## 2020-10-19

### Book Review: "The Drunkard's Walk" by Leonard Mlodinow

The book is not too long, and it is a quick & engaging read. The author uses many interesting examples to motivate the discussion of fallacious reasoning in the context of probability as well as ways that probability enters daily life even in areas where people expect more determinism. There are also many interesting historical anecdotes about the development of probability theory, especially how ancient Greece and certain medieval European societies believed that any discussion of uncertainty would go against their conceptions of a pure & deterministic universe (whatever the prime mover might be). Also, in the tenth chapter, there is an interesting discussion of how the development of chaos theory itself is an example of the unpredictable & seemingly random nature of human life (though I didn't like the conflation of chaos theory itself with probability, as chaos is a separate mathematical phenomena that can emerge in purely deterministic systems). Additionally, in the tenth chapter, I appreciated how the author is careful to state that determinism is a bad model only of human behavior (at individual & societal levels) and makes no claim about the applicability of determinism to the universe at large, and how the author makes a call for humility and for rewarding people based on their character instead of perpetuating beliefs that people who are successful are wholly responsible for their successes while people who are in marginalized circumstances are somehow rightfully being punished for past mistakes. Overall, I think the book does a good job of achieving its purpose of illustrating to lay readers how ubiquitous probabilistic phenomena are in even seemingly deterministic aspects of daily life.

Before getting into other criticisms, I should point out that my copy of this book has several printing errors (mostly missing words) and a few typographical errors, but these occurred maybe once every 10 pages (based on an instinctive guess), so these therefore didn't affect my understanding of the book. Also, the author errs in claiming that Germanic rule in the Dark Ages (commonly understood to be the medieval period) preceded the ancient Roman civilization, but this again doesn't undercut the overall argument.

There are other aspects of human behavior that this book fails to adequately capture; these may technically be beyond the scope of this book, but I think they are worth noting anyway, as they speak to larger problems with the ability of people (even those well-trained in STEM fields) to really understand probability theory. The second chapter goes over many examples of how, in the technical language of probability, given events $$A$$ and $$B$$, certain questions can be framed such that laypeople and professional specialists (particularly doctors & lawyers) fall into the trap of believing that $$\operatorname{Pr}(A \cap B) > \operatorname{Pr}(A)$$ even though the opposite is mathematically always true. However, I can already see that the phrasing of many of those questions, particularly the way that events $$A$$ & $$B$$ are juxtaposed (especially if $$B$$ is additional information that may be relevant to the assessment of $$A$$), may make people believe either that what should be interpreted as $$\operatorname{Pr}(A)$$ is actually $$\operatorname{Pr}(A \cap \neg B)$$, in which case $$\operatorname{Pr}(A \cap B) > \operatorname{Pr}(A \cap \neg B)$$ could in fact be true, or that what should be interpreted as $$\operatorname{Pr}(A \cap B)$$ is actually the conditional probability $$\operatorname{Pr}(A|B)$$, in which case $$\operatorname{Pr}(A|B) > \operatorname{Pr}(A)$$ could in fact be true. This speaks more to the way that natural human language is unsuited to the subtleties of the language of probability theory, yet rather than address these possibilities, the author again leaves the discussion there, implying disdain for people who are too stupid to know better. Another problem is that throughout the book, the author raises the question of how to determine whether a particular sequence of observations of outcomes for a process that may be random reflects a specific probability distribution model, but never clearly explains how to do this in practice, instead only giving hints about this through various examples. This is related to the question of why one may prefer an explanation based on probabilities than based on deterministic phenomena, particularly for small sample sizes. For this, I will give an example. Consider exactly 5 observations of an event, which has binary outcomes (either success or failure), for which no other observations are made, and for which in all of those 5 observations, success occurs every single time. Intuitively, laypeople might be inclined to believe that there is a deterministic cause of this, while if a probability theorist were to initially believe that this is consistent with a binomial distribution with $$(N, p) = (5, 0.6)$$ but then later revise this to $$(N, p) = (5, 0.99)$$, laypeople could reasonably wonder why this would be justified, and why the probability theorist refuses to believe in the possibility of some deterministic causal relationship. Of course, this is a contrived example, I understand why causation needs to be proved as an alternative to a null hypothesis, and I understand that probability distributions closer to uniform probabilities are favored as those that maximize entropy (which essentially means that subject to certain known constraints, the probability distribution that best reflects the state of ignorance about a system is closest to uniform), but the author does not properly explain these points. Finally, the broadest problem with this book is that the author only superficially acknowledges the issue that if every calculation in probability theory or statistics, whether of a certain event happening, a string of events being a true "hot streak", or a model fitting data correctly, is itself a probability, then the aforementioned disconnect of this language of probability from natural human language makes it difficult to translate probabilities into robust rules for deterministic (usually binary) decisions that laypeople must make; this is related to the idea that in game theory, a single person playing a single-shot game cannot play a mixed strategy, and the concept of a mixed strategy only makes sense in the context of observing a large ensemble of independent players, possibly playing repeatedly. Perhaps asking the author to address this problem is too much, but I still feel like such failures diminish the book in comparison to its hype.

Without hyping my own credentials, I admit that it is possible that my reaction to this book is more of a reflection of my greater experience with STEM, humanities, and social science fields and with science education/communication compared to when I was in high school. Furthermore, just as this book exhorts, I cannot be overcome by either positivity bias or negativity bias; it would only be fair to take the good & bad parts of this book together as appropriate, without believing that one outdoes or cancels the other. Given this, I can't really make a strong recommendation that readers should or should not read this book.

## 2020-09-30

### Ongoing problems connecting a Canon CanoScan 4400F scanner to Linux Mint

This post is about the experiences I've had connecting a Canon CanoScan 4400F scanner to various computers, primarily focusing on my current laptop which, as of the time of first writing this post, ran Linux Mint 19 "Tara" MATE along with Microsoft Windows 10. For context, I am hoping to scan some of my personal & work notebooks for personal archival. I figured that this scanner, which I've had for a long time, does a good job at rendering images, even though it is quite old & slow, so I should continue using it for as long as it continues to work.

I used to use this scanner regularly with my previous laptop, which is an ASUS U30Jc and, when I last ran it regularly, ran Linux Mint 18.3 "Sylvia" along with Microsoft Windows 7; initially when I connected the scanner to the old laptop (a few years ago), it didn't work with Linux Mint out-of-the-box, so I decided to do all scans in Microsoft Windows and then transfer files between partitions later. I stopped using that laptop approximately 2 years ago, and since then until the beginning of this month, it just sat in a box gathering dust. At the beginning of this month, desirous of using this scanner again for the aforementioned purposes, I brought out the old laptop & scanner, but found out that in the intervening 2 years, the damage to the laptop's screen & hinge had worsened, the battery had completely died due to no charging in that time, and the laptop (on either OS) would randomly overheat & shut off. At this point, I now believe that old laptop should be junked.

My current laptop is an ASUS ZenBook UX331UN. I didn't think the scanner would work with it, because it uses USB 1.1, and I remember having trouble getting this laptop to read an older USB device. Just for the heck of it, I decided to connect the scanner to see what happens. Just as with my old laptop, in Linux Mint, the Simple Scan application didn't find any connected scanners. However, I had the idea to run the command "sudo simple-scan" from the terminal. That showed that the scanner was in fact being recognized, so this was probably a permission problem; I also realized that the earlier problem with another old USB device was specific to that device and not a general issue with this laptop reading any older USB device. That said, when I tried to scan a document, I got a window showing the error "Failed to scan: Unable to connect to scanner". Follow the jump to see more.

## 2020-08-10

### Eighth, Ninth, Tenth, and Eleventh Papers

My eighth, ninth, tenth, and eleventh papers have been published! These require subscriptions to read, so here are alternate links to older preprints for the eighth, ninth, tenth, and eleventh papers, respectively (which have most of the same content, with some minor changes to explanations, citations, and figures relative to the published versions). As with my previous papers, in the interest of explaining these ideas in a way that is easy to understand, I am using the ten hundred most used words in English (except for the two lines that came before this one), as put together from the XKCD Simple Writer. I will use numbers sometimes without completely writing them out, use words for certain names of things without explaining further, and explain less used words when they come up. Keep reading to see what comes next. While these papers aren't as closely related to each other as the previous three, there are enough relations that I'm putting them together in a single post. These papers need a lot more math (note: "math" isn't one of the ten hundred words) than the papers before, and because they need a lot of thinking to get, I actually won't say as much about them.

On another note, this is a milestone for me because these are the last papers from my PhD in which I was a leading author. I still have one more review paper left to be published, but as that has been submitted to the journal and as I'm not the leading author, I don't really need to worry about that at this point. (Of course, once that is published, I will write a blog post summarizing it, though as it is a review paper, that summary will probably be quite short.) Thus, I am truly done with the work from my PhD, and can fully shift my mindset away from physics toward thinking about problems in transportation policy, as I will do in my postdoctoral research at UC Davis.

## 2020-08-03

### Book Review: "The Worldly Philosophers" by Robert L. Heilbroner

I've recently read the book The Worldly Philosophers by Robert L. Heilbroner; this was a book that I got from a friend who moved away a few years ago, but never got around to reading until now. This book is essentially a survey of the lives & works of famous philosophers whose works & thoughts had fundamental impacts on the development of economics as a field, and who considered the general problems faced by & ultimate evolution of society to be within the purview of their grand theories. The preface gives some background regarding the writing of this book, the first chapter explains how economic philosophy can be especially dangerous as it has arguably much more immediate relevance to human society but much less rigorous testability than natural sciences, the second chapter explains why economics as a distinct discipline did not emerge until societal change in Europe (and its colonies in North America) had led to a state where the interconnections of goods, services, and money pervaded all aspects of life even for ordinary people (i.e. going far beyond the raising of stocks & bonds for the large colonial corporations like the Dutch East India Company, which had to deal with financial instruments only at the level of the national interest), the eleventh (final) chapter recapitulates the ideas of the book and explains that there may be no further grand theorists of "worldly philosophy" because the apparent inability of capitalism to effectively regulate itself (in the author's view, at the time of the publication of this edition in 1986) would mean all further development would have to come more from active political decisionmaking, and each chapter in between catalogs the lives & works of famous "worldly philosophers". A key feature of this book is that the historical context of each of these philosophers' lives is made clear, such that the development of those philosophies can be read as essentially a natural consequence of those circumstances; as examples, the optimism of Adam Smith is seen as coming from his observation of improved standards of living arising from the proliferation of many small factories, while the pessimism of Thomas Malthus & David Ricardo came from their observations of growing numbers of people living in abject poverty and in unsafe & overcrowded conditions without their living standards seeming to improve as a whole.

The book is written in a very engaging, accessible, and clear way. The details of the philosophers' lives make for a more interesting read, and they sometimes (though not always) even add further context for understanding how the mindsets behind their philosophies. Moreover, the author's contextualization of each philosophy in its historical place & time is combined with clear explanations of the more generally applicable features of those philosophies, so that it becomes clear whether certain aspects of some philosophies that are dependent on the historical contexts leading to their development might suggest that applying those philosophies today may be problematic. This is also combined with cogent & clear critical analysis of those philosophies in the present context by the author, as appropriate; perhaps there could have been a little more critical analysis of some of the assumptions of Karl Marx, and I felt like the author made John Maynard Keynes's analysis of the emergence of economic recessions from savings gluts seem unduly different from prior ideas that economic recessions are essentially mass panics, but these are ultimately minor points. (As "present" means 34 years ago, some of those analyses & predictions have obviously not aged well, but in fairness, I cannot hold that against the author, because none of those analyses suggest an arrogance on the part of the author in claiming that nothing of those analyses would change 34 years later.)

Overall, I rather enjoyed reading this book. I would recommend it to anyone who is interested in starting to learn about economic philosophies, as the engaging storytelling helps to leaven the philosophical parts that may seem drier to some readers.

## 2020-07-01

### Classical Phase Space Densities for One or a Few Particles

This is the first time in several years that I've done a post about physics that didn't have to do with my research. This came about from thinking about applying techniques in statistical physics to game theory; although I still have a lot more to learn about that and need to do more to flesh out those ideas, it occurred to me in the process that I never had such a good intuition for the phase space density in classical mechanics, and notes that I've found online focus almost exclusively on the phase space density of a large number of particles in an explicitly statistical treatment. I intend to use this post to shed light on why this may be the case, help build intuition for how things like the Liouville equation work for simple systems of one or a few particles, and reinforce the notion that there is no classical analogue to the phenomenon of a multi-particle entangled quantum state yielding a mixed single-particle state under a partial trace. Follow the jump to see more.

## 2020-06-23

### Book Review: "The Social Contract" by Jean-Jacques Rousseau

Now that I have been able to properly enjoy the summer, having essentially finished my PhD work, I've recently read the book The Social Contract by Jean-Jacques Rousseau (translated from French to English by Willmoore Kendall); this was a book that I got from a friend who moved away a few years ago, but never got around to reading until now. This is one of the classic texts of political philosophy from the European Enlightenment era, and came before many of the seminal events of world history, including the American & French Revolutions and the European colonization & subsequent independence of much of Asia, Africa, Australia, and South America. The author provides his own refutations of many of the arguments for hereditary monarchy and instead forcefully argues for a legislature, separate from the executive, that is conducted as a direct democracy, even while acknowledging that different circumstances for different states may suggest different forms & sizes for the executive. The book includes many examples from ancient & medieval European history, and while much of the discussion of cultures outside of Europe seems antiquated or racist to modern eyes, I imagine it was typical of its time & place.

It was really interesting to see such broad imagination of democratic & republican societies before they came to be in Europe & North America. However, the book itself is not an easy read: it basically feels like a polemical political treatise written in the terse style of the textbooks by the physicists Landau & Lifshitz, in which every definition and proposition must be carefully parsed & understood individually and also as part of a broader whole. The arguments are built up slowly, so patience is required too; frequently, I found myself wondering how the author could fail to acknowledge certain seemingly-elementary rebuttals to his arguments, only to find such acknowledgments after several pages. Originally, I thought the translator's introduction about how to read the book were basically excuses meant to cover for bad writing, but as I read through more of the book, I came to appreciate it more.

There are a few comments that I have about the contents. The first is that it isn't clear to me how citizens, in the author's view, are supposed to resume the exercise of natural rights, which have been pooled into the sovereign & redistributed as civil rights, when the social contract is thought to be violated, especially as it also isn't clear to me how to distinguish a violation of the social contract from an individual's unhappiness with the general will going against that individual's private will. Related to this, it isn't clear to me how a citizen, acting to debate & make laws for the sovereign to further the general will, is supposed to act completely separately, as a sort of Jekyll/Hyde situation, from that person's thoughts as an individual, because the execution of laws furthering the general will may affect that individual and others perhaps not particularly naming those people but naming a certain group affiliation, and it becomes hard then to define the general will in that context. The second is that so many of the author's arguments regarding the formation of a new state seem to depend on their being a full vacuum of power beforehand, with only the barest acknowledgment that new societies & nations don't emerge from a vacuum; to be fair, many of the great upheavals that figure prominently in my imagination regarding this point came after the publication of this book, but enough had happened which the author mentioned that this sparing treatment of the issue seems odd. I also have some more minor comments, namely that I'm not sure if the author's specific claims about the intertwined nature of politics & religion in ancient societies would be validated by modern scholarship, and the author's claims about there being no "true" Christian soldiers seems to rely too much on a no-true-Scotsman fallacy.

I would certainly need to reread this book carefully to better appreciate it, and perhaps that could address at least some of my comments. In any case, I'd only recommend this book to people with a serious deeply-rooted interest in political philosophy, who can appreciate the book and the context of its time & place, as opposed to novices like myself.

## 2020-05-28

### Reflection: My Graduate Experiences at Princeton University

Please note: there will be mentions of the current global public health crisis in this post. I have no background in medicine, public health, or closely-related fields. Please consult public health agencies and other governmental agencies for guidance regarding responses to this crisis, and please consult actual professionals as appropriate for individual problems in this context.

This post is the third in a series of three posts about the end of my time as a PhD student in Princeton University (in this post henceforth referred to simply as "the university" when there is no ambiguity). As a write this, I have successfully defended my PhD thesis! Furthermore, I will officially be graduating this coming weekend. This post follows the first, which was meant as a reflection of the events of this public health crisis that led to my premature physical departure from the university campus combined with a paean to the friends I made over the course of 6 years in the PhD program, and the second, which explained the experiences & thought processes that led to my decision to change careers from research in physics to transportation policy. This post is a broader reflection of my time and experiences at the university, with all of its ups and downs, and a message of gratitude toward the people in the university and elsewhere who meant so much to me during my time in the program; a lot of it is taken from the acknowledgments in my thesis, though for privacy reasons, I won't be giving explicit names. Additionally, there will undoubtedly be many comparisons over the course of this post to my undergraduate experiences at MIT, for which I wrote a post around the time of graduation 6 years ago. Follow the jump to see more.

## 2020-04-28

### Reflection: Starting a Shift to a New Career in Transportation Policy

This post is the second in a series of three posts about the end of my time as a PhD student in Princeton University (in this post henceforth referred to simply as "the university"). As a write this, I am still technically a PhD student enrolled full-time in the university, working on topics in nanophotonics & fluctuational electromagnetics. Next fall (assuming the current public health crisis abates to an extent that it is safe for me to do so — please note that I am not a public health expert or epidemiologist, so I am not making predictions in this regard), however, I will start a postdoctoral research position in the University of California Davis analyzing transportation policy, with a particular eye toward the effects of such current & future policies on the mobility and resulting socioeconomic opportunities for those who have been marginalized by current transportation systems, including people who are poor or have disabilities (like myself). This is a fairly drastic, and arguably surprising, change of career; I have told many friends and relatives about this, but not all of them, so I'd like to use this space to explain my thought process over the years leading up to this decision. Follow the jump to see more.

## 2020-03-17

### Reflection: A Week of Downward-Spiraling Public Health News Culminating in Unexpected Adjustments

Please note: this is about the current widespread disease outbreak that is dominating the news. I will not mention the name of this disease or other common words used to describe its spread, because for good reason, popular search engines are cracking down on articles and videos other than those from official public health agencies and related well-established organizations to stop the spread of misinformation. I have no background in epidemiology or public health. This post is merely my musings about the last week, and the implications for my near-future plans. Please consult public health agencies and other governmental agencies for guidance regarding responses to this crisis.

This post is the first in a series of three posts about the end of my time as a PhD student in Princeton University (in this post henceforth referred to simply as "the university"). As a write this, I am still technically a PhD student enrolled full-time in the university. The second and third posts will be somewhat more traditional reflections for the end of my time, but this first one has been precipitated by the current public health crisis. Follow the jump to see more; it is effectively a chronological history of the developments of this crisis from my very narrow perspective, and my own (in hindsight, arguably delusional) reactions to these developments.

## 2020-02-03

### Book Review: "Michael Polanyi" by Mark T. Mitchell

I've recently read the book Michael Polanyi by Mark T. Mitchell. (As an aside, it may be worth noting that some listings of this book carry the subtitle The Art of Knowing, but the usage of this subtitle within the copy of the book I got was inconsistent.) The book gives a relatively brief summary of the life and times of the physical chemist-turned-economist/philosopher Michael Polanyi in the first chapter, and then goes into a little more detail about his philosophies on economics, politics, science, morality, knowledge, religion, and other things in the second through fourth chapters, concluding in the fifth chapter with a comparison of his philosophical views to those of his contemporaries along with a little discussion about the implications of Polanyi's views for the present day.