The idea of traveling across the fabric of time is as old as time itself. Human culture has harbored the notion of time travel in several ways: by writing fiction novels, by painting future landscapes, by creating motion picture movies etc. Literature is replete with time travel stories, several big Hollywood hits and TV series have been centered around the idea of time travel. But we can only use these creative tools to kindle our imagination. Time travel is far from the reality today but what if I tell you that you’re already living in the past?
The way our brain, a three-pound mass hidden away in the darkness of the cranium makes sense of the environment owes a lot to the senses — after all, they are its only point of contact to the outside world. These senses act as outposts which send signals back to the HQ (Brain) from far-away body parts through these long nerve bundles. The longer the outpost the longer it takes for the signal to reach the brain. For example, signals arriving from your toe would take relatively longer than signals arriving from your right ear or nose. To add to the complexity, signals from different modalities (light, touch, sound, etc.) are processed at different speeds in the brain.
Building on this backdrop, at any given time, a barrage of signals are reaching the brain and the brain has to put together these multitudes of signals coming at different time points into a temporally coherent story. The way our brain works this problem is by waiting, waiting for a small period of time. This wait, this delay has to be as close to the present as possible, everybody would agree that it is advantageous to perceive a tiger as early as possible yet it has to be long enough so that enough information from all senses to stream in. This time lag has been found to be around a tenth of a second, so you’re experiencing things 100 milliseconds into the past.
This latency in perception has several implications. Firstly, As the perception of the present gets pushed in the past, we’re always experiencing an event slightly after its actual occurrence. We’re all walking with a slight delay, with this dissonance between subjective time and neural time. David Eagleman, an eminent neuroscientist working on time perception sums it succinctly, “This window of delay means that awareness is postdictive, incorporating data from a window of time after an event and delivering a retrospective interpretation of what happened.” He even hypothesizes this seemingly ridiculous astounding idea that tall people may live slightly further in the past than shorter people, owing to longer conduction times along their limbs.
This knowledge of perceptual delay has wide appeal and use. TV producers know well that as long as the audio and video signal is kept within an 80-millisecond window, their viewer’s brain wouldn’t be able to tell the difference. Our brains, in fact, act something similar to an airing of a live show, which broadcasts at a slight delay than its actual timeline to make last-minute editing, if necessary.
So to sum it up, the next time somebody makes fun of you for being short, know that you’re living a tiny bit closer to the present than tall people, not sure what advantage that gets you apart from nerdy bragging rights. All of us nonetheless, albeit slightly, live in the past.
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Complement this piece by listening to What Is Reality? on The Infinite Monkey Cage and David Eagleman’s interview on Rob Reid’s After On podcast.
Pratik Pawar
