Life isn’t a stream; it’s a movie. Like a projectionist stitching together reels without audiences noticing, the brain collects the frames of reality sent to it and weaves them into one apparently seamless whole. The human frame rate shows us life at a certain speed, but life can be much faster or slower if we change it.
Have you ever been next to a moving car with wheels that looked like they were going backwards? Blame the human frame rate. According to research that determined how many light flashes per second the human brain can discern as separate before they look like a steady beam, scientists have found that for us, life is a movie running at around 60 frames per second. When a car’s wheel is spinning fast enough to simulate that frame rate, it can look like the wheels spin backwards. What’s happening is that the wheel’s position is only slightly behind where it was when the last frame was stitched together by your brain.
If you get a car’s wheel spinning in sync with the frame rate, it can even look as though a car is gliding rather than rolling:
What would something like a car wheel spinning the wrong way look to other animals? Human experience is like a stuttering video game trying to render too much to a golden-mantled ground squirrel—it sees the world at 120 frames per second. But at least humans don’t see life like stop-motion animation. “Booralana tricarinata, a deep-sea cousin of the roly-poly, boasts the lowest known C.F.F. (Critical Flicker Frequency): four flashes a second. Its view of life may be something like a fitful and grainy stop-motion film,” writes Ferris Jabr in The New Yorker.
You can actually force illusions based on the human frame rate if you alter the frequency that light hits our eyes. The water fountain below is indeed flowing straight down the whole time, but a precisely tuned strobe light can make it appear as though it flows upwards, and in perfect droplets:
The best way to see the world at a different speed is to change how fast the brain can put frames together. Since we can’t exactly go poking around in people’s brains, using a mechanical eye—a camera with a variable shutter speed—is the next best thing. By matching a camera’s shutter speed to the rotation of a helicopter’s rotors, for example, you can make it look as if some giant, invisible child is playing with a toy:
And if you have a camera that samples images top-to-bottom, instead of all at once, you can get an incredible “rolling shutter effect” (top image) that gives airplane propeller blades bizarre orientations and movements.
You can also visualize synced frame rates by sending a certain frequency of sound through flowing water and matching that frequency with a camera’s shutter. Water can stand still, move in slow motion, and even flow backwards all while moving just as physics would dictate.
Ferris Bueller famously said, “Life moves pretty fast. If you don’t stop and look around once in a while, you could miss it.” Philosophically, that’s not bad advice. But the scientific truth is that life moves only as fast as you can perceive it. No matter how much you look around, there are species that get to see much more or much less life. I’m not sure how that fact works philosophically though.
Kyle Hill is the Chief Science Officer of the Nerdist Enterprise. Follow the continued geekery on Twitter @Sci_Phile.