- Hardcover: 432 pages
- Publisher: Knopf; 1st edition (January 7, 2014)
- Language: English
- ISBN-10: 0307599809
- ISBN-13: 978-0307599803
- Product Dimensions: 6.6 x 1.6 x 9.5 inches
- Shipping Weight: 1.8 pounds
- Average Customer Review: 374 customer reviews
- Amazon Best Sellers Rank: #81,607 in Books (See Top 100 in Books)
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Hardcover – Deckle Edge, January 7, 2014
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The first chapter serves as an introduction, setting the stage by considering the core question with which the book is concerned, “What is reality?” The book then proceeds in three parts. The first, Chapters 2 through 6, discuss the universe at the scale of the cosmos. Chapters two and three consider space and time and answer such questions as how big is the universe and where did everything come from. Chapter 4 explores many examples of mathematics’ “unreasonable effectiveness” in explaining our universe with respect to expansion and background radiation and the like (a more extensive discussion is in Ch. 10.) The fifth chapter investigates the big bang and our universe’s inflation. The last chapter in part one introduces the idea of multiverses and how the idea of multiple universes acts as an alternative explanation to prevailing notions in quantum physics (e.g. collapsing wave functions)—and, specifically, Tegmark describes the details of the first two of four models of the multiverse (i.e. the ones in which parallel universes are out there spread out across and infinite space), leaving the other two for the latter parts of the book.
Part two takes readers from the cosmological scale to the quantum scale, reflecting upon the nature of reality at the smallest scales—i.e. where the world gets weird. Chapter 7 is entitled “Cosmic Legos” and, as such, it describes the building blocks of our world as well as the oddities, anomalies, and counter-intuitive characteristics of the quantum realm. Chapter 8 brings in the Level III approach to multiverses and explains how it negates the need for waveform collapse that mainstream physics requires we accept (i.e. instead of a random outcome upon observation, both [or multiple] outcomes transpire as universes split.)
The final part is where Tegmark dives into his own theory. The first two parts having outlined what we know about the universe, and some of the major remaining mysteries left unexplained or unsubstantiated by current theories, Tegmark now makes his argument for why the Mathematical Universe Hypothesis (MUH) is at least as effective at explaining reality as any out there, and how it might eliminate some daunting mysteries.
Chapter 9 goes back to the topic of the first chapter, namely the nature of reality and the differences between our subjective internal reality, objective external reality, and a middling consensus reality. Chapter 10 also elaborates on the nature of reality, but this time by exploring mathematical and physical reality. Here he elaborates on how the universe behaves mathematically and explains the nature of mathematical structures—which is important as he is arguing the universe and everything in it may be one. Chapter 11 is entitled, “Is Time and Illusion?” and it proposes there is a block of space-time and our experience of time is an artifact of how we ride our world lines through it—in this view we are braids in space-time of the most complex kind observed. A lot of this chapter is about what we are and are not. Chapter 12 explains the Level IV multiverse (different laws for each universe) and what it does for us that the others do not. Chapter 13 is a bit different. It describes how we might destroy ourselves or die out, but that, it seems, is mostly a set up for a pep talk. You see, Tegmark has hypothesized a universe in which one might feel random and inconsequential, and so he wants to ensure the reader that that isn’t the case so that we don’t decide to plop down and watch the world burn.
While this book is about 4/5ths pop science physics book, the other 1/5th is a memoir of Tegmark’s trials and tribulations in coloring outside the lines with his science. All and all, I think this serves the book. The author avoids coming off as whiny in the way that scientists often do when writing about their challenges in obtaining funding and / or navigating a path to tenure that is sufficiently novel but not so heterodox as to be scandalous. There’s just enough to give you the feeling that he’s suffered for his science without making him seem ungrateful or like he has a martyr complex.
Graphics are presented throughout (photos, computer renderings, graphs, diagrams, etc.), and are essential because the book deals in complex concepts that aren’t easily translated from mathematics through text description and into a layman’s visualization. The book has endnotes to expand and clarify on points, some of which are mathematical—though not all. It also has recommended reading section to help the reader expand their understanding of the subject.
I enjoyed this book and found it to be loaded with food-for-thought. If Tegmark’s vision of the universe does prove to be meritorious, it will change our approach to the world. And, if not, it will make good fodder for sci-fi.
I have heard for a long time that the math for relativity or the very large and the math for quantum mechanics or the very small each work very well in their own settings, but try to put them together and they produce non-sense. The math that puts the two together predicts strings or loops that exist in many more than our usual four dimensions.
So we go from atoms to sub-atomic particles like protons to sub-sub-atomic fuzzy particles like up and down quarks to sub-sub-sub atomic vibrations – or equations. Things get fuzzier as we go down. Quarks are pretty fuzzy things. They are not building blocks. Stings or loops are not things at all. It is not that something is vibrating, it is the vibrations themselves that make up reality. There is no “thing” or building block of reality. There is no uncuttable thing like Democrates' atom that is at the basis of it all. There is only an abstraction or a number, according to Tegmark. Reality is based on numbers, math – a Platonic world of forms in a way.
I can say those words, just like I can say that a singularity is a point of infinite density and temperature without mass or space, but I really don’t know what that means.
But reality is not just independently existing vibrations. Reality comes from their relationships. Mathematical structures are about the relationships between units, in these cases vibrations. (“A mathematical structure is as set of abstract entities with relations between them.” p. 259) I have no idea why they relate at all to each other in certain ways to produce things like quarks, etc. But they do, or we would not be here. Beyond that, I can say things like gluons mediating the strong force that relates up and down quarks to each other in defined ways that lead to protons and neutrons. Relationships between particles are maybe even more real than the the particles themselves.
Why should the various forces, from the strong to weak to electromagnetic to gravity etc etc have the values they do? There is no reason for it. It is just that in our universe they do, or we would not be here. There are many other possible mathematical values for these and other possible forces, and all of those universes exist too, Tegmark argues. Most of them won’t lead to anything that we could recognize as structured reality since their values and math don’t go there. But out of an infinite number of possible values, there is at least one that has the ones that permit us to have evolved. Without all the many goldilocks conditions that have to exist for us to be here, we would not be here to be aware of our own universe and that others must exist as well.
Tegmark argues for four levels of multiverses and how each realizes a different mathematical structure.
Just a century ago, we thought that the Milky Way galaxy was the universe. We wondered if there were any other habitable planets. We now know there are billions of other galaxies and planets. Why shouldn't there be that many other universes? And math does have an uncanny ability to describe a reality that is more remarkable than we can grasp yet. Does math create universes? Do universes keep breaking off to form new ones every time we act in different ways at the same time? It's worth the time to read Tegmark's arguments for all this.
Combining the information with personal and world events that were occurring while various discoveries were made, kept the reading more lively. Not a textbook, more like an adventure. I seldom recommend a book this highly.