The Integral Trees is an exercise in constructing an alien environment, a standard form of science fiction. While some writers such as Ursula K. Le Guin, Frank Herbert, or C. S. Lewis make exploring a new world a spiritual journey with the alien world symbolic of the human consciousness or soul, Niven, like other science fiction world builders, makes the Smoke Ring a new part of the physical universe. Niven challenges himself to design a free-fall environment scientifically consistent and filled with details ranging from astronomy to anthropology. The Integral Trees may be best compared to such works as Foul Anderson's Fire Time (1970-1974), Robert L. Forward's Dragons Egg (1980), and Niven's own Ringworld (1970). Niven, in fact, dedicated Integral Trees to Forward for his help in designing the Smoke Ring. Niven exercises care in presenting his Smoke Ring without slowing down the plot with exposition...