I think this is getting the causality backwards:

> As such we listen for radio signals as a way of communication, because that's what we are doing.

It’s not because we expect aliens to be using radio communication or to follow the same path we did. It’s more because electromagnetic radiation is the only thing we can reasonably detect. If the aliens are communicating with gravity waves somehow, our sensors are probably not good enough to determine it. And if it’s some new physics we haven’t discovered, how would we even know what to look for? EM waves are really the only good option we have right now.

That said, it is reasonable to assume that a technologically advanced civilization is using some fashion of electromagnetic devices, which therefore generate radio waves and could be detected.

But I don’t think anyone is claiming that every technologically advanced civilization will have a detectable radio signal. It’s just the best tool we have.

While your basic point stands, I have to point out that "wireless telegraphy", like many other inventions, was almost simultaneously invented on different sides of the Atlantic. There are many inventions which have American and European "inventors", because the news of one had not gotten across the Atlantic to the other before they invented it as well. Which suggests, that once an invention is possible, it is likely to be discovered, whether an accident is involved or not.

I can't see a good reason to assume an alien civilization would be industrial to begin with, whatever discovery path might lead one there.

And I don't even mean they could be underwater creatures etc., which is also a possibility.

Imagine Earth as we know it, inhabited by humans as we know them, but no fossil fuels (due to a different geological history), very few metal ores (making every metal as scarce as, say, platinum) - and you're stuck in an eternal stone age, possibly with more advanced social organization, but never getting beyond our ancient or medieval standards.

That seems like an interesting plot for a story. Stonepunk? It seems a sufficiently advanced society could have Antikythera type computing mechanisms ground from stone. And extravagant "wood"-working artifacts shaped by sharp stone tools (obsidian single point turning tools for your lathe?). So you could have advanced looms for textiles, etc.. And then without metals you don't have electrical conduction, but what could you do with electrostatics? And telescope and microscope optics seem in the realm of possibilities. How much of our chemistry knowledge depends on metals? Could we have genetic engineering without metals? Interesting.

Children of Time touches on this in some interesting ways: https://en.wikipedia.org/wiki/Children_of_Time_(novel)

Just as likely for there to be no fossil fuels and no metal is for there to be vastly more fossil fuels and metals.

I don't see any reason why it's more likely for an alien civilisation to be suffering from a comparative lack of resources than it is for us to be suffering from a comparative lack of resources.

And if both types exist, we'd be more likely to hear from the ones that have resources than from the ones that don't.

From the western culture point of view I'm sure it seems very weird to not have oil/metal, but you're describing numerous historical non-western cultures. Easter Island, Japan, etc.

Exactly. The human species mirrors its expectations and technological limits into the parameters it uses to conduct the searches for extraterrestrial species. Implicit guesses on the details of the alien species are done: for example, use of radio signals implicitly assumes the aliens prefer to use radio over lasers or some other technology.

Like the Ashen Lights (small glows on the unlit side) of Venus: these were theoreticized to be big fires used for agriculture or a form of celebration of the Venusian Emperor... Think about that for a second: a civilization on another planet would 1. use a slash-and-burn method of agriculture (why not hydroponics), and 2. would have a hierarchical society with an emperor (why not autonomous cells), and 3. require/facilitate celebrations of their leader(s) (why not leaderless), and 4. use possibly some evolved form of fire worship (why not water, why not nothing), and so on.

All these are Earth constructs. An alien race would likely not understand those concepts at all.

So, suppose we made contact, there would not be a common frame of reference at all, except by using mathematics, physics and chemistry and the like. Describing foundational things like numbers and carbon chemistry would be possible, but at some point that language would reach its limits. Anything abstract like "hate", or "love", or "exploring" would be impossible to describe.

Also, the technology levels of the two species would have to be close to each other. I mean, just try describing a transistor to a pet, or describing a cloud-based service to a person from the year 1700.

I'd say the chances of any kind of contact are very, very small, but still non-zero.

> How likely is it for another civilization to follow the same path?

Maybe not likely. But for other paths, we don't know what to look for. Presumably, if there are technologically advanced alien species out there, some fraction of them followed a path involving radio signals. And that's what we know to look for.

If you have any sort of electrical technology is hard not to produce some form of radio waves. We have to have regulations that limit the interference caused by our appliances.

If you’re producing radio anyway, it’s not a big leap to come up with a practical application.