Aliens

"If elementary life forms are common throughout the cosmos, could intelligent beings have evolved elsewhere, and are they seeking us out? A father-and-son-team of scientists - both with research background in astronomy and physics - gives us the most up-to-date scientific answers about extraterrestrial civilizations and our attempts to find them. If they exist, why haven't we been able to make contact? Could they be reluctant or unable to make themselves known? If aliens visited us before recorded history, are we now overdue for another visit? Even if we discount most UFO sightings as erroneous, how do we explain that more than four million Americans claim they have been abducted by aliens? Is there a case to be made for a future scientific study of UFOs?"--BOOK JACKET.