# Timeline for ``Modern Physics''

450-300 BC -
Greek Atomists:
**Leucippus, Democritos, Epicurus** . . .

335 BC -
**Aristotle**: continuous
elements
(earth, air, fire, water)

300 BC -
**Zeno **of Cition (founder of Stoics) popularizes
Aristotelian view.

60 BC -
Titus Lucretius **Carus** of Rome epitomizes
"Atomist" philosophy.

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1879 - Josef **Stefan** [expt]
power emitted as blackbody radiation *P = A
T *^{4 }

1884 - Ludwig **Boltzmann** [theor]
explains Stefan's empirical law

1885 -
Johann Jakob **Balmer** [expt]

empirical description of
**line spectra**
emitted by **H atoms**

1890 -
Johannes Robert **Rydberg** [expt]

1893 - Wilhelm **Wien** [expt]
blackbody spectrum *displacement law*:
peak wavelength varies as *T*^{-1}

1895 -
Wilhelm Conrad **Roentgen** [expt]
discovers *X-rays*

1897 -
Joseph John **Thomson** [expt]
measures *q/m*
of the *electron *

1900 - Max **Planck** [theor]
derives correct *blackbody radiation spectrum *

1902 -
Philipp E.A. von **Lenard** [expt]
measures *photoelectric effect*

1905 -
Albert **Einstein** [theor]
explains *photoelectric effect*

1905 -
Albert **Einstein** [theor]
publishes *Special Theory of Relativity
(STR)*

1905 -
Albert **Einstein** [theor]
explains *Brownian motion*
(gives **mass of atoms**!)

1905 -
Ernest **Rutherford** [expt]
performs first *alpha-scattering*
experiments at McGill Univ. (Canada)

1907 -
Robert A. **Milliken** [expt]
measures *electron charge*
(now know both *q*_{e}
and *m*_{e}).

1912 -
William (H. & L.) **Bragg** [expt]
shows that *X-rays*
scatter off *crystal lattices*

1913 -
Hans **Geiger** & Ernest **Marsden** [expt]
confirm *Rutherford scattering*
results at Univ. of Manchester (U.K.)

1913 -
Niels Henrik David **Bohr** [theor]
pictures *H atom*
with *quantized angular momentum*

1916 -
Albert **Einstein** [theor]
publishes *General Theory of Relativity
(GTR)*

1916 -
Robert Andrews **Milliken** [expt]
confirms *photoelectric effect*
in detail

1922 -
Arthur Holly **Compton** [expt]
scatters *X-rays*
off *electrons*

1924 -
Louis Victor **de Broglie** [theor]
hypothesizes ``*matter waves*''
with
*
= h/p*

1925 -
Wolfgang **Pauli** [theor]
formulates his *exclusion principle*

1925 -
Max **Born** & Werner **Heisenberg** [theor]
introduce *quantum mechanics*

1926 -
Erwin **Schroedinger** [theor]
develops a nonrelativistic
*wave equation*
for *quantum mechanics*

1927 -
Werner **Heisenberg** [theor]
formulates his *uncertainty principle*

1928 -
Paul A.M. **Dirac** [theor]
develops a
*relativistic wave equation*
for electrons and predicts
*antimatter*

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