Docking in a luxury marina is about the only place to catch a random glimpse of Tiger, who moves through the world in a cocoon of his own creation. When he bought his plane, he blocked the tail number from tracking websites: It ends in QS, the standard code for NetJets. Many athletes, by contrast, have some sort of vanity registration, and some even have custom paint jobs; Michael Jordan's plane is detailed in North Carolina blue, and his tail number is N236MJ -- the "6" is for his titles. Jack Nicklaus flies around in N1JN nicknamed Air Bear. Sitting on a tarmac, Tiger's plane looks like it belongs to an anonymous business traveler, nothing giving away its famous owner. He comes and goes quietly. ... He'd long struggled to sleep, and when he wasn't texting or playing video games, he'd read, often military books about lone men facing impossible odds, such as Roberts Ridge or Lone Survivor, or books about theoretical physics and cosmology. The intro to Get a Grip laid out the basic rules of early science, from Newton and Galileo, focused on the concepts of friction and gravity. These had long interested him. Five-year-old Tiger once made a drawing that showed stickmen swinging different clubs, with the clubface sketched, as well as the flight path of the ball, including distance and apex. ... He grew up without siblings or many friends. Tiger and Earl did everything together, hitting balls into a net out in the garage, or spending hours at the golf course, and when they'd finish, Earl would order a rum and Diet Coke, and Tiger would get a Coke with cherries, and they'd sit and nurse their drinks like two old men. The golf pro at the Navy course, Joe Grohman, worried that Tiger didn't have friends his own age until high school. His friends were Earl and Earl's old military buddies. ... Tiger heard the stories and saw the deep love even strangers felt for each other. His entire childhood revolved around these men and their code.