Answer
Niels Ryberg Finsen was not a physicist; he was a physician and scientist. He is renowned for his contributions to phototherapy and his pioneering work in treating skin diseases, particularly lupus vulgaris, with ultraviolet light. His groundbreaking research in this field earned him the Nobel Prize in Physiology or Medicine in 1903. Therefore, while he wasn't a physicist, his medical discoveries had a significant impact on the field of medicine.