‘For centuries, and as late as the early 19th century, a “moment” was something quite specific—a 40th of an hour, or around 90 seconds.

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Because most of the world’s landmass is in the northern hemisphere, Lowe says, heavy winter snowfall can impact how quickly the Earth rotates in certain months. “It’s like a skater putting their arms out—all the snow gets accumulated to higher and higher altitudes, and you can physically see the Earth slow down,” he says. “And as that snow melts and recedes back down into the ocean, the Earth will speed back up a little bit again, just like a skater pulling their arms in.”

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Take snapping your fingers. It might seem instantaneous, and is a sort of shorthand for something that happens in a moment. Instead, it is like live television with a short delay. By the time your brain has processed the command to move your fingers, the visual of your middle finger sliding down your thumb, the feeling of that finger striking the corner of your palm, the vibrations of your eardrum from sound waves in the air—all passing through nerves like electricity through copper wire—the snap has long since come and gone. All these stimuli seem to be happening simultaneously, even though they aren’t. And your brain is rewriting this perception in the moments between when it occurs and when the stimuli are threaded together. “Your perceptual world always lags behind the real world,” he says.

The lag is further complicated by what our brains know about causality and anticipation—and that any given perceived moment is influenced by what happens before and after it. “The part that we fall for … is that there are these crisp moments in time, instead of blurry,” Eagleman says, “which is to say, you know, if you’re incorporating information from the past and also from what happens next in an event, it means that the moment ‘now’ is not a crisp moment in time. It’s actually smeared out, over at least a half a second, maybe longer.”’