Synthesized answer
The provided passages do not directly state what questions remain unanswered. However, the description of Peter Sloterdijk's "Spheres" suggests a broad reinterpretation of Western metaphysics and the history of being.
The project explores spatial and immunological concepts, from the discovery of self to the exploration of world and the poetics of plurality [Passage 1]. It synthesizes spatial theories into a morphology of dwelling, identifying the question of being as bound up with aerial technology, architectonics, and anthropogenesis [Passage 1]. While this indicates the scope of the inquiry, the specific unanswered questions are not enumerated.
Synthesized from the book passages below. Chat with the book on Feynman for follow-up.
From the book
Title: Spheres by Peter Sloterdijk Description: "An epic project in both size and purview, Peter Sloterdijk's three-volume, 2,500-page Spheres is the late-twentieth-century bookend to Heidegger's Being and Time. Rejecting the century's predominant philosophical focus on temporality, Sloterdijk, a self-described "student of the air," reinterprets the history of Western metaphysics as an inherently spatial and immunological project, from the discovery of self (bubble) to the exploration of world (globe) to the poetics of plurality (foam). Exploring macro- and micro-space from the Greek agora…