That, much as the gravitational pull of the Earth slows the ascent of an apple tossed upward, the gravitational pull of each galaxy on every other must be slowing the expansion of space.
就像万有引力 减慢了抛向空中的苹果上升的速度， 每个星系 对其他星系的万有引力 必须减缓 空间的扩展。