The Doctor slowly stepped back and forth and sped up until he was hopping. "Gravity test. So, it'll be very time consuming and messy, and rather wasteful, because I think I might just possibly be able to help you. You see, I am a super-intelligent alien being who flies in time and space." He floated into the air. "And just flies in general." He floated down and back up. "Are you going to shoot me?"
"No," Lundvik answered.
"Good. Why have you got all these nuclear bombs? No, no, no. Easier question. What's wrong with my yo-yo?" The Doctor produced a yo-yo and spun it up and down.
"Doctor, it goes up and down," Clara said.
"Bingo," the Doctor said.
"Ah . . ." Clara finally realized.
"Ah ha. We should be bouncing about this cabin like fluffy little clouds," the Doctor said, turning on his back and spinning the yo-yo up to the ceiling and back to his hand, "But we're not. What is the matter with the moon?" He played with the yo-yo, flipping it wherever he wanted for a moment before returning to the ground.
"Nobody knows," Lundvik replied.
