For the past two decades, increasing numbers of scientists have been optimistic about finding other intelligent life forms in our galaxy. On the other hand, as knowledge has grown regarding how life developed on earth, a scientific counterrevolution has evolved. Simply stated, it questions the inevitability of widespread life within our galaxy, let alone elsewhere in the vast universe. These scientists believe that the first extraterrestrials we shall meet will be our own grandchildren, and not some alien intelligent beings. Various speculations and probabilities concerning the existence of extraterrestrial life are explored including where intelligent life may exist, characteristics of such life, methods of contact, and evidence indicating the existence of intelligent, extraterrestrial life. Additional topics discussed include planetary atmospheres, stars, evolution of life, natural selection, and implications of these topics for intelligent, extraterrestrial life. United States and Soviet space programs, space colonization, and interstellar travel are also discussed. (Author/JN)