David, physics teachers in general teach all sorts of silly things because
(1) that's the way we learnt it (2) because they are simple models and the
students can understand them (3) because that is "what the book says" .
I am sure that many can make an argument that this is OK -- must crawl
before walk before run sort of thing usually -- and I agree that we need to
teach Newton's Laws before Special Relativity. But in most of these cases it
is just laziness -- we just don't want to write corrected lecture notes.
However, in most of these cases it is just as easy for the students to
understand the correct story as it is the myths. We insist on excusing
ourselves for saying "tidal bulge", "heat flows", "mass is converted to
energy", etc etc etc -- simply because it is easiest just not to change our
ways.
But *later* some conscientious teacher is going to have to unteach that
stuff along with all the cartoon physics the kids learned from TV.
What is worse is that those kids are going to be the teachers soon enough
and will be saying -- as we hear frequently now -- hey this is what I learnt
in school and its good enough for me now.
I personally see no reason to talk about a tidal bulge. One could
productively talk about tidal FORCES which *do* make a daily march around
the Earth. Why pollute the student's heads with more cartoon physics? Say
it correctly the first time. And maybe it would be better to talk about the
tides *after* the introduction to oscillatory motion.
But I urge that we teach no false doctrine.
Just me in the corner babbling -- with flame retardant suit on.