What do you think so far after reading the introduction? If you have read the rest of the book, how well do you think the introduction covered the book? Do you think Saunders painted a fair picture of the arguments for and against the many worlds interpretation (MWI) in the introduction or do you think he was biased?
I could tell he supported MWI but I still think he did a reasonably good job writing a summary from an objective standpoint especially in regards to tone. One way I noticed he did this well was that when he used rhetorical wording or points he would do it in the context of paraphrasing, citing or summarize specific points made in other essays and especially in other essays in the book, which meant he as author still kept that quasi-journalist objectivity.
Most of the raw math and some of the other parts went over my head. One complaint I had about our previous book of the month, The Grand Design by Hawking and Mlodinow was that I felt they made things too basic. So far this book seems to have the opposite problem, it jumps in too deep too quick and its hard to follow along as a layman. As an introduction to MWI or worse yet as an introduction to Quantum Mechanics, and a basic understanding of the later seems to be a prerequisite to understanding the former, this introduction is no good. But I suppose it is not meant to be an introduction to MWI but rather an introduction to -- or quick, rushed summary of -- this book. Hopefully, the rest of the book doesn't get even harder to follow along and more complex, but rather the authors of each chapter take a little more time to explain some of the ideas involved in their arguments to help us non-experts follow along. In any case, despite some of the complex issues quickly rushed over, I think overall the introduction provides a decent broader context in which to prepare looking at more specific in-depth articles and points.
Overall, I am happier than expected about how much of this book seems to be philosophy rather than science.
One thing I love about this book is that it has plenty of specific citations and references that are well-organized. Other books of the month like On Kindness had a lot of lost potential because they lacked citations and for that matter helpful background or supporting data that would most warrant sources and citations.
Moving on, I have a few notes I took while reading the introduction.
On page 16 of my copy of the book, Saunders addresses a point I found fascinating about symmetry. It reminds me of an old philosophical question about a dog walking in a symmetrical room with two bowls of food and which food he eats. It takes some somewhat unrealistic assumptions to believe such a symmetry particularly for the likes of a dog, but as a thought experiment it addresses some presumably real issues. Such a philosophical quandary likely may have existed long before MWI. But Saunders using not a dog but a coin-flip makes me realize how MWI compliments that would-be problem:
Saunders wrote:As Wallace points out, at the heart of his arguments for the equivalence rule (and Deutsch's original argument) is a certain symmetry -- the case of the equi-amplitude outcomes--that cannot possibly be respected in any one-world theory. A tossed coin in any one-world theory must land one way or the other. However perfect the symmetry of the coin, this symmetry cannot be respected (not even approximately) by the dynamics governing its motion on any occasion on which it is actually thrown. But it can in Everettian quantum mechanics.
Whether one world or many, I doubt a dog in a room or a coin-flip ever really represents an equi-amplitude because in those cases I suspect the seeming symmetry is an illusion, i.e. made up of what Saunders may call an epistemic probability as opposed to an objective one, and a true symmetry at that macroscopic level might lead to highly unexpected results like a coin landing straight-up or cracking into pieces rather than landing on either side. However, the point of the thought experiment and thus the point in the quote by Saunders regarding true symmetry remains.
Here is another idea touched on that has me looking at things in a new light:
Saunders wrote:And betting, in the fission picture, at least once the structure of branching and amplitudes are all known, is a matter of caring about what goes on in some worlds, not beliefs about what happens in those worlds. In Albert's words: But remember (and this is the absolutely crucial point) that deciding whether or not to bet on E, in the fission picture, has nothing whatsoever to do with guessing at whether or not E is going to occur. It is, for sure. And so is -E. And the business of deciding how to bet is just a matter of maximizing the payoffs on those particular branches that -- for whatever reason -- I happen to care most about.
This seems to me to pretty much be an argument over semantics, but it's a useful one and this is a powerful albeit semantic argument for Albert's way of looking at things in my opinion. I find parallels between this argument regarding betting as a representation of preferences in MWI wit the kind of issues that come up when we question personal identity even in an assumed one-world reality that make us wonder why we might care about our future self more than anyone else now or in the future and even why anything matters when we will all be dead at some point.
Anyway, I am sure these issues will each be covered more specifically in later chapters. I am very interested to read the rest of this book.