Omega, written by astronomer Camille Flammarion (1842-1925), is no less than an epic history of our future--a startling and unforgettable vision of the end of the world. Reasoned scientific speculation combined with probing philosophical inquiry lend credibility and magnitude to this tale of how humankind will physically and culturally evolve over the next several million years.   The end begins in the twenty-fifth century, when a comet threatens to collide with the earth. The consequences of that frightening cosmic event are far-reaching, setting in motion a series of physical, psychic, and social changes that will profoundly affect the planet and its people far into the future. The earth's surface drastically transforms over time. Cultures radically alter, collapse, and fade away. Nations rise and fall, species become extinct, and human beings find themselves at the end of the world, alone and changed in fundamental ways. This melancholic, poetic science fiction tale of things to come is as compelling and disturbing today as when it was first written.