Path: ...!feeds.phibee-telecom.net!weretis.net!feeder8.news.weretis.net!newsfeed.xs3.de!nntp-feed.chiark.greenend.org.uk!ewrotcd!news.eyrie.org!beagle.ediacara.org!.POSTED.beagle.ediacara.org!not-for-mail From: El Kabong Newsgroups: talk.origins Subject: Re: New SETI search Date: Tue, 27 Aug 2024 06:27:53 -0700 Organization: A noiseless patient Spider Lines: 32 Sender: to%beagle.ediacara.org Approved: moderator@beagle.ediacara.org Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: beagle.ediacara.org; posting-host="beagle.ediacara.org:3.132.105.89"; logging-data="56176"; mail-complaints-to="usenet@beagle.ediacara.org" To: talk-origins@moderators.isc.org Cancel-Lock: sha1:ElAXH6sx4zvjEwDoO5h7wiw1+kc= Return-Path: X-Original-To: talk-origins@ediacara.org Delivered-To: talk-origins@ediacara.org id 1BD2122986F; Tue, 27 Aug 2024 09:27:57 -0400 (EDT) by beagle.ediacara.org (Postfix) with ESMTPS id 03C6322978C for ; Tue, 27 Aug 2024 09:27:54 -0400 (EDT) id 237B0872B4; Tue, 27 Aug 2024 09:27:58 -0400 (EDT) Delivered-To: talk-origins@moderators.isc.org by mod-relay.zaccari.net (Postfix) with ESMTPS id E81CB7FC26 for ; Tue, 27 Aug 2024 09:27:57 -0400 (EDT) DKIM-Filter: OpenDKIM Filter v2.11.0 mod-relay.zaccari.net E81CB7FC26 (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-256) server-digest SHA256) (No client certificate requested) by smtp.eternal-september.org (Postfix) with ESMTPS id C1DD85F85B for ; Tue, 27 Aug 2024 13:27:55 +0000 (UTC) Authentication-Results: name/C1DD85F85B; dmarc=none (p=none dis=none) header.from=the.noodle id 5D9E6DC01A9; Tue, 27 Aug 2024 15:27:55 +0200 (CEST) X-Injection-Date: Tue, 27 Aug 2024 15:27:55 +0200 (CEST) X-Newsreader: Forte Agent 4.2/32.1118 X-Auth-Sender: U2FsdGVkX1/KYDCEV/kBNwxFAvfRJ6TkKGcXsBxjpe0= HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_VALIDITY_CERTIFIED_BLOCKED, RCVD_IN_VALIDITY_RPBL_BLOCKED,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=no autolearn_force=no version=3.4.6 smtp.eternal-september.org Bytes: 4006 RonO wrote: > On 8/27/2024 2:11 AM, Ernest Major wrote: > > On 27/08/2024 06:24, El Kabong wrote: > >> Previous searches at Aricebo and other sites looked for > >> alien signals at 1420 Mhz.  They picked that frequency > >> because it is a hydrogen line.  The thinking is that > >> aliens would more likely broadcast there than an > >> arbitrary frequency.  It never made sense to me because > >> the signal will be attenuated by any hydrogen lying in > >> the path, and because if you tune in to the hydrogen > >> line, you'll find... hydrogen noise! > > > > The argument is that the 1420 MHz line is less arbitrary, and is not > > absorbed by interstellar dust. Any radio signal is less absorbed by dust than optical wavelengths. 1420 was probably a good pick, but it does have that drawback. > If the aliens had broadcast at 1420 MHz what would be the frequency that > we would detect in an expanding universe? I realize that some galaxies > are moving towards us, but the red shift indicates that most things are > getting further away from us in all directions due to the Big Bang. Any radio signal we receive will be redshifted. But we are not looking for extragalactic signals, they would be way too faint. We are looking for something here in our own neighborhood of the Milky Way, around 10k lightyears max. At that distance the redshift is measurable but unimportant, even for a narrow-band receiver.