Except that when Matt first activates the homemade calibrator, a "shoebox-sized machine," it vanishes briefly, then reappears. Subsequent trials by Matt reveal that the machine is traveling forward (and only forward) in time, and also getting displaced somewhat in space. And these jumps are getting exponentially bigger along every dimension, a feature beyond Matt's control.

When Matt loses his job and his girl, Kara, he decides to use the machine to journey forward himself and earn fame and fortune. After all, the next jump will span only 39.5 days. No biggie. But when he materializes at that point in time—in the middle of Boston traffic—he finds he's wanted for murder.

After escaping the authorities, Matt believes his only recourse is to jump again. This time for a duration of some 15 years. Upon arrival in the 2070s, Matt discovers he's hit the jackpot. He's acknowledged as the co-discoverer of time travel—although his old mentor Professor Marsh has hogged most of the credit—his ex-girlfriend, a middle-aged Kara, has the nostalgic hots for him and he's been granted tenure at MIT in absentia. Sure, there are some confusing aspects to life here and now, but Matt resolves to deal with them.

Except he can't. He's hooked on time-traveling, for emotional and practical reasons. So he jumps again, this time 177.5 years into the future. It's only when he encounters horse-drawn carts and ruined freeways that he realizes he's made a very unwise move.

And if he wants to escape this time, it will involve a jump of 2,000 years. Then 24,709, then 300,000, then 3,440,509—

Addictively transparent prose

Time travel, in the words of Rudy Rucker, is an SF "power chord," one of those tropes that just keep on giving in generation after generation. One might imagine that all the riffs have been played on this particular chord—until an ingenious writer is able to coax a brand-new tune from it. That's obviously the case here, as veteran scribe Haldeman turns his attention to the theme. Let's try to see how he accomplishes his magic.

First off, as with all good fiction, comes character, finding an essential protagonist for this big adventure. In Matt, Haldeman has deftly conjured up a bright, albeit slackerish Everyman with whom the reader can instantly identify. (The very adjective "accidental" in the title conveys this quality of Matt's nature.) Matt's motives are always honorable, if not selfless, so we never second-guess his actions in a critical fashion.

Then, midway through the book, we get the arrival of Martha, a woman of the future who becomes Matt's traveling companion. I won't say too much about her for fear of spoiling surprises, except to mention that she's a perfect foil and a fine invention in her own right. And there are more fresh-faced characters that appear in her wake.

After this crucial business, we need a voice. Haldeman's finely honed yet simple prose succeeds perfectly in creating clear-eyed descriptions of complex events, as well as suspense and ineluctable narrative flow. Like primo Heinlein, it's a voice that is witty and alluring without doing handstands and showing off. A line such as this one is typical: "Having to go out into the sun [to use a portable display unit] would make its utility as an adjunct to masturbation questionable."

But of course in any SF novel we want speculative juice, and Haldeman delivers plenty of that. Look at how many different eras he invents and limns, and the twisty ending. His fecundity is on fine display.

This is a book that manages to conflate flavors of Stephen Baxter, Walter Miller, Keith Laumer and Cyril Kornbluth into one unique and potent cocktail that is unmistakably Haldeman.