Episode Details

This episode follows a single three-letter word, tap, across medicine, engineering, espionage, gaming and science. It starts with the two physical meanings behind the word: drawing liquid out of a pressurized container, as with a faucet or beer tap, and a brief intentional strike, as in tap dancing, guitar tapping, a touchscreen tap, or the tap consonant, where the tongue flicks once against the alveolar ridge in the way many North Americans say the middle of butter. Medicine borrows the extraction sense for the spinal tap, the abdominal tap and the pleural tap.

The word then moves into interception and hacking, from telephone taps and passive network taps to the 1970s phone phreaking magazine TAP, founded by the Youth International Party. As an acronym, TAP names the Trans Adriatic Pipeline, the Trans-Alaska Pipeline System, India's Tarapur Atomic Power Station, the Polish wartime resistance Tajna Armia Polska, the Molson Coors stock ticker, and The Atlantic Paranormal Society. The episode ends with scientific uses, including a three apogee orbit for raising satellites, tandem affinity purification for studying proteins, and 2,4,6-triaminopyrimidine, a molecule discussed in research on the chemical origins of life.

• Early Ethernet vampire taps clamped onto thick yellow coaxial cable and drove a metal spike through the insulation to reach the copper core.
• Prisoners of war used a tap code built on a five by five letter grid, with C and K sharing a square, tapping out row and column numbers.
• In online gaming, a lag switch lets a player cut their own connection so they appear frozen, then seem to teleport when data floods back.
• Researchers suggest triaminopyrimidine could form hydrogen bonds with other early molecules, a possible step toward self-assembling structures before RNA.
• The word also shows up in Los Angeles County's TAP transit card, contactless payment, and the bugle call Taps played at military funerals.