In a discussion about a spaceship traveling between the Earth and the moon, participants explore the effects of pushing a large vehicle in space. They clarify that mass exists in space, and while objects may experience weightlessness, gravity is still present. According to Newton's third law, when a person pushes off a tractor-sized vehicle, they will be pushed back due to equal and opposite forces, but the accelerations will differ due to the mass of the objects involved. The analogy of jumping on Earth illustrates that a person's force is insufficient to significantly move a massive body. Overall, the conversation emphasizes the principles of mass, force, and inertia in a zero-gravity environment.