Comment by giantrobot
18 hours ago
They read the Three Body Problem but forgot that light exists. For aliens with interferometers looking at Earth there's little question there's some sort of interesting active chemistry (life) here.
Theres no hiding that fact. If they're within about 100 light years they'll be watching the effects of the Industrial Revolution on the atmosphere. Even if they're don't know the exact cause the spectra of pollutants and rates of change will give hints the changes are unlikely to be from random natural processes.
Outside of 100 light years but pretty much anywhere in the galaxy (assuming interferometers capable of getting spectra of Earth) will know there's some sort of life here. Even if you want to assume some aliens don't recognize life as we understand it they'll at least see extremely interesting and varied chemistry.
The idea you're going to hide Earth's biosignatures is silly. Trying to hide our technology signatures is pointless. At about 70 light years any interested aliens will start seeing isotopes resulting from above ground nuclear testing.
Telescopes aren't magic, and space is big. There are 100 billion+ stars in the galaxy. Within a 100 light-year radius, there are 27 ( https://en.wikipedia.org/wiki/List_of_star_systems_within_95... ). Nobody's looking at Earth. If any hypothetical civilization were to find our system, it would be by blanketing the entire galaxy in 100 billion drones and checking every single star, in which case the dark forest doesn't matter anyway.
First that's just star systems within 100 lightyears of Earth, systems with one of more gravitationally bound stars in them. There are thousands of stars within 100 light years of Earth. Most are red dwarfs but there's about a thousand F, G, and K class stars.[0]
While telescopes indeed are not magic, an alien species at least as advanced as us could have telescopes capable of not only finding Earth but gathering spectra from it. It's certainly no guarantee Earth would be found but there's no hiding from anyone looking. There's no masking the chemistry of life on Earth and likewise no masting techno-signatures in the atmosphere.
[0] https://chview.nova.org/solcom/stars.htm
If they are at our current tech level, to "see" Earth, then Earth would need to pass in front of the Sun from their point of view. That means they would need to be somewhere in the same pane as the Earth's orbit.