Did comets bring prefabricated building blocks for life to Earth? Did the oceans come from comets? How were the first living cells formed? Did life also exist on Mars? How has Earth managed to maintain a constant climate for more than four billion years despite solar heat having increased dramatically? For two billion years, Earth was dominated by flora consisting of unicellular blue-green algae and bacteria, until oxygen contamination caused their extinction. Thus, the way was made for the evolution of the modern cell and multicellular organisms. Measured on a scale on which the total time span for life on Earth is one year, man has existed for less than seven hours and our civilization for one second. Will man continue to exist for as long as the sun shines, or has civilization condemned itself to destruction? Will nature allow civilization to continue to exist for more than "one second" in the eternities of evolution, or is the short existence of civilization the reason why we have never heard from any others out in space?
(From the book: "Science or God?" ("Videnskaben eller Gud?") edited by Bent Raymond Joergensen and Uffe Graae Joergensen)