Numerous experiments have confirmed that if the distance between a light source and an observer...

The statement that if the distance between a light source and an observer is doubled, the intensity of the light decreases by a factor of four, describes a consistent, repeatable observation that has been confirmed through numerous experiments. This describes a scientific law, specifically the inverse square law of light. A law summarizes a pattern found in nature, whereas a hypothesis is an untested prediction, a theory is a well-substantiated explanation, and an inference is a conclusion drawn from evidence. References:

Integrated Physical Sciences, Chapter 4: Scientific Laws and Theories