In this series of books mankind has developed Virtual Copies of scientists to populate Probes sent out exploring space. One probe discovers a planet with an ancient Spire existing on the surface. An alien ship is discovered there. While the human clones are investigating, a different alien ship appears and destroys all traces of the technology. From this point the humans follow the path of these Spires from one planet to another. While being followed by the ships that continue to destroy every location. Eventually the humans learn that the ships destroying the spires are the same entities that built the Spires but are now travelling backwards through time.
I know this isn't a very good description of the series, but its been a while since I read them. I think there was 3 books in all. The series deals with problems humans will face with alien encounters. The alien races they eventually encounter are of various levels of technology and mindsets.
I am also looking for the name of the book or author pertaining to a book about an evil presence that brings about complete darkness on Earth by making the daylight times shorter and shorter each day. Meanwhile large holes appears around the world. Each night various "horrors from hell" exit the holes killing humans each night. Meanwhile, the hero of the story is a person chosen to wield a sword with the ability to give him immortality each time it is drawn. He basically wants to die because he has outlived everyone he has ever cared for. But each time he thinks that he will finally rest in peace he is forced to battle once again and thus restoring his youth again.
I am also interested if Julian May (author of the Pliocene series and the Galactic Milieu series) ever filled in the events that led to the evolution of the Tanu race and Marc Remillard into the Llymic race.