vanhees71 said:
...why one should empasize Minkowski diagrams. Usually I find them more confusing than the algebra/calcculus in covariant form.
It was Minkowski's reformulation of Einstein's papers that led to the "covariant" way of thinking.
Minkowski formulated "space-time" geometry, "proper-time", "light-cone", "world-line", and 4-vectors [developed further by Sommerfeld].
(Einstein didn't appreciate all of this at the time. Sommerfeld quotes Einstein "Since the mathematicians have invaded the theory of relativity, I do not understand it myself any more".)
Did you learn [or would you teach] introductory Euclidean geometry with algebra and calculus, but no diagrams?
Are diagrams of Euclidean geometry confusing?
(Is it helpful to draw the intersection of two figures? Or just write a system of equations?)
In PHY 101, we often draw "position vs time" diagrams (a.k.a. space-time diagrams... although one often does not recognize or explicitly use its underlying non-euclidean metric) to supplement the typical algebraic and calculus-based kinematic equations. This is especially helpful for piecewise motions that are not easy to write down algebraically.
(Later, we also draw Free-Body diagrams and do vector-addition graphically.. to support an algebraic computation.)
Finally, I like this quote from
J.L. Synge in Relativity: The Special Theory (1956), p. 63 ,
"Anyone who studies relativity without understanding
how to use simple space-time diagrams
is as much inhibited as a student of
functions of a complex variable who
does not understand the Argand diagram."