Geoscience Reference
In-Depth Information
shut down for half a century or more. Officer's opposition, and espe-
cially his style, made the pro-impactors try all the harder.
W
HERE
FROM
H
ERE?
Science and evolution both operate as punctuated equilibria. Al-
most all scientists work to extend and perfect the prevailing para-
digm, and continue doing so until a new discovery, often made by
accident, requires that the paradigm be reexamined. At first, at-
tempts are made to fit the new discovery in, and often they succeed
for a while. But gradually it becomes clear to the more progressive
practitioners of a discipline that the old paradigm simply cannot
explain enough of the new evidence and must be replaced. The
progress of science is then punctuated by the arrival of a new para-
digm, which in most cases was developing offline, like a shadow
government, ready to step in when needed.
Just after the arrival of a new paradigm, things are muddled and
confused. Some questions have been answered but more have been
raised. Like species after the punctuation of biological equilibrium,
science is now evolving rapidly. It is not always a pretty sight as
some continue to hang back while others shoulder in. Because it is
hard to know which research directions are apt to be the most fruit-
ful, false leads are followed and dead-end sidings are entered. The
old methods and theories prove unable to explicate the new para-
digm and new methods have to be invented. The immediate after-
math of the arrival of a new paradigm presents many niches of
opportunity into which the nimble, the young turks, and the out-
siders can move. (This was the state of physics during the 1930s and
1940s, of which a young turk named Luis Alvarez took full advan-
tage.) In time, these birthing pangs recede, scientists turn to extend-
ing and perfecting the new paradigm, and the cycle begins anew.
Earth scientists know that this is the way a paradigm shifts, for
between 1966 when plate tectonics arrived and, say, 1976, when it
was fully developed and accepted, we were witnesses. Now, with the
Alvarez theory just a decade-and-a-half old and the crater discov-
ered only in the 1990s, geology once again finds itself in a time of
great opportunity. If impact has played the broader role hinted at in
these chapters, important discoveries may lie just ahead.
What do we know today about the role of meteorite impact?
We know that it was the dominant process in the primordial solar
system. As the objects that had just condensed from the solar dust
cloud collided with each other, sometimes fragmenting and some-
