The Fabric of the Cosmos the book, such as discussions revolving around classical physics, quantum mechanics, and cosmological physics. Chapter 2, "The Universe and the Bucket", features space as its key point. The question posed by Greene is this: "Is space a human abstraction, or is it a physical entity?" The key thought experiment is a spinning bucket of water, designed to make one think about what creates the force felt inside the bucket when it is spinning. The ideas of Isaac Newton, Ernst Mach, and Gottfried Leibniz on this thought experiment are discussed in detail. Chapter 3, "Relativity and the Absolute", focuses on spacetime.
N-entity the lowest, "i.e.", the physical layer, to the highest, so that the -th layer is above the "n"-th layer and the -th layer is below. N-entity In telecommunication, a "n"-entity is an active element in the "n"-th layer of the Open Systems Interconnection--Reference Model (OSI-RM) that (a) interacts directly with elements, "i.e.", entities, of the layer immediately above or below the "n"-th layer, (b) is defined by a unique set of rules, "i.e.", syntax, and information formats, including data and control formats, and (c) performs a defined set of functions. The "n" refers to any one of the 7 layers