higher speeds	Quantum Field Theory (1920s-1970s)	Relativistic Mechanics (1905)
lower speeds	Quantum Mechanics (1926)	Classical Mechanics (1687)
	smaller distances	larger distances

Specific dates for each theory are a little misleading, because they were shaped over many years, with many workers involved in their creation, criticism, experimental testing, refinement, and development.

• "strong"
• "electromagnetic"
• "weak"
• "gravitational"

Note that all of these examples of forces are fundamentally electromagnetic!

Example: electricity, magnetism, and optics

• an electric current can deflect a magnetic compass needle (Ørsted 1820)
• Ampère hypothesizes that all magnetic effects are due to charges in motion (1820)
• Ampère conducts experiments on the magnetic effects of electric currents (1820)
• a moving magnet can create an electric current in a wire (Faraday 1831)
• Faraday observes that magnets can affect light ("Faraday rotation," 1845)
• Faraday proposes the underlying unity of all physical phenomena, including light, heat, electricity, and magnetism (1845)
• Faraday's lines of force (1830s); Maxwell's field concept (1850s)
• Maxwell's theory of electromagnetism (1861)
• Maxwell derives a wave equation from his theory; his calculations gave strong support to the hypothesis that light is an electromagnetic wave (1864)
• Hertz conducts experiments to generate, transmit, and detect electromagnetic waves, and study their properties, confirming Maxwell's theory of electromagnetic waves (1886)
• special theory of relativity (Einstein, 1905)

• Leucippus, Democritus (500 BCD - 400 BCE)
• law of conservation of mass in chemical reactions (Lavoisier, 1789)
• law of definite proportions (Proust, 1798)
• Dalton's atomic theory: one type of atom for each element, and compounds are formed by combining atoms in fixed proportions (Dalton, 1803)
• samples of gas with equal P, V, T have equal numbers of particles (Avogadro, 1811)
• Brownian motion of pollen observed (Brown, 1827)
• Faraday states that the atomic hypothesis is still an unverified hypothesis, although it is commonly treated as fact (1844)
• kinetic theory of gases (Bernoulli, 1738; ... Maxwell 1859; Boltzmann, 1871)
• empirical periodic table of elements (Mendeleev, 1869)
• Mach's anti-atomism (lived 1838-1916)
• Einstein's theory of Brownian motion, and five (!) other independent ways of calculating Avogadro's number (1905)
• experimental verification of Einstein's theory of Brownian motion, and of Avogadro's number (Perrin, 1908)
• electron discovered (J.J. Thomson, 1897)
• quantum hypothesis for emission and absorption of electromagnetic waves (Planck, 1900)
• photon concept (Einstein, 1905)
• a plethora of atomic models: dynamid model (Lenard, 1903), plum-pudding model (J.J. Thomson, 1904), Saturnian model (Nagaoka, 1904), electron-fluid model (Rayleigh, 1906), vibrating-electron model (Jeans, 1906), expanding-electron model (1906), archion model (Stark, 1910)
• discovery of atomic nucleus (Geiger, Marsden, Rutherford, 1909)
• Rutherford's planetary atomic model (1911)
• Bohr's atomic model (1913)
• X-ray diffraction experiments reveal microscopic structure of crystals (von Laue, 1912; Bragg, 1912)
• discovery of atomic isotopes (J.J. Thomson, 1912)
• spectroscopic experiments explain periodic table of elements in terms of atomic structure and supports Bohr's atomic model (Moseley, 1913)
• matter waves (de Broglie, 1924)
• quantum mechanics (Bohr, Heisenberg, Schrodinger, Dirac, etc.; 1926)
• modern quantum-mechanical atomic model (1927)
• band theory of conductors and semi-conductors (1928 - 1931)
• discovery of the neutron (Chadwick, 1932)
• idea of, and theory of, the laser (Einstein, 1917)
• first working laser (Maiman, 1960)
• magnetic atom trap (Paul, 1960)
• scanning tunnelling microscopes observe single atoms (Binnig and Rohrer, 1981)

• Hertz conducts experiments to generate, transmit, and detect electromagnetic waves, and study their properties, confirming Maxwell's theory of electromagnetic waves (1886)
• first trans-Atlantic radio transmissions using Morse code (Marconi, 1902)
• first radio transmission of voice and music (Fessenden, 1900)
• first radio program broadcast (Fessenden, 1906)
• first TV broadcasts (1930s); plasma TV invented (1936); TV became popular in the 1960s
• ENIAC computer (27 tonnes, 1000 sq. ft. floor space, 5000 operations per second) (1946)
• invention of the transistor (1947)
• prototype transistor radio (1948)
• Whirlwind computer (memory: 256x16 bits) (1951)
• first commercially-available transistor radios (1954)
• first working integrated circuit (Kilby; Noyce, 1958)
• IBM series of transistorized computers (1959)
• I got my first transistor radio (1970)
• my family got our first colour-TV (1972)
• I bought my first hand-held calculator (1974)
• I take my first computing course (1976)
• first home computers go on sale; about 4 kB of memory (1977)
• I bought my first stereo (vinyl recordings) (1978)
• Sony Walkman (1979)
• first hard disk drive for microcomputers (Seagate, 5 MB) (1980)
• first CD players (early 1980s)
• first video stores (mid-1980s)
• cable TV (1950s; became popular in the late 1970s and early 1980s)
• I bought my first home computer (1987)
• mobile phones (1950s; started becoming popular in the 1990s)
• commercial email software appears (1976); email explodes in popularity (1990s)
• world-wide-web invented (Berners-Lee, CERN, 1990)
• web browsers, web servers (1991)
• by the end of 1992 there were 26 web sites world wide; by 1998 there were nearly 1 million commercial web sites
• 30 April, 1993: CERN announces that it will make internet technology freely available to anyone
• internet search engines (mid 1990s)

• briefly overview the whole chapter, before lecture
• read each section in detail, before lecture
• active reading: write down questions as you read
• work through some examples, and solve some problems, before lecture
• re-read difficult or problematic passages after lecture; then work through more examples and problems
• repeat in a condensed form in preparation for mid-term exam
• repeat in a condensed form in preparation for final exam
• thus, you end up reading and re-reading at least 3 or 4 times

• The Brain that Changes Itself, by Norman Doidge, MD
• hardware and software
• function localization in the brain
• neural plasticity

Moral: You make yourself smart by the mental and physical activities that you choose to do.