iPh136abc 2008-2009Kip Thorne [version 08.1.K]APPLICATIONS OF CLASSICAL PHYSICS1. COURSE DESCRIPTION AND PHILOSOPHYThis course has been taught here at Caltech since the 1980s by various faculty, basedinitially on not es that I [Kip] wrote and later on drafts of a textbook by me and RogerBlandford. A few uears year ago Roger moved to Stanford to create and direct a newCenter for Particle Astrophysics and Cosmology there. He and I are now finalizing thetextbook for publication.This course is designed to introduce students to the fundamental s of all the majorbranches of classical physics (except classical mechanics, electromagnetic theory, and ele-mentary thermodynamics, which we assume the students have already learned elsewhere),and also t o expose students to many of the exciting modern develo pments involving clas-sical physics. We [Roger and I] regard such a course as important for two reasons: (i) Webelieve that every PhD physicist should be familiar with the basic concepts, the spirit anda few applications of all the major branches of classical (and also quantum) physics. (ii) Alarge fraction of Caltech’s physics and astronomy graduate students use classical physicsextensively in their research a nd even more of them g o on to careers in which classicalphysics is an essential component. This is not surprising as many of the most importantrecent developments in physics—and more generally in science and engineering—involveessentiall y “classical” subjects such as optics, fluids, kinetic theory, and general relativ ity.This course is a survey course designed to accomplish two goals. First, we seek to giv ethe student a clear understanding of the basic concepts and principles of classical physics.We present these principles in the language of modern physics (not nineteenth centuryapplied mathematics), and present them for physicists as distinct from mat hemati ci ans orengineers. As far as possible, we emphasize theory t hat involves general principles thatextend well beyond t he particular subjects we study.Second, we teach the student how to apply classical physics ideas . We do so by present-ing contempo ra ry applications from a vari ety of fields, such as fundamental physics, experi-mental physics and applied physics; astrophysics and cosmology; geophysics, oceanographyand meteorology ; engineering, radio science, and information science. Why is the rangeof applications so wide? Because we believe that physicists should have at their disposalenough understanding of general principles to attack problems that a rise in quit e unfamil-iar environments. In the modern era, a large fraction of PhD physics students will go onto careers away from the core of fundamental physics. For such students, a broad exposureto non-core applications will be of great value; for those who wind up in the core, such anexposure is of value culturally, and also because ideas from o ther fields often turn out tohave impact back in the core of physics. Our examples will illustrate how basic conceptsand problem solving techniques are freely interchanged between disciplines.The amount a nd variety of material covered in this course may seem overwhelming.If so, please keep in mind the key goals of the course: to teach the fundamental concepts,which are not so extensive that they should overwhelm, and to illustrate those concepts.iiiThe g oal is not to master the many illustrations, but rather to learn the spirit o f how toapply the concepts.The course material will also seem much more manageable and less overwhelmingwhen one realizes that the same concepts and problem solving techniques are appearingover and over ag ain, in a variety of different subjects and applications. We shall identifythese unifying concepts as the course proceeds and shall remind the student of where theyhave arisen before.Classical physics is defined as the physics where Planck’s constant can be approxi-mated as zero. To a large extent, it is the body of physics for which the fundamental equa-tions were established prior to the development of quantum mechanics in the 1920’s. Doesthis imply that it should be studied in isolation from quantum mechanics? Our answer is,most emphatically, “No!”. The reasons are simple. First, quantum mechanics has primacyover classical physics: classical physics is an approx imation, often excellent, sometimespoor, to quantum mechanics. Second, in recent decades many concepts and mathematicaltechniques developed for quantum mechanics have been imported into classical phy sicsand used to enlarge our classical understanding and enhance our computational capability.An example that we shall discuss occurs in plasma physics, where nonlinearly interactingwaves are treated as quanta, despite the fact that they are solutions o f classical field equa-tions. Third, ideas developed initially for “classical” problems are frequently adapted forapplication to avowedly quantum mechanical subjects; examples are found in supersym-metric string theory and in the liquid drop model of the atomic nucleus. Because of theseintimate connections between quantum and classical physics, quantum physics will appearfrequently in this course, and in a variety of ways.After a preliminary week and chapter on this course’s geometric viewpoint on physics(both Newtonian and relativistic), the course a nd textbook are divided into si x parts: Wecover sta tistical physics and optics in the first term, elasticity and fluids in the second, andplasmas and general relativity in the third. Each part is organised into chapters; we coverone chapter per week. It is our intention that each term can be ta ken indep endently, thougha considerable degree of cross-referencing is unavoidable and, of course, helpful. No te thatbasic electromagnetic theory, classical mechanics and equilibrium thermodynamics, trulyclassical subjects, are absent. This is because they a re usually sti ll part of an undergraduatephysics curriculum. We shall assume that the student has some familiarity with thesesubjects.2. COORDINATES OF INSTRUCTOR, TA AND WEB SITE.• Instructor:* Kip Thorne: 152 West Bridge, X4598, [email protected]* Kip’s administrative assistants a re:Shirley Hampton, 151 Bridge Annex, extension 4597 , [email protected]— for issues related to the TAPIR research group (Theoretical AstroPhysicsIncluding Relativity and cosmology), in which Kip resides.JoAnn Boyd, 161 West B ridge, extension 4298,
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