1) In recent comments about my methods, Leigh Palmer and Brian McInnes
wrote about angels. I don't think either of them meant my methods were
angelic in any flattering sense; I'm pretty sure they were using angels as
a metaphor for something unnatural, capricious, and abysmally lacking in
predictive power.
2) It was quite startling to see that they put expressions such as E=mgh
into the "capricious" category.
3) I concede that E=mgh is inexact.
If that concession makes them happy, then we're all happy. That's because
I have always considered physics to be a natural science, which is by no
means the same as an exact science. In the real world, a big part of
physics is the art of making well-controlled approximations.
I imagine a ranking of exactitude, something like this:
=========================================================
^ ^ ^ ^
pure too inexact good perfectly
caprice to be useful enough exact
4) I was using E=mgh in situations where it was vastly better than good
enough. Categorizing it as capricious, just because it is slightly
inexact, is (a) impractical and (b) not physics. Anybody who requires such
a high standard of exactitude should stay away from natural science and
stick to something like arithmetic, where expressions such as 2+2=4 hold
exactly.