"Superposition" by David Walton (Pyr/Pyr)

It’s not the kind of language you’d expect to hear from a guy who grew up finessing life with his fists in South Philly, sometimes in the ring, sometimes not. Early in David Walton’s new sci-fi novel, “Superposition,” tough-guy narrator Jacob Kelley has a little pre-sex banter with his wife, telling her, “You are so hot.” And when she asks, “How hot?” he replies, “Ionizing radiation hot. Neutral pion decay hot.”

If you smile at this kind of nerdy heavy breathing, you will find an expanding universe of delight in the particles-run-amok landscape of this book. Kelley, we learn, is not only volatile but also extremely brainy. For a while he submerged his smarts — there was little place for them. His larcenous father died in prison when the boy was a toddler, and his stay-at-home mother preferred drinking to working, and she entertained a parade of men. By the time we meet Kelley, he has his life pretty much in line: married with three kids and a fine job teaching physics at Swarthmore College. His ticket out of the dark side of South Philly was his giant aptitude for physics. By high school, he’d taken to studying hard and punching a speed bag in his basement until his hands bled. With perfect grades and an address in a low-income neighborhood, he was admitted to Princeton, Berkeley and MIT, all on full scholarships. He chose MIT, then went on to Princeton for his PhD and fell deeply in love with physics.

“So much of the rest of my life was complicated,” he says. “Physics was simple. It was how the world ought to be.”

Except that physics can get pretty messy — sci-fi messy — when the bizarre subatomic world of quantum physics comes alive on a human scale. “Superposition” is a thriller ride through Walton’s vision of the chaos that might ensue if scientists ever achieve the ability to step into the quantum world, with its inexplicable probabilities. Fueling the bedlam is the concept of superposition, which one of the characters describes in digestible form as “being in more than one place, or more than one state, at the same time.”

The thrill kicks into gear when Kelley is visited one day by an obnoxious college friend, Brian Vanderhall. He and Vanderhall worked together as researchers at the New Jersey Super Collider until Kelley departed for Swarthmore. Now, in front of Kelley and his wife, Elena, Vanderhall demonstrates some pretty freaky things. He picks up a simple steel and plastic gyroscope off the floor that Kelley had given to his son, who had then lost the string for it. “Brian held the gyroscope up like a magician displaying a coin that was about to disappear,” Kelley says. “Without the string, there was no way to set the gyroscope spinning. When Brian lets go of the wheel, however, it started spinning on its own. He removed his hand, and it kept going.” The three of them, Kelley, Vanderhall and Elena, watch it spin, and spin; it keeps going for two minutes, then three minutes, then four, and it doesn’t slow down at all until Elena snatches it and presses her fingers against the spinning wheel.

When Kelley demands an explanation, Vanderhall turns grave. “They showed me,” he says. “The quantum intelligences.”

Vanderhall has another trick: He points a Glock 46 at Elena and fires. The bullet slams into the wall behind her on a direct line through her chest. “Look at her,” Vanderhall cries. “She’s not hurt! The bullet diffracted around her. . . . I was just showing you.”

By now Kelley is on his feet, advancing toward Vanderhall, imagining his face as a speed bag. Vanderhall turns and races out the door, and Kelley, seeing that his wife is unharmed, lets him go. But it’s only the beginning of Kelley’s warped odyssey. After Vanderhall is found dead in a secret, underground bunker at the super collider where he did scientific experiments, Kelley finds himself on trial for his murder.

The chapters shift between the real world of the courtroom and the alternate universe of quantum physics. This fine effect highlights the contrast between how ordinary society operates, seeking a legal, rational conclusion to an investigation of murder, and how another, unknown world resolves the same murder in an environment of quantum intelligences and humans managing to be in more than one place at the same time.

At its heart, the story is a standard variation on the mad scientist taking his experiments a step too far, but that worn format gets an electron-charged update in Walton’s hands. If the science seems too mind-bending to follow, the author is a sympathetic guide, wedging in clear explanations without slowing the story line. But don’t expect to come away being any clearer what’s really going on inside this mad other world. Even Kelley has his doubts about ever understanding. “The truth is,” he admits, “everyone is confused by quantum physics, no matter how much they’ve studied it. We learn all the technical jargon, and we can do all the math, but nobody really understands it, because it defies all common sense.”

Steven Levingston is the nonfiction editor of The Washington Post Book World.

SUPERPOSITION

By David Walton

Pyr. 301 pp. Paperback, $17