Outline - 19thCenSci (11-24-03)

Outline - 19thCenSci (11-24-03) - 1 2 Nineteenth Century...

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Unformatted text preview: 1 2 Nineteenth Century Unification Unification and Dissolution nSearch for unifying concepts and laws in physics nConfidence in the completeness & certainty of physics 3 The Core Problems nHeat nLight nElectricity uEnergy--the Central Unifying Concept of 19th century physics Energy--the nMatter 4 Heat nA substance: caloric uNot the same as phlogiston uCaloric is heat 5 The problem of friction nHow can the caloric theory explain the heat produced by friction? uIs caloric liberated by rubbing objects? uExperiments to test this-tBoth objects get warm 6 Observations of frictional heat nBenjamin Thompson (Count Rumford) uBlunt objects produce more heat than sharp ones (the opposite of what you would expect if caloric is being rubbed out of an object) 7 Humphry Davy's experiment nDavy observes that two pieces of ice, kept at freezing, will melt each other by frictional heat 8 How does heat behave? nNotice-- a different question from "what is heat?" heat?" nJoseph Fourier: Analytical Theory of Heat (1822) nSadi Carnot: Reflections on the Motive Force of Fire (1824) Carnot: nFormed the basis for thermodynamics 9 Mechanical theory of heat nHeat is a form of motion nDerived from experiments and from the 19th century search for unification of the phenomena of nature 10 Robert Mayer 1 nFirst notion of "energy" -- heat and motion are two forms of something more energy" general 11 James Prescott Joule nMeasures mechanical equivalent of heat nAdds electricity to the unification nJoule's law:E = k I2/R Joule' law: 12 First Law of Thermodynamics nEnergy cannot be created or destroyed nHermann von Helmholtz 13 Second Law of Thermodynamics nWilliam Thomson (Lord Kelvin) nHeat does not, in nature, move from a colder body to a warmer body 14 Entropy n Rudolf Clausius n in a system in which there are irreversible flows of energy, the amount of entropy or randomness in that system will always increase n "Heat death of the universe" 15 Light nWhat is it? 16 Particles nThe Newtonian model -- consistent with mechanical view of nature nBUT -- not consistent with certain aspects of light's behavior light' 17 18 19 Diffraction Interference Interference n Constructive and destructive interference of waves 20 Polarization nLight appears to have a plane of motion nExplained in terms of transverse waves 21 Waves nThomas Young nLight travels as transverse waves through the medium of the ether 22 Electricity nA key unifying phenomenon 23 Electrochemistry 2 nHumphry Davy nDiscovery of electrolysis 24 Electromagnetism nH.C. Oersted nDiscovery of electromagnetism 25 Electrodynamics nA. M. Ampere nlaws of electric currents 26 Thermoelectricity nThomas Seebeck nThe relation between electricity & heat 27 Unifying theories of electricity nMichael Faraday nThe electomagnetic field 28 James Clerk Maxwell nEquations of electromagnetic propogation 29 Unifying Chemistry nLinking organic and inorganic chemistry nFriedrich Whler and the synthesis of urea W 30 Electrical Nature of Matter nJons Jacob Berzelius nIon theory 31 The Periodic Table nElements put in series, in order of atomic weights, and organized by valence (combining number) nDmitri Mendeleev nThe table reveals gaps 32 33 The Periodic Table Question: nWhy is the concept of energy so important for 19th century physics? 3 ...
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