‘Immersive journalism’ is a rather popular trope these days, and GQ editor A.J. Jacobs is one of its most entertaining adherents, performing a public service with his quest for knowledge in his latest book, THE GUINEA PIG DIARIES…His experiments, alternately Herculean and banal, are emblematic of how difficult it is in this modern age to find enlightenment; ‘know thyself’ regularly brushes up against the cold, rocky bottom of daily life.