When Musicians put aside their Day Job

After making his name in the White Stripes and the Raconteurs, this week rocker Jack White debuts Dead Weather, a supergroup featuring members of three other indie-rock bands. It raises the questions of what makes for successful side projects or supergroups, and why do artists take them on? Today we explore this tradition with Wall Street Journal pop music critic Jim Fusilli and Mark Beaumont, music critic for London's Guardian newspaper.