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These methods focus on finding extraterrestrials with an equivalent or greater technological advancement to our own. How would you find an alien civilization wi

by kylec 9y ago

These methods focus on finding extraterrestrials with an equivalent or greater technological advancement to our own. How would you find an alien civilization with a 17th-century Earth level of technological development? We were not emitting radio signals or using light pulses to communicate, nor were we flying around in antimatter-powered rockets.

jaclaz 9y ago
>These methods focus on finding extraterrestrials with an equivalent or greater technological advancement to our own. ... AND actually willing to communicate with us, which is not IMHO to be assumed as given. We need to find a rather "narrow" set of aliens with a technology similar enough to ours, and animated by a similar curiosity about the rest of the universe.
api 9y ago
We could perhaps detect distant alien life by finding signatures of oxygen or another oxidizer in a planet's atmosphere. These would be highly unlikely to persist long without something alive to keep the thermodynamic gradient up. O2, F2, etc. are extremely reactive.
nkoren 9y ago
In the main, I think we'd simply have no chance of detecting such civilisations. In the next couple of decades, however, advanced space telescopes with starshade coronagraphs could be able to start doing spectroscopy on exoplanet atmospheres.[1] This would definitely reveal (some kinds of) biologically-active atmospheres, although it wouldn't necessarily to be able to tell the difference between a complex biosphere with a low-tech civilisation, and a uni-cellular algae soup. I suppose there's an outside chance that such a telescope could detect combustion compounds that are difficult to explain geologically or biologically, and that might be used to hypothesise a civilisation. Something like lead smelting might leave a pretty distinct signature, for example. But that would just lead to a hypothesis, not proof, and I imagine it'd be pretty contentious. Longer-term, it should be possible to create arbitrarily large space-based optical interferometers[2], to the point where one would be capable of imaging cities and agricultural activity on exoplanets. That'd settle matters (Unless it's under water or impenetrable cloud decks, and then you're just out of luck). But that level of resolution is probably a couple of centuries and/or one singularity away from happening, so don't hold your breath. 1: http://www.planetary.org/blogs/guest-blogs/2017/20170623-starshade-helping-space-telescopes.html http://www.planetary.org/blogs/guest-blogs/2017/20170623-sta... 2: https://www.noao.edu/meetings/interferometry/workshop-files/Carpenter-Space-comp.pdf https://www.noao.edu/meetings/interferometry/workshop-files/...
bluGill 9y ago
In the 17th century we were experimenting with static electricity, the sparks of which emit radio waves. You cannot tell them from atmospheric lightening, but they are detectable. I wonder if an alien species has been listening for a while they might be able to go back in their archives and conclude that some emissions actually were our experiments - once they have hindsight that humans really were playing with static electricity in those time frames.

by kylec 9y ago

jaclaz 9y ago

>These methods focus on finding extraterrestrials with an equivalent or greater technological advancement to our own. ... AND actually willing to communicate with us, which is not IMHO to be assumed as given. We need to find a rather "narrow" set of aliens with a technology similar enough to ours, and animated by a similar curiosity about the rest of the universe.

api 9y ago

We could perhaps detect distant alien life by finding signatures of oxygen or another oxidizer in a planet's atmosphere. These would be highly unlikely to persist long without something alive to keep the thermodynamic gradient up. O2, F2, etc. are extremely reactive.

nkoren 9y ago

In the main, I think we'd simply have no chance of detecting such civilisations. In the next couple of decades, however, advanced space telescopes with starshade coronagraphs could be able to start doing spectroscopy on exoplanet atmospheres.[1] This would definitely reveal (some kinds of) biologically-active atmospheres, although it wouldn't necessarily to be able to tell the difference between a complex biosphere with a low-tech civilisation, and a uni-cellular algae soup. I suppose there's an outside chance that such a telescope could detect combustion compounds that are difficult to explain geologically or biologically, and that might be used to hypothesise a civilisation. Something like lead smelting might leave a pretty distinct signature, for example. But that would just lead to a hypothesis, not proof, and I imagine it'd be pretty contentious. Longer-term, it should be possible to create arbitrarily large space-based optical interferometers[2], to the point where one would be capable of imaging cities and agricultural activity on exoplanets. That'd settle matters (Unless it's under water or impenetrable cloud decks, and then you're just out of luck). But that level of resolution is probably a couple of centuries and/or one singularity away from happening, so don't hold your breath. 1: http://www.planetary.org/blogs/guest-blogs/2017/20170623-starshade-helping-space-telescopes.html http://www.planetary.org/blogs/guest-blogs/2017/20170623-sta... 2: https://www.noao.edu/meetings/interferometry/workshop-files/Carpenter-Space-comp.pdf https://www.noao.edu/meetings/interferometry/workshop-files/...

bluGill 9y ago

In the 17th century we were experimenting with static electricity, the sparks of which emit radio waves. You cannot tell them from atmospheric lightening, but they are detectable. I wonder if an alien species has been listening for a while they might be able to go back in their archives and conclude that some emissions actually were our experiments - once they have hindsight that humans really were playing with static electricity in those time frames.