[ben_w]

A perfectly parallel source wouldn't fall off with inverse square, but all real sources are not — and cannot be — perfectly parallel.

What you get from lasers is very high gain in the direction it is pointed in, but it's still subject to the inverse square law.

It's capable of being enough gain to be interesting, to be seen from a great distance.

If you engineer it so the gain is enough to outshine the rest of the parent galaxy in the direction it is pointed, then that's effectively good enough because the galaxy is also following inverse-square and you'll continue to outshine the parent galaxy even as you and it both get weaker, but it's still falling off inverse-square.

[shagie]

I stand corrected on the inverse square.

I still hold that it would be possible to send and detect signals set with intention with not too much more advanced technology than what we have.