Applied Physics from Newton to World War I. Philadelphia World Exposition, 1876, Corliss Engine

Transcription

1 Applied Physics from Newton to World War I Philadelphia World Exposition, 1876, Corliss Engine

2 Last time Electromagnetic waves in space Predicted by Maxwell, observed by Hertz Troubling phenomena not explainable by classical physics Constancy of speed of light, regardless of direction of movement in the aether ( s)? Absorption (1814) and emission (1850s) spectral lines, unique to every chemical element--why? Advance of perihelion of Mercury? X-rays, radioactivity and sub-atomic particles (electrons) (next week)

3 Baconian classical physics? Bacon s dream, 1627: The empire of man over things is founded on the arts and sciences alone, for nature is to be commanded only by obeying her... The true end of knowledge... [is] the benefit and use of life. Task of lecture Did classical physics fulfill Bacon s dream? Did, inversely, technological advances affect practice of classical physics? How, when and why did physics become a profession?

4 Applied Newtonian physics? Marxist analysis (1931) of Principia? Hydrodynamics for shipbuilding or a refutation of Descartes? Newton at the Royal mint and mines 18c Newtonian lectures for merchants and seamen in London s coffee houses Longitude at sea & lunar theory? Accurate clocks, not lunar theory, win the Admiralty prize Steam engines & Newtonian mechanics? Mathematicians (Denis Pappin in 1690) or artisans (Thomas Newcomen in 1712, James Watt in 1760s) Steam engines as context for energy conservation law Lightning rods & electrical theory? Non-Newtonian physics

5 The Industrial Revolution Precipitated European modernity Shift from agrarian, handicraft economy to industrialization and machine manufacturing Colonization prompted by economic growth, need for markets and raw materials, and technologies of domination Guns, steel and germs Rise of cities, urban social classes, domestic sphere, new gendered roles, bureaucratized governments, experts European population doubles between 1750 and 1850 Driven by 4 technological changes Muscle power replaced by water & steam Human skill replaced by machines Increased production of raw materials (iron, steel, coal) Improved transport and communication (canals, railroads, telegraph, steamships, cheap newspapers)

6 Physics in the Industrial Rev. Chemistry (not physics) in early industries Soaps, bleaches, synthetic dyes in textile mills Early industrial research labs usually for quality control not innovation Electrolysis in heavy chemical industry Newtonian inventors & lecturers Vaguely empirical, not mathematical Newtonianism as ideology rather than scientific content Untrained practitioners innovate in iron and steel industries Henry Bessemer s accidental invention of steel not sciencebased, but derived from trial and error in the foundry Read paper to BAAS, 1856, on new process of forcing air through molten iron, to burn out carbon

7 Physics in the Second Industrial Revolution? Defined by new science-based industries after 1850 Advanced railroad and ship-building Long-distance telegraph and telephone Automobile and internal combustion engines Optical and glass industries Heavy electrical industries, distributing light and power Measuring physics after 1850 Apparatus and value of precision for making reasonable citizens and factory workers International standards for international industries Imperial Physical-Technical Institute, 1887, Berlin World s largest physics lab before WWI National Physical Laboratory, 1899, London National Bureau of Standards, 1901, Washington D.C.

8 Optical industries Mutual benefit of physics and optical industry Problems of chromatic aberration in lenses solved by physics of refraction and achromatic lenses White light Lens Red Violet R V Fraunhofer s accidental discovery of spectral lines, 1814 Zeiss Optical Works, Jena, with large research laboratories in the factories, produced glass for precision instruments

9 Electrical industries Physics in the electrical industries First major, new industry derived from physics Physics and telegraphy Needs: batteries, insulation, signal decay and detection, trans- Atlantic cables, multiplexing (many signals over same wire) First transatlantic cable, failed in 1857, successful in 1868, William Thomson becomes Lord Kelvin Encourages manufacturing of electrical lab instruments Physics and electric lighting Needs: light bulbs, dynamos, motors, power distribution systems, user meters, corporate structures, state regulation, physics-trained electrical engineers Edison as non-physicist exception Physics and telephony: long-distance transmission

10 Inventing the telephone, I Helmholtz s electromagnetic sound generator for physiology (1860s) Electromagnet Switch 2 Sender 1 Receiver Battery Mercury switch, cycles at frequency of Fork 1 Switch at 1, only Fork 1 sounds; switch at 2, both forks sound

11 Inventing the telephone, 2 Bell s multiplexed telegraph, 1873 Two messages over one set of wires, using different frequencies! Receiver 1 Sender 1 Sender 2 Receiver 2 Sender Battery Distant receiver

12 Inventing the telephone, 3 Bell s telephone, 1873 Replace the tuning fork with a multi-frequency receiver and generator Watson, I need you! Watson, I need you! Sound generator Battery Sound receiver

13 Electricity as Big Business Edison--telegrapher, inventor, business man Menlo Park Lab, seeks to factory-produce invention DC power generating systems, Merger with AC competitor to form GE, 1892, negotiated by banker J. P. Morgan; kept trying to buy all competitors (and their patents!) to create a giant corporation, required as many lawyers as engineers GE Research Laboratory, 1902 Charles Steinmetz (German engineer), Willis Whitney (MIT) Success with tungsten filaments for lamps (monopoly) $30 million annual profit by 1920, solely from lamp sales Largest, best-equipped physics laboratory in USA (perhaps world) by 1916

14 Physics becomes a profession Physics as a discipline separates from natural philosophy by 1850 in the German universities University labs by 1870s; Wilder Laboratory by 1899 German Physical Society, 1847 Industrial research labs by 1890s Professional physicists with PhDs by 1900 Ca. 500 academic physicists Includes 103 in Germany, 99 in USA, 86 in UK Ca. 100 non-academic physicists

15 Physics and World War I Physics more important than chemistry Poison gas used on both sides, not crucial in outcome of the war USA s National Research Council, Placed academic physicists in Army Significant applications of physics to war Range-finding, submarine detection, synchronization of machine-gun fire through plane propellers Disbanded after 1918; little new physics Would provide model for WWII