<div dir="ltr"><div class="gmail_extra"><div class="gmail_quote">On Sat, Jun 21, 2014 at 8:49 AM, The Avantguardian<span dir="ltr"></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
1. There is some very rare astronomical phenomenon that has only been observed once that sends out extremely powerful pulses of narrow band radiowaves centered on the emission line of hydrogen.<br>
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2. Some secret conspiracy in the government used a powerful transmitter tuned to a forbidden frequency for some unknown purpose and it happened to get reflected off of some space debris and was then detected by Jerry Ehman.<br>
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3. We have, in that instance, detected a radio communication by an intelligent extraterrestrial species but chose to ignore it because it only lasted a short time and was not repeated. <br></blockquote><div><br></div><div>
Of those I'd favor #1 - we haven't spent all *that* much time, cosmologically speaking, studying the heavens beyond the visible light spectrum.<br><br></div><div>But there are at least two variants of #2 that seem more likely. Either some signal was accidentally transmitted on that frequency (and whoever did it isn't stepping forward because illegal or illegal) and bounced off, or one was transmitted on a nearby frequency and got frequency shifted in the process of bouncing off.<br>
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When we (presumably an intelligent species) sent out the Arecibo message, we only did it *once*. Why would they do any differently?<br></blockquote><div><br></div><div>Because they wanted there to be no mistake on the receiving end? Or they wanted to avoid the chance that the listener happened not to be listening at that moment?<br>
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<a href="https://en.wikipedia.org/wiki/Arecibo_message" target="_blank">https://en.wikipedia.org/wiki/Arecibo_message</a><br>
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Of course as of 2013, you got these guys offering to send your tweets to Gliese 526 for 25 cents each:<br>
<a href="http://thelonesignal.tumblr.com/" target="_blank">http://thelonesignal.tumblr.com/</a><br></blockquote><div><br></div><div>Exactly. Arecibo is not the most reliable indicator of a civilization like ours. It's going to take repeated signals.<br>
</div><div> <br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Either a hail mary into the void or eavesdropped communications not intended for us. The idea of an ET civilization setting up a beacon seems a little strange from a Darwininian perspective unless it were like the glowing lure of an angler fish.</blockquote>
<div><br></div><div>And yet, in the one example we definitely know of, "a beacon" is exactly what was set up. Maybe civilizations that incautiously broadcast do not, in fact, inevitably attract interstellar marauders? (Who would want...what, from a nascent civilization? Certainly not raw materials that can be gained in larger quantities from unresisting unpopulated star systems. And just as simply as one could suppose they want to destroy potential competitors, one could suppose they want potential augmentations to their society to grow until they can usefully contribute: "Oh, hey, these guys can colonize our otherwise-useless oxygen-polluted water worlds, once they learn how to stop ripping up their own planet.")<br>
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"Thousands" of non-repeated signals per day? What if just 1% of them were genuine?</blockquote><div><br></div><div>This is astronomical stuff we're talking about. 1%, no matter how nice a round number it sounds like, is pretty much not happening. More realistic fractions are very small fractions of a percent, if not actually 0.<br>
</div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> then put a freakin radio telescope on the far side of the moon. No "side lobes" from terrestrial communications then. You could have a com satellite in lunar L4 or L5 to function as a relay station.<br>
</blockquote><div><br></div><div>Indeed. Until we can get such instrumentation, I'm reluctant to pay much attention to most chain-of-logic-from-minimal-observations, such as the whole "dark matter" thing (a hypothesis to explain calculated differences in measurement, when measurement error - including systematically overlooking certain types of objects - could readily explain).<br>
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