“AppliedPhysics” from

Newton toWorld War I

Philadelphia World Exposition, 1876,Corliss Engine

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 (1880-90s)? 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)

Baconian classical physics? Bacon’s dream, 1627:

– “The empire of man over things is founded on the artsand sciences alone, for nature is to be commanded onlyby obeying her.... The true end of knowledge ... [is] thebenefit 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?

“Applied” Newtonian physics? Marxist analysis (1931) of Principia?

Hydrodynamics for shipbuilding or a refutation ofDescartes?

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

The Industrial Revolution Precipitated European “modernity”

– Shift from agrarian, handicraft economy to industrializationand machine manufacturing

– Colonization prompted by economic growth, need formarkets and raw materials, and technologies of domination Guns, steel and germs

– Rise of cities, urban social classes, domestic sphere, newgendered 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)

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 andsteel industries

– Henry Bessemer’s accidental invention of steel not science-based, but derived from trial and error in the foundry

– Read paper to BAAS, 1856, on new process of forcing airthrough molten iron, to burn out carbon

Physics in the SecondIndustrial 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.

Optical industries Mutual benefit of physics and optical industry

– Problems of chromatic aberration in lenses solved by physicsof refraction and achromatic lenses

– Fraunhofer’s accidental discovery of spectral lines, 1814– Zeiss Optical Works, Jena, with large research laboratories in

the factories, produced glass for precision instruments

LensRed

VioletWhite light

R

V

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 distributionsystems, user meters, corporate structures, state regulation,physics-trained electrical engineers

Edison as non-physicist exception– Physics and telephony: long-distance transmission

Inventing the telephone, IHelmholtz’s electromagnetic sound

generator for physiology (1860s)

Battery

Sender Receiver

SwitchElectromagnet

Mercury switch, cycles at frequency of Fork 1Switch at 1, only Fork 1 sounds; switch at 2, both forks sound

1

2

Inventing the telephone, 2Bell’s multiplexed telegraph, 1873

Two messages over one set of wires, using differentfrequencies!

Battery

Sender 1 Sender 2

Receiver 1

Receiver 2

Sender Distantreceiver

Inventing the telephone, 3Bell’s telephone, 1873

Replace the tuning fork with a multi-frequencyreceiver and generator

BatterySound receiverSound generator

“Watson, I need you!” “Watson, I need you!”

Electricity as Big Business Edison--telegrapher, inventor, business man

– Menlo Park Lab, 1876--seeks to factory-produce invention– DC power generating systems, 1882

http://americanhistory.si.edu/lighting/19thcent/hall19.htm– Merger with AC competitor to form GE, 1892, negotiated by

banker J. P. Morgan; kept trying to buy all competitors (andtheir patents!) to create a giant corporation, required as manylawyers 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

Physics becomes a profession Physics as a discipline separates from

“natural philosophy” by 1850 in the Germanuniversities

– 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

Physics and World War I Physics more important than chemistry

– Poison gas used on both sides, not crucial in outcome ofthe war

USA’s National Research Council, 1916-18– Placed 12-15 academic physicists in Army– Significant applications of physics to war

Range-finding, submarine detection, synchronization ofmachine-gun fire through plane propellers

– Disbanded after 1918; little new physics– Would provide model for WWII