We’re all time travelers nowadays. We project ourselves mentally into the misty past and the risky future. We revisit and revise our memories. We invent possible futures and explore them with anticipation and desire. We’re temporal experts and manipulators; we have flashbacks and flashforwards and stop motion and instant replay and time gates and time shifting and time forks. Not content with nostalgia for the past that never was, we begin to feel nostalgia for futures that will never come.

We time travel in our imaginations. We time travel in our storytelling. But we still want more. Would an actual time machine be too much to ask for? Can’t science come to our aid?

Science-fiction authors have a lot of experience in turning our time-twisting desires into realities. They naturally rely on a certain amount of—for want of a better term—mumbo-jumbo. That comes with the territory. But the best time-travel stories respect real science, too. The problem sometimes is telling which is which.

H. G. Wells was the first. He built a vehicle. “Parts were of nickel, parts of ivory, parts had certainly been filed or sawn of rock crystal… Quartz, it seemed to be.” His contraption had a bronze frame and a saddle for its rider. It looked closer to a bicycle than a sedan, which isn’t surprising: In 1895, the automobile barely existed.

Was it scientific? The Wells time machine has no evident source of fuel, or even pedals, but it did have some mysterious dials. You just throw the lever and off it goes. As Wells tries to persuade the skeptical reader in his pseudoscientific introduction, in order to believe in the time machine, you have to reconsider everything you thought you knew about time itself. You have to recognize that time is the fourth dimension.

“Well, I do not mind telling you I have been at work upon the geometry of Four Dimensions for some time,” the Time Traveller, the book’s nameless protagonist, solemnly explains. “There is no difference between Time and any of the three dimensions of Space except that our consciousness moves along it.”

We modern folk tend to agree. Nowadays everyone knows time is the fourth dimension—only no one knew it when Wells penned this tale, in 1895, while Albert Einstein was just a schoolboy in Munich. Wells thought his four-dimensional patter was in the category of mumbo-jumbo, little realizing that it was about to become real science.

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