In 1946, my mother, Myfanwy, was 16 and going to school in Cape Town, South Africa, when she wrote a letter to Albert Einstein that changed her life forever. She shared her dreams of becoming a scientist, describing how she and her best friends would stay up late to study the stars. To her amazement, he responded with an encouraging note. She wrote again, this time confessing that he’d been corresponding with a girl. He replied a second time, saying he didn’t mind that she was a girl—and that most importantly, she shouldn’t mind. At the time, men and women were not yet seen as equals, and my mother really struggled with being a girl and yet wanting to become a scientist. But she gathered that if the Albert Einstein didn’t care, she shouldn’t either.