Inspiration can strike any place — or at any age. Of the 81 inventions that rocked the 20th century (based on Encyclopaedia Brittanica‘s list of 325 inventions that had profound effects on human life), seven were the brainchildren of Americans age 50 or older working solo. Here’s why it pays to keep plugging away. MUZAK, 1922 George Owen Squier (1863-1934)