All that we really need to plot out the future of our universe are a few good measurements. This does not mean that we can sit down today and (36) the future course of the universe with anything like (37) There are still too many things we do not know about the way the universe is put together. But we do know (38) what information we need to fill in our knowledge, and we have a pretty good idea of how to go (39) getting it. Perhaps the best way to think of our present situation is to (40) a train coming into a switchyard. All of the switches are set before the train arrives, so that its path is completely (41) Some switches we can see; others we cannot. There is no doubt if we can see the setting of a switch: we can say with confidence that some of the (42) futures will not be realized and others will. At the unseen (43) , however, there is no such certainty about it. (44) The unseen switches are the true decision points in the future, and (45) When we think about the future of the universe, we can see our "track" many billions of years into the future, but after that there are decision points to be dealt with and possible fates to consider. (46)