Light Energy Converted to Mechanical Energy Without Detectable Heating

Abstract

Electromagnetic energy can be converted into mechanical energy in several light/matter systems such as solar panels, semiconductors, or plant chloroplasts that generate electron flow by absorption of light. Shining light onto dark leaflets in a Crookes radiometer system quickly induces rapid mechanical rotation that may be quantified as a function of light intensity and radial distance from the spin axis. Coincident measurements were made of leaflet temperature with an infrared laser thermometer while observing rotation rate. Light-induced rotation occurs rapidly and remains without detectable warming over chronic periods of time. Shining light on the reflective white leaflets does not induce motion. Heating and cooling cause forward or backward rotation but only with substantial temperature changes, and this effect stops when a fixed temperature is reached. The data indicate that neither pressure from momentum collisions nor heating are involved in the conversion of EM energy to mechanical energy in the system. It appears that electrons directly energized by light produce a force at the electron surface/atmosphere interface. The significance of these findings in physicochemical and biological processes is discussed.