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An arXiv preprint suggests that evidence of intelligent (or trashy) life could be found by looking for space junk:
Its author, Héctor Socas-Navarro, spends most of his time at the Canary Islands Institute of Astrophysics in Spain studying the sun. But he was struck by a weird side effect of the ring of active and retired satellites circling Earth: it's a little bit opaque. And the more satellites we throw up there, the more opaque it gets. He realized that if we—or any technologically advanced aliens out there—build enough satellites, they'll eventually become dense enough to leave a faint shadow around the planet when it passes in front of a star.
And that's awfully convenient given that one of the best ways we have of spotting alien planets is by staring at their stars and waiting for tiny dips in brightness as planets pass in front of them. Essentially, Socas-Navarro's new paper proposes, if aliens have put enough satellites into orbit around their planet, we'll be able to spot the faintly opaque bubble before and after we spot the brightness dip of the planet itself.
The scale of the endeavor would be a real challenge for the aliens, however, since this idea relies on between 10 billion and one trillion satellites. "It's like building the pyramids," Avi Loeb, an astronomer at Harvard University, told New Scientist. "Each building block is easy, but putting it together is the hard engineering task."
(Score: 2) by HiThere on Friday March 09 2018, @05:58PM (1 child)
The concentration of metals in ores is something that takes a long time. The dinosaurs isn't far enough back. Now if the trilobites had a technological civilization, I don't think we'd detect it unless they left traces on the moon, and we have explored enough there to rule that out...but the plausibility is quite low. The dinosaurs were (nearly?) evolved enough, but there were too many big ones for it to be plausible. (Just consider trying to fence out an apatosaurus.)
So I'm rather certain that we're the first technological civilization on Earth.
I guess I should have read the article, since people are talking about fragments and derelict civilizations, etc., but my first thought was that a topopolis should be rather detectable. The problem, though, is that it wouldn't be planet centric, but solar centric. Still, the inner rings would need to be as close as feasible to derive maximal energy/area from solar power, and that would mean it would need to be highly reflective to maintain a livable temperature inside. This should result in a sustained radiation spike in certain frequencies that would otherwise be hard to explain. There should also be certain effects in the heat spectrum...I don't want to say infra-red, because that's making assumptions about the habitable temperature of that lifeform. Still, it would obviously be easier to detect creatures that preferred a high temperature over those that preferred a lower temperature, unless the inner rings were automated.
I really doubt that a civilization that had been long in space would remain planet centric, so I have my doubts about their entire scenario. Still...if they *did* find one that way...well, I'd need to revise my thinking.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by HiThere on Friday March 09 2018, @06:08PM
1) We haven't explored the moon enough. I don't know how I left out that "n't".
2) Reading the article I see that they're proposing certain particular orbits, and only a very slight advance over our space capabilities. I find it hard to believe that this would be detectable, but they say they've calculated it, and certainly polished metallic objects are a lot more reflective than asteroids. I do think they're assuming that the targets would stay at approximately our level of space advancement for an extended period of time, however, and I find that implausible. We're going to either rise or fall, and soon. If we fall, we probably won't be able to get back up. If we rise, then I think the topopolis is more probable than dense clusters around the planets. (More probably, it will be something nobody's thought of.)
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.