source file: mills3.txt Date: Wed, 31 Dec 1997 18:14:15 +0100 Subject: Re: phonons From: John Starrett Gary Morrison wrote >> Or equivalently, the elasticity of the vibration of a string, a steel >>string for example, is manifested at the sub/atomic level by the >>distortions of crystaline lattices. Crystaline lattices are, once again, >>generated by electron attraction and repulsion, which again is conveyed by >>photons. >>...... So sound is, at this otherwise not very interesting sub/atomic level, >>ultimately conveyed by photons. The invention of a new particle, the >>phonon, seems to be no more than a pointless complication that side-steps >>well-accepted physical models for no apparent reason. Phonons are the quanta of the normal vibrational modes of a crystaline lattice. If you were immersed in a crystaline lattice (didn't this happen on Star Trek?) the displacement of ensembles of molecules (a lattice wave) would correspond to sound, and if you were another molecule in that lattice, your interaction with the phonon would quantized. Thus molecules experience quantized 'musical pitches'. Just as relativistic effects are only noticable at incredibly high velocities, quantization of frequency is only noticable at very high frequency and/or small scale. Our ears, capable of hearing, at best, a 66 cent pitch difference ;-), would never be able to detect quantum effects. Phonons can be thought of as particles of fixed energy and momentum that move with the ensemble velocity of the lattice wave (they also work in continuous media calculations). Using the idea of a particle with these properties, one finds that phonons interact in many ways like the particles we use to imagine thermodynamic physical process, and thus are a convenient mathematical fiction, like photons, electrons, etc. for describing measured phenomena. John Starrett SMTPOriginator: tuning@eartha.mills.edu From: "Paul H. Erlich" Subject: RE: Wilson scale PostedDate: 31-12-97 18:56:51 SendTo: CN=coul1358/OU=AT/O=EZH ReplyTo: tuning@eartha.mills.edu $MessageStorage: 0 $UpdatedBy: CN=notesrv2/OU=Server/O=EZH,CN=coul1358/OU=AT/O=EZH,CN=Manuel op de Coul/OU=AT/O=EZH RouteServers: CN=notesrv2/OU=Server/O=EZH,CN=notesrv1/OU=Server/O=EZH RouteTimes: 31-12-97 18:54:27-31-12-97 18:54:27,31-12-97 18:53:49-31-12-97 18:53:50 DeliveredDate: 31-12-97 18:53:50 Categories: $Revisions: Received: from ns.ezh.nl ([137.174.112.59]) by notesrv2.ezh.nl (Lotus SMTP MTA SMTP v4.6 (462.2 9-3-1997)) with SMTP id C125657E.00625C8C; Wed, 31 Dec 1997 18:56:18 +0100 Received: by ns.ezh.nl; (5.65v3.2/1.3/10May95) id AA05669; Wed, 31 Dec 1997 18:56:51 +0100 Date: Wed, 31 Dec 1997 18:56:51 +0100 Received: from ella.mills.edu by ns (smtpxd); id XA04785 Received: (qmail 21452 invoked from network); 31 Dec 1997 09:56:46 -0800 Received: from localhost (HELO ella.mills.edu) (127.0.0.1) by localhost with SMTP; 31 Dec 1997 09:56:46 -0800 Message-Id: Errors-To: madole@mills.edu Reply-To: tuning@eartha.mills.edu Originator: tuning@eartha.mills.edu Sender: tuning@eartha.mills.edu