Adele, Lady Gaga, Katy Perry and Rihanna make great music, but according to Forbes, they’re doing something much more important: … they’re reinventing the world.  The magazine polled its readers and several panels of industry experts to compile its first-ever ”30 Under 30″ list of tomorrow’s brightest stars, none of whom have hit the big 3-0 yet.  Thirty people who are “making a difference” and who “matter” were chosen in each of 12 industries.  In music, those who made Forbes’ list include Adele, Gaga, Katy and Rihanna, as well as Bruno Mars, Drake, Nicki Minaj, Hillary Scott of Lady Antebellum, Taylor Swift, Lil Wayne and Florence Welch of Florence + the Machine.  As for why each of these artists were chosen, Forbes points to their blockbuster record sales, tour earnings, endorsements, business ventures, award nominations and wins.