Why Darry say your living in a vacuum?

Darry tells Ponyboy that he's "living in a vacuum" to emphasize that Ponyboy is isolating himself emotionally and not fully engaging with the realities of their lives. Darry believes that Ponyboy is not acknowledging the challenges they face as a family and is instead retreating into his own thoughts and dreams. This statement serves as a wake-up call for Ponyboy to recognize the importance of connecting with his family and the outside world.