The interplay between moony optimism and the weariness of a 49-year-old pop star who’s fought huge obstacles-the famously tough showbiz parenting of the Jackson family, two divorces, one big Super Bowl scandal, and the sudden death of the iconic brother she deeply loved-is what makes Unbreakable more fascinating than most would-be comeback albums for one-time chart-toppers. The question of whether the world can be saved by art comes up again on Unbreakable, Jackson’s first album in seven years, on a song called “Shoulda Known Better.” Alternating ballad-like verses with frothy crests of marching-band beats and EDM whooshes, Jackson coos that she “doesn’t want to be the poster child for being naïve” but says that she “just can’t feel casual about casualties.” In the outro, over contemplative piano with a touch of Disney sparkle in her voice, she sings, “I had this great epiphany, and Rhythm Nation was the dream / I guess next time I’ll know better.” Looking at the 2015 headlines, it’s clear her pleas for listeners to heal society’s divisions through love and dance were not 100 percent effective. But its political legacy is about as mixed as Jackson expected. 1 hits, 20 million copies sold, with factory-floor sound effects and strident lyrics about bummer topics-poverty, racism, war, homelessness. Rhythm Nation’s commercial achievement seems more and more improbable with each passing year: four No.