生存是文明的第一需要 The first demand of every civilization is to survive 文明不断增长和扩张,但宇宙中的物质总量保持不变 In order to survive and develop,every civilization has to contiuously increase their strength and expand ,however,the whole amount of the substabce in the universe never changes 文明进步的速度和加速度不见得是一致的，弱小的文明很可能在短时间内超越强大的文明 The speed and acceleration of a civilization's progress is not always in the same,a weak civilization has much possibility to surpass a strong one in a short period