"For Engineers perhaps, predictive models are sufficient, they may not
be (very?) interested in explaining *why* a particular material has
the properties it does, merely *what* those properties are and how
reliable the properties might be under a variety of conditions."
I don't think this currently true. A big chunk of what used to be
labeled "physics" is now in academic engineering departments with the
name "material science". This consists of exploiting models that
explain observed properties of materials, with the goal of looking for
opportunities to change parameters to get improved behavior. In the
early 1990s I heard a talk by an engineering professor at the science
museum in Toronto, where he explained how such research had led to
concrete many times stronger than it had been, and that the iconic
tall tower in Toronto could not have been built not many years before
it was built, as it relied on much stronger concrete.
In some cases someone sees how, starting from fundamental physics
principles, one can predict that such and such should happen or be. In
other cases an observed phenomenon gets explained in terms of
fundamental physics principles (post-diction), which then suggests how
changes in the situation might yield an improved behavior. Pre-diction
and post-diction both require a deep understanding of how to go from
underlying fundamental principles to the behavior, but pre-diction in
addition requires the imagination to run the argument forward, not
already knowing the answer. That's why I claim that post-diction
("explanation") is more common than pre-diction.
There's a fruitful interplay between pre-diction and post-diction. An
example I've mentioned some time ago, from our intro physics textbook:
When searching for an explanation for spark formation in air (we see
the spark and ask how it occurs, which is post-diction or explanation)
there are a couple of tentative explanations that one can rule out.
Another explanation seems to explain the phenomenon, and the validity
of this post-diction is greatly strengthened by noting that it (and
not the other explanations) pre-dicts that it takes twice the critical
electric field to trigger a spark if the air density is doubled, a
pre-diction that is consistent with observations.
Bruce
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