Those are huge assumptions IMO. Maybe they don't feel the need or comprehend the concept of communicating over long distances. Maybe they discovered a different force we don't know of. Just because radio waves worked for us, it doesn't mean every advanced civilization will makes use of them. The possibilities are so vast and endless.

If they are a space faring civilization, they need long distance communication. No the possibilities aren't endless, there's a lot of physics that we know that strongly constrains the search space. AFAIC, I think compression is the big issue, we should be looking for forward error correcting codes in the data.

I do agree with you, but I have the feeling you have a narrow view of how these guys look like. Your argument was not too compelling. For all I know they could be giant gas clouds, silicon life forms, dark matter creatures, a fungi-like thing that spans the whole interior of a small planet and manages to shoot spores into space. Their motivations are not going to be in line with those of the average American. Their lives could span milliseconds, or aeons. Their brain could function at so extremely different rates than ours, that we or they wouldn't consider each other sentient. They could be highly intelligent* and/or propagate successfully without radio communication.

But I think we might be discussing semantics. When you say "intelligent", you probably have something specific in mind. Which probably boils down to "can do math". But a different intelligence could also grasp the laws of physics at an intuitive level, in the same way a dog can catch a frisbee. Perhaps they can "get" turbulence or higher dimensions,understand a trees as a whole, something we completely fail at.

So to me it's a stretch to think that we can find them by looking at error correcting codes. But then again, I have no better proposal.

Laser communication seems more likely for long distance communication. Omnidirectional radio broadcasts need a comparatively huge amount of energy.

https://en.wikipedia.org/wiki/OPALS

I agree, but that's a very different argument from "who are we, measly little ants to think we can understand..."

> If there are structured radio signals being emitted,

Why should there be? Earth itself is getting quieter. Our electronics are more sensitive, for the applications that still use radion. For a lot of things, we are using plain boring fiber-optic (and copper) connections.

The earth is getting louder. 150 years ago, we'd have had almost zero light pollution. Nowadays you can't even see stars when you go outside.

Not only are there more lights, we are getting more efficient at producing energy to power them.

That's noisier, but it isn't a louder signal. We're talking about detecting alien species across vast distances. You can't do that by looking at a planet's light pollution AFAIK, because giving off this level of light is just not very notable — the sun reflecting off our planet is much brighter.

But sunlight reflecting off a random planet (including ours) is not useful. Sure, you can detect it, but it doesn't say anything about whether the planet has intelligent life or not. It would just be noise in the cosmos, no signal.

I'm not a physicist, but my understanding is that all EM frequencies -- visible light, radio, infrared, etc -- travel away from earth at the same speed (c). Since space has (almost) nothing to slow them down, then they'll just keep going forever. Thus, "strength" (however you want to measure it) is largely irrelevant so long as the signal it produces is detectable apart from all the other outgoing information. So the "light" broadcast from a TV tower is the same as the light from a spotlight at a shopping mall, in terms of its ability to travel through space and get noticed by aliens.

The only exception I can think of would be our atmospheric interference. Some light may penetrate our own cloud layers better than others. So all light may not be created equal, in that sense.

The GP was talking about how we're quieter now (i.e. using lower-powered radio signals), and you replied that we're louder because we have a lot of light pollution nowadays. My point was that AFAIK light pollution does not produce a signal for detecting life. We're producing louder noise and a quieter signal.

Isn't encryption the bigger issue? Agreed otherwise.

Quantium communication would be a far better alternative then to sending radio-waves through space.