science

Before anyone gets too cocky, remember that signal strength drops off at the square of distance. Even this tiny blip of range generally pales in comparison to the background radiation. We're still almost invisible to our own technology at any serious distance.

For a reference, see how absolutely difficult it is to talk to the Voyager probes. The signal they receive is absolutely tiny. (20 billion times smaller than what it takes to run a digital watch, see the Deep Space Network for what does the talking).

If any aliens have heard us, their technology already outstrips ours by orders of magnitude.

There are around 20000 stars in that little 200-light-year-wide dot.

https://www.pas.rochester.edu/~emamajek/memo_star_dens.html and 1pc≈3.3ly.

The Fermi Paradox doesn't seem that paradoxical when you see a map like this. Civilizations could be screaming into the void for millenniums without reaching the other side of the galaxy. Signal strength drops fast too. How would would ever distinguish a faded signal from background noise?

So remember when you're feeling very small and insecure

How amazingly unlikely is your birth

And pray that there's intelligent life somewhere up in space

'Cause there's bugger all down here on Earth!

This is an approximation, right? Because there's no giant cosmic mirror that lets us see our galaxy from far away like this?

200 light years radius is for radio signals to reach someone. 100 years radius for possibly receiving a signal back.

And that is if they received our signals, are able to identify that they are artificial signals out of the background noise of the rest of the universe because the signal degrades and gets weaker as the broadcast expands, they decide to send a reply back (even though they just recieve chatter at that point, not intentional communication to them), and then actually sends us a signal back. It's no wonder that hasn't happened yet.

There's around 10-15,000 stars in a 100 light years radius. The chance that any of those stars have habitable planets with intelligent life with the technology to receive and send radio signals and is listening for extraterrestial signals and can discern those broadcasts from background noise and would reply to chatter... that's a small chance. For context, we have only been explicitly listening for and sending signals intended for extraterrestrials for 64 years ourselves, so an identical civilization 100 light years away that received and replied to us immediately would still have 36 years of transit left on their reply.

Apparently "the first audio radio broadcast of voice and music occurred on December 24, 1906, when Canadian-American inventor Reginald A Fessenden transmitted from Brant Rock, Massachusetts. This historic transmission, heard by shipboard radio operators along the Atlantic Coast, included Fessenden playing the violin solo of 'O Holy Night' and reading from the Bible, marking the beginning of amplitude modulation (AM) broadcasting".

I wonder if that's what aliens would hear as the first sign of humans?

Further than I would have guessed!

@zedgeist

True, but somebody could do a cool count-up "clock" like the "debt clock" that would count the stars that have heard our transmissions, so far.

Call the start 1926, though we had some largish transmitters earlier. By '26, I think they were all over the world, broadcasting every direction.

So call it 100ly, and get a count, then advance by 1ly/yr. The number of stars would go up as the cube of time.