Quote Originally Posted by sycld View Post
You obviously didn't even bother to read my post. I never said optical communication isn't possible or feasible, so don't say I did.
Let's recap how this started: I made a comment that lasers would work well for interstellar communications, you have done nothing since then except snarkily try to harp on all the ways that this isn't true ("they won't stay collimated", "they would perform essentially the same as dipole emitters", "who ever heard of a raser" even though I didn't say anything about rasers and was talking about normal visible-light lasers, then "RF masers aren't the kind of rasers I was asking about because their radio emissions aren't long-wave enough", etc.).

If you aren't trying to claim that interstellar communications by laser isn't impossible/infeasible/pointless, then great, we agree! But then if that's the case, I also don't know why you've been posting the things you've been posting thus far. I'm content to drop it, though. Again, I didn't start this thread to hash out which specific method of interstellar communications is best.

Quote Originally Posted by sycld
That seems to be a wild claim to make. As a species, humans are only 200,000 years old. Agriculture is only 15,000 years old, and what we consider to be the history of civilization is only aroun 7 thousand years old. We have only had a conception of "interstellar communication" at all for a little over 100 years. As a species we are young, and as a highly organized, "civilized" species, we are even younger, so there is very little reason to believe that most civilizations would be as young as we are.
Right, hence my earlier statement: "Of course, again, who knows how much longer we will last as a civilization capable of receiving radio signals."

Quote Originally Posted by sycld
Also, we have no idea if humans developed civilization faster or slower than other intelligent species would, nor do we know how common it would be for intelligent species to develop civilization. Maybe the probability for an "intelligent" (or rather "sapient") species to produce civilization given enough time is unity, or maybe it is far less than that.
Right, hence my earlier statement: "Again, based just on the example of human history which of course might not be anything like a representative norm."

Quote Originally Posted by sycld
And we really don't know how long a civilization survives on average after it has any ability to achieve interstellar communication. Drake and his contemporaries estimated 10,000 years (rather arbitrarily), and so we, by comparison, are a barely nascent "interstellar" civilization, an arguably we haven't even entered this phase since we don't really have as of yet a firmly established protocol for interstellar communication.
Right, hence my earlier statement (again) that we really have no idea how much longer human civilization will last with the ability to communicate between stars.

I've never once used human civilization as a guideline to guess about other civilizations without also clearly qualifying those guesses with the points you have needlessly reiterated here. Speaking of not bothering to read posts....


Quote Originally Posted by mrbazoun
How sensitive is the equipment we're using to detect radio transmissions? Can we detect the waves if they enter our solar system for sure? What about our galaxy? If not, then aliens would have to deliberately target us, correct? Depending on the sensitivity of our instruments, it could be that aliens have no interest in contacting us. That would certainly explain everything. Sorry if you have already discussed this, I don't really have time yet to read everything.
We can (of course) only detect a signal if it hits the dishes of our radio telescopes. Which means that, yes, alien civilizations in other star systems would most likely have to be deliberately squirting high-powered radio, laser, etc. transmissions at other star systems (including ours) in order for us to detect them. And yep, one of the explanations for the "Great Silence" is that maybe other civilizations exist but aren't interested in doing that sort of thing (perhaps for practical/strategic reasons; there is a fairly sound argument that an intelligent species revealing it's presence to other such species is inviting an attack aimed at exterminating them). Certainly we ourselves haven't done it very seriously, yet. So, a good point.