It is difficult for anyone unfamiliar with astronomy to grasp the concept of the Black Hole.不熟悉天文学的人很难理解黑洞的概念。One guest at the crowded reception was heard to mutter "It's like the Black Hole of Calcutta in here."有人听到拥挤的接待处的一个客人念叨说：“这个地方真像加尔各答黑牢一样闷热。”