Article View: sci.physics.cond-matter
Article #49Re: Neutrino Masses
From: Matt Carey
Date: Wed, 18 Jul 2001 17:05
Date: Wed, 18 Jul 2001 17:05
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2629 bytes
"Gordon D. Pusch" wrote: > This is known as a ``hypothetical'' question, i.e., a ``what if?'' > *IF* it where possible for neutrinos to be at equilibrium at what > humans consider ``room temperature,'' what would their mean speed be? > (Note that the question is not entirely silly --- somewhere between > the neutrino decoupling time (T_\nu ~= 1e10 Kelvin) and the current > epoch (T_\nu ~= 2 Kelvin), they must have passed through T_\nu ~= 300 K... It wasn't orginally posed as a hypothetical question, but that isn't really important. Why would the original neutrinos have cooled at all? Another odd statement by the other poster mentions "thermalized" neutrinos. Once in the universe as we know it now, how do you thermalize a neutrino? Can it scatter elastically off some other particle? Even if it could the huge mass difference would require a large number of such collisions. For a particle with nearly zero cross section for any interaction, it wouldn't seem likely that a neutrino would thermalize. Matt
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 1141dc,f4dfcde22ee4c9c6 X-Google-Attributes: gid1141dc,public X-Google-Thread: 104752,f4dfcde22ee4c9c6 X-Google-Attributes: gid104752,public X-Google-Thread: 100065,f4dfcde22ee4c9c6 X-Google-Attributes: gid100065,public X-Google-Thread: 106ae0,f4dfcde22ee4c9c6 X-Google-Attributes: gid106ae0,public X-Google-ArrivalTime: 2001-07-18 10:08:58 PST Path: arc1-ca.pugleaf.net!archiver1.google.com!newsfeed.google.com!newsfeed.stanford.edu!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!news-was.dfn.de!znr.news.ans.net!news.chips.ibm.com!newsfeed.btv.ibm.com!gazette.almaden.ibm.com!not-for-mail From: Matt Carey <matt.carey@ieee.org> Newsgroups: sci.physics.cond-matter,sci.materials,sci.mech.fluids,fj.sci.matter Subject: Re: Neutrino Masses Date: Wed, 18 Jul 2001 10:05:32 -0700 Organization: IBM Almaden Research Center Lines: 26 Message-ID: <3B55C1DC.E342796E@ieee.org> References: <a786eec.0107151054.5e5c867b@posting.google.com> <3B51F2D9.CEB79A8B@hate.spam.net> <3B5390E4.6056173A@ieee.org> <3B54A1A6.BE529082@grc.nasa.gov> <3B54DB55.4F633BDA@ieee.org> <m2y9pnm34i.fsf@pusch.xnet.com> Reply-To: matt.carey@ieee.org NNTP-Posting-Host: carey1.almaden.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: gazette.almaden.ibm.com 995475745 19628 9.1.18.139 (18 Jul 2001 17:02:25 GMT) X-Complaints-To: postmaster@almaden.ibm.com NNTP-Posting-Date: Wed, 18 Jul 2001 17:02:25 +0000 (UTC) X-Mailer: Mozilla 4.72 [en] (Windows NT 5.0; U) X-Accept-Language: en