In the final book of his astonishing career, Carl Sagan brilliantly examines the burning questions of our lives, our world, and the universe around us. These luminous, entertaining essays travel both the vastness of the cosmos and the intimacy of the human mind, posing such fascinating questions as how did the universe originate and how will it end, and how can we meld science and compassion to meet the challenges of the coming century? Here, too, is a rare, private glimpse of Sagan's thoughts about love, death, and God as he struggled with fatal disease. Ever forward-looking and vibrant with the sparkle of his unquenchable curiosity, Billions & Billions is a testament to one of the great scientific minds of our day.

卡尔•萨根（Carl Sagan，1934—1996 ），美国天文学家，20世纪最著名的科普作家之一。他曾任美国康奈尔大学行星研究中心主任，被誉为“大众天文学家”和“公众科学家”。作为美国航空航天局的顾问，萨根参与了美国的空间计划，与同事一起设计了探索金星的“水手1号” 项目。他对人类将无人航天器发送到太空起过重要的作用，在行星科学、生命起源、外星智能的探索方面也有诸多成就。在冷战时期，萨根建立气象模型说明全球范围内的核战争可能导致地球生态失衡，并提出了“核冬天”的假说。20世纪70年代起，他开始主持电视科学节目，出版了大量科普书籍，他主持的电视系列节目《宇宙》在全世界取得热烈反响，科普作品《伊甸园的飞龙》荣获普利策奖。