Our Mathematical Universe by Max Tegmark
If you're a frequent reader of Scientific American, New Scientist, and the like, you've probably seen at least one article by or featuring Max Tegmark. Tegmark, a Swedish physicist, has as his main claim to fame a four-level classification scheme for multiverses. Our Mathematical Universe is the ultimate explication of Tegmark's multiversal ideas, and a philosophical manifesto of sorts, arguing that not only does math describe our universe, but that our universe is math.
Leavened with biographical details, Our Mathematical Universe is an enjoyable read, though often a mind-bending one. Is it convincing? I'm not so sure about that. Tegmark is a lucid writer, and does good work explaining difficult concepts in understandable ways, though definitely not everything, but one gets the impression that some of his assertions and assumptions seem both perfectly clear and rock-solid to him, but not necessarily others.
Tegmark must be lauded, though, for fully admitting the controversial nature of his ideas, and the arguments against them. He, of course, ultimately thinks these arguments invalid, but he does give them more discussion and respect than in a lot of books of this type. His breezy and jovial tone keeps the polemic down. I was also pleasantly surprised by how string-theory-neutral he is. He goes into interesting digressions into consciousness, life, and the future of humanity, which were very interesting even if, again, not always wholly convincing.
I must give notice to the copious tables, charts, and illustrations, which are well-done and informative, which is not always the case in such books. Also, the chapter-end bullet-point summaries are a good way of refreshing and clarifying for when you find your eyes crossing by the end of a chapter.
This is a work of wild speculation, controversial and even perhaps crazy, but it is interesting in a very deep way. Reject every word he says or fully buy into it, the book makes you think.
(For a more skeptical review, which also contains links to still more reviews, from someone more knowledgeable about the actual content, see Peter Woit. See the comments, especially, for a good dialogue between Woit and Tegmark himself.)
Trespassing on Einstein's Lawn by Amanda Gefter
It all began with a father asking his teenaged daughter "What is nothing?" It turned into a quest to understand the universe. Amanda Gefter and her father bonded over trying to figure out the world, and this propelled her into a self-made science journalism career. Trespassing on Einstein's Lawn is the chronicle of how this happened and what she learned.
It's unusual for this genre in its tone. It has curse words! I was shocked by this, but not in an unpleasant way. These sorts of books never have that kind of language, but for the tone of the book, it fits. Physicists are human! Talking like regular people do, crudity and all! So weird!
It's also, sadly, an unusual story because women don't usually write about this stuff. I can only think of a few female writers in this genre, like Kitty Ferguson (who's written mostly about and related to Stephan Hawking) and Dava Sobel maybe (though mostly her work is historical). Lisa Randall wrote a popular book a few years ago about her work, but she's a scientist. Most of the authors in this area are white males. Thus, Gefter's voice is different and desperately neeeded in the game.
The goal of the book is to understand reality, and the conclusion she comes to is, basically, that there is no universe. Every observer has their "own" universe defined by their frame of reference, and it is all ultimately Nothing, which looks like Something due to the boundaries imposed upon it by the reference frames of the observer. The observer, since it does not exist in other reference frames, is ultimately just Nothing as well. I'm not really doing the conclusion justice, of course; she wrote a whole book to get to and explain it. But that's a basic summary, I think.
I can't say I come away particularly convinced. I don't think the definition of what an observer is is really interrogated enough, though it is noted here and there. I also think the "and then the observer disappears!" trick at the end is a bit of a cop-out. Also, a lot of the steps towards the conclusion are based on concepts and theories in physics that are far, far from as settled and proven, or even provable, than I think she ever lets on. There are major, major differences of opinion and radically different interpretations at work on these issues. She does explain a lot of those controversies, but ultimately just goes with whatever interpretation "feels right" to her and fits with stuff she's already decided. Even to begin with, philosophically, she starts with two assumptions: One, her father's definition of Nothing (which they term the "H-state") as "a state of infinite, unbounded homogeneity"; Something is merely Nothing with a boundary. Two, that what is not invariant is not "real." The first is a legitimate approach to Nothing, but it also isn't the only one. The second I just don't think is obviously true.
This is a personal story, and a lot of it involves personal encounters with physicists. And, as is always the case, you can tell she likes some more than others, and thus naturally gravitates towards their point-of-view over those of whom she does not like, though she is always fair in hearing them out. John Wheeler is who really jump-started the project; her and her father spent the time to read all of his journals in an effort to understand his thinking. He's sort of the spiritual father of the quest, and thus his ideas shape the entirety of her thinking. You can tell she became friends with Leonard Susskind, and was intimidated/disliked David Gross. Which do you think proved more relevant to her conclusions?
This isn't all to knock her journey or her conclusions. After all, this is, to reiterate yet again, a memoir, a personal story of discovery, and ultimately just one person's Deep Thoughts about the what and why of reality informed by a lot of cutting-edge physics. This is also an area where, if you've been following along with me for a while, I have a great deal of interest and follow very closely. I have an idea of a lot of the stuff she's leaving out or glossing over. I also have my own prejudices and preferences which heighten my skepticism and heighten my criticism.
I admit to feeling slightly jealous of her. She is interested in many of the same questions I am, but had a cohort in her father to actually talk about them with. She has had the chutzpah to take her interest and make a living and a life out of it. She and her father have spent countless hours of their lives thinking, reading, and fretting about the meaning and origin of reality, an endeavor to which I can really, really relate. Her father has a whole room filled with books on physics and such! Oh what bliss. She also seems comfortable and satisfied with what she's found, which I envy.
Despite all the disagreements I may have with it, I can't help but recommend the book. She's a very good writer, and hers is a fascinating and enjoyable story.
Two matters of book design to close: One, it has a great paper smell. Sort of tea-like? Two, and much less positively, there is no index. Perhaps because it's sorta-kinda a memoir? But it has a glossary and footnotes. It's very strange, to me.
(For another take on the book, again see Peter Woit.)