterrestrial life is whether or not. The fact is, that’s a very boring question. Its answer would be revolutionary, and plenty of scientists are pursuing it, but sitting here posing it to a vast and empty sky doesn’t tell us anything. We should really be asking what if?”

“Through it all, our visions of alien worlds are reflections of ourselves, arising from our research, our dreams, and our subconscious like mist from a field at dawn. When we imagine a dozen ways for an alien to be, we’re imagining a dozen different kinds of people. When we invent alien languages, we learn more about the human brain. When we dream of a benevolent visitation, we’re telling a story of what we think we need.”

“We fear that, as we learn more about what’s beyond our solar system, silence and loneliness await us.”

“To consider the Earth as the only populated world in infinite space is as absurd as to assert that in an entire field sown with millet, only one grain will grow.”

“Our inventive abilities can really only extend so far beyond the real. Copernicus’s genius for shattering these confines only followed after a series of mathematical solutions created a new possibility. And so it is in storytelling, too.

People weren’t imagining aliens on other planets because other planets weren’t understood as such. But once other worlds were made available to imagination, those stories came in like a flood.”

“The sky had once been a closed dome but now was an infinite blackness. We once lived under God’s gaze; now, if he even still existed, his attention was spread across infinite worlds.”

“We haven’t found life yet on Mars (unless some really wild things have happened since I sent this book to the printer), but every conversation about that possibility hinges on the presence of water, either currently or in the Martian past.”

“Life is information and energy and awareness. It’s a squirreling away of entropy, so that one bit of ordered matter can look at another and try to know it. It’s momentum rolling, for a moment, uphill.

Life seems sometimes like it should be impossible, and yet here we are, and yet here our whole planet is.

Understanding life’s origin is a way to understand what it means to be alive, matter with memory, matter that brings new complexity into the world. And understanding how those origins - plural! - can happen helps us think about where else to look.”

“With a telescope, just like Galileo, I can even see Saturn’s rings. And the first time I did, on a college rooftop observatory, I felt that sudden shock: Holy shit, that’s a planet. Something I’d already known, now known in an entirely new way.”

“Scientists aim their telescopes and then infer and deduce. I’ve heard it described as trying to photograph a gnat flying around a floodlight - and both the gnat and the floodlight are at the opposite end of a football field from you. Only rarely and with great effort have exoplanets been directly imaged, little dots on photographs we can point to and say Aha.”

“Astronomer David Kipping told me, ‘Our moon obviously isn’t habitable, but it’s in the habitable zone. And if it were a bit bigger - if it were the size of Mars - it would probably be a habitable world in its own right.’

The moon has 1.2 percent the mass of Earth; get closer to 10 percent, he said, which is more like the proportional sizes of Pluto and its moon Charon, ‘then I think there’s a very good chance that Neil Armstrong would have been stepping out in a t-shirt and shorts. It’s wild to think how different human history would have been if we’d known there was a habitable world right above us.’”

“There’s a cosmic humility to be found in understanding that we’re just one of life’s infinitely diverse expressions. Even if we can’t imagine truly strange, truly different life, we push against the inherent xenophobia of our imaginations when we try, while what we know pulls us back like gravity.”

“Neuroscientist and cetacean advocate Lori Marino is a common presence at SETI conferences today, offering not just Earthly analogy but often a caution against hubris: we don’t even understand other intelligent species here.”

“But for his research to work, this drive doesn’t need to be universal among the stars. It just has to have happened sometimes, enough for us to see the results. As he put it, ‘There’s nothing that drives all life on Earth to be large. In fact, most life is small. But some life is large.’ And if an alien were to come to Earth, they wouldn’t need to see all the small life to know the planet was inhabited. A single elephant would do the trick.”

“While Earth has faced near extinctions, plagues, and genocides, it’s only in the last century that humanity has attained the power to fuck things up so extraordinarily.”

“Adam Frank and coauthor W.T. Sullivan III wrote a paper in 2015 calculating what they call ‘the pessimism line,’ a measure of just how rare technological civilizations would have to be for ours to be the first.

He found that in order for our civilization to be the first in the galaxy, the odds of a technological civilization evolving on a habitable planet would have to be less than 1 in 10²⁴, or one in one thousand billion trillion.

At that rate, Frank thinks it’s safe not only to imagine alien civilizations but to really believe that they have existed.”

“It was early spring, and I was surrounded by birdsong. The winter crows hadn’t left yet, but a few grackles and sparrows had settled in, and one swooped in front of me on its way from tree to tree. And I found myself marveling.

These alien creatures, able to eschew the ground for flight, alive to a cacophony of meaning in chirps and twitters that was entirely opaque to me. Their feathers and hollow bones and delicate, scaly legs.

They were amazing! And incomprehensible. And real, right there.”