PARIS — By calculating the equivalent in muscle mass of the energy that powers gadgets used by humans, engineer Jean-Marc Jancovici, a Mines ParisTech professor and president of the Shift Project, concluded that a typical French person lives as if they had 600 extra workers at their disposal.

People's wrists are adorned with the equivalent power of a supercomputer — all thanks (or not) to Apple, which made the smartwatch a worldwide phenomenon when it launched the Apple Watch in 2014, just as it did with the smartphone with the 2007 launch of the iPhone.

Similar watches existed before 2014, but it was Apple that drove their dazzling success. Traditional watchmakers, who, no matter what they say, didn't really believe in them at first, are now on board. They used to talk about complications and phases of the moon, but now they're talking about operating systems.