This is in response to the "deafening silence" mentioned in the article referenced by
Wolfhound's post.
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I would comment that the "deafening silence" is due to the fact that even us have been sending signals into space, intentional or not, for only about 120 years. And they may not even be strong enough after that much distance to be detected.
Although there may be earth-like planets within that range, have any developed sapient/sentient life with a level of technology where they are actively searching for other life? We have only been actively searching ourselves for only about 50 to 60 years. If those other earth-like planets do have an AASC (advanced actively searching civilization), and have sent their own signals out, would the signal be strong enough for us to detect?
Remember, even if we were to send out a terawatt powered signal, after only about the distance from here to the Centauri system (about 4.3 LY), that signal would only be micro-watts, perhaps even nano-watts, in strength by the time reached Centauri. The closest suspected earth-like planet is Gliese 581-c, about 20.3 LY, or almost 4.75 times further. The signal strength by then would most likely be beyond any form of detection technology we currently possess. Most likely swallowed up by the CBRN (cosmic background radiation noise).
Then we must also think on this. There is such a thing as signal attenuation. If a signal were sent out at 2.5 GHz, by the time it reached the Centauri system, that signal would have attenuated to about 566 Hz. A huge drastic difference. Although I have heard SETI@Home scans all frequencies, would we even recognize a signal at 566 Hz with only micro-watts of power?
566 Hz means the signal would go from a 0 to a 1 back to 0 only once every 566 seconds. Or 9 minutes, 26 seconds.
In my honest and humble opinion, even for us to send a signal from here to Centauri, we would need to figure a way for that signal to perhaps punch through the quantum foam to arrive there with no signal power loss or attenuation. I.E. - the infamous subspace signals from Star Trek, or the Tachyon Beam Dictors from Spacemaster. We could definitely use the Ansible communications from
Ender's Game.
Author's Note: The numbers above were using equations I have. They may be the wrong equations. Thus, the numbers may be incorrect. I apologize for any incorrectness and being too lazy to web-search.rmfr
