Tag Archives: astrobiology

Taking in the garbage

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Reading Interstellar by Avi Loeb for New Scientist, 30 August 2023

On 8 January 2014, a meteor exploded above the Pacific just north of Papua New Guinea’s Manus Island.

Five years later Amir Siraj, then a research assistant for Harvard astronomer Avi Loeb, spotted it in an online catalogue at the Center for Near-Earth Object Studies, part of NASA’s Jet Propulsion Laboratory.

Partway through Interstellar, Loeb explains why he thinks the meteor comes from outside the solar system. This would make it one of only three objects so identified. The first was ‘Oumuamua, detected in 2017: a football-field size pancake-shaped anomaly and the subject of Loeb’s book Interplanetary, to which Interstellar is a repetitive, frenetic, grandiose extension.

Since Interstellar was sent to press, Loeb’s team have gathered particles from the crash site and packed them off to to labs at Harvard University, the University of California, Berkeley, and the Bruker Corporation in Germany for further analysis. Metallic spherules from outside our solar system would be a considerable find in itself.

Meanwhile Loeb is publically airing a hypothesis which, thanks to an opinion piece on 10 February 2023, is already familiar to readers of New Scientist. He reckons this meteor might turn out to have been manufactured by extraterrestrials.

Already there has been some bad-tempered push-back, but Loeb does not care. He’s innoculated against other people’s opinions, he says in Interstellar, not least because “my first mentor in astrophysics… had a professional rival, and when my mentor died it was his rival that was asked to write his obituary in a prestigious journal.”

Loeb, who has spent a career writing about black holes, dark matter and the deep time of the universe, does not waste time arguing for the existence of spacefaring extraterrestrials. Rather, he argues that we should be looking for spacefaring extraterrestrials, or at any rate for their gear. Among the possible scenarios for First Contact, “a human-alien handshake in front of the White House” is the least likely. It’s far more likely we’ll run into some garbage or a probe of some sort, and only then, says Loeb, because we’ve taken the trouble to seek it out.

Until very recently, no astronomical instrument was built for such a purpose. But this is changing, says Loeb, who cites NASA’s Unidentified Aerial Phenomena study, launched in December 2022, and the Legacy Survey of Space and Time — a 10-year-long high-resolution record of the entire southern sky, to be conducted on the brand-new Vera C. Rubin Observatory in Chile. Then there’s Loeb’s own brainchild, The Galileo Project, meant to bring the search for extraterrestrial technological signatures “from accidental or anecdotal observations and legends to the mainstream of transparent, validated and systematic scientific research.” The roof of the Harvard College Observatory boasts the project’s first sky-scanning apparatus.

There’s more than a whiff of Quixote about this project, but Loeb’s well within his rights to say that unless we go looking for extraterrestrials, we’re never going to find them. Loeb’s dating metaphor felt painfully hokey at first, but it grew on me: are we to be cosmic wallflowers, standing around on the off-chance that some stranger comes along? Or are we going to go looking for things we’ll never spot without a bit of effort?

Readers of grand speculations by the likes of Freeman Dyson and Stanislaw Lem will find nothing in Interstellar to make them blink, aside maybe from a rather cantankerous prose style. Can we be reassured by Loeb’s promise that he and his team work only with scientific data openly available for peer review, that they share their findings freely and only through traditional scientific channels, and will release no results except through scientifically accepted channels of publication?

I’m inclined to say yes, we should. Arguments from incredulity are always a bad idea, and sneering is never a good look.

Normal fish and stubby dinosaurs

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Reading Imagined Life by James Trefil and Michael Summers for New Scientist, 20 September 2019

If you can imagine a world that is consistent with the laws of physics,” say physicist James Trefil and planetary scientist Michael Summers, “then there’s a good chance that it exists somewhere in our galaxy.”

The universe is dark, empty, and expanding, true. But the few parts of it that are populated by matter at all, are full of planets. Embarrassingly so: interstellar space itself is littered with hard-to-spot rogue worlds, ejected early on in their solar system’s history, and these worlds may outnumber orbiting planets by a factor of two to one. (Not everyone agrees: some experts reckon rogues may out-number orbital worlds 1000 to one. One of the reasons the little green men have yet to sail up to the White House, is that they keep hitting space shoals.)

Can we conclude, then, that this cluttered galaxy is full of life? The surprising (and frustrating) truth is that we genuinely have no idea. And while Trefil and Summers are obviously primed to receive with open arms any visitors who happen by, they do a splendid job, in this, their second slim volume together of explaining just how tentative and speculative our thoughts about exobiology actually are, and why.

Exoplanets came out in 2013; Imagined Life is a sort of sequel and is, if possible, even more accessible. In just 14 pages, the authors outline the physical laws constraining the universe. Then they rattle through the various ways we can define life, and why spotting life on distant worlds is so difficult (“For just about every molecule that we could identify [through spectroscopy] as a potential biomarker of life on an exoplanet, there is a nonbiological production mechanism.”). They list the most likely types of environment on which life may have evolved, from water worlds to Mega Earths (expect “normal fish… and stubby dinosaurs”), from tidally locked planets to wildly exotic (but by no means unlikely) superconducting rogues. And we haven’t even reached the meat of this tiny book yet – a tour, planet by imaginary planet, of the possibilities for life, intelligence, and civilisation in our and other galaxies.

Most strange worlds are far too strange for life, and the more one learns about chemistry, the more sober one’s speculations become. Water is common in the universe, and carbon not hard to find, and this is as well, given the relative uselessness of their nearest equivalents (benzene and silicon, say). The authors argue enthusiastically for the possibilities of life that’s “really not like us”, but they have a hard time making it stick. Carbon-based life is pretty various, of course, but even here there may be unexepected limits on what’s possible. Given that, out of 140 amino acids, only 22 have been recruited in nature, it may be that mechanisms of inheritance converge on a surprisingly narrow set of possibilities.

The trick to finding life in odd places, we discover, is to look not out, but in, and through. “Scientists are beginning to abandon the idea that life has to evolve and persist on the surface of planets” the authors write, laying the groundwork for their description of an aquatic alien civilisation for whom a mission to the ocean surface “would be no stranger to them than a mission to Mars is to us.”

I’m not sure I buy the authors’ stock assumption that life most likely breeds intelligence most likely breeds technology. Nothing in biology , or human history, suggests as much. Humans in their current iteration may be far odder than we imagine. But what the hell: Imagined Life reminds me of those books I grew up with, full of artists’ impressions of the teeming oceans of Venus. Only now, the science is better; the writing is better; and the possibiliities, being more focused, are altogether more intoxicating.