(3) To be sure, no one can prove that life
exists beyond earth. Moreover, as recent
ly as two or three decades ago it was pur
e speculation even to suggest the possi
bility. But that has changed.With our rapi
dly growing understanding of the univers
e has dawned the profound belief thatwe
are not alone. Not long ago at a symposi
um on this subject, an astronomer declar
ed, "The question has become not so m
uch one of if as of where."
