Ancient Mesoamerican Concave Mirrors: A Physical Approach

Abstract

Utilizing a radiation transfer thermodynamic equilibrium approach, the burning power of 13 Olmec and Maya concave mirrors has been calculated, theoretically assessing their capability to ignite fire on blackened cellulose targets. Analogous models experimentally demonstrate their incendiary ability corroborating our theoretical results. Our analysis demonstrates that all the studied specimens can surpass the ignition temperature of cellulose-lignin mixtures, and most of their analogs actually ignite fire, supporting the hypothesis that they were used as incendiary artifacts, since their size and curvature strongly suggest their burning power was a deliberate criterion on crafting them.

A conspicuous Maya mirror from the Classic period, the Turquoise Plaque from Chichen Itza, is identified as being concave, showing the continuity of concave mirrors manufacturing from the Preclassic. Its curvature and focal distance were calculated from the transverse section of its restoration diagrams. In addition, two fragments from an Olmec mirror were studied in order to determine their surface figure, finding that it was a precisely carved paraboloid. From our measurements, their focal distances and burning power were calculated, finding agreement with the incendiary utilization hypothesis for all the studied specimens.