Theoretic physics vs. programming. Which is more challenging?

An opinion from one that had a degree in theoretic physics:

“The next important moment in my life was in 1955 when I decided to become a programmer; I took that decision because I had concluded that of theoretic physics and programming, programming embodied the greatest intellectual challenge” – Edsger W. Dijkstra

What does that comment make you think? (Especially if you perform or manage programming activities)

The prima donna in me feels self praise, as first gut feeling because I consider myself a programmer.

Next I feel kind of remorse thinking “Do the pieces of software I have programmed with my own hands have the quality that makes them excel or reflect the mediocrity of a so-called programmer?”