Featured Comments: Week of 2012 February 19

There was one post that got a handful of comments this past week, so I will try to repost most of those.

Review: KahelOS 020212

An anonymous reader asked, "Is KahelOS a rolling release?"
Commenter kelvin said, among many other things, "kahelOS is progressing nicely and its a fairly new distro memory is quite high arch with gnome3 and a few extensions running idles at 230mb on my laptop. to install from AUR you need yaourt/packer I find yaourt better uses the same commands as pacman they both find and install dependencies. "I don't understand the statement I would probably use the Arch repositories in KahelOS to install a different DE (probably either Xfce or GNOME 3/Cinnamon". What is the point of installing a OS then mutilating it with bloat to install another DE. if you want open-box use archbang uses 65mb ram. if you want xfce Gnome, KDE, etc. Install arch then add what you want Arch is no harder to install than any other distro you only install what you neednothing more nothing less. Its all in the mind if a 60+ yr old with no education can read and understand the beginners Wiki young people like you should be able to do it."
Reader Dr.Saleem Khan had an alternative suggestion: "Nothing against KahelOS , I have used it for long time in past , was never impressive if we are looking for an Arch Linux alternate for newbies but Bridge Linux (http://millertechnologies.net/) is very impressive,stable and user-friendly for new archers."

Thanks to those who commented on this past week's posts. This coming week, I may or may not have a post put out; it depends on my workload. Anyway, if you like what I write, please continue subscribing and commenting!


Review: KahelOS 020212

I have reviewed Chakra GNU/Linux a number of times here both before and after its split from the Arch base, and I have fairly consistently said that it is an amazing distribution and has a great implementation of KDE. But when it comes to Arch-based distributions, I have never tried the other side of the DE coin — GNOME — until now.

Main Screen + KahelOS Welcome Center
That is where KahelOS comes in. It is an Arch-based distribution that ships with GNOME and aims to make it user-friendly, though like Chakra, it expects that users will be at least somewhat willing to learn and work with the system. It was originally targeted at a primarily Filipino audience, but now it has a more international perspective.

I tested the live session through a live USB made with MultiSystem. I tested the installation in a VirtualBox VM in a Xubuntu 11.10 "Oneiric Ocelot" live USB host with 1024 MB of RAM allocated to the guest OS. Follow the jump to see what this other offspring of Arch is like.


Requiem for a Gauss

During the spring semester of last year, I took 8.022 which is the slightly more difficult version of freshman E&M. Contrary to most classes which use SI units (meter, kilogram, second), 8.022 used Gaussian CGS units (centimeter, gram, second — hereafter referred to simply as "CGS units") partly because of tradition and partly because the professor is personally more comfortable using CGS units as he uses it in his own research too.

I have a few friends who are freshmen taking 8.022 during this spring semester, and I was rather surprised and disappointed to see that 8.022 has switched to SI units. I bumped into the professor recently and asked him about it, and he said that while he is not in favor of the change, he has to do it because the textbook ("Electricity and Magnetism" by Edward Purcell) now has a 3rd edition which has switched from CGS units to SI units, as specified by archived letters from Purcell himself when he was still alive. The professor also said that as a result, except for possibly some very specialized fields, CGS units are on the way out. Given that, I think it is appropriate to take a moment to eulogize the values of CGS units.

First of all, in electricity and magnetism, CGS units are not simply corresponding SI units divided by powers of 10. Constants in fundamental laws are redefined, meaning quantities in E&M have different dimensions altogether in CGS versus SI, so they cannot be compared directly. I'm going to give just a few examples (though eventually I hope to write up something a little more comprehensive) of where CGS shines.

Coulomb's law: In CGS, Coulomb's law is very sensibly defined. Although the consequence is that charge can be expressed dimensionally in terms of mass, length, and time, there are no annoying prefactors in Coulomb's law compared to those present in SI.

Relativity: This is where CGS really shines. The point of E&M in relativity is to show that the electric and magnetic fields are components of the same geometric object viewed in different frames of reference. In CGS, those fields have the same dimensions, so the comparison becomes even easier. Plus, there is a greater amount of symmetry in the rules for transforming the fields between frames. Finally, invariant quantities involving the fields can be constructed by adding and subtracting the fields freely in CGS, which cannot be done in SI.

Biot-Savart law: In either system, the magnetic field created by a moving charged particle is very weak. In SI, this is explained on account of the prefactors in front of that law, but that is quite misleading. The truth is that strong magnetic fields require very fast moving charged particles, and CGS shows exactly that often the speed of a moving charged particle is very low compared to the speed of light, thus explaining the weakness of the magnetic field relative to the electric field. In SI, comparing the magnetic and electric fields is like comparing apples to oranges.

Ampère's law: In SI, the prefactor in front of the current term is the permeability of free space, but there is no real reason for this, and the equation just looks more messy. In CGS, the prefactor is exactly equal to the impedance of free space; although there may not be much meaning, the symmetry is quite nice, because in general the opposite of the path integral of the electric field (i.e. the voltage) along a wire that may have some impedance is equal to the current through that impedance multiplied by the value of the impedance. Similarly, the circulation of the magnetic field around a wire is equal to the current multiplied by the impedance of free space (because that is what surrounds the wire).

Waves: In CGS, the electric and magnetic fields have the same dimensions, so the magnitudes of sinusoidal fields will also have the same dimensions and can be freely added and subtracted; in SI, this is not possible without extra prefactors. In addition, the Poynting vector is just equal to the cross product of the fields divided by the impedance of free space, which sort of shows how the vacuum can support a traveling electromagnetic wave; in SI, the prefactor is the reciprocal of the permeability of free space, but that begets the question of why the permittivity of free space is absent.

Material media: In CGS, all of the auxiliary fields, like the electric displacement field, the magnetizing field, the electric polarization density, and the magnetic polarization density have the same dimensions as the electric and magnetic fields, which themselves have the same dimensions. In SI, this is not the case, so the formulas become far more complicated and asymmetrical. This asymmetry is also present when considering the electric and magnetic susceptibilities in SI; these quantities are more consistently defined in CGS.

There's a lot more to the story than just this, and in a few days I hope to update this post with a more comprehensive writeup (probably done in LaTeX, though I have to figure out how to upload it for people online to see). It's sad to see CGS on the way out, but I suppose that is the way things must be.


Featured Comments: Week of 2012 February 12

There was one post this past week that got a couple comments, so I will repost those.

Review: Salix OS 13.37 Xfce Live

An anonymous reader said, "Good to see a review of a less well known distro. Salix is rather less newbie friendly than (say) Vector Linux and I think that is intentional. It's meant to be close to the real Slackware experience with a few conveniences, but dependency checking in Sourcery is not one of them. It's meant to be 100% compatible with Slackware, so if the base distro uses an old version of xfce then so will Salix. It does take a bit of effort to set things up just so, but the devs are very knowledgeable if you ask on the forum. The reward for your efforts is a stable, fast distro that just keeps out of your way. I'm using the installed version by the way. Testing the live version is valid of course, but it only tells you half the story. I didn't like the live version much last time I tried it."
Another anonymous commenter asked, "Did audio work? I see so many distros where it doesn't."

Thanks to those two for commenting on that post. This coming week, I intend to have another review and at least one other post out. Anyway, if you like what I write, please continue subscribing and commenting!


Review: Salix OS 13.37 Xfce Live

Main Screen + Xfce Right-Click Menu
I have wanted to review Salix OS for a while now. It does seem to be the one derivative of Slackware that really synchronizes itself with Slackware development, to the point where even the version numbering system is the same. I have already tried out a few other derivatives, like Zenwalk, Kongoni, VectorLinux, and Porteus; on the whole, all of those worked relatively well, but there were a few things here and there that bothered me about each of them. I would like to see if Salix OS can overcome that.

Salix OS is a derivative of Slackware that comes in a multitude of versions; it has installable and live editions with Xfce, KDE, LXDE, Fluxbox, Ratpoison, and other DEs. According to its website (which, while very slightly more on the technical side, is pretty nice to use), Salix OS is meant to be fast, easy to use, and fully compatible with Slackware packages.

I tested the live session on a live USB made with MultiSystem. I did not test the installation because although this edition is installable, it has really been optimized more for usage in the live session, so I am going to stick with that. Follow the jump to see what it's like.


Thoughts on "Photograph 51"

A few days ago, I and the rest of MIT SPS went to see the play "Photograph 51". It details [and dramatizes] the life and work of Rosalind Franklin, who was the first to see the helical nature of DNA. For all her professional life (which tragically ended rather early due to ovarian cancer), she worked extremely methodically and refused to draw any conclusions or make any models unless there was solid data to support that. By contrast, Crick & Watson, who are traditionally the ones credited with discovering the structure and nature of DNA, went for models even if there wasn't always the most solid evidence to support them. What they did do that Franklin did not (according to the play, at least, which I believe and hope is pretty close to what actually happened) was to model how DNA base-pairing works and where the phosphates are in the nucleic acids.

One of the things that struck me as interesting is just how isolated Franklin made herself even from her colleagues at the King's College in London. I mean, I knew that she was generally reluctant to share her work because she knew that any work she published would be attributed to her male colleagues (even those under her in the research hierarchy), but I didn't realize she was practically antagonistic toward her fellow researchers. I fully understand how she did so essentially to maintain her own dignity and not submit herself to the male-dominated research community, but if she tried that today in a culture where females are quite prevalent (though of course there is still much progress to be made) in scientific research, I would think her actions would be unacceptable as they would be antithetical to the ideas of open science and collaborative research.

On the other hand, though, it's hard to discount just how pervasive the sexism present at that time was. Crick & Watson in the play were both quite patronizing toward her. Her colleague Maurice Wilkins could not really accept her as an equal until around the time when she first fell ill with ovarian cancer. She was segregated from the other male researchers. So of course she had to do everything she could to make sure she would be recognized as an equal to the other researchers rather than as an assistant of some sort.

There's another point to be made regarding open science in this context, and that is in the premature publication of Franklin's data. She didn't want to publish because she felt that she didn't have sufficient data to back up any claims she made (and this is also why she was opposed to making models as prematurely as Crick & Watson did). Ultimately, it should have been left to her as to whether she wanted to publish the data or not. Yet Crick, Watson, and Wilkins were overeager to publish and "win the race" (to finding the "secret to life"), so they managed to get a hold of one of Franklin's photographs without her permission and used it to complete their own work. Consequently, she didn't make it onto their Nobel Prize-winning paper, so the paper she published looked like it simply supported the paper from Crick & Watson. A lot of accounts describe the process as them "stealing" her data. On the one hand, I disagree with this because ultimately it is the results that matter to science more than the personalities behind them. On the other hand, they did acquire that data without her permission, and in the end it should have been up to her whether her own data should have been published or not. There wasn't any doubt that she would publish everything once she got around to it; it's just that she felt that the time wasn't right, and the other researchers violated her prerogative as a research scientist to make that call.

As I think about this more, the whole story really is a good deal more ethically knotty than how it is initially presented. Also, I would encourage you to go and see the play "Photograph 51" if you are in the Boston area; it is playing in the Central Square Theater in Cambridge.


Featured Comments: Week of 2012 February 5

There were no featured comments the previous week because I didn't post anything for that week due to my end-of-IAP business. There was one post this past week that got a couple of comments, so I will repost both of those.

Comparison Test: Linux Mint 12 "Lisa" KDE vs. Netrunner 4.1 "Dryland"

Reader Bart said, "It is a bit.. surprising to see a Facebook shortcut installed on a Linux desktop by default. You write that Netrunner also considers for example Google docs, GCal and Youtube as applications. So in that way it is a sort of a net-runner after all. Thanks for the comparison, I was indeed curious to hear more about Netrunner."
An anonymous commenter had this to say: "Given the web oriented mood Netrunner seems to have ... it would have been interesting checking, as a level of polish, the integration of Dropbox in Dolphin (context menu for Dropbox folders, etc...). On the other hand ... it would have also been interesting knowing a bit more about Blue-Systems, the main sponsor of Netrunner and Linux Mint by now. Good review, but as you can see the curiosity is even bigger. Ps.- Do you really believe they will join together ???"

Thanks to those commenters for commenting on this past week's posts. Depending on my workload this week, I may or may not be able to post anything, but if I do have that kind of time, I do have at least one thing in mind. In any case, if you like what I write, please continue subscribing and commenting!


Comparison Test: Linux Mint 12 "Lisa" KDE vs. Netrunner 4.1 "Dryland"

Linux Mint: Main Screen
Both of the latest releases of these particular distributions came out this week. Also, Linux Mint now has a partnership with Netrunner for Linux Mint with KDE; hence, this comparison test may be the last meaningful one between the distributions while they remain as separate as possible, because I think they will converge in the coming months. Finally, Kubuntu just lost its funding at Canonical, so like Xubuntu, Lubuntu, and Edubuntu, after (but not including) version 12.04 LTS "Precise Pangolin" it will be recognized by Canonical as an official derivative but will only be supported by the community. This means that there will need to be a new top dog for Ubuntu-based KDE distributions, and these two distributions seem like the most likely candidates. That is why I am comparing these two distributions now.

Linux Mint of course needs no introduction here. Interestingly, considering that for almost all of its history it has made Ubuntu with GNOME better and more usable, it actually started out in version 1 "Ada" as a KDE distribution, and KDE was still prominently featured until around version 3.1 "Celena" (and that is also around the time KDE made the transition from version 3 to version 4, which caused many users to move away to other DEs). After that, though, GNOME became the really prominent DE in Linux Mint, and KDE has almost become a second-class citizen in Linux Mint; in the last few releases, though the main GNOME edition has received extensive customizations, the KDE edition has been just a lightly-rebranded version of Kubuntu with a few other small customizations here and there. I will see whether or not that continues to be the case.

Netrunner: Main Screen
Netrunner, despite the name, is not a cloud-oriented distribution. It is a traditional desktop distribution like any other, and it aims to provide KDE mixed with useful tools taken from GNOME along with other helpful installed programs and customizations.

I tested both using a multiboot live USB made with MultiSystem. I did not test the installation processes, because both are based on Ubuntu so there is really no need; all I am really comparing are the first impressions created by each distribution (so the whole post may seem a bit superficial), because soon they will more likely than not converge. Follow the jump to see what each distribution is like.


Fourth Semester at College

Yesterday my fourth semester here started. This semester, I am taking 8.04 (Quantum Physics I), 8.044 (Statistical Physics I), 14.02 (Principles of Macroeconomics), and 18.06 (Linear Algebra). In addition, I am continuing my UROP (though my work will likely change soon) and doing some other work too.
It's going to be a busy semester, but given that I am now used to this kind of workload from last year, I think I will be able to manage it better. Plus, now that my classes start each day no earlier than 11am, I can get more sleep! Yay! That aside, it's going to be an exciting semester, though I can already feel the heat with problem sets and such.