Star Wars: 10 Greatest Disturbances In The Force
6. Vader Senses Obi-Wan Kenobi
Another disturbance occurs when Lord Vader feels his former friend's familiar presence on the Death Star and immediately takes action. Having assumed all Jedi were either dead or in exile, the presence perturbs him. And because connections can continue between opposing sides of the Force, the bitter bond they shared many years prior reawakens as a menacing disturbance.
The significance surrounding this disturbance deals with how it directs Darth's subsequent search for Obi-Wan; without the notification, he might have stayed in the control room overseeing the Death Star's rollout and Obi-Wan might have lived longer.
More importantly, the disturbance is responsible for old Ben becoming a more powerful Force ghost than Vader can ever imagine. His death also alters Luke's development because the mentor's departure means young Skywalker must go forward alone, which is a quintessential step in the hero's journey.