Due to sheer distances and expanses of space involved, any extraterrestrial civilization would have great difficulty communicating with ours. Detecting planets outside our solar system requires more sophisticated instruments than are currently available. There are many stars that are not orbited by planets. Forms of life other than life as we know it exist on other planets.
To the Editor: In 1960, an astronomer proposed a mathematical model for determining whether extraterrestrial life exists. It was based on the assumptions that life as we know it could exist only on a planet and that many stars are, like our Sun, orbited by planets. On the basis that there are nine planets in our solar system and one of them has life as we know it, the astronomer predicted that there are as many as one million extraterrestrial civilizations across all solar systems. Yet astronomers to date have not detected even one planet outside our solar system. This indicates that the astronomer' s model is wrong, and life as we know it exists only on the planet Earth.
Clay Moltz Which one of the following, if accepted by Clay Moltz, would require him to reconsider his conclusion?