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The Nuclear Atom (1904-1912)

  • Alan A. Grometstein

Abstract

We have touched on light’s odd behavior in acting as if it were a particle when encountering matter but as if it were a wave when in flight. We have seen a comparable oddity in the behavior of electrons, and it has been suggested that other “particles” are equally odd. It is time to move to larger structures: in this chapter, we discuss models of the atom that were developed early in the 20th century. The details of the models are less important than the underlying concepts and the phenomena they were intended to explain. We are running beyond the limits of classical physics and will repeatedly find that classical explanations are inadequate. Novel explanations are required.

Keywords

Impact Parameter Point Mass Alpha Particle Deflection Angle Gold Atom 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Endnotes

  1. 1.
    In the invasion of England in 1066, the point man for William of Normandy was his knight Taillefer. Reciprocally, the invasion of the Continent from England in 1945 was led by a man named Eisenhower. “Taillefer” and “Eisenhower” each means “hewer of iron.”Google Scholar
  2. 2.
    [Descartes 1955. Part 2, Principle 20].Google Scholar
  3. 3.
    [Newton (1730) 1979: Book Three, Part I].Google Scholar
  4. 4.
    In his delightful book Knowledge and Wonder, Victor Weisskopf asserts that 1 mm3 of oil will cover up to 3 m2 of water. From this he deduces that an oil molecule is 0.3 mn wide. [Weisskopf 1979:70]. Can you reproduce his calculations? I understand that Benjamin Franklin made similar calculations in his day.Google Scholar
  5. 5.
    Nobel Award address, November 12, 1922; qu [Gleick 1992:38].Google Scholar
  6. 6.
    Z is the atomic number of the element. It is the number of electrons in the neutral atom and, consequently, the total positive charge in the atom. Z ranges from 1 for hydrogen to over 100 for the transuranic elements.Google Scholar
  7. 7.
    Rather, they are more distinctive: rare cases have been reported of individuals with the same fingerprints but the spectrum of an element is unique. The story has often been told how helium was discovered by observing a novel set of spectral lines in sunlight. (Hence, helium, after Helios, the god of the sun.) The gas was later found on earth.Google Scholar
  8. 11.
    Sommerfeld (1868–1951), a major figure in German physics as the quantum revolution developed. One of the first senior classical physicists to appreciate the new ideas, he contributed many improvements to the emerging theory. Like so many of the pioneers in quantum mechanics, he was a gifted musician. The anecdote about the piano is found in [Guillemin 1968:56].Google Scholar
  9. 12.
    Rutherford, English physicist (1871–1937), Nobel laureate, 1908.Google Scholar
  10. 14.
    A famous problem debated by medieval scholastics was posed by Jean Buridan—he of the double-ended spear (see endnote 1 of Chapter 4). To illustrate the point of moral indifference, Buridan postulated an ass which was tethered exactly halfway between two identical bales of hay. Will it starve to death, having no rational basis for turning to one bale rather than the other?Google Scholar
  11. 15.
    If you don’t like repulsive,is repellent any better? It is difficult to avoid the overtones of negative emotion in the adjectives. You must have heard of the apocryphal courtier who ran to Louis XVI, shouting, “Sire, the people are revolting!” Louis responded, “Yes, aren’t they.”Google Scholar
  12. 16.
    The appendix on spheres may shed light on the field inside the core.Google Scholar
  13. 17.
    Calculating the path of an alpha inside a Thomson core is not difficult, neither is it enlightening. Good approximations can be found in [Krane 1996:Chap. 6], an excellent text.Google Scholar
  14. 18.
    Gold does not have a crystalline structure, so, while the atoms are closely packed in the foil (adjacent atoms being separated by one diameter), you cannot expect a repetitive placement of atoms, one behind the other.Google Scholar
  15. 22.
    qu [Resnick & Halliday 1985:234].Google Scholar
  16. 23.
    A comet passing through the solar system with too much energy to be captured traces out a hyperbola. Any comet made of antimatter would also follow a hyperbolic path.Google Scholar
  17. 24.
    It is possible, from the equation of the hyperbolas, to derive a relation between impact parameter and deflection: cp = 2 x arccot(K x s/114) (i)Google Scholar
  18. 25.
    The DCA is related to the kinetic energy by DCA = 228/K fm, where K is, as usual, in MeV.Google Scholar
  19. 26.
    “. such emptiness at length/Seems at the heart of all things.” Wordsworth, Poems Dedicated to National Independence. Google Scholar
  20. 28.
    I am assured by my brother-in-law and baseball maven, Al Cohn, that these dimensions (except for the height of the root) are reasonable for Yankee Stadium.Google Scholar
  21. 29.
    The size—if any—of an electron is unknown, but is assuredly not larger than 10-16 m. So an electron is not 1% of the size of the nucleus.Google Scholar
  22. 30.
    Alfred Edward Housman (1859–1936), Epitaph on an Army of Mercenaries. Housman had in mind the British Army of Mesopotamia in World War I, one of those wasted by the war chiefs in London. See also Kipling’s exceedingly angry poem, “They Shall Not Return to Us”Google Scholar
  23. 32.
    “Quantentheorie and Storungsrechnung,” Die Naturwissenschaften 27(1923), 537–550; qu [Miller 1982:378].Google Scholar

Copyright information

© Springer Science+Business Media New York 1999

Authors and Affiliations

  • Alan A. Grometstein

There are no affiliations available

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