"How many licks does it take to get to the center of a Tootsie pop? The world may never know," a timeless commercial might have us believe. What the world of advertising seems to neglect, however, is scientists' astute resilience to rhetoric. As it happens, it takes an estimated 1,000 licks to reach the center of a lollipop, according to a paper published in the Journal of Fluid Mechanics, by researchers from New York University and Florida State University.
The researchers developed a model of how flowing liquid dissolves and shrinks material which they then used to determine how long it would take to dissolve a lollipop. Specifically for Tootsie Rolls, it takes some 2,500 licks to reach the center.
To formulate their theory of how a lollipop dissolves, the team placed spherical and cylindrical pieces of hard candy up to two inches long in a water tunnel, which allows for washing of these bodies by well-controlled flows. Using high-speed photography, the candy's dissolving was image frame by frame. The shapes and patterns that arose from their analysis allowed the researchers to formulate mathematical relations that predict how the candy behaves under flow and how long it takes to reach its gummy center.
This estimation, however, seems to be way off. Elsewhere, a group at Purdue University actually built a licking machine that mimicked the human tongue and the licking motion. They then tested this machine against real tootsie pops with the results being an average of 364 licks to get to the center of the tootsie pop licking from only one side constantly. Not satisfied with this only, the same team tested this against their own tongues and found that it took an average of 252 licks to get to the center, again only licking from one side, but this time with real tongues.
Some might find the findings liberating, while others will dismiss them as a useless science. This isn't necessarily the case, though. The pharmaceutical industry is very concerned wit monitoring and controlling how substances dissolve inside the human body. Also, the findings might aid geological research providing a basis for modeling the morphology of eroding and dissolving surfaces to present water or wind flows.