Radio Signal From Direction of Proxima Centauri

[Drashner1]

I can buy any of those arguments w/r/t a particular civilization, but I can't get behind the idea that any of them might apply to all civilizations.  

Yes - but what if it's not a 'simple' matter of either xeno civs are readily detectable, either due to deliberate effort or a side effect of going about their business or it's not because they all build dysons or engage in birth control or whatever? What if instead it's a case of a civ being detectable (by us at our present level of capability) or all of the other options?

Some civs may limit their populations such that they never build sufficiently large megastructures (dysons or whatever).

Some may build them but make them so efficient that we can't readily detect them.

Some may destroy themselves.

Some may decide not to contact aliens.

Some may employ comm tech that we can't detect - not necessarily 'magical' tech based on physics we don't know about either. If they're using really tight beams and/or using their star's gravitational focus as a lens, and/or being really efficient about encrypting or data compressing their signals...would we be able to detect them even if they were talking their heads off all around us (assuming for sake of argument they have heads )?

And so on and so forth. I don't claim to be up on current thinking in this area, but in past years the list of suggested reasons why we might not be receiving any signals from aliens ran to about a dozen or two possibilities. What if it's not a case of just one of those options having to apply to everybody, but rather a case of Option 1 applies to X percent of civs and Option 2 applies to Y % and on and on until we are left with just a tiny percentage of civs that are either actively attempting to communicate with a civ like ours and/or are engaged in activities that our tech can detect across interstellar distances?

For an added complication, I would suggest there is also the issue of time. In a nutshell:

What if xeno civs don't spend all of their history only doing one thing - instead they go thru different periods doing different things, of which 'attempting to communicate with civs like our human civ at its present level' or 'engaging in activities we humans can detect' are only two out of many activities they might spend their time on over the lifetime of their civ, even if it is a very long-lived one. And for a sufficiently long lived civ, the periods where they aren't doing stuff we can detect (on purpose or not) might be measured in thousands of years or more - and we've only been looking for others for less than a century.

Putting this all together, we may be in the position of trying to find that subset of civs that are choosing to engage in activities that make them detectable to our current technology at the time we are looking for them - and one or more of those conditions may not be being met right now.

Maybe there was a really talky/noisy civ broadcasting all over local space a million years ago, but then they stopped for whatever reason. And maybe the next talky/noisy civ won't start doing its thing for another 100,000 years. Of course if they're located in the Virgo Cluster and everyone closer is currently occupied doing stuff we can't detect - that isn't going to do us much good in the immediate term.

Just some thoughts,

Todd