A 2002 file photo of a prototype of the Bluetooth wireless communication headset, weighing less than 100g, which enables a user to control computers by speech, in Tokyo. One of the most famous modern technologies owes its name and symbol to a Nordic king of the Viking era with a blue tooth: a quarter of a century ago, the idea of the name ‘Bluetooth’ was born in the minds of two engineers. — AFP One of the best-known modern technologies owes its name and logo to a Viking-era king with a bad tooth: a quarter century ago, two engineers hatched the idea for the moniker “Bluetooth” over beers.