“No matter what any rock star tells you, they’re all conscious of the cult of personality,” Alex Ebert said, looking like a tenured musicology professor with his tan button-down shirt, shaggy beard and horn-rimmed glasses, while seated amid grand pianos and organs. “For a lot of them, that’s their primary occupation.”

Mr. Ebert, 43, would know. In 2009, the founder of the Los Angeles folk-rock band Edward Sharpe and the Magnetic Zeros led a 12-member troupe of neo-hippie troubadours into rock n’ roll satori with the seismic single “Home.”

Maybe you’ve heard the ebullient chorus, “Home is wherever I’m with you!” Or perhaps you can recall the almost revival-choir hook, “Laugh until we think we’ll die, barefoot on a summer night, never could be sweeter than with you,” set to accordions, trumpets, and Seven Dwarfs-style whistling.

The band got big overnight, hitting the late-night talk show circuit and leading giant singalongs at festivals, to adoring fans with actual flowers in their hair. “Home” was such a runaway hit that it even popped up in commercials, including one for the N.F.L.

The band cut four studio albums and toured for a decade. But it wasn’t enough for Mr. Ebert.

“A few years back, I knew I was dying inside,” he said in a videoconference call from his recording studio in New Orleans. “I told the band I had to stop touring. I just had to allow for some space to jump.”

He felt like he couldn’t do it anymore. “Verse, chorus, verse, chorus, bridge, chorus, out,” he said. “How many times can you do that? How many times must I force myself to rhyme bed with head?”

And now the pop star has taken a leap indeed. A decade after his breakout musical success, he’s aiming for an unlikely second act: public intellectual.

“Is avoiding death killing life on earth?”

Mr. Ebert, who takes private lessons in theoretical astrophysics from a former Massachusetts Institute of Technology instructor for fun, has been producing a cerebral Substack newsletter, Bad Guru. It explores, well, um, how to define?

When asked for an elevator pitch on the newsletter’s focus, he launched into a minutes-long exegesis about the “commodification of spiritualism” and “the religion of self” that name-checked Descartes, Norman Vincent Peale, Galileo and Kellyanne Conway.

Broadly speaking, Bad Guru is a blend of philosophy and cultural analysis, with a smattering of self-help. Reading like a series of manifestoes from a highly caffeinated cultural omnivore, the newsletter takes aim at Silicon Valley self-empowerment mantras, for-profit spins on Eastern religion by wellness gurus, and sugar-high promises from reality-denying politicians.

“Is avoiding death killing life on earth?” he asked in an essay called “A Void Dance” last June. Expanding on the familiar humans-as-a-cancer-on-the-planet idea, he noted how cancer cells avoid programmed cell death — apoptosis — and thereby kill the host, much like humans, who try to deny death by spending trillions on plastic surgery, wellness products and private space rockets, all at a cost to Earth. “What a tremendous irony it would be if avoiding our mortality posed the gravest threat to our collective survival,” he wrote.

While unflinching in its views, Bad Guru steers clear of the hyper-partisanship and self-righteous vitriol seen across Twitter, and offers Mr. Ebert’s take on human folly from a distance, like a scientist peering into a Petri dish.

He acknowledges that he has his own philosophical contradictions to deal with. “My ideology is more anarcho-communist than anything else,” he said of his political leanings. “But I’m also sitting here eating Whole Foods popcorn.”

Mr. Ebert owns a quaint Victorian house in the Bywater district of New Orleans. In 2014, he bought Piety Street Recording Studio, a studio in an abandoned post office next door where U2 and Arcade Fire have recorded, for $750,000.

“New Orleans feels slightly removed from the capitalist hustle,” said Mr. Ebert, who moved to the city from his native Los Angeles in 2012. “The rungs of the ladder only go so high here, so you’re forced to find other kinds of meaning in life.”

Unlike some Substack writers who have turned their self-published missives into a source of subscription income, Mr. Ebert does not charge for Bad Guru, saying that he is “pretty much set” financially from his music. “Otherwise, people are going to be like, ‘What, this rich musician is going to charge me $10 a month?’” he said.

Mr. Ebert draws inspiration from other newsletters blending culture, technology and philosophy such as Astral Codex Ten, by Scott Alexander, the psychiatrist who ran the popular but controversial Silicon Valley blog Slate Star Codex, and The Stoa, by the writer and podcaster Peter Limberg, a devotee of Stoic thought.

His audience includes seekers, armchair philosophers, Big Tech skeptics and New Age types looking for meaning beyond wellness-industry platitudes, he said. Others are lured in through Instagram, where he posts heady photo carousels on topics like “the story of the spiritualization of capitalism.” And some, he acknowledged, are Edward Sharpe fans who are “just putting up with me for the moment and waiting for more music.”

“We are in a time when what some call ‘sense-making’ has become a fraught, ambiguous enterprise,” said the writer Daniel Pinchbeck, an admirer of Bad Guru. “We need more people like Alex using their voice and intellect to define a level of coherence that is beyond the current dichotomies of left and right, spiritual or atheist.”

A year in, the Bad Guru audience is still small but growing; the most popular essays attract around 5,000 views on Substack.

But again, profit is not the point. Mr. Ebert had been writing for years — the name “Edward Sharpe and the Magnetic Zeros” is taken from an unfinished novel he was writing in his early 20s (the “magnetic zeros” themselves were a phrase from a mathematical theory he devised). The 2020 lockdown finally gave him an opportunity to cut out music-industry distractions and focus on the ideas themselves, without trying to cram them into song lyrics and come up with a head-turning stage concept that will work on Colbert.

“I’ve never felt more alive than I do right now,” he said. “For years, I kept all of my intellectual pursuits private. I was afraid of letting my ideas speak, without the window dressing of melody or flash and spectacle.”

“Completions themselves are deaths.”

His intellectual tendencies have landed him in awkward spots. In 2014, for example, he won a Golden Globe for best original score for the Robert Redford sailing film “All Is Lost.” After the ceremony, he found himself chatting with Mr. Redford and Bono when the former declared, “You know who really understands silence? This guy,” in reference to Mr. Ebert’s hauntingly spare soundtrack.

“Immediately I launch into this theory about interstitial space in poetry, the negation between objects and Eisenstein’s theory of montage,” he said. “They just kind of looked at me. I realized I have no understanding of silence.”

His obsessions themselves are obsessions, to the point that he recently asked his sister, Gaby Ebert, who is a psychotherapist, if he might be diagnosed with narcissism or some other condition.

“If there’s anyone on the planet who would take a potshot at me — in a sisterly way — it’s her,” he said. But to my surprise, she said, ‘No, Alex, you’re just different. You get turned on by starting over.”

This is not to say he has abandoned music. Mr. Ebert released a solo album, “I vs I,” in 2020, and has two more in the works. And he is proud of his band’s legacy.

“People get married to ‘Home,’” he said. “It’s been the soundtrack to peoples’ lives. Every time someone has come up to me on the street, their overt expression is ‘thank you.’ It’s beautiful to think that I’ve contributed to making life more magical for people.”

But Mr. Ebert never intended that moment to last. Nothing does. Nothing should. “The Magnetic Zeros was really no fun once it was completed, because it’s dead,” he said. “Completions themselves are deaths.”

Having killed off that persona, Mr. Ebert has little interest in forging a new one.

“If the Bad Guru thing does end up accidentally with some cult of personality,” he said, “I’ll burn that too.”