If you’re curious about the universe, if you always had a hankering to understand relativity, quantum mechanics, string theory, M-theory, and how many supersymmetric particles can dance on the head of a pin, one of the ways to make a little progress on your never-ending journey of understanding reality is to read Brian Greene’s The Fabric of the Cosmos: Space, Time, and the Texture of Reality.
He begins with a spinning bucket of water to illustrate the notions of motion held by Newton, Leibniz, Ernst Mach, and Einstein in their conflicting views of absolute versus relative space. For a couple of chapters and most of a hundred pages he threads the ideas of those thinkers through that simple spinning bucket and concludes unsurprisingly that Einstein has the best handle on the issue with his general relativity theory supporting a surprisingly absolute concept of spacetime and accelerated motion. And Greene manages this while not putting you to sleep, keeping you entertained with intuitive analogs and earthy examples such as a pistol duel between two whimsically named characters, Itchy and Scratchy.
Although my educational background is physics (from a long time ago), I learned something new—an astounding revelation for me in a chapter devoted to quantum theory. To the counter-expectations of Einstein and many others, physics (aka nature and reality) was proven to be non-local as a result of experiments in the 1970s and 1980s based on an insight by physicist John Bell in 1964. This earth-shaking result, violating the cherished notion of the locality of physics, establishes that things can be interconnected instantaneously at a distance, sinking Einstein’s notions of hidden variables and the incompleteness of quantum mechanics. The experimental establishment of quantum entanglement and the discovery that it apparently disobeys the law—the speed limit of light—nearly brought down the Special Theory of Relativity, leaving it in a delicate and unsteady balance with quantum theory.
The book progresses through three more broad themes—“Time and Experience,” “Spacetime and Cosmology,” “Origins and Unification”—before concluding with a final “Reality and Imagination.” The topics within those themes include the ebb and flow of time and its dance with entropy (which way does time’s arrow point?), the teeming fullness of the cosmic vacuum, the Higgs field and the Big Bang, repulsive gravity, inflation and a runaway universe, string theory and M-theory, and curled-up six-dimensional Calabi-Yau shapes in ten-dimensional spacetime.
As might be expected, the last theme, “Reality and Imagination,” is full of blue sky (or should that be black sky?) conjectures on dark matter, dark energy, and the fate of the universe among other things, but among those other things is discussed the concrete and tantalizing possibility that strings (the fundamental constituents of string theory whose different vibrational modes constitute everything we’re made of) might be much larger than previously thought, which would translate into the CERN Large Hadron Collider finding scads and scads of previously unseen supersymmetric particles, like ”a well-hit golf ball ricocheting around the inside of a piano.” The book was written in 2004, and since then the first phase of collider operations has concluded with the discovery of the Higgs particle but not much else. Although this is not a refutation of string theory, it puts a damper on some aspects of it that Greene waxes enthusiastically about. There remains a chance that the future upgraded version of the collider will find something in its extended energy range.
This book manages to make an entertaining story out of an incredibly esoteric and still unsettled field. Greene is a master of the simple and easily grasped analogy, which is why his explanations are so easy to follow and understand. He more than acknowledges the incompleteness of our knowledge of the cosmos, and in fact revels in its incompleteness as an exciting path forward through a jungle of unknowns, a never-ending path of adventure for the human spirit. If you’re curious about the cosmos and the meaning of space and time, then The Fabric of the Cosmos is your book. It does a damn good job of laying out some of the answers and being entertaining as well, but leaves plenty more unknowns to ponder …
But then that’s the nature of the infinite journey we’re on, isn’t it?