“I didn’t allow myself to work on it during the day,” she said, “because I didn’t consider it to be real math. I thought it was, like, my homework.” The question asked whether the Conway knot—a snarl ...

When faced with an unsolvable problem, you are said to face a “Gordian knot,” a rope that is tied so intricately or tangled so completely that it is impossible to untie. If you dive a little deeper ...