The way we see in three dimensions is fascinating: our eyes see two slightly different images and our brains combine them to get stereopsis: a 3D view of the world. Around one in twenty people don’t have stereopsis, but most still use two eyes – the brain comparing the two images – to perceive depth, they just don’t combine the two into a single 3D image.
To be effective, 3D TVs and cinema screens must present your eyes with two different images. So far, they’ve done this with glasses. One popular sort uses polarised lenses; these are the lightweight, battery-free glasses you get in cinemas and with some TVs. The other sort - ‘active shutter’ 3D glasses - use liquid crystal to opaque each lens, alternating so fast you can’t perceive it, in sync with the screen displaying two different images.
Neither is satisfactory and when cinemas reopened after Covid lockdowns they stopped 3D screenings, ostensibly because of the need to sanitise the glasses. Most...