“I’m bored of the early 21st,” our narrator Spens tells us at the beginning of Robert Dickson’s sci-fi thriller The Tourist. By “21st,” he means “century.” He’s a tour guide leading groups of time-traveling tourists on journeys through our mundane present — the travelers are horrified and fascinated by our shopping malls, for instance. Mostly, he sits and drinks coffee and eats pastry for the novelty of it (it's simultaneously tasteless and too sweet for his future-palate) while his group wanders around having innocuous interactions with 21st century residents.

Spens continues…

I’ve been doing this for a year and a half now, and I’m tired of the cramped houses, the noise, the crowds, the gathering pollution, the omnipresent advertising. I’m unmoved by their entertainments (they use pictures, even for grown-ups)…

Spens is from so far in the future that his supervisor can’t even remember the word for “car.”

“…you can work on your own, can’t you? You know how to drive their” — he gropes for the word, gives up — “their things?”

“I have a license.”

“Good. I’ll authorize the use of a thing.”

And the memory of Nazis has been diminished by the slow erosion of history:

If a native wants to imply a rival political movement is bad they will compare them to Nazis and, in entertainments, all a character has to do to represent evil is wear an armband with some kind of cross. Entertainment Nazis are shorthand for monstrousness, simplified versions of a movement that was simple to begin with.

This is all a very clever set-up. By making Spens so completely jaded about our time and the mechanics of time travel, Dickson is emulating the audience’s weariness. We’ve seen all the clever time travel tropes, and so like Spens we sit back and watch from a distance as the time tourists go about their predictable behavior. We’re part bemused and part bored; it’s all been done before.

Not so long after that opening scene, The Tourist kicks into action. A minor fender-bender distracts from the routine trip, and then one of the time-traveling tourists disappears. None of this has been predicted, but then the time stream is conveniently muddied around this period in history, so nobody from the future knows how the mystery will be resolved.

The Tourist is a twisty-turny story about manipulating the time stream for one’s own benefits, and while it never quite breaks new ground, it at least acknowledges how much ground in time-travel narratives has already been covered. I read The Tourist a few months ago on a plane — pretty much the perfect setting for reading The Tourist, by the way — and, truth be told, I can’t even remember how it ends. Like most time travel stories, the journey is the most important part.

If you’re in the mood for a time travel narrative, you might consider James Gleick’s new non-fiction book Time Travel. Gleick, author of biographies of Richard Feynman and Isaac Newton, and an excellent scientific historian who has written about concepts like information and chaos theory, is one of the most competent guides in literature. His writing is clean and clear, his research is impeccable, and his conclusions are always groundbreaking but he always presents them in such a way that they feel, retroactively, like something you’ve understood for a long time.

Gleick casually rearranges a reader’s understanding of time travel in fiction from the beginning of the book. The very concept of time travel, turns out, is a relatively new one; in fact, he credits credits H.G. Wells’s novel The Time Machine with the invention of the idea:

Nowadays we voyage through time so easily and so well, in our dreams and in our art. Time travel feels like an ancient tradition, rooted in old mythologies, old as gods and dragons. It isn’t. Though the ancients imagined immortality and rebirth and lands of the dead time machines were beyond their ken. Time travel is a fantasy of the modern era. When Wells in his lamp-lit room imagined a time machine, he also invented a new mode of thought.

That is a potent paragraph. Upon reading it, your mind immediately travels back in time, to try to conceive of a world without time travel. It’s basically an impossible thought experiment. Wells cracked open a Pandora’s box when he allowed us to imagine manipulating our own histories as easily and permanently as we manipulate the world around us. Regret has existed as long as the human mind, but the idea of altering the flow of past events on a whim changed the dimension of regret, made it more bittersweet and physical than we once understood it to be.

Once the concept of time travel was introduced to humanity, humanity immediately started exploring its limits. Paradoxes formed — the classic case of someone trying to kill their grandfather — and the flimsiness of time travel as a concept began to make itself plain. Not very long after the invention of time travel, its most famous hypothetical victim strutted onto the world stage:

If only Hitler can be unmade. The entire twentieth century gets a do-over. The idea arose even before the United States entered the war: the July 1941 issue of Weird Tales featured a story called “I Killed Hitler” by Ralph Milne Farley, pseudonym for a Massachusetts politician and pulp writer, Roger Sherman Hoar. An American painter resents the German dictator for several reasons and goes back in time to wring the neck of ten-year-old Adolf. (Surprise: the result, when he returns to the present, is not what he expected.) By the end of the 1940s, Hitler’s death at the hands of time travelers was already a meme. It is taken for granted in “Brooklyn Project,” a 1948 story by Philip Klass, publishing under the name William Tenn. The Brooklyn Project is a secret government experiment in time travel. “As you know,” an official explains, “one of the fears entertained about time travel to the past was that the most innocent-seeming acts would cause cataclysmic changes in the present. You are probably familiar with the fantasy in its most currently popular form — if Hitler had been killed in 1930.”

The realization that people wanted to go back in time to kill a baby Hitler before adult Hitler was even dead is another one of those little explosions that Gleick sets off for his readers. It’s delivered with such a cheery, chatty voice that all Gleick’s hard work and research becomes basically invisible.

In the pantheon of Gleick’s books, Time Travel feels a little slighter than, say, Genius, or The Information. In that way, the book resembles its subject — while time travel is a fun toy to play around with, it doesn’t generally withstand a deep investigation. But the quality of Gleick’s work elevates Time Travel into something no less fascinating, and no less mind-altering, than his other books.

Since the election, thousands of people have cracked some variation on the joke that time travel must not exist, since someone from the future would undoubtedly have appeared in the present to stop us from voting for Donald Trump. It’s gallows humor, but it hints at something deeper — our anxiety that we’re destroying the future, and our profound feeling of powerlessness against the crush of history.

Time travel may be a relatively new concept, but we’ve been relentless in our thought experiments ever since it was created. Like our ancient incantations of free will and fate and karma, we continue to poke at our place in the universe, and our ability to make a mark. Better to be an actor in the halls of history, after all, than a tourist.