# How much is the greatest distance of a communication link that man can reach? Intergalactic? (ascertainable)

I have no data to add, just to say that I would like an answer that includes data and calculations to verify Shannon's law in that case.

Concrete examples of this type of communication: http://en.wikipedia.org/wiki/Interstellar_communication
Deep Space Network

https://ieeexplore.ieee.org/document/1091955/references#references Excellent document with calculations

• given that we will all be long dead by the time any communication reaches another galaxy, I'm not sure the point... Sep 5, 2021 at 3:15
• The transmit power (with some consideration of antenna gain) determines how far it can go before it attenuates below background radiation noise. Assuming no QRSSS methods are considered, the signal strength transmitted, pure geometry, and the level of the background noise are the major determining factors. (Attenuation due to dust is probably minor.) Sep 5, 2021 at 4:08
• @Phil I mean to find concrete examples of this type of communication, this is the point. en.wikipedia.org/wiki/Interstellar_communication Sep 5, 2021 at 17:34
• I think this is a valid and very interesting question. How far away could a message such as the Arecibo message of 1974 be received, if the transmission had been aimed directly at the receiving antenna, and the receiving antenna were comparable to the Arecibo radio telescope (back when it was fully functional)? Of course the question may not be practical to those of us reading this web page in 2021, but I still think it's interesting. Sep 7, 2021 at 17:11
• Mauricio, I think that you should undo your acceptance of the answer by @hotpaw2. The question deserves an answer with a calculation. If you undo the acceptance, and there are no answers with calculations after a few days, then I will consider offering a bounty. Sep 8, 2021 at 14:20