Take a look around the room - what do you see? All those colours, the walls, the windows - everything seems so self-evident, just so there. It's weird to think that how we perceive this rich milieu boils down to light particles - called photons - bouncing off these objects and onto our eyeballs.
This photonic barrage gets soaked up by approximately 126 million light-sensitive cells. The varying directions and energies of the photons are translated by our brain into different shapes, colours, brightness, all fashioning our technicolour world.
Wondrous as it is, our sense of vision is clearly not without certain limitations. We can no more see radio waves emanating from our electronic devices than we can spot the wee bacteria right under our noses. But with advances in physics and biology, we can test the fundamental limits of natural vision. "Everything you can discern has a threshold, a lowest level above which you can and below which you can't," says Michael Landy, professor of psychology and neural science at New York University.
We'll explain these visual thresholds initially through the lens - pun intended - of what many of us first think of when we consider vision: colour.
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