In 2012 alone, 41.45 million 3D televisions shipped worldwide. By 2017, every major manufacturer had stopped making them. This episode follows the full arc of that collapse, starting long before the flat screen: Sir Charles Wheatstone’s stereoscope in 1838, John Logie Baird’s stereoscopic TV demonstration in London in 1928, the 1950s cinema boom of Bwana Devil and House of Wax, and the 1997 sweeps stunt in which NBC viewers collected cardboard glasses from fast food chains to watch Third Rock from the Sun.

After Avatar broke box office records at the end of 2009, Panasonic, Sony, Samsung, and LG declared 3D the new baseline at the 2010 Consumer Electronics Show. What followed was a collision of dim pictures, battery-powered active shutter glasses, punishing live production demands, and a basic conflict with human vision. Viewers reported headaches, eye strain, and motion sickness, and a large share of the population could barely perceive the effect at all. Consumers wanted sharper, brighter 2D pictures, and the industry’s bet evaporated within a few years.

• Active shutter glasses used liquid crystal lenses that went opaque and transparent 120 times a second or more, cutting the perceived brightness of an expensive screen.
• Rendering the yellow first down line for a live 3D NFL broadcast took about 1,000 times more processing power than in 2D, and directors could cut between cameras only about one-fifth as often.
• The vergence-accommodation conflict forces the eyes to converge on a floating object while focusing on a screen across the room, decoupling two functions that evolution linked.
• Roughly 12 percent of people cannot properly see 3D images, and up to 30 percent have weak stereoscopic vision.
• The BBC suspended 3D programming and ESPN 3D shut down in 2013, Vizio quit in 2014, and Samsung, Sony, and LG ended production by early 2017.