Martin Harwit  has argued that we cannot have made more than ten
per cent of the crucial discoveries in Astronomy. He uses what
John Barrow aptly calls `the proof-readers argument'. If two
independent readers look at a manuscript then it is possible to
estimate, by comparing their different results, how many errors
there must be in total, including those not identified. In an
analogous way two independent astronomical channels (say optical
and X-ray) can be used to examine the Universe and a comparison
of their separate key discoveries will yield an estimate of the
numbers still to be found. In any case with so little data to
work on it shouldn't be too difficult to devise a plausible
theory to account for them. It is, however, sobering to compare
the cosmological situation with the history of other sciences.
Take geology. Men were living on the earth for millions of
years, and quarrying rock, digging mines and canals and puzzling
over its fossils for thousands of years, before unexpected
palaeomagnetic patte