Select Historical Papers on Cosmology
These papers are relevant to the observational discovery of the expansion
law, homogeneity, and isotropy of the universe.
- H. Shapley
& M. B. Shapley, 1919 "Studies based on the colors and magnitudes in
stellar clusters. XIV. Further remarks on the structure of the galactic
system." (Astrophysical Journal, vol. 50, p. 107)
- H. Weyl,
1923 "Zur allgemeinen Relativitatstheorie" (Physikalische
Zeitschrift, vol. 24, p. 230)
- C. Wirtz, 1924
"De Sitters Kosmologie und die Radialbewegungen der Spiralnebel"
(Astronomische Nachrichten, vol. 222, p.21)
K. Lundmark, 1924
"The determination of the curvature of space-time in
de Sitter's world" (Monthly Notices of the Royal Astronomical Society,
vol. 84, p.747-770)
- K. Lundmark,
"Nebulae, The motions and the distances of spiral"
(Monthly Notices of the Royal Astronomical Society, vol. 85, p.865)
G. Stromberg, 1925
"Analysis of radial velocities of globular clusters and non-galactic nebulae"
(Astrophys. J., vol. 61, pp. 353-362)
- E. Hubble,
1926 "Extragalactic nebulae" (Astrophys. J., vol. 64, pp. 321-369)
G. Lemaitre, 1927 "Un Univers homogene de masse constante et de rayon
croissant rendant compte de la vitesse radiale des nebuleuses
extra-galactiques" (Annales de la Societe Scientifique de Bruxelles,
A47, pp. 49-59)
H. P. Robertson, 1928 "On Relativistic Cosmology" (Phil. Mag., vol. 5,
E. Hubble, 1929 "A Relation between Distance and Radial Velocity
among Extra-Galactic Nebulae" (Proceedings of the National Academy of
Sciences of the United States of America, vol. 15, Issue 3, pp. 168-173)
W. De Sitter, 1930 "On the magnitudes, diameters and distances of the
extragalactic nebulae and their apparent radial velocities" (Bulletin of
the Astronomical Institutes of the Netherlands, vol. 5, p.157)
E. Hubble, 1934 "The Distribution of Extra-Galactic Nebulae"
(Astrophysical Journal, vol. 79, p.8)
Early Review Papers
J. H. Reynolds, 1932 "Physical and Observational Evidence for the
Expanding Universe" (Nature, 130, 458)
J. H. Plaskett, 1932 "A Review of the Progress of Astronomy" (PASP,
H. P. Robertson, 1933 "Relativistic Cosmology" (Rev. Mod. Phys., 5,
E. A. Milne, 1933 "World-Structure and the Expansion of the Universe.
Mit 6 Abbildungen." (Zeitschrift fur Astrophysik, Vol. 6, p.1)
H. P. Robertson, 1955 "The Theoretical Aspects of the Nebular
Redshift" (PASP, 67, 82)
Comments on expansion law
Everyone relied on the same set of velocities, a complete set of which are
listed in Stromberg (1925) (~46 in total).
Shapley & Shapley (1919) noted a correlation in brightness and redshift: "The
speed of spiral nebulae is dependant to some extent upon apparent brightness,
indicating a relation of speed to distance or, possibly, to mass."
Wirtz (1924) assumed that galaxy diameters are "standard rulers" and
found a loose correlation between velocity and diameter. He did not list
his set of galaxies nor did he make any figures. He did not have any
absolute distance calibration.
Stromberg (1925) assumed that galaxy absolute magnitudes are "standard
candles". He did not find any significant correlation between velocity
and apparent magnitude.
Lundmark (1924, 1925) combined both diameter and magnitude information
to estimate galaxy distances, thus combining the "standard ruler" and
"standard candle" assumptions. He used a variety of distance indicators
(novae; Opik's method) to set the distance scale. He found a quadratic
polynomial relation between distance and velocity with a large constant
offset. (Beware: Lundmark's distances from apparent magnitudes are a
complete mess.) He also tried a linear relationship but rejected it (line
Lemaitre (1927) assumed that galaxy absolute magnitudes are "standard
candles". He used Hubble's 1926 calibration but ignore Hubble's caveats
about the standard candle assumption. He assumed a linear relationship
between velocity and distance and made the first estimate of the slope
(625 km/s/Mpc) (actually the second estimate, but, unlike Lundmark, he did
not reject it.)
Robertson (1928) largely repeated Lemaitre's analysis and made the
second estimate of the slope (463 km/s/Mpc).
Hubble (1929) assumed that the brightest stars in late-type spirals are
"standard candles". (Additionally, for the Virgo cluster, he assumed that
the cluster galaxy luminosity function matches the luminosity function
of nearby field galaxies.)
He used his distances to 7 nearby galaxies to calibrate
the brightest star intrinsic magnitude.
He derived a linear relation between velocity and distance
and made the third estimate of the slope (500 km/s/Mpc).
Comments on Homogeneity
Hubble (1926) made the first test of homogeneity by counting galaxies
as a function of apparent magnitude and comparing with a Euclidean model.
Comments on Isotropy
Fath (1914, AJ, 28, 75) made one of the first uniform photographic
surveys over a substantial portion of the sky. Seares (1925, Ap. J., 62,
168) made a detailed analysis of Fath's counts, determining corrections
for limiting mag., aberration, etc. The biggest confounding effect was
dust extinction, but the effect of large-scale structure was also
understood. Because both bright and faint galaxies (presumably at
different distances) showed the same pattern of number count variations,
the interpretation of it being due to dust came to be favored. Seares
claimed to find that counts in the South are 3/4 of those in the North.
Hubble (1926) claimed that this is due to the Virgo cluster in the North:
"When the influence of the cluster in Virgo is eliminated the density
appears to be roughly uniform for all latitudes greater than about 25