1/9/2016 User:Guy vandegrift/sandbox ­ Wikipedia, the free encyclopedia User:Guy vandegrift/sandbox From Wikipedia, the free encyclopedia < User:Guy vandegrift Condensing Wikipedia's Quantum mechanics timeline See also v:How things work college course/Quantum mechanics timeline This "timeline of quantum mechancis" shows some of the key steps in the development of quantum mechanics, quantum field theories and quantum chemistry.[1][2] Contents 1 19th century 2 20th century 2.1 1900–1909 2.2 1910–1919 2.3 1920–1929 2.4 1930–1939 2.5 1940–1949 2.6 1950–1959 2.7 1960–1969 2.8 1971–1979 2.9 1980–1999 3 21st century 4 References https://en.wikipedia.org/wiki/User:Guy_vandegrift/sandbox 1/15 1/9/2016 User:Guy vandegrift/sandbox ­ Wikipedia, the free encyclopedia 19th century 1859 – Kirchhoff introduces the concept of a blackbody and proves that its emission spectrum depends only on its temperature.[1] 1860–1900 – Ludwig Eduard Boltzmann, James Clerk Maxwell and others develop the theory of statistical mechanics. Boltzmann argues that entropy is a measure of disorder.[1] Boltzmann suggests that the energy levels of a physical system could be discrete based on statistical mechanics and mathematical arguments; also produces a primitive diagram of a model of an iodine molecule that resembles the orbital diagram. Image of Becquerel's photographic 18871888 – Heinrich Hertz discovers the photoelectric effect, and also demonstrates experimentally that plate which has been fogged by exposure to radiation from a uranium electromagnetic waves exist, as predicted by Maxwell.[1] salt. The shadow of a metal Maltese 1888 – Johannes Rydberg modifies the Balmer formula to include all spectral series of lines for the hydrogen Cross placed between the plate and atom, producing the Rydberg formula. the uranium salt is clearly visible. 1895 – Wilhelm Conrad Röntgen discovers X­rays in experiments with electron beams in plasma.[1] 1896 – Antoine Henri Becquerel accidentally discovers radioactivity while investigating the work of Wilhelm Conrad Röntgen; he finds that uranium salts emit radiation that resembled Röntgen's X­rays in their penetrating power, and accidentally discovers that the phosphorescent substance potassium uranyl sulfate exposes photographic plates.[1][3] 1896 – Pieter Zeeman observes the Zeeman splitting effect by passing the light emitted by hydrogen through a magnetic field. 1896–1897 Marie Curie investigates uranium salt samples using a very sensitive electrometer device that was invented 15 years before by her husband and his brother Jacques Curie to measure electrical charge. She discovers that the emitted rays make the surrounding air electrically conductive. Through a systematic search of substances, she finds that thorium compounds, like those of uranium, emitted "Becquerel rays", thus preceding the work of Frederick Soddy and Ernest Rutherford on the nuclear decay of thorium to radium by three years.[4] 1897 – Ivan Borgman demonstrates that X­rays and radioactive materials induce thermoluminescence. 1899 to 1903 – Ernest Rutherford investigates radioactivity and coins the terms alpha and beta rays in 1899 to describe the two distinct types of radiation emitted by thorium and uranium salts. With Frederick Soddy he discovers nuclear transmutation as radioactive thorium is convertd itself into radium through a process of nuclear decay and a gas (later found to be 4 [5] 2He). He also invents the nuclear atom model and becomes known as the "father of nuclear physics"[6] 20th century https://en.wikipedia.org/wiki/User:Guy_vandegrift/sandbox 2/15 1/9/2016 User:Guy vandegrift/sandbox ­ Wikipedia, the free encyclopedia 1900–1909 1900 – To explain black­body radiation (1862), Max Planck suggests that electromagnetic energy is emitted in quantized form, in multiples of the elementary unit E = hν, where h is Planck's constant and ν is frequency. 1902 – To explain the octet rule (1893), Gilbert N. Lewis develops the "cubical atom" theory in which electrons in the form of dots are positioned at the corner of a cube. Predicts that single, double, or triple "bonds" result when two atoms are held together by multiple pairs of electrons between the atoms. 1903 – Antoine Becquerel, Pierre Curie and Marie Curie share the 1903 Nobel Prize in Physics for their work on spontaneous radioactivity. 1904 – Richard Abegg notes the pattern that the numerical difference between the maximum positive valence, such as +6 for H2SO4, and the maximum negative valence, such as −2 for H2S, of an element Einstein, in 1905, when he wrote the tends to be eight (Abegg's rule). Annus Mirabilis papers 1905 – Albert Einstein explains the photoelectric effect. He postulates that light itself consists of individual quantum particles (photons). 1905 – Einstein explains the effects of Brownian motion as caused by the kinetic energy (i.e., movement) of atoms, which was subsequently, experimentally verified by Jean Baptiste Perrin, thereby settling the century­long dispute about the validity of John Dalton's atomic theory. 1905 – Einstein publishes his Special Theory of Relativity. 1905 – Einstein theoretically derives the equivalence of matter and energy. 1907 to 1917 – To test his planetary model of 1904 [7] he sent a beam of positively charged alpha particles onto a gold foil and noticed that some bounced back, thus showing that an atom has a small­sized positively charged atomic nucleus at its center. However, he received in 1908 the Nobel Prize in Chemistry "for his investigations into the chemistry of radioactive substances",[8] which followed on the work of Marie Curie, not for his planetary model of the atom; he is also widely credited with first "splitting the atom" in 1917. In 1911 Ernest Rutherford explained the Geiger–Marsden experiment by invoking a nuclear atom model and derived the Rutherford cross section. 1909 – Geoffrey Ingram Taylor demonstrates that interference patterns of light were generated even when the light energy introduced consisted of only one photon. This discovery of the wave–particle duality of matter and energy is fundamental to the later development of quantum field theory. 1909 and 1916 – Einstein shows that, if Planck's law of black­body radiation is accepted, the energy quanta must also carry momentum p = h / λ, making them full­fledged particles. 1910–1919 https://en.wikipedia.org/wiki/User:Guy_vandegrift/sandbox 3/15 1/9/2016 User:Guy vandegrift/sandbox ­ Wikipedia, the free encyclopedia 1911 – Lise Meitner and Otto Hahn perform an experiment that shows that the energies of electrons emitted by beta decay had a continuous rather than discrete spectrum, in apparent contradiction to the law of conservation of energy. A second problem is that the spin of the Nitrogen­14 atom was 1, in contradiction to the Rutherford prediction of ½. These anomalies are later explained by the discoveries of the neutrino and the neutron. 1911 – Ștefan Procopiu performs experiments in which he determines the correct value of electron's magnetic A schematic diagram of the apparatus dipole moment. In 1913 he is also calculated a for Millikan's refined oil drop theoretical value of the Bohr magneton based on experiment. Planck's quantum theory. 1912 – Victor Hess discovers the existence of cosmic radiation. 1913 – Robert Andrews Millikan publishes the results of his "oil drop" experiment that measures the charge of the electron. This makes it possible to calculate the Avogadro constant and the atomic weight of the atoms. 1913 – Ștefan Procopiu publishes a theoretical paper with the correct value of the electron's [9] magnetic dipole moment.B. 1913 – Niels Bohr theoretically obtains the value of the electron's magnetic dipole moment. 1913 – Johannes Stark and Antonino Lo Surdo independently discover the shifting and splitting of the spectral lines of atoms and molecules due to an external static electric field. 1913 – To explain the Rydberg formula (1888), which calculates the emission spectra of atomic hydrogen, Bohr hypothesizes that electrons revolve around a positively charged nucleus at certain fixed "quantum" distances, with specific energies such that transition between orbits requires "quantum" emissions or absorptions of energy. 1914 – James Franck and Gustav Hertz conduct an experiment on electron collisions with mercury atoms, that provides new verification of Bohr's model of quantized atomic energy levels.[10] 1915 – Einstein presents what are now known as the Einstein field equations. They specify how the geometry of space and time is influenced by matter, and form the core of Einstein's General Theory of Relativity. 1916 – Paul Epstein[11] and Karl Schwarzschild,[12] working independently, derive equations for the linear and quadratic Stark effect in hydrogen. 1916 – To account for the Zeeman effect, Arnold Sommerfeld suggests electrons in an atom might be "elliptical orbits" in addition to "spherical orbits". 1918 – Sir Ernest Rutherford notices that, when alpha particles are shot into nitrogen gas, his scintillation detectors shows the signatures of hydrogen nuclei. Rutherford determines that the only place this hydrogen could have come from was the nitrogen, and therefore nitrogen must contain hydrogen nuclei. He thus suggests that the hydrogen nucleus, which is known to have an atomic number of 1, is an elementary particle, which he decides must be the protons hypothesized by Eugen Goldstein. 1919 – Building on the work of Lewis (1916), Irving Langmuir coins the term "covalence" and postulates that coordinate covalent bonds occur when two electrons