Introduction
The late biologist J.B.S.Haldane once wrote: "The universe is not only queerer than we suppose, but queerer than we can
suppose." One of the queerest things about the universe is that virtually all the galaxies in it (with the exception of a few
nearby ones) are moving away from the Milky Way. This curious fact was first discovered in the early 20th century by
astronomer Vesto Slipher, who noted that absorption lines in the spectra of most spiral galaxies had longer wavelengths
(were "redder") than those observed from stationary objects. Assuming that the redshift was caused by the Doppler shift,
Slipher concluded that the red-shifted galaxies were all moving away from us.