The release week for June 19 brings even more summer big-idea science fiction, led by two much-anticipated novels. The first (though how do you pick between them?) is Existence by David Brin, Narrated by Kevin T. Collins, Robin Miles, and L. J. Ganser for Audible Frontiers, concurrent with its hardcover and e-book release from Tor Books. At 32 and a half hours, it’s no lightweight, combining several point of view characters along with multiple “non-fiction” tracks as Brin follows the story of an alien