A Fire Upon the Deep by Vernor Vinge

One of the best Sci-Fi books of the past 20 years, this book is so chocked full of extrapolations, interesting cultures, strange aliens, unusual physical phenomena, and just rousing ADVENTURE, that I couldn't put it down and read it straight through in one sitting. The book is set in the same sci-fi universe in which Vinge set his sequel "A Deepness in the Sky", though that storyline occurred 10,000 years earlier. In this universe, the laws and physical constants of physics change as one goes further from the galactic center. Near the center, physical laws become restrictive, physics breaks down, and complex devices and even life become impossible, while further from the center such things as faster than light travel, communications, and even god like AI are not only possible, but common. Human explorers, having escaped the restrictive mid section of the galaxy with slower than light ships, and colonized worlds in the 'transcend', the section of the galaxy between the restrictive zone and the dangerous outer periphery occupied by a variety of mysterious godlike super-beings. Here, near the edge of transcend, they find a mysterious archive from which they hope to extract new knowledge to compete with the myriads of other emerging life in the transcend. But ancient archives are dangerous, and unfortunately for the human researchers, this archive is a trap. The exploration team, and soon the human civilization from which it came, is 'absorbed' by a rouge super-being called an 'abomination' which they inadvertently released from the archive. Two children, survivors of the exploration team manage to escape, but soon find themselves on a world with some of the strangest and most imaginative aliens I have ever seen. Meanwhile the Abomination continues to absorb nearby civilizations on the galactic periphery at an ever increasing rate. The origins of the abomination must be found, and something must be done to stop it before it's too late. An artificial man (Pham Nuwen), and a human woman and survivor of another of the Abomination's victim civilizations search for the missing research ship and the two children that escaped from the birthplace of the Abomination in order to stop it. In the mean time, the children find themselves at the hostages in the center of an ancient feudal conflict on the strange world they escaped to. The aliens are truly unique, and very imaginative. It took me a while to figure out what was going on when they are first described, but once you understand, you'll find it marvelously inventive. As with all Vinges books, a great deal of attention is paid to strong characterization, and great storytelling. The extrapolations and sci-fi inventions are incredibly interesting, but never overshadow the human drama and wild seat of the pants adventure. Certainly one of the best books I've read, and I've read a large number of them.