When Chicagoan Bryan Johnson sold his tech company Braintree to PayPal for about $800 million, he was overweight and unhappy. He divorced, moved to California, and started a two-million-dollar-a-year scientific quest to roll back the odometer on his 45-year-old body to the age of 18. Bloomberg’s Businessweek writer Ashlee Vance tells WGN’s Steve Alexander about the lengths Johnson is going to to try to achieve his teenage dream. Is it working? Check out the audio clip below. If Vance’s name is familiar, it may be because of his best-selling biography of Elon Musk, and other books, or his YouTube tech-travel series, “Hello World.”