|Slipher and the Nature of the Nebulae
|471, Origins of the Expanding Universe: 1912-1932
|Why do some discoveries, which appear in hindsight to be obviously
major discoveries, have so little impact when they were made. These are
discoveries that were ahead of their time, but for some reason the scientific
community was not ready to absorb them. I got interested in Slipher after
learning that by 1914 he had observed nebular redshifts up to 1000 km s-1.
Why did this not convince people at the time that the nebulae were extragalactic?
Was this another example, like the Zwicky (1933)
discovery of dark matter in
the Coma cluster, of a discovery which was too far ahead of its time? I
conclude that Slipher's situation was different from Zwicky's. The significance
of Slipher's nebular redshifts was partly recognised at the time, but I believe
that its full significance was masked by van Maanen's work which turned out to
be erroneous and reduced the impact of Slipher's discoveries.