Here about the beach I wander'd, nourishing a youth sublime With the fairy tales of science, and the long result of Time… ---Tennyson Temporal coincidence plays havoc with our ideas about other civilizations in the cosmos. If we want to detect them, their society must at least have developed to the point that it can manipulate electromagnetic waves. But its technology has to be of sufficient strength to be noticed. The kind of signals people were listening to 100 years ago on crystal sets wouldn’t remotely fit the bill, and neither would our primitive TV signals of the 1950s. So we’re looking for strong signals and cultures older than our own. Now consider how short a time we’re talking about. We have been using radio for a bit over a century, which is on the order of one part in 100,000,000 of the lifespan of our star. You may recall the work of Brian Lacki, which I wrote about four years ago (see Alpha Centauri and the Search for Technosignatures). Lacki, now at Oxford, points out...

It's no surprise, human nature being what it is, that our early detections of possible life on other worlds through 'biosignatures' are immediately controversial. We have to separate signs of biology from processes that may operate completely outside of our conception of life, abiotic ways to produce the same results. My suspicion is that this situation will persist for decades, claim vs. counter-claim, with heated conference sessions and warring papers. But as Alex Tolley explains in today's essay, even a null result can be valuable. Alex takes us into the realm of Bayesian statistics, where prior beliefs are gradually adjusted as new data come in. We're still dealing with probabilities, but in a fascinating way, uncertainties are gradually being decreased though never eliminated. We're going to be hearing a lot more about these analytical tools as the hunt continues with next generation telescopes. by Alex Tolley Introduction The venerable Drake equation’s early parameters are...

Finding unusual things in the sky should no longer astound us. It’s pretty much par for the course these days in astronomy, what with new instrumentation like JWST and the soon to be arriving Extremely Large Telescope family coming online. Recently we’ve had planet-forming disks in the inner reaches of the galaxy and the discovery of a large molecular cloud (Eos by name) surprisingly close to our Sun at the edge of the Local Bubble, about 300 light years out. So I’m intrigued to learn now of Teleios, which appears to be a remnant of a supernova. The name, I’m told, is classical Greek for ‘perfection,’ an apt description for this evidently perfect bubble. An international team led by Miroslav Filipović of Western Sydney University in Australia is behind this work and has begun to analyze what could have produced the lovely object in a paper submitted to Publications of the Astronomical Society of Australia (citation below). Fortunately for us, Teleios glows at radio wavelengths in...

Communicating with extraterrestrials isn’t going to be easy, as we’ve learned in science fiction, all the way from John Campbell’s Who Goes There? To Ted Chiang’s Story of Your Life (and the movie Arrival). Indeed, just imagining the kinds of civilizations that might emerge from life utterly unlike what we have on Earth calls for a rare combination of insight and speculative drive. Michael Chorost has been thinking about the problem for over a decade now, and it’s good to see him back in these pages to follow up on a post he wrote in 2015. As I’ve always been interested in how science fiction writers do their worldbuilding, I’m delighted to publish his take on his own experience at the craft. Michael is also the author of the splendid World Wide Mind: The Coming Integration of Humanity, Machines, and the Internet (Free Press, 2011) and Rebuilt: My Journey Back to the Hearing World (Mariner, 2006). by Michael Chorost Ten years ago, Paul Gilster kindly invited me to guest-publish an...

The sublime, almost fearful nature of deep time sometimes awes me even more than the kind of distances we routinely discuss in these pages. Yes, the prospect of a 13.8 billion year old cosmos strung with stars and galaxies astonishes. But so too do the constant reminders of our place in the vast chronology of our planet. Simple rocks can bring me up short, as when I consider just how they were made, how long the process took, and what they imply about life. Consider the shifts that have occurred in continents, which we can deduce from careful study at sites with varying histories. Move into northern Quebec, for example, and you can uncover rock that was found on the continent we now call Laurentia, considered a relatively stable region of the continental crust (the term for such a region is craton). Move to the Ukraine and you can investigate the geology of the continent called Baltica. Gondwana can be studied in Brazil, an obvious reminder of how much the surface has changed. Image:...