I think your assumptions about what is hard and what is easy to detect need some recalibrating.
Alien life forms wouldn't need to use technology to make themselves harder to detect. It's extremely difficult by default.
They would need to use technology to deliberately spread a message in a way that is at all likely to be detectable, and even then would still have to get quite lucky.
Alien life forms wouldn't need to use technology to make themselves harder to detect. It's extremely difficult by default.
They would need to use technology to deliberately spread a message in a way that is at all likely to be detectable, and even then would still have to get quite lucky.