Stories about time travel generally share one trait: They believe, by implication or open statement, that yesterday remains a malleable canvas, if only you could access it.

Stories about time travel generally share one trait: They believe, by implication or open statement, that yesterday remains a malleable canvas, if only you could access it.

"The past," William Faulkner wrote, "is never dead. It's not even past."

In the United States, one of the most obsessed-upon pivot points of our recent past — the moment when people felt the country took a hard turn down a fraught and unpleasant path — was the assassination of John F. Kennedy in Dallas.

The date is etched forever upon the American psyche: 11/22/63. Which is exactly the minimalist title of Stephen King's new book.

The behemoth "11/22/63" postulates what might have happened if an English teacher named Jake Epping slipped back in time from now to 1958, then lived out five years of his life waiting for Kennedy's appointment with Lee Harvey Oswald's bullet 48 years ago — and possibly preventing it.

In other words: One of the Baby Boomers' most celebrated authors is spending three pounds of bookage examining whether the course of the 1960s and the decades beyond would have changed if a single traumatic event had been averted.

It's like a mashup of "Back to the Future" and "In the Line of Fire."

This is a wrenching and subtle book, but that's not what we're here to discuss. More important is this: The 849 pages of "11/22/63" channel the angst and longing that so many Boomers feel about a past that, perhaps, didn't go in the direction they had hoped — and possibly even about lives that didn't turn out quite as planned.

The cover of "11/22/63" distills this duality. On the front is a newspaper bearing the familiar headline: "JFK Slain in Dallas, LBJ Takes Oath." On the back, though, is a might-have-been banner from another lifetime — "JFK Escapes Assassination, First Lady Also OK! Americans Breathe Sigh of Relief."

It almost hurts to read it, to envision the possibility.

Imagine: giving someone a pen to rewrite the 1960s and beyond — to make Beatles survive, new presidents emerge, things turn out differently. Imagine how that could play with Americans who watched the Kennedy mystique peter out and dreams of revolution melt into ads that use Janis Joplin songs to sell cars.

King is able to address questions that have been raised so often in the years since that lunch hour on Dealey Plaza in Dallas: Would we have gone so far into Vietnam? Would so many have died? Would JFK, had he lived, have produced an enduring foundation for peace and prosperity? Would the children of the 1960s have come of age in a different world?

Those are the obvious tensions. But, through the eyes of Jake Epping and his Brave-Old-World road trip through pre-Vietnam-era America, King also burrows into some less frequently articulated national themes, both philosophical and theological. Among them:

Even if we could put a rewrite guy on the history books, could a single man, even one with foreknowledge, have changed everything? In a culture so based on individualism, this is a central question. Is there such a thing as fate? Are some things just destined to happen? Was the American past actually better, simpler, kinder, more bursting with possibility? Is the national zest for yesterday justified, or is it just a crutch that we use when we want to escape?

As the 1960s dawned, the future was a central part of the American experience. From "The Jetsons" to Kennedy's New Frontier, we shaped and shared optimistic visions of it, made it part of the political dialogue, elevated it to one of the fundamental expressions of our national optimism.

That has long since faded. Today, visions of the future are generally dystopian and menacing. Instead we look back, using entertainment and shopping and casual dining and home decor to evoke pasts that we never lived, to surf among our yesterdays without having to grapple with the tough questions.

This makes King impatient. At one point in 1963, the woman Jake loves in the past learns of his origin and his intent and snaps at him: "That's what all this is to you, isn't it? Just a living history book."

King is gentle about it, but he indicts people who bathe themselves in the aura of nostalgia, who look back rather than forward and blindly glorify what came before.

Yes, Jake Epping allows, in 1958 we hadn't destroyed the environment quite so much yet, independent businesses were still serving great pie a la mode and life didn't move quite so fast. But things were a lot smellier, a lot smokier — and, most saliently, a lot more unfair to people who weren't white and male. It wasn't, Jake says, "all Andy-n-Opie."

By the book's end, King's constant readers can place "11/22/63" in the context of his previous work and legitimately wonder: After all the rotting corpses and sharp-toothed clowns, after all the ghosts and aliens and possessed cars and possessed dogs, could this, at long last, be the thing that truly haunts Stephen King?

Could the master of American horror, he who bravely shepherded us through the unspeakable in the 2000s, the 1990s, the 1980s and the 1970s, be afraid of the 1960s?

And could the sheer capriciousness of history, and how it rearranges all of us like tiny chess pieces, be the most terrifying thing of all?

King actually addresses this. Toward the end of the book he writes, in Jake Epping's voice, one of the most eloquent passages he's ever produced:

"For a moment everything was clear, and when that happens you see that the world is barely there at all. Don't we all secretly know this? It's a perfectly balanced mechanism of shouts and echoes pretending to be wheels and cogs, a dream clock chiming beneath a mystery glass we call life. Behind it? Below it and around it? Chaos, storms. Men with hammers, men with knives, men with guns. Women who twist what they cannot dominate and belittle what they cannot understand. A universe of horror and loss surrounding a single lighted stage where mortals dance in defiance of the dark."

Revealing how "11/22/63" ends would, of course, spoil the book. But it kind of doesn't matter, because the lesson is clarion: Don't mess with yesterday. It may bite. Pulling at the threads of time's tapestry is done at our own peril, and the conventional assumption that changing one thing about the past would make today better is simplistic.

Besides, King writes: "The past doesn't want to be changed."

Boomers and Beatles may have believed in yesterday, but salvation doesn't necessarily lie there. No matter how deeply we feel, King seems to say, the answers were never just blowin' in the wind.

They weren't even about whether one young president lived or died. They were, and remain, far more complicated.