Biomedical Engineering Reference
In-Depth Information
The following tabulation highlights some of the important historical markers in
the development of modern atomic and radiation physics.
1810 Dalton's atomic theory.
1859 Bunsen and Kirchhoff originate spectroscopy.
1869 Mendeleev's periodic system of the elements.
1873 Maxwell's theory of electromagnetic radiation.
1888 Hertz generates and detects electromagnetic waves.
1895 Lorentz theory of the electron.
1895 Roentgen discovers X rays.
1896 Becquerel discovers radioactivity.
1897 Thomson measures charge-to-mass ratio of cathode rays (electrons).
1898 Curies isolate polonium and radium.
1899 Rutherford finds two kinds of radiation, which he names “alpha” and “beta,”
emitted from uranium.
1900 Villard discovers gamma rays, emitted from radium.
1900 Thomson's “plum pudding” model of the atom.
1900 Planck's constant,
h
=
10
-34
Js.
1901 First Nobel prize in physics awarded to Roentgen.
1902 Curies obtain 0.1 g pure RaCl
2
from several tons of pitchblend.
1905 Einstein's special theory of relativity (
E
6.63
×
mc
2
).
1905 Einstein's explanation of photoelectric effect, introducing light quanta (pho-
tons of energy
E
=
).
1909 Millikan's oil drop experiment, yielding precise value of electronic charge,
e
= 1.60 × 10
-19
C.
1910 Soddy establishes existence of isotopes.
1911 Rutherford discovers atomic nucleus.
1911 Wilson cloud chamber.
1912 von Laue demonstrates interference (wave nature) of X rays.
1912 Hess discovers cosmic rays.
1913 Bohr's theory of the H atom.
1913 Coolidge X-ray tube.
1914 Franck-Hertz experiment demonstrates discrete atomic energy levels in
collisions with electrons.
1917 Rutherford produces first artificial nuclear transformation.
1922 Compton effect.
1924 de Broglie particle wavelength,
λ =
h
/momentum
.
1925 Uhlenbeck and Goudsmit ascribe electron with intrinsic spin
=
h
ν
h
/2.
¯
1925 Pauli exclusion principle.
1925 Heisenberg's first paper on quantum mechanics.
1926 Schroedinger's wave mechanics.
1927 Heisenberg uncertainty principle.
1927 Mueller discovers that ionizing radiation produces genetic mutations.
1927 Birth of quantum electrodynamics, Dirac's paper on “The Quantum Theory
of the Emission and Absorption of Radiation.”
1928 Dirac's relativistic wave equation of the electron.
