system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:If radio waves dissipate and aren't able to be separated from background noise after a small distance traveled (a couple light years), what's the point of SETI?
gpt
Kind of complicated to explain. Basically what you say is true of earths basic radio communications. Since we aren't looking to blast our signals in any particular direction, they get really quiet, really fast.

On the other hand, a focused signal can travel very far depending on how much power is used to send a radio signal.

The premise is that extraterrestrial life has similar or better technology than us (and we can detect "earth like" or "possible life" planets in the galaxy), that they would detect that Earth is earth-like, and would blast it with radio signals to see if we can receive and respond to them.

Such a radio blast, if enough energy were used, could easily travel a few hundred light years, but its still a very narrow window that we are looking at to try and detect alien life.