Posts Tagged ‘Life’
“I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.”*…
The Fermi paradox, named for physicist Enrico Fermi, is the apparent contradiction between the lack of evidence for extraterrestrial civilizations and various high estimates for their probability (e.g., some of the optimistic estimates for the Drake equation). Fermi wondered, “where are they?”
By way of context, Tim Urban in his wonderful Wait But Why?:
As many stars as there are in our galaxy (100 – 400 billion), there are roughly an equal number of galaxies in the observable universe—so for every star in the colossal Milky Way, there’s a whole galaxy out there. All together, that comes out to the typically quoted range of between 1022 and 1024 total stars, which means that for every grain of sand on every beach on Earth, there are 10,000 stars out there.
The science world isn’t in total agreement about what percentage of those stars are “sun-like” (similar in size, temperature, and luminosity)—opinions typically range from 5% to 20%. Going with the most conservative side of that (5%), and the lower end for the number of total stars (1022), gives us 500 quintillion, or 500 billion billion sun-like stars.
There’s also a debate over what percentage of those sun-like stars might be orbited by an Earth-like planet (one with similar temperature conditions that could have liquid water and potentially support life similar to that on Earth). Some say it’s as high as 50%, but let’s go with the more conservative 22% that came out of a recent PNAS study. That suggests that there’s a potentially-habitable Earth-like planet orbiting at least 1% of the total stars in the universe—a total of 100 billion billion Earth-like planets.
So there are 100 Earth-like planets for every grain of sand in the world. Think about that next time you’re on the beach.
Moving forward, we have no choice but to get completely speculative. Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life (if that’s true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth. That would mean there were 10 quadrillion, or 10 million billion intelligent civilizations in the observable universe.
Moving back to just our galaxy, and doing the same math on the lowest estimate for stars in the Milky Way (100 billion), we’d estimate that there are 1 billion Earth-like planets and 100,000 intelligent civilizations in our galaxy.1
SETI (Search for Extraterrestrial Intelligence) is an organization dedicated to listening for signals from other intelligent life. If we’re right that there are 100,000 or more intelligent civilizations in our galaxy, and even a fraction of them are sending out radio waves or laser beams or other modes of attempting to contact others, shouldn’t SETI’s satellite dish array pick up all kinds of signals?
But it hasn’t. Not one. Ever…
Perhaps. as we’ve mused here at (R)D before, life is there, but we’re not seeing it because it isn’t a form of life that we recognize: c.f., “Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying” and “That is a very Earthling question to ask, Mr. Pilgrim.”
But there are some who’ve refused to give up on the search for more traditionally-defined life; indeed, a new study quantifies the “fraction” (to which Urban alludes, above) of civilizations that could (should?) be communicating around our galaxy:
One of the biggest and longest-standing questions in the history of human thought is whether there are other intelligent life forms within our Universe. Obtaining good estimates of the number of possible extraterrestrial civilizations has however been very challenging.
A new study led by the University of Nottingham and published [earlier this month] in The Astrophysical Journal has taken a new approach to this problem. Using the assumption that intelligent life forms on other planets in a similar way as it does on Earth, researchers have obtained an estimate for the number of intelligent communicating civilizations within our own galaxy -the Milky Way. They calculate that there could be over 30 active communicating intelligent civilizations in our home Galaxy…
Details at (the slightly misleadingly-titled): “Research sheds new light on intelligent life existing across the galaxy.”
* Arthur C. Clarke
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As we stay tuned, we might send far-seeing birthday greeting to Fred Hoyle; he was born on this date in 1915. A prominent astronomer, he formulated the theory of stellar nucleosynthesis. But he is rather better remembered for his controversial stances on other scientific matters—in particular his rejection of the “Big Bang” theory (a term he coined, derisively, in one of his immensely-popular series The Nature of the Universe on BBC radio) and his promotion of panspermia as the source of life on Earth.
“That is a very Earthling question to ask, Mr. Pilgrim”*…
What does it mean to be alive? Science, shockingly, still doesn’t have a consensus. For example, is it fair to say that the novel coronavirus now sweeping the world is alive? The short answer is there isn’t one agreed-upon answer — for something so basic, you’d think life would be easier to define.
The first recorded definition of life came from Aristotle in ancient Greece, around 350 BC. He posited that to be alive, something must grow, maintain itself, and reproduce. In contrast, the most well-known modern definition is probably NASA’s, which says living things must be “a self-sustaining chemical system capable of Darwinian evolution.” Take, for example, great apes: given appropriate resources like food and water, the “machinery” of a great ape — its organs and nervous system — regulates itself, keeping the great ape functioning in most conditions. They are also capable of evolution — just look at us. But this isn’t the only accepted definition of life. There are actually over 100 published definitions!
A lot of the debate comes down to the fact that the various fields of science approach the topic quite differently. A geneticist, whose focus is on known organisms and their genomes, will very likely have a different view on what constitutes life than an astrophysicist, who considers a more expansive, universal definition.
But beyond that, most of these definitions of life fall short in another, very subtle way: They are based on the origins of life on our planet. This means our hypotheses for what sentient and conscious aliens look like almost always reflect humankind. You only have to look at a Star Trek episode to see it — humanity likes to make the world in our image, which is partially why in sci-fi and fantasy a lot of the “aliens” look a lot like ourselves. (Okay, and because it’s easier to dress a human up as a humanoid alien)…
Cal Tech scientist (and published poet) Alison Koontz explains why none of the 100 definitions of life we have may be accurate away from “home”: “Our concept of life is too Earth-centric — alien life might look totally different.”
* Slaughterhouse-Five
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As we confront our chauvinism, we might send speculative birthday greetings to Harlan Jay Ellison; he was born on this date in 1934. A member (with Philip K. Dick, Samuel Delany, Thomas Disch, Ursula K. LeGuin, and Roger Zelazny) of the American “new wave” science fiction vanguard, Ellison wrote more than 1,700 short stories, novellas, screenplays, comic book scripts, teleplays, essays, and a wide range of criticism covering literature, film, television, and print media. Some of his best-known work includes the Star Trek episode “The City on the Edge of Forever“, his A Boy and His Dog cycle, and his short stories “I Have No Mouth, and I Must Scream” and “‘Repent, Harlequin!’ Said the Ticktockman“… for which he won many, many awards, including multiple Hugos, Nebulas, and Edgars.
Ellison is also remembered for his outspoken, sometimes combative personality, of which Robert Bloch (the author of Psycho) said “[Ellison is] the only living organism I know whose natural habitat is hot water.”
“It is a good day to study lichens”*…
Wolf lichen
Science is sometimes caricatured as a wholly objective pursuit that allows us to understand the world through the lens of neutral empiricism. But the conclusions that scientists draw from their data, and the very questions they choose to ask, depend on their assumptions about the world, the culture in which they work, and the vocabulary they use. The scientist Toby Spribille once said to me, “We can only ask questions that we have imagination for.” And he should know, because no group of organisms better exemplifies this principle than the one Spribille is obsessed with: lichens.
Lichens can be found growing on bark, rocks, or walls; in woodlands, deserts, or tundra; as coralline branches, tiny cups, or leaflike fronds. They look like plants or fungi, and for the longest time, biologists thought that they were. But 150 years ago, a Swiss botanist named Simon Schwendener suggested the radical hypothesis that lichens are composite organisms—fungi, living together with microscopic algae.
It was the right hypothesis at the wrong time. The very notion of different organisms living so closely with—or within—each other was unheard of. That they should coexist to their mutual benefit was more ludicrous still. This was a mere decade after Charles Darwin had published his masterpiece, On the Origin of Species, and many biologists were gripped by the idea of nature as a gladiatorial arena, shaped by conflict. Against this zeitgeist, the concept of cohabiting, cooperative organisms found little purchase. Lichenologists spent decades rejecting and ridiculing Schwendener’s “dual hypothesis.” And he himself wrongly argued that the fungus enslaved or imprisoned the alga, robbing it of nutrients. As others later showed, that’s not the case: Both partners provide nutrients to each other…
Gorgeous and weird, lichens have pushed the boundaries of our understanding of nature– and our way of studying it. Learn more at: “The Overlooked Organisms That Keep Challenging Our Assumptions About Life.”
A Year in Thoreau’s Journal: 1851
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As we contemplate cooperation, we might spare a thought for John James Audubon; he died on this date in 1851. An ornithologist, naturalist, and artist, Audubon documented all types of American birds with detailed illustrations depicting the birds in their natural habitats. His The Birds of America (1827–1839), in which he identified 25 new species, is considered one of the most important– and finest– ornithological works ever completed.
Book plate featuring Audubon’s print of the Greater Prairie Chicken
“It would be a very naive sort of dogmatism to assume that there exists an absolute reality of things which is the same for all living beings”*…
Detail of the nerves of the trunk from Cerebri Anatome 1664 by Thomas Willis
The model of nature as a complex, clockwork mechanism has been central to modern science ever since the 17th century. It continues to appear regularly throughout the sciences, from quantum mechanics to evolutionary biology. But for Descartes and his contemporaries, ‘mechanism’ did not signify the sort of inert, regular, predictable functioning that the word connotes today. Instead, it often suggested the very opposite: responsiveness, engagement, caprice. Yet over the course of the 17th century, the idea of machinery narrowed into something passive, without agency or force of its own life. The earlier notion of active, responsive mechanism largely gave way to a new, brute mechanism…
The idea that nature is a humming, complex, clockwork machine has been around for centuries. Is it due for a revival? “Alive and Ticking.”
An Essay on Man: An Introduction to a Philosophy of Human Culture
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As we muse on the mechanical, we might send insightful birthday greetings to Loren Eiseley; he was born on this date in 1907. An anthropologist, educator, philosopher, and natural science writer, he was one of the preeminent literary naturalists of our time. Publishers Weekly called him “the modern Thoreau.” Fellow science writer Orville Prescott praised him as a scientist who “can write with poetic sensibility and with a fine sense of wonder and of reverence before the mysteries of life and nature.” And Ray Bradbury, praising Eiseley’s “The Unexpected Universe,” remarked, “[Eiseley] is every writer’s writer, and every human’s human… One of us, yet most uncommon…”
You can find his annotated bibliography here.
“Humans as we know them are just one morphological waypoint on the long road of evolution”*…
Imagine a world where the human race is no longer the dominant species.
Extinct through war or spectacular accident. By devastating pandemic, super-natural disaster, or cosmic cataclysm.
Passed through the Singularity to become unrecognisably posthuman, and left the natural order forever behind.
Infected by a virus, hijacked by a parasite or otherwise co-opted to become ex-human – a “bio zombie” – moved sideways to a new position as ecological actor.
Gently absorbed into – or completely overshadowed by the unfathomable actions of – a superior civilisation comprising benevolent – or unacknowledging – emissaries from the stars (or extra-dimensions).
Dethroned by the return of ancient species, the reawakening of the slumbering Old Ones… Out-competed by the arrival of an invasive species from another world making the Earth just one habitat in a galactic ecology.
It could be far into the future or The Day After Tomorrow.
Robots may rule the world… not so much enslaving as letting us retire to a life of Fully Automated Luxury Gay Space Communism; life in The Culture as Iain M. Banks foresaw it could be.
What is the world like then? After us…
Imagine a world where the human race is no longer the dominant species: “What is the Post-Human World.”
* Annalee Newitz in “When Will Humanity Finally Die Out?”
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As we stretch our frames, we might spare a thought for Marvin Minsky; he died on this date in 2016. A biochemist and cognitive scientist by training, he was founding director of MIT’s Artificial Intelligence Project (the MIT AI Lab). Minsky authored several widely-used texts, and made many contributions to AI, cognitive psychology, mathematics, computational linguistics, robotics, and optics. He holds several patents, including those for the first neural-network simulator (SNARC, 1951), the first head-mounted graphical display, the first confocal scanning microscope, and the LOGO “turtle” device (with his friend and frequent collaborator Seymour Papert). His other inventions include mechanical hands and the “Muse” synthesizer.
