Fidget spinners ― kids spin them and spin them ― and while parents may not "get" why the boomerang-shaped toys have caught on with such force, there's real physics to explain how the distracting devices work. <img src="http://www.bearing.com.cn/RecommendedCompany/3.webp.jpg"> "I was introduced to fidget spinners a few months ago by professor Kenneth Brecher from BU [Boston University]," said Paul Doherty, a physicist at the Exploratorium in San Francisco. "He makes his own spinning toys and handed me a fidget spinner and asked me to guess what it was. I described what it did but had no idea why someone would buy one ;-)," Doherty told Live Science in an email. For Doherty, the spinners are interesting for another reason: "To me, these show the coolness of ball bearings that reduce friction and allow things to rotate freely for a long time." (On a basic level, friction is the resistance to motion that occurs when one object moves relative to another. Here's a look at what's happening when your child, or you, balance a fidget spinner on your finger and give it a whirl.