Since it was published last September, Carlo Rovelli's book, "Seven Brief Lessons on Physics," has sold more copies in Rovelli's native country, Italy, than E.L. James' smash hit "Fifty Shades of Grey," The Spectator reported.

And the English translation has quickly risen to become Penguin's fastest-selling science debut in the publishing company's history.

So what's Rovelli's secret?

After all, it's not like physics is a topic that people flock toward. In fact, physics has been the least popular STEM (science, technology, engineering, and mathematics) major for US undergraduates since the late '60s.