jamesycakes231 t1_j9tc6aa wrote
It's possible to detect signals, but even if a planet 2,000 ly away has the same tech and sends us a message, we won't receive it until 4023. By then we could well be long gone.
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.
Substantial_Chair_78 t1_j9td59z wrote
What if they’ve been sending us messages for thousands of years? Maybe one every year to wish us a happy new year?
OhioVsEverything t1_j9texj4 wrote
What if it takes them 5000 Earth years to rotate around their own star just once and the last time they called was the earth year 1001. They'll not call again for a while.
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