Lacking a standard unit for light measurement, scientists devised a spectral sensitivity curve in the early 20th century. This graph, representing an "average human observer," mathematically quantifies light. Though imperfect, it remains the standard today, but an update could significantly improve the energy efficiency of lighting.

Growing Impact is a podcast by the Institute of Energy and the Environment at Penn State. Each episode explores cutting-edge projects of researchers and scientists who are solving some of the world's most challenging energy and environmental issues.

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