There is a point in the expanding universe where things are moving away from us at the speed of light. Since nothing can exceed the speed of light, we can know nothing of what lies beyond that point. Not only that, but any currently known object that speeds beyond that horizon is lost to us forever. The only other way an object in space can disappear forever is by being sucked into the strangest type of star, a black hole. This second way of vanishing is the topic of controversy in Susskind's Black Hole War. Is something really completely lost when it goes into a black hole? Does it matter? Stephen Hawking (the other side in the "war") believed the radiation that escapes from black holes is entirely uniform, devoid of information, and that once something crossed the horizon of a black hole, it was truly lost. Susskind, and a few others believed this theory of information loss was so dangerous that it undermined and threatened all we think we know about post-newtonian physics.Not to spoil the ending, but as you might expect, Susskind won. Information isn't annihilated in black holes and the laws of physics prevail. But in Black Hole War, the journey is the show. In the battles on the way to discovering how black holes work, there is plenty to appreciate. For example, the holographic principle which says that the amount of information that can be contained in an area of space is equal to the amount of information that can be encoded in its perimeter. So if I take a sphere of space, maybe the one that includes your house and computer and you, I can know everything about what is in that sphere based solely on the information found on the outside of the sphere. It's weird. It's counter-intuitive I still don't really get it. Strange as it is, having fairly solid evidence of its truth was so important that was after Juan Maldacena, an Argentine physicist, showed strong evidence for it, a version of the song Macarena was written for him by another physicist, Dr. Jeffrey Harvey, and performed at a conference. Here's the last verse:M-theory is finishedJuan has great repute The black hole we have mastered Q.C.D. we can compute Too bad the glueball spectrum is still in some disputeEhhhh! Maldacena! Bits like this make Black Hole War a fun, readable, first-hand account of a historical debate among the titans of physics that lasted years and led to a profusion of extremely fascinating research.