Well one interesting thing to add to the mix is that signals (like, say, wifi) don't actually last that long. They disappate to below detectable levels pretty quick, to appear just part of the cosmic microwave background.

Therefore if that's your method of detection, you can't really detect very far across the galaxy. Maybe a few hundred or few thousand light years even with the best technology we could assume would exist in the near-mid future. And the milky way is about 90k light years across. And we are on the end of an arm, in a sparse area of the galaxy. Probably the bulk if life is with the bulk of stars towards the centre which we have pretty much no way of seeing what happens that far away (at a planet level).

So probably the inability to know what others are doing would be a big reason why dark forest doesn't really work.

[–] absGeekNZ 2 points 1 year ago

This is a problem; but we also don't know what sensing technologies are available in the future.

There is a very interesting sensor that I was reading about; it uses entangled photons (microwave) one is sent to what is to be detected in a electromagnetically noisy environment, but the measurement is made on the entangled partner which is in a low noise environment. This allows the measuring precision way beyond the noise floor of the measured environment.

I'm not sure what breakout tech will come along; I know that beyond about 300ly, even powerful signals like the original Olympics broadcast in 1936 would be below the noise floor of the CMB. But that is not really a hard limit to detection, the GPS signals are below the noise floor yet they are used everyday by billions of people.