Almost from the moment he first picked up a guitar, in the fifth grade, Steven Mackey could coax ­amazing sounds out of it. By the time he was 13, his two older brothers, then 23 and 28, enlisted him to serve as a sort of magical-­mystery-tour guide during their ­experiments with LSD.

“They would drop acid and I would play the guitar,” writes Mackey in liner notes to his 2001 album Tuck and Roll.

This was northern California in the late ’60s, in the sunny afterglow of the Summer of Love. To Mackey, who did not indulge, it felt safe and wonderful. They would light candles, turn on colored lights, and little bro would begin to play — serving, as he put it, as their “designated driver of sorts.”

The music sent the brothers spinning in circles, dancing, laughing. “For a teenage boy, it was like having a magical power. ... I could improvise for six hours,” Mackey says. “It made me feel I had a talent for it.”

Forty-three years later, Mackey has proved beyond a doubt he has a talent for it. It’s not just that he’s the chairman of Princeton’s music department, who this spring is teaching an Atelier class on musical theater and a graduate composition course. He also is a versatile, highly sought-after composer — one of the leading composers of his generation. Last year Mackey’s piece Lonely Motel: Music from Slide, on which he collaborated with singer and librettist Rinde Eckert and the group eighth blackbird, was nominated for four Grammys and won one, for “best small ensemble performance.” Mackey played guitar on the piece.

“I don’t think we’ve ever had a composer at Princeton who’s played so much in the big leagues,” says Mackey’s colleague Paul Lansky *73, a major composer himself, citing Mackey’s collaborations with famed conductors such as Gustavo Dudamel of the Los Angeles Philharmonic and Michael Tilson Thomas of the San Francisco Symphony. In August, Mackey completed a piece that is sure to draw attention when it debuts at Carnegie Hall Feb. 12. Commissioned for the Brentano String Quartet, it commemorates the 50th anniversary of the assassination of President John F. Kennedy.

Mackey was 10 when he joined his first band, playing in a fifth-grade ­talent show. He quickly learned the Rolling Stones’ “(I Can’t Get No) Satisfaction,” and was hooked: “The sound of an electric guitar is mother’s milk to me.” He learned guitar licks the way most people did back then: by picking up the needle on his turntable and lowering it again and again, listening over and over until he figured out what his musical heroes were doing. They were the usual suspects: at first, Jimi Hendrix, Carlos Santana, Jimmy Page, and Duane Allman; then jazz players like Al DiMeola and John McLaughlin. At age 17, he became the youngest member of a band called Good Day, which played clubs all over northern California. When touring bands came to Sacramento, Good Day was the opening act of choice, playing on the same bill as Tower of Power and Canned Heat, among others.

Still playing in the band, Mackey went to the University of California, Davis, to study physics. He was good at it, and the counterintuitive world of 20th-century physics remains a touchstone, guiding his understanding of sound waves and vibrating strings but also giving him a profound sense of the world’s uncertainty. But he found himself pondering the point of getting a degree in physics. “Was I going to join the military-industrial complex and design nuclear weapons or something?” he wondered. He was, he says, “a long-haired, guitar-playing teenager from northern California in the 1970s.”

A new direction began to appear. Entering an arena for a rock concert in Sacramento, he heard some of the weirdest, most wonderful music he’d ever encountered coming over the ­public-address system. “I thought, ‘Whoa!! What is this?!’” It turned out to be Igor Stravinsky’s Firebird Suite. In a survey class at college he was encountering more fantastic music: Beethoven’s late piano sonatas, works by Debussy, and more Stravinsky: The Rite of Spring. With the innocence of someone who has not yet been blinkered by a formal education, it did not seem to be all that different from the music he was aiming for. “My first exposure to classical music was like, ‘Wow! This is the most psychedelic rock music I’ve ever heard!’” he recalls. “And that’s what I’m doing now: I’m trying to make the most psychedelic rock music I’ve ever heard.” From physics, he moved to music, earning a Ph.D. at Brandeis University and writing his dissertation on octaves in 12-tone music.

As a young professor at Princeton 27 years ago, Mackey picked up the guitar again, having largely set it aside in graduate school, and began writing music for electric guitar and classical ensembles like the string quartet. One of Mackey’s acts of rebellion was to introduce the electric guitar into music that is composed, classical, and “serious.” “When I listen to 19th-century orchestral music, I admire it,” he says. But it doesn’t speak to our experience today, he suggests: He had to trust his youthful instincts, the stuff that had gotten him into music in the first place.

At the time, says Lansky, Mackey’s blend of classical and electric guitar music was looked upon “like oil and water,” and the young composer paid the price with some very bad reviews: One disparaged Mackey’s combination of electric guitar and string quartet but found a bright side: At least no one would ever play it again.

Wrong. In the 20 years since, the piece has been performed more than 150 times by 30 quartets. “What was heresy when I tried it is no big deal now,” he says. “All the kids are doing it!”

Mackey describes his musical approach as “quirky psychedelia.” If you hear that term and think, “not for me,” think again. His music is melodic and playful, at times bringing to mind of Bernstein or Prokofiev. It moves in surprising fits and starts, but always has sly humor and a strong story line. “If it’s sad, it will be sad with a three-legged-dog quality,” says his wife, Sarah Kirkland Snider, a much-praised composer herself. “If it’s happy, it’s with a three-legged-dog quality too.”

He eschews what he calls “the big return,” the tendency in music to announce where it’s going and recapitulate themes. “When I come back [to an earlier theme]”, he says, “it’s more like a 40-year-old man visiting his sixth-grade school playground and thinking, ‘Wow! That looks weird given all we’ve come through.’”

Much of Mackey’s approach comes from his undergraduate training in physics, his grappling with the uncertainty and quantum weirdness of the universe. “My worldview could be boiled down to [the idea that] the universe doesn’t make sense,” he says. “We as individuals have to make sense of it. And that’s the challenge I give myself as a composer: to pass through all these diverse topographies, musically speaking. Yes, things change quickly. It’s psychedelic, it’s kaleidoscopic. My music is about movement. It’s like some kind of amusement-park ride.”

He is known for his love of getting unusual sounds out of familiar instruments. Reviewing his piece “Indigenous Instruments” in 2007, The Detroit Free Press complimented his use of “quirky tuning to evoke the sounds of a fantastical bestiary.” In “Micro-Concerto,” the percussionist plays assorted toys and kitchen utensils and achieves unique sounds with standard percussion instruments. Mackey explained in liner notes that a seminal influence was a clinic on playing crash cymbals that he had attended: “I left inspired to imagine particular ways to coax sound out of pieces of wood, metal, and skin.” (The approach doesn’t work for everyone: Critic David Hurwitz wrote on the website, “It’s rather ­difficult to predict who will enjoy this music, so redolent of avant-garde rock/experimental noodling of the late 1970s and early ’80s. ... It’s full of interesting ideas and unusual sounds, and it probably sounds better if you’re high.”)

For his piece “Beautiful Passing,” in a cadenza describing the death of his mother, Mackey asked MacArthur Award-winning violinist Leila Josefowicz to achieve a unique sound by playing the natural harmonic — a ringing tone achieved by barely touching the string at a fraction of its full length — high on the D string. Then, Josefowicz was to release the tension so the open string would sound, and find the “balance point” between the two, where the tone would “flicker” back and forth. Josefowicz said this was impossible, that it had to be either a harmonic or a full tone.

Mackey, using both his physicist’s understanding of a vibrating string as well as the do-it-yourself sensibility he’d developed as a guitar player, knew it was possible and showed her how. “The music will be in your struggle to find that balance point,” he told her. It took Josefowicz many hours of practice to get this sound, but when she did, she agreed with Mackey. “It’s very virtuosic, but not in the traditional way like Paganini,” she says. “It’s more eccentric and, I think, more fascinating.”

When Dudamel and the Los Angeles Philharmonic performed “Beautiful Passing” on a bill with Brahms, it was Mackey’s piece that got the raves: “This is fresh, rapturous violin writing, full of swirling harmonies, as if played by an electric guitar transformed by a choir of particularly musical angels into something heavenly,” wrote a critic in the Los Angeles Times. “After that, violin and orchestra dance together, happily and with what sounds like a brief stop in Indonesia.”

That description captures many of the distinctive features of Mackey’s music: its shifts in tone, its tendency to evoke an electric guitar even when there is none in sight, and its willingness to embrace just about any style of music: “I want my music to be like Mahler,” says Mackey, “where the whole world is in every piece.”

With the JFK piece, Mackey knew that his “quirky psychedelia” wasn’t going to work. “My music often takes humorous and/or ironic turns, and there is absolutely nothing funny about those dates in late November 1963,” he acknowledged in his blog recently.

To write the piece, Mackey drew partly on his boyhood memories. His parents had been civilian employees of the Air Force and were great admirers of the handsome young president and his beautiful wife. “My parents were down with the Camelot thing,” recalls Mackey. “[The Kennedys] were a good-looking couple their age. They inspired so much optimism.”

On that awful day in November, Mackey, 7, was home from school, sick. He remembers one thing clearly: “It was the first time I’d ever seen my mother cry. ... My parents never really recovered. Everything that happened subsequent to that — Vietnam and the assassinations of Bobby Kennedy and Martin Luther King — was the ­unraveling.”

His first step in composing the piece was to refresh his memory about what had happened. He read several books and watched the famous film shot by Abraham Zapruder, who was watching the president’s motorcade pass by and documented the assassination. Mackey knew he could not be too literal. “I didn’t want to represent the horror of this even if I could, because I wanted the music to be listenable,” he says. He thought about opting for something safe, “a solemn offering that really doesn’t have anything to do with the event, but is a remembrance.”

Then, he had a breakthrough: “I latched on to Jackie.”

Jacqueline Kennedy, in his reading of things, was a hero. Having lost a newborn son, Patrick, just three months earlier, she hadn’t wanted to go to Dallas. But Texas was then a battleground state, and she allowed herself to be talked into it. She experienced the most horrific violence up close, going from bright sunshine one moment to cradling her dying husband the next, even scrambling over the back of the speeding limousine to retrieve a piece of his skull in case something could be done with it at the hospital.

“I was taken by her personal strength, her bravery, and her compassion,” says Mackey. “She was out of the White House that week and had to make a life for herself. Suddenly she was a widowed, single mother of two.”

Jackie gave him a window on the assassination. His two children were virtually the same ages as the two Kennedy children at the time of their father’s death. He remembered the death of his own mother and that of his brother.

“I pick things that interest me, like how time works, and channel that into my own life experiences and then just write music,” he says. “It’s not Jackie’s theme, it’s my theme.”

He wound up with three parts, all named for traditional musical forms. The first, “Five Short Studies,” is exactly that: five miniatures that give a sense of that day, which, like 9/11, was beautiful and sunny. One is a “song of admiration for Jackie, just a pretty little song.”

The second, “Fugue and Fantasy,” has two parts and explores “what time must have been like for Jackie, to see all these things going on but to feel that time has stood still for her.” A fugue, Mackey points out, literally is a chase; it is also a musical form. “I’ve got this fugue subject, and the music is scurrying around and it just sort of melts away a couple of times into this timeless thing, then you can ominously hear the fast music sort of start to percolate underneath and take over again. It’s very abstract.”

He wrote the third section first. It’s called “Anthem/Aria.” An anthem is a public expression; an aria is more a personal statement. The anthem is basically the solemn tribute to the fallen president that Mackey first had considered. For inspiration, he watched film of the state funeral. He found himself thinking of “Taps,” and the stately way it moves along. “I also put in some symbolism, a 21-gun salute. There are no guns firing 21 times, but it’s this ritualized thing that happens an equidistant amount of time — just another way of setting up this sense of ritualized public mourning.”

The aria part is Jackie’s private ­grieving. “The state funeral was for the rest of the country,” says Mackey. “She had to keep a stiff upper lip, but now she’s got to, for lack of a better term, have a good cry.” The third section is really about public versus personal mourning.

Mackey decided to call the entire piece “One Red Rose,” a reference to the rose the Secret Service found on the limousine floor after the shooting. The work runs about 25 minutes. Mackey is very pleased with it.

He is booked with commissions until 2016, among them a trumpet concerto; a symphony commissioned by three major orchestras; and a piece commissioned by the Aquarium of the Pacific to highlight the “urban ocean” — the population of people and marine life along the Southern California coast.

“I do pinch myself,” Mackey says. He points to a promotional poster hanging on his office wall. It’s for a 2000 concert in San Francisco where Mackey played guitar, performing his Tuck and Roll at Davies Hall with the San Francisco Symphony. “Right after I made this recording, I thought, ‘My career will never eclipse this. I’m a soloist playing my own piece with a great orchestra and one of the world’s great conductors, for a major label.’”

But he got over that. “About two weeks later, with all the adrenaline flushed out of my system, I thought, ‘Wait — that’s not why I do this. I do this because every day I get to wake up and make up music.’” 

Freelance writer Merrell Noden ’78 is a frequent PAW ­contributor.