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Ruadhan2300 t1_j9tep90 wrote

There's also signal-attenuation to consider.

Radio signals disperse in open space and eventually become indistinguishable from the background radiation.
For all but our most powerful directed transmissions, this is in the realm of a couple hundred lightyears at most.

A world 2000 lightyears away wouldn't be able to understand or recognise the signal even when the radio waves start passing it by. At best it'd be a slight increase in radio complexity drowned out by the cosmic background noise.


failurebeatssuccess t1_j9tjrs9 wrote

Is there a way to deal with that - surely if you average over time then you can pick up even a very weak signal if it is repeated often enough. If we had a constant brief repeated signal at regular intervals over, say, the course of a year - wouldn't that be enough to be detected among noise if averaging was used?


Ruadhan2300 t1_j9tpe48 wrote

Sure, if you're looking for that kind of signal I guess!

Though bear in mind that repeated radio signals like that also exist in nature in the form of things like spinning black holes and neutron stars.

If we were looking in the Cosmic Background Radiation for subtle repetition, we probably wouldn't be able to differentiate it from natural sources.

Also bear in mind that the other reason such signals get lost is also because they fall below the signal strength of the CBR, and get entirely overwhelmed, not just masked in the random noise.
I'm not expert on signals-analysis or radio-waves, but I don't think there's a way to extract meaningful data out of that.