|JP Vossen on 2 Mar 2017 15:01:25 -0800|
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|Re: [PLUG] "Nearby"|
On 03/02/2017 04:08 PM, Walt Mankowski wrote:
This is getting more and more off-topic
And that's relevant here *how* now? <ducks>
On Thu, Mar 02, 2017 at 03:49:18PM -0500, Rich Kulawiec wrote:
The Drake equation is an attempt to enumerate the probabilistic factors that go into an estimate of the number of civilizations in our galaxy. (Let's pause to ask ourselves if the number on this planet is 1 or 0.)
Even if it is >=1, there may be arguments that humans don't count. _So long and thanks for all the fish_ and all... Without taking sides, I'd factor in all of American politics & politicians as about a -1,000.
Having been in a few of those bar arguments with other physicists, all of whom were much better qualified than I am to be participating, my fallback position is what I call the Kulawiec hypothesis (hey, it's mine -- get your own!) which is that our best chance of detecting a *former* intelligent civilization will be the electromagnetic emissions generated when they annihilate themselves in a planetary thermonuclear exchange. This is the interstellar equivalent of "HELLO OUT THERE!...errr...ummm...goodbye." Of course if they do themselves in via other means (destroying their planet's ecosystem, mass drivers, epidemic, Nicki Minaj) then they may pass without our knowledge.
There's a related question which I'm totally unqualified to even consider, but yet, I will. The electromagnetic radiation (EMR) that Earth emits is an expanding spherical shell. It started when we started emitting, and is subject to attenuation per the cube/square law. How much longer are we going to emit like that? Broadcast radio & TV are, at least arguably, declining. A lot of internet is in glass fibers that don't emit much or any EMR into space. But there may be lots of other things emitting EMR I'm not thinking about. So--how much longer are we going to be emitting at detectable levels?
Now, extrapolate that out with whatever Drake variables you want. If we assume other civilizations follow a similar pattern, then for us to detect them via emitted EMR (not the only means, but the biggest/easiest, I think), then we have to intersect their expanding EMR shell before it attenuates to background noise, *and* while they are still emitting it! That means they have to be:
* Pretty close or * Really loud for * A really long time and they* Probably had to start a while ago 'cause light-speed and our detectors and stuff
Now of course, all of this ignores those civilizations that go out of their way to broadcast, "hey, we're here, come eat us and steal our water!" or who like to create warp emissions just outside the atmosphere (Z. Cochran I'm looking at you). Or...the Kulawiec hypothesis...
:-) JP -- ------------------------------------------------------------------- JP Vossen, CISSP | http://www.jpsdomain.org/ | http://bashcookbook.com/ ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug