Much like the actual universe, the hop-hop universe continues its tireless sprawl in every direction.

Now in its mid-30s, the genre is made up of stars in bloom and stars in decline, all burning as though the others revolve around them. Area fans seeking the most comprehensive tour of the constellations will want to block out the last weekend in September, when the annual Rock the Bells hip-hop festival will set up shop at RFK Stadium on Sept. 28 and 29.

Of the 56 artists expected to perform at the touring festival’s D.C. stop — it will touch down only in Los Angeles, San Francisco, New York and the District this year — Kendrick Lamar qualifies as the most widely liked.

Since the release of his 2012 major label debut, “Good Kid M.A.A.D City,” the 26-year-old Los Angeles rhyme-sayer has achieved unicorn status as hip-hop’s consensus torchbearer. He’s a rapper’s rapper, applauded for his vibrant lyricism, as well as an innovator whose latent appeal lies in his ability to differentiate between classicism and nostalgia.

He’s also a cool-headed persona who can make an entire genre jump up and take notice. Nearly every neck in hip-hop turned last month when Lamar called out his competition in a cameo verse on an otherwise middling Big Sean tune called “Control.”

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“Jermaine Cole, Big K.R.I.T., Wale, Pusha T, Meek Mill, A$AP Rocky, Drake, Big Sean, Jay Electron’, Tyler, Mac Miller,” Lamar rapped, rattling off his friendly competitors. “I got love for you all but I’m tryna murder you [expletive]/Tryna make sure your core fans never heard of you [expletive]/They don’t wanna hear not one more noun or verb from you [expletive].”

The hierarchy-obsessed rap world convulsed with pleasure. Across generations, hip-hop has always bristled with competitive tension and now one of its greatest young practitioners had surfaced an often-unspoken pecking order in rhyme.

Which is another reason this year’s Rock the Bells should be such a kick. Of the 11 rappers Lamar mentioned in “Control,” six are scheduled to step onstage at RFK — Washington’s own Wale, his tour-buddy J Cole, Mississippi drawler Big K.R.I.T., Clipse alum Pusha T, Harlem peacock A$AP Rocky and Cali oddball Tyler, the Creator.

And true to the approach Rock the Bells has taken for 10 years now, the youngsters will be joined by hip-hop royals — Doug E. Fresh, Slick Rick, KRS-One and others. If that clash-of-the-generations doesn’t provide enough to argue about, there are some highly unexpected participants, too.

Riff Raff, the outlandishly tattooed Texas native who allegedly inspired James Franco’s character in Harmony Korine’s “Spring Breakers,” will try to transcend his reputation as purist hate-object, while Christian rapper Lecrae will quite literally be working to convert concert-goers into believers.

And then there are the “holograms.” Ever since an animated image of the late Tupac Shakur was unveiled on stage at the Coachella Valley Music Festival in 2012, promoters have assumed that rap fans want more of this creepy stuff. At Rock the Bells, they’ll get it. Wu-Tang Clan are expected to rap alongside a CGI projection of late member Ol’Dirty Bastard. Cleveland rappers Bone Thugs N Harmony will do the same with fallen mentor Eazy-E.

But why? There’s plenty to talk about at this year’s Rock the Bells, but let’s stop this branch of the conversation right here. These “holographic” performances are tacky, ghoulish and degrading. Unplug the projectors, please.

One more pre-show beef: Where are the women? It’s great to see the mysteriously underrated Jhene Aiko on the RFK bill, but for a festival that spans generations and geographies in a way that reflects hip-hop’s increasing breadth, it’s disappointing to see gender so severely neglected.

All in all, it’s a two-day mega-concert that aims to please and threatens to overwhelm. So if Rock the Bells seems like too much to chew on, shift your attention to the rising class of young rappers cutting their teeth in our proverbial back yard.

Shy Glizzy lifted the scene’s rising bar a few more notches in August with “Law 2,” a mixtape of melodically sneered rhymes that felt equal parts menacing and heartfelt. He’ll open for Memphis veteran Yo Gotti at the Howard Theatre on Nov. 11.

Meantime, Northeast tough-talker Fat Trel also made a dramatic pivot in August with his new mixtape, “SDMG.” It’s short for “sex, drugs, money, guns,” but the mixtape’s most musical tracks capture the rapper at his most emotionally vulnerable, too. Trel will headline at the Howard Theatre on Sept. 10.

Catch them while you can. These two — along with fellow rising DMV rappers Ras Nebyu, Lightshow, Kingpen Slim, Phil Ade and others — sound poised to land Rock the Bells spots of their own in the years not too far ahead.

Rock the Bells

Sept. 28 and 29 on the grounds of RFK Stadium

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