The Fabric of the Cosmos

Chapter 1

Space, Time and Why Things Are as They Are

What is Reality?

"Surely, reality is what we think it is; reality is revealed to us by our experiences."

"To one extent or another, this view of reality is one many of us hold, if only implicitly. I certainly find myself thinking this way in day-to-day life; it's easy to be seduced by the face nature reveals directly to our senses. Yet, in the decades since first encountering Camus' text, I've learned that modern science tells a different story. The overarching lesson that has emerged from scientific inquiry over the last century is that human experience is often a misleading guide to the true nature of reality. Lying just beneath the surface of the everyday is a world we'd hardly recognize."

The Fabric of the Cosmos, p.5, Brian Greene

Classical Physics

Relativistic Physics

Quantum Physics

Cosmological Physics

Unified Theory

String Theory

"Each generation takes over from the previous, pays homage to its predecessors' hard work, insight, and creativity, and pushes up a little further. New theories and more refined measurements are the mark of scientific progress, and such progress builds on what came before, almost never wiping the slate clean. Because this is the case, our task is far from absurd or pointless. In pushing the rock up the mountain, we undertake the most exquisite and noble of tasks: to unveil this place we call home, to revel in the wonders we discover, and to hand off our knowledge to those who follow."

The Fabric of the Cosmos, p.22, Brian Greene

Chapter 2

Is Space a Human Abstraction or a Physical Entity?

What Is Space?

Relativity Before Einstein

"It is indeed a matter of great difficulty to discover and effectually to distinguish the true motions of particular bodies from the apparent, because the parts of that immovable space in which those motions are performed do by no means come under the observations of our senses."

Sir Isaac Newton's Mathematical Principle of Natural Philosophy and His System of the World, trans. A. Motte and Florian Cajori (Berkeley: University of California Press, 1934, vol. 1, p. 12)

"So Newton leaves us in a somewhat awkward position. He puts absolute space front and center in the description of the most basic and essential element of physics - motion - but he leaves its definition vague and acknowledges his own discomfort about placing such an important egg in such an elusive basket. Many others have shared this discomfort."

The Fabric of the Cosmos, p. 29, Brian Greene

Is Space Real?

"Generations of physicists have found it deeply unsettling to imagine that the untouchable, ungraspable, unclutchable fabric of space is really a something - a something substantial enough to provide the ultimate, absolute benchmark for motion. To many it has seemed absurd, or at least scientifically irresponsible,, to base an understanding of motion on something so thoroughly imperceptible, so completely beyond our senses, that it borders on the mystical .Yet these same physicists were dogged by the question of how else to explain Newton's bucket. Mach's insights generated excitement because they raised the possibility of a new answer, one in which space is not a something, an answer that points back toward the relationist conception of space advocated by Leibniz. Space, in Mach's view, is very much as Leibniz imagined - it's the language for expressing the relationship between one object's position and another's. But, like an alphabet without letters, space does not enjoy an independent existence."

The Fabric of the Cosmos, p. 37, Brian Green

"During the first few decades after Mach introduced his ideas, these questions couldn't be answered. For the most part, the reason was that Mach's suggestion was not a complete theory or description, since he never specified how the matter content of the universe would exert the proposed influence. If his ideas were right, how do the distant stars and the house next door contribute to your feeling that you are spinning when you spin around? Without specifying a physical mechanism to realize his proposal, it was hard to investigate Mach's ideas with any precision."

The Fabric of the Cosmos, p. 38, Brian Greene

Chapter 3

Is Spacetime an Einsteinian Abstraction or a Physical Entity?

Is Empty Space Empty?

The Luminiferous Ether

Relative Space and Relative Time

General Relativity

"In Newton's view and subsequently that of special relativity, space and then spacetime were invoked as entities that provide the reference for defining accelerated motion. And since, according to these perspectives, space and spacetime are absolutely unchangeable, the notion of acceleration is absolute. In general relativity, though, the character of space is completely different. Space and time are dynamic in general relativity; they are mutable; they respond to the presence of mass and energy; they are not absolute. Spacetime and, in particular, the way it warps and curves, is an embodiment of the gravitational field. Thus, in general relativity, acceleration relative to spacetime is a far cry the the absolute, staunchly unrelational conception invoked by previous theories. Instead [...] acceleration relative to general relativity's spacetime is relational. It is not acceleration relative to material objects like stones or stars, but it is acceleration relative to something just as real, tangible, and changeable: a field - the gravitational field."


The Fabric of the Cosmos, p. 75, Brian Green