<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=utf-8"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>From:</span></b><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'> extropy-chat <extropy-chat-bounces@lists.extropy.org> <b>On Behalf Of </b>BillK via extropy-chat<br><b>Sent:</b> Friday, 24 July, 2026 3:00 PM<br><b>To:</b> ExI chat list <extropy-chat@lists.extropy.org><br><b>Cc:</b> BillK <pharos@gmail.com><br><b>Subject:</b> Re: [ExI] Wrong frequency? Astronomers rethink where to hunt for alien signals<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>On Fri, 24 Jul 2026 at 19:49, <<a href="mailto:spike@rainier66.com">spike@rainier66.com</a>> wrote:<br>><br>> BillK…<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>> Once you have that answer, note that a signal can be sent by rotating a group of reflective objects, such as MBrain nodes. It takes a while, but... if you don't need to say much and you have plenty of time... what's the big hurry? For practical purposes, we should speak slowly but listen quickly.<br>><br>> spike<o:p></o:p></p><p class=MsoNormal>> --------------------------------------------------<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Perplexity AI says that we probably wouldn't notice such signals, as they would be lost in the noise of the universe.<o:p></o:p></p><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black'>BillK<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Arial",sans-serif;color:black'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Arial",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>BillK, it isn’t clear Perplexity understood the idea. Think of the star’s spectrum as analogous to a carrier frequency for an AM radio signal. Imagine an enormous swarm of nodes which can rotate a half pi radians in an hour. A signal could be sent by turning to allow the star’s full spectrum thru, then an hour later every node is turned to block as much spectrum as it can. Result: the star goes from full brightness to partially dim. About one bit per hour could be sent that way.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>Perplexity is right in that such a signal would probably be lost in the noise of the universe: we humans have only developed the technology to see or notice such a signal recently. Also… good chance the maximum signal rate would be more like one bit per month. But what’s the hurry? If a civilization doesn’t need to send out a lot of signal quickly, it will not. It will signal its presence perhaps by repeatedly sending out the signal 2, 3, 5, 7, 11, 13 (ja, I stole the idea from Sagan (but it is a good one (for it leads to an interesting question: what is the shortest message that would unambiguously indicate an intentional signal from an alien intelligence?))))<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri",sans-serif'>spike<o:p></o:p></span></p></div></body></html>