Everbach, E. Carr

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Swarthmore CollegeWorksEngineering Faculty Works Engineering1-1-2008Sound Commentary: ReplyE. Carr EverbachSwarthmore College, ceverba1@swarthmore.eduFollow this and additional works at: http://works.swarthmore.edu/fac-engineeringPart of the Engineering CommonsThis Response or Comment is brought to you for free and open access by the Engineering at Works. It has been accepted for inclusion in EngineeringFaculty Works by an authorized administrator of Works. For more information, please contact myworks@swarthmore.edu.Recommended CitationE. Carr Everbach. (2008). "Sound Commentary: Reply". Physics Today. Volume 61, Issue 1. 75-75.http://works.swarthmore.edu/fac-engineering/31Physics Today  Sound commentaryE. Carr Everbach  Citation: Physics Today 61(1), 75 (2008); doi: 10.1063/1.4796644 View online: http://dx.doi.org/10.1063/1.4796644 View Table of Contents: http://scitation.aip.org/content/aip/magazine/physicstoday/61/1?ver=pdfcov Published by the AIP Publishing    This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to  IP:  130.58.65.13 On: Fri,18 Jul 2014 14:03:54See www.pt.ims.ca/16296-33Optical LiquidsCatalogCargille Laboratories Inc.55 Commerce Road, Cedar Grove, NJ 07009973-239-6633 • Fax 973-239-6096cargillelabs@aol.com • www.cargille.comNew catalog of specialty optical liquidsfeatures high-transmission, safe-handling,laser liquids, plus fused silica matchingliquids, and specific refractive index liquids(1.300-2.11 nD). Now includes comparativediagrams of glasses and optical liquids. Write or call for free catalog.www.physicstoday.org January 2008    Physics Today 75frequencies. As Dyre points out,processes on both time scales are takingplace in glass-forming systems. How dowe relate one to the other?I admit I’m puzzled by the other twoletters. True, all molecular interactionsare ultimately quantum mechanical innature; but, like most specialists in thisfield, I see no reason to think that thegeneric glass transition is intrinsically a quantum, as opposed to classical, phenomenon. Hans-Jürgen Hoffmannseems to imply otherwise. In reply toBrahama Sharma, perhaps it will behelpful to say that when I talk about the“glass transition,” I am thinking ofmetallic glasses, polymeric glasses, anda wide variety of other noncrystallinematerials, not just silicate glass.James Langer(langer@physics.ucsb.edu)University of California, Santa BarbaraSound commentaryI’m tickled to see that the feature article“Medical Diagnostic Ultrasound”(PHYSICS TODAY, March 2007, page 44)is by my neighbor, Carr Everbach, andI enjoyed it. He starts by mentioning“sounding” water depths from thesound given by a lead weight hitting thebottom; he also mentions “the propaga-tion time” and that the phrase “tosound something out” is connected.I’m puzzled, though, since the soundof the sounding lead hitting the soft,muddy Mediterranean Sea bottomwould hardly be heard in the air, giventhe acoustic mismatch. Is there evi-dence that stethoscopes were heldagainst the ship’s hull? Or did someoneperhaps press an ear against the hull?The online edition of the Oxford Eng-lish Dictionary says that “sound” in thismeaning is simply related to water, alas,and not to aural sound. Moreover, thespeed of sound in water is so high thatthe tiny propagation-time interval forsound to travel from the sea bottom ishard to discern. Maybe that interval wasthe fall time in water, a viscous medium?Perhaps Carr has other evidence, soI may sleep soundly about this.Leonard Finegold(L@drexel.edu)Drexel UniversityPhiladelphia, PennsylvaniaEverbach replies: Leonard Fine-gold’s points are sound on severalcounts. The “sounding machine” usedby the ancient Greeks and for thou-sands of years thereafter consisted of alead weight that was thrown over-board, into the sound, tied to a knottedrope. The “propagation time” was thetime for the weight to fall at its terminalvelocity to the sea bottom; that time wasproportional to the length of rope paidout—that is, distance from the source.Thanks for sounding me out on thisquestion, Len!E. Carr Everbach(ceverba1@swarthmore.edu)Swarthmore CollegeSwarthmore, PennsylvaniaProfessionalkindnessesIn harkening back to life in physics 60or more years ago, it is useful to look atthe American Astronomical Society,whose membership today is aboutwhat American Physical Society mem-bership was then.Chatting recently with an as-tronomer friend, I was interested tolearn that he regularly receives compli-mentary preprints or reprints from col-leagues doing similar research. I cannotrecall from my personal experience en-joying that particular form of collegialexchange, but it reminds me of a timewhen professional relationships weremore personal, more cordial, and lesscompetitive. Preprint exchange strikes me as a so-cial amenity that should be encouragedtoday to foster friendly personal andprofessional relationships. It should bea general practice to send preprints orreprints to anyone who has made a sig-nificant contribution to one’s work andis mentioned, or should have been men-tioned, in the acknowledgments. Lawrence Cranberg(info@lawrencecranberg.org)Austin, TexasCorrectionNovember 2007, page 76—The PhysicalScience Study Committee was mistak-enly referred to as the Physics ScienceStudy Committee. You may make single copies of articles ordepartments for private use or for research.Authorization does not extend to systematicor multiple reproduction, to copying for pro-motional purposes, to electronic storage ordistribution (including on the Web), or torepublication in any form. In all such cases,you must obtain specific, written permissionfrom the American Institute of Physics.Contact theAIP Rights and Permissions Office,Suite 1NO1,2 Huntington Quadrangle,Melville, NY 11747-4502Fax: 516-575-2450Telephone: 516-576-2268E-mail: rights@aip.orgRights & Permissions This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to  IP:  130.58.65.13 On: Fri,18 Jul 2014 14:03:54

Sound Commentary: Reply

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