## 2022-08-07

### Review: KDE neon 5.25

It has been a long time since I've reviewed a Linux distribution on this blog; the last one was of Linux Mint 19 "Tara" from 4 years ago [LINK]. In a more recent post about problems that I had with a scanner that required me to install Linux Mint 20 "Ulyana" MATE because the existing operating system was damaged beyond repair [LINK], I explained that I had come to trust the consistency & stability of Linux Mint enough and liked it enough that, in conjunction with the lack of novelty in Linux distributions compared to 10 years prior, I no longer felt motivated to do such reviews. Thus, it may seem strange that I should do a review like this now. In truth, the motivation wasn't hugely compelling, but I thought it might make for a nice post on this blog as I didn't have much else in mind. I thought of checking out a showcase of KDE, namely KDE neon, because it had been a long time since I tried KDE and I was getting a little concerned that the odd artifacts I was starting to see in Linux Mint 20 "Ulyana" MATE when hovering over right-click menus might be the tip of an iceberg of problems. While the latter concern has thankfully not come to pass even after several months of experiencing these more minor issues, I figured it might be nice to see what KDE is like now.

 Default desktop, before changes
This review will be a bit different from past reviews. In particular, in past reviews, I took the perspective of a newbie to Linux trying to do ordinary tasks, whereas the purpose of this review is to see whether I can replicate the look & feel of my desktop in Linux Mint 20 "Ulyana" MATE. Thus, I will focus mostly on changing the desktop and on using the default KDE applications; I will not focus on the presence or absence of other applications or on other parts of the live USB environment. Follow the jump to see what it is like.

## 2022-07-10

### FOLLOW-UP: Some Recent Troubles with pCloud and Google Chat

Almost exactly 11 months ago, I wrote a post [LINK] about problems I was experiencing with pCloud and Google Chat. I don't have any updates about Google Chat (or Google Meet), but I do have an update regarding pCloud. In the previous post, I noted that for files & folders protected by standard encryption (as opposed to stronger zero-knowledge encryption, for which this problem doesn't exist in pCloud), some files & folders require multiple attempts to transfer; I also speculated that pCloud may have been secretly deleting files & folders. After having spent more time using pCloud, I've been able to verify that my files & folders protected by standard encryption have transferred properly, and I think I've figured out why they initially seemed to require multiple attempts to transfer.

As I understand, pCloud creates a temporary folder, essentially like a cache, on the local hard drive, to transfer files before they are uploaded to pCloud. The process of transferring from the local cache to pCloud is limited by upload speeds, which are quite slow (as I mentioned in the previous post). Additionally, once the pCloud program is closed and the remote drive is unmounted, file transfer stops, so many folders & files that the user might think were transferred might not have been transferred. A good way to verify this is to leave the desktop application for pCloud open, monitor how many files as well as what total amount of data still remain to be transferred, and only close the application when all folders & files have been transferred; I like to think of it as a practice similar to leaving a torrent open for uploading after it has finished downloading.

## 2022-06-01

### Nonlocality and Infinite LDOS in Lossy Media

While I have written many posts on this blog about various topics in physics or math unrelated to my graduate work as well as posts promoting papers from my graduate work, it is rare that I've written direct technical posts about my graduate work. It is even more unusual that I should be doing so 2 years after leaving physics as a career. However, I felt compelled to do so after meeting again with my PhD advisor (a day before the Princeton University 2020 Commencement, which was held in person after a delay of 2 years due to this pandemic), as we had a conversation about the problem of infinite local density of states (LDOS) in a lossy medium.

Essentially, the idea is the following. Working in the frequency domain, the electric field produced by a polarization density in any EM environment is $$E_{i}(\omega, \vec{x}) = \int G_{ij}(\omega, \vec{x}, \vec{x}')P_{j}(\omega, \vec{x}')~\mathrm{d}^{3} x'$$ which can be written in bra-ket notation (dispensing with the explicit dependence on frequency) as $$|\vec{E}\rangle = \hat{G}|\vec{P}\rangle$$. The LDOS is proportional to the power radiated by a point dipole and can be written as $$\mathrm{LDOS}(\omega, \vec{x}) \propto \sum_{i} \mathrm{Im}(G_{ii}(\omega, \vec{x}, \vec{x}))$$. This power should be finite as long as the power put into the dipole to keep it oscillating forever at a given frequency $$\omega$$ is finite. However, there appears to be a paradox in that if the position $$\vec{x}$$ corresponds to a point embedded in a local lossy medium, the LDOS diverges there.

I wondered if an intuitive explanation could be that loss should properly imply the existence of energy leaving the system by traveling out of its boundaries, so the idea of a medium that is local everywhere (in the sense that the susceptibility operator takes the form $$\chi_{ij}(\omega, \vec{x}, \vec{x}') = \chi_{ij}(\omega, \vec{x})\delta^{3} (\vec{x} - \vec{x}')$$ at all positions) and is lossy at every point in its domain may not be well-posed as energy is somehow disappearing "into" the system instead of leaving it. Then, I wondered if the problem may actually be with locality and whether a nonlocal description of the susceptibility could help. This is where my graduate work could come in. Follow the jump to see a very technical sketch of how this might work (as I won't work out all of the details myself).

## 2022-05-01

### Book Review: "Algorithms to Live By" by Brian Christian & Tom Griffiths

I've recently read the book Algorithms to Live By by Brian Christian & Tom Griffiths. This book shows how many problems & heuristics in computer science can be applied to explain or improve human decision-making. Each chapter focuses on a certain class of problems or issues. Such classes include the optimal stopping problem, the multi-armed bandit problem, searching & sorting, task scheduling, Bayesian inference, overfitting data, constraint relaxation, random stimulus, communication protocols, and social interaction. Additionally, most chapters try to show how results from computer science can either improve or justify certain human behaviors.

There are two other minor criticisms I have of the book too. First, the chapter about overfitting seems to use the word "overfitting" to mean too many different things, which is ironic and undermines any clarity that the discussion could have provided. Second, the chapter about randomized algorithms attempts to make a tenuous connection between randomized algorithms used in computer science and the way that random mental stimuli can produce very creative responses in people, but it never makes clear whether the latter result is true at an individual level or only holds statistically for large populations.

Overall, I think the author's goals were laudable and that each chapter is interesting to read in isolation. However, other readers may be disappointed, as I was, in the way that the authors fail to synthesize many of the ideas across chapters in a smooth & unified manner. Thus, I would advise that readers who may be interested in these topics go into this book with lower expectations.

## 2022-04-04

### FOLLOW-UP: How to Tell Whether a Functional is Extremized

This post is a follow-up to an earlier post (link here) about how to tell whether a stationary point of a functional is a maximum, minimum, or saddle point. In particular, as I thought about it more, I realized that using the analogy to discrete vectors could help when formulating a more general expression for the second derivative of the nonrelativistic classical action for a single degree of freedom (i.e. the corresponding Hessian operator). Additionally, I thought of a few other examples of actions whose Hessian operators are positive-definite. Finally, I've thought more about how to express these equations for systems with multiple degrees of freedom (DOFs) as well as for fields and about how these ideas connect to the path integral formulation of quantum mechanics. Follow the jump to see more

## 2022-03-05

### How to Tell Whether a Functional is Extremized

I happened to be thinking recently about how to tell when a functional is extremized. Examples in physics include minimizing the ground state energy of an electronic system expressed as an approximate density functional $$E[\rho]$$ with respect to the electron density $$\rho$$ or maximizing the relativistic proper time $$\tau$$ of a classical particle with respect to a path through spacetime. Additionally, finding the points of stationary action that lead to the Euler-Lagrange equations of motion is often called "minimization of the action", but I can't recall ever having seen a proof that the action is truly minimized (as opposed to reaching a saddle point). This got me to think more about the conditions under which a functional is truly maximized or minimized as opposed to reaching a saddle point. Follow the jump to see more. I will frequently refer to concepts presented in a recent post (link here), including the relationships between functionals of vectors & functionals of functions. Additionally, for simplicity, all variables and functions will be real-valued.

## 2022-02-20

I recently read [Chin, The Verge (2022); Raphael, Computerworld (2022)] that Google is releasing a version of Chrome OS called Chrome OS Flex which can be copied to a USB storage drive and installed on computers that didn't come with Chrome OS. This seems very similar to how many popular Linux distributions work, so I initially wondered if Chrome OS Flex will succeed with the muscle of Google behind it where similar efforts by Linux distributions backed by smaller not-for-profit organizations have failed. At the same time, it seems clear to me that Google will not hesitate to use this as an opportunity to collect more valuable data from people who use Chrome OS Flex. This got me to think more broadly about how much ordinary people who might consider using Chrome OS Flex really care about their privacy (especially considering that such people would typically use Microsoft Windows 10/11, which are known to collect significant amounts of data from users) even after revelations about Facebook's practices, earlier revelations about government surveillance, and so on.

However, upon closer reading, I noticed that the first article makes clear that the target audience is schools & businesses which have many old computers whose Windows versions may no longer be supported. This makes more sense to me than targeting ordinary individuals, because I get the sense that the learning curve even to copy an ISO file onto a USB storage drive and install it onto a computer is steep for most ordinary individuals (despite the significant progress that distributions like Ubuntu & Linux Mint have made in making the installation process easy). By contrast, it seems more reasonable to expect specialists in schools & businesses to learn these things once and then do them for many different computers. Meanwhile, the second article makes clear that while traditional Chrome OS is capable of running many programs built for Windows, Chrome OS Flex will not have such capabilities. This suggests to me that while many schools may take up this opportunity given that few user-facing applications need to be installed on the computer and most user-facing applications can be accessed through web equivalents, this might not be the case for many businesses, so it is unclear to me which businesses will actually take this up.

Ultimately, I don't expect to see much adoption among ordinary individuals even though they aren't forbidden from installing & using Chrome OS Flex. That said, I would be interested to see how adoption evolves in schools & businesses over time.

## 2022-01-17

### Turning off Comments for this Blog Going Forward

This is a quick post to say that I have unfortunately had to turn off comments for this blog. Recently, I had trouble using the comment feature on various posts in this blog (despite being its sole author & maintainer). Furthermore, for the last few years, the vast majority of comments have been unwanted commercial solicitations, while I haven't really gotten much useful feedback about posts themselves. I recognize that there are very few humans who regularly read this blog and that most, if not all, of those readers probably know me personally, so I trust that they can reach out to me if they want to share their thoughts about posts. In any case, going forward, comments will no longer be available on this blog. This also necessarily means that the "Featured Comments" blog post series cannot continue.

## 2021-12-22

### Hit by a Car

I was recently hit by a car when crossing the street in Davis, California. This explains why I haven't posted anything on this blog this month until now (late in the month) and why I may be slower to post next month too. I'm sure I will have much more to say about this at a later date, but for now, for legal reasons, this is all I can say.

## 2021-11-01

### Book Review: "The Heartbeat of Wounded Knee" by David Treuer

I've recently read the book The Heartbeat of Wounded Knee by David Treuer. This book was a gift to me from a family friend who heard that I like reading about American history and other nonfiction topics, and when that person gave me this book, we further discussed the historical injustices inflicted by white Americans upon Native Americans, the deep connections that Native American religions & spirituality have with land & nature, and the way that Native Americans see themselves as truly indigenous as opposed to being traveling groups of humans like any other group passing through a given land. In that conversation, I also noted that reading this book would be professionally useful to me given that my professional interest in transportation equity would intersect with how Native Americans have been at the forefront of many recent social & environmental justice movements and how Native cultures & issues are much more visible in the Southwest than in the Northeast (due to the history of forced removal). It was with these conversations in mind that I read this book.

This book is a combination of historical accounts, contemporary interviews, and observations by the author. The author is a Native American (from the Ojibwe tribe) who grew up on a reservation, and his stated goal in writing this book was to create a more complete picture of how Native Americans have continued to live (especially but not exclusively under adverse conditions) in every part of the US since the Wounded Knee massacre in 1890, as he felt that too many people (both people sympathetic to Native Americans and those wishing to exterminate them) wrongly framed that massacre as the final death of Native American culture, life, and identity.