>We wouldn't be able to detect them optically or electromagnetically.
We can have have radio (electromagnetic) communication between the Earth and the Moon just fine.
We can have have radio (electromagnetic) communication between the Earth and the Moon just fine.
How do you imagine focusing "any transmitter in the galaxy" to converge at a distance of, say, 200 light years?
Any rough calculations on the method, focusing array size?
The moon is our celestial roommate.
Light need 1.3 seconds on average to travel from Earth to the Moon.
Do you still think your comment makes any sense?
Yes, because the nearest celestial neighbor is the moon and the nearest star is the sun. I don't see how Proxima Centauri is relevant here.