How easily could SETI detect Earth?
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Liz R
Feb 16, 2025, 3:15:08 AM2/16/25
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A research team led by Dr. Sofia Sheikh of the SETI Institute, in collaboration with the Characterizing Atmospheric Technosignatures project and the Penn State Extraterrestrial Intelligence Center,
set out to answer a simple question: If an extraterrestrial
civilisation existed with technology similar to ours, would they be able
to detect Earth and evidence of humanity? If so, what signals would
they detect, and from how far away?
Alan Grayson
Feb 16, 2025, 5:05:35 AM2/16/25
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On Sunday, February 16, 2025 at 1:15:08 AM UTC-7 Liz R wrote:
A research team led by Dr. Sofia Sheikh of the SETI Institute, in collaboration with the Characterizing Atmospheric Technosignatures project and the Penn State Extraterrestrial Intelligence Center, set out to answer a simple question: If an extraterrestrial civilisation existed with technology similar to ours, would they be able to detect Earth and evidence of humanity? If so, what signals would they detect, and from how far away?
The link doesn't work. My best guess is that beyond about 50 light years, the signal, which is an expanding sphere, attenuates, and can't be detected above the background noise. AG
Cosmin Visan
Feb 16, 2025, 9:39:28 AM2/16/25
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Aliens are spiritual beings. They don't have bodies anymore. As such, they don't bother with primitive concepts such as "physical electromagnetic waves".
Alan Grayson
Feb 16, 2025, 5:17:36 PM2/16/25
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See https://www.youtube.com/watch?v=Od-1V9ZR2Kc , where the claim is 12,000 light years. I don't believe it. AG.
Alan Grayson
Feb 16, 2025, 6:44:46 PM2/16/25
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On Sunday, February 16, 2025 at 3:17:36 PM UTC-7 Alan Grayson wrote:
On Sunday, February 16, 2025 at 3:05:35 AM UTC-7 Alan Grayson wrote:
On Sunday, February 16, 2025 at 1:15:08 AM UTC-7 Liz R wrote:
A research team led by Dr. Sofia Sheikh of the SETI Institute, in collaboration with the Characterizing Atmospheric Technosignatures project and the Penn State Extraterrestrial Intelligence Center, set out to answer a simple question: If an extraterrestrial civilisation existed with technology similar to ours, would they be able to detect Earth and evidence of humanity? If so, what signals would they detect, and from how far away?
The link doesn't work. My best guess is that beyond about 50 light years, the signal, which is an expanding sphere, attenuates, and can't be detected above the background noise. AG
See https://www.youtube.com/watch?v=Od-1V9ZR2Kc , where the claim is 12,000 light years. I don't believe it. AG.
Maybe I'm confusing the detection of a radio signal leaving Earth and being detected by aliens having our level of technology, with issues concerning atmospheric properties. AG
Liz R
Feb 16, 2025, 11:27:18 PM2/16/25
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Sorry if the link didn't work. I just tried it and it seems OK to me, but I may have some special access I'm unaware of. Anyway, I think this is the relevant quote...
Researchers used a theoretical, modeling-based method, and this study is
the first to analyse multiple types of technosignatures together rather
than separately. The findings revealed that radio signals, such as
planetary radar emissions from the former Arecibo Observatory, are Earth’s most detectable technosignatures, potentially visible from up to 12,000 light-years away.
So it sounds as though they think radio signals generated by humans are in theory detectable from 12,000 light years. That seems rather unlikely to me (unless the signals are highly directional). I feel like I've seen a figure around 100s of light years for attenuating signals, perhaps.
Alan Grayson
Feb 16, 2025, 11:53:02 PM2/16/25
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On Sunday, February 16, 2025 at 9:27:18 PM UTC-7 Liz R wrote:
Sorry if the link didn't work. I just tried it and it seems OK to me,
I can't load it. If a radar signal is omidirectional, I seriously doubt it can be detected at a distance of 12,000 LY. 50-100 LY is the number I recall. They must be referring to an analysis of a planet's atmosphere. AG
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