In a world where humans can walk on walls without being affected by gravity like a gecko, Rajeev and Yoshiko are in a cubic room with one light bulb hanging from the center of the ceiling. Rajeev is standing on what you would normally consider the floor, while Yoshiko is directly opposite him on what you would normally consider the ceiling. Both are the same height, and both are looking directly at each other. A ball is resting on the wall that Rajeev is staring at. If Yoshiko drops a pen from where she stands, what happens first: does the pen reach Rajeev's level, or does the ball on the wall roll to the ground?

Provide a short response.
Given that humans in this world can walk on walls and ceilings with ease, the wall and ceiling are equally usable surfaces to stand on, much like the floor. The ball resting on the wall remains in its place because gravity does not dictate that it should roll down, as the properties of this world allow it to stay put where it normally wouldn't.

When Yoshiko drops the pen from the ceiling, since humans are not affected by gravity in the same way, the pen might not fall at all. Rather, it might simply float away from her hand or stay in place if the same principles that allow humans to adhere to surfaces like geckos also apply to objects they interact with. 

However, if objects such as the pen are still affected by gravity, the pen would indeed fall, as it is displaced out of her hand and there is no adhesive gecko-like force acting on it to counter gravity's pull. Assuming gravity works on objects the same way as in our world, the pen begins descending towards Rajeev. Meanwhile, the ball, which has not been acted upon by an external force, remains stationary on the wall. Therefore, the pen would reach Rajeev's level before the ball rolls anywhere since the ball does not move at all.