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Detecting life on Earth could be done with a telescope able to take spectra of Earth from the aliens' home system. They could look at Earth compared to the Sun
by giantrobot 3y ago
Detecting life on Earth could be done with a telescope able to take spectra of Earth from the aliens' home system. They could look at Earth compared to the Sun and other planets in the system and see Earth has a bunch of biosignatures that would be broken down by the Sun's UV radiation if not constantly regenerated.
One or two markers would be inconclusive but a bunch of different ones would give a high probability of life existing here. It's why the "Dark Forest" concept is fundamentally silly. There's no hiding Earth's biosignatures.
If the arbitrarily advanced aliens have a long enough measurement baseline and are within 150 or so light years they could also see the technosignatures of the Industrial Revolution with different air pollutants. If they're within about 60-70 light years they'd start seeing evidence of radioactive isotopes from above ground nuclear testing.
- bluGill 3y agoThe nearest star is ~4 light years, and it is of a type that we think unlikely to have life. Even at 150 light years there isn't a whole lot out there, though I guess it is no longer in the impossible realm, it also isn't really enough stars to think of the Fermi paradox applying yet.
- kjkjadksj 3y agoWe send humans to live in orbit where there wouldn’t normally be conditions fit for life thanks to our technology. I don’t think habitability precludes life from being there, especially if it emerged elsewhere and this is more of an outpost or research station akin to the ISS or antarctic stations of our own. Perhaps there are interesting things there in uninhabited systems, or they make a ripe environment for certain experiments or work that is unfit to perform so close to a habitable system.