Of the five smartest people, who put forward theories related to space?

参考解析：

细节理解题。根据第二段第二句“His work on the origins and structure of the universe, from the Big Bang to black holes, revolutionized the field, while his best-selling books have appealed to readers who may not have Hawking’s scientific background.”以及第五段第一句“Albert Einstein，whose theories on space time and matter helped unravel the secrets of the atom and of the universe, was chosen as ‘Person of the Century’ by Time magazine on Sunday.”可知，霍金和爱因斯坦所提出的理论和太空空间有关，故选C。