Superman: "I can fly aroun the world in minutes, right? Well, I've always thought... in theory... I ought to be able to focus that energy and vastly increase my speed."
Lois: "How does speed help us escape?"
Superman: "Because if I can gear up my speed and shift its direction back and forth, I'll vibrate. Vibrate so fast I can displace (?) my molecular structure."
Lois: "And turn yourself into a mass of loose molecules?"
Superman: "...And pass through the force field."
From: Don't Tug On Superman's Cape
