WHY LEGO HURTS
Science explains a rec room terror — when foot meets cube,
Recently, in an act of movie promotion-slash-celebrity torture, comedian and actor Will Arnett walked barefoot across a pile of Lego bricks. The pit was styled in the fashion of firewalkers’ embers, to highlight these toys’ sole purpose: pain.
Arnett, who voices Batman in the The Lego Batman Movie, hustled through the pit on Jimmy Kimmel Live. The physical sensation of walking on the bricks, as thousands of parental feet have felt before him, was clear; Arnett’s face set into a grimace.
In the decades since the first Lego brick was manufactured in 1949, the toys have earned a widespread reputation as a scourge of bare feet. The unpleasantness stems from the combination of biology and materials science — what happens when a sensitive appendage stomps on an icon of Danish durability.
The bricks are constructed of ABS plastic.
The plastic is a polymer chain made up of three different molecules: acrylonitrile, which gives the bricks strength; butadiene, which helps the toys resist deformation; and styrene, for that reflective Lego lustre.
The plastic imbues the toys with impressive material qualities. A small and square Lego brick can withstand a force of up to 4,240 Newtons, according to tests performed by mathematician Ian Johnston.
Enter the sensitive human foot. There are an estimated 100,000 to 200,000 sensory nerves, called exteroceptors, in the bottom of each foot. These nerves inform our brains when we are walking over, say, freshcut grass or a sandy beach, so we can adjust our gait accordingly. The nerves, particularly the pain-transmitting neurons known as nociceptors, also inform us when we have encountered a small toy left on the carpet.
When we step down, our feet don’t produce the necessary force to squish a Lego brick. The brick, remaining rigid, will respond with a force in kind. If the average adult American male, weighing 195 pounds, stands atop the smallest square Lego brick with one foot, the resulting pressure will be roughly 550 pounds per square inch. Even if you’re the Dark Knight, that massive amount of pressure is agony.