On the one hand, I like that they're doing old physics. There is a tendency to do only cutting edge physics such as modern quantum mechanics research, particle

On the one hand, I like that they're doing old physics. There is a tendency to do only cutting edge physics such as modern quantum mechanics research, particle physics, even string theory. There is little chance to convey an accurate understanding of this to a layperson. Every part of physics was at the cutting edge at one point in time. The physics that is now hip will be old in 100 years, and it will be no longer interesting for science journalists. Celestial mechanics, classical optics, classical electrodynamics were at the cutting edge some time ago, and they're still super interesting. They also have the advantage of being thoroughly understood, so there's a chance to convey genuine understanding. In that sense, this article is great: it truly explains Fermat's principle as a physics college student would learn it. It would be even greater if it had more physics and less metaphysics. On the other hand, would that have reached the front page of HN? Probably not.