Timeline, Chapters 1-­‐4 Not on exam, just a summary za vaš We did cover other things where I didn’t provide dates. This is only to give you a be`er appreciaRon for how these developments in so many different areas were happening at the same Rme •
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1760: Bernoulli and ½ m<v2> = 3/2 kT 1800’s: Law of Definite ProporRons 1800’s: evidence for breakdown of classical physics via atomic spectra measurements 1828: Brown observed random walk/irregular jiggling moRon of pollen grains suspended in water (aka Brownian moRon) 1867: Discovery of “cathode rays” 1879: Crookes found cathode rays travel in straight line, carry momentum, can be bent by B field & are negaRvely charged 1885: Balmer fit H spectrum, discovery of Balmer-­‐Rydberg equaRon for light emi`ed from atoms 1895: X-­‐Rays discovered by Roentgen 1897: Thomson discovered electron (cathode rays are “charges of negaRve electricity carried by parRcles of ma`er”) 1900: Idea of atoms sRll doubted by prominent scienRsts 1900: Planck performed empirical fit to black body data, proposed quanRzaRon of radiaRon 1905: 6 history making papers of Einstein 1905: Einstein used Planck’s quanRzaRon to explain photo-­‐electric effect 1908: Minkowski space 1909: Millikan’s oil drop experiment, measurement of q and m of electron 1911: Rutherford’s planetary model of atoms 1912: Von Laue suggested using crystals as 3-­‐D graRng 1912: Observed frequency of sca`ered light < frequency of incident light 1913: Bohr proposed quanRzaRon of energy of electrons in atoms 1916: Mach died, sRll refusing to believe in atoms 1919: Rutherford discovered p, nucleus can be divided 1923: Compton argued light is quanRzed, thus observaRon of 1912 is expected 1932: Chadwick discovered n in nucleus 1953: Individual atoms first imaged with field-­‐ion microscope