About Me

When not at work with students, I spend my time in my room either reading, calculating something using pen and paper, or using a computer. I read almost anything: from the pornographic to the profound, although my main interests are mathematics and physics. "When I get a little money I buy books; and if any is left I buy food and clothes." -Erasmus

Thursday, December 30, 2010

Children's Books


While at the mall a few days ago, I indulged in searching through a used book sale. I originally had no intention of looking through the book sale but could not resist. I did remember I was supposed to give a Christmas gift for my nephew and niece, so I decided to scan the shelves for good children's books. Happily, I found two good books by Dr. Seuss, And To Think That I Saw It on Mulberry Street, and Mr. Brown Can Moo! Can You?, and for a good price.

Good children's books are always on my list of gifts to give. Before I give them out though, I make sure that I've read it before giving it away. (One of my pet peeves is to be given a book by someone who has obviously not read the book. I will mention no names to protect the guilty.) I admit that I also wanted to reread the Mulberry street book; it brings back the time when I was in second grade and I newly discovered the joys of library access.

Not all of the books I give out to kids are American or British. When looking for children's books, one local source I use is Adarna House, a publisher that specializes in Filipino children's books. Adarna books, as well as other children's books written and published in the Philippines, can be a good buy. A typical book costs only around PhP 75 or about a dollar and a half, so they make cost-effective gifts. Before giving them out, though, make sure you've read the book. :-)

Advanced Reading and MIT OCW

I've noticed that working through the material on my own is much more effective than trying to follow the lectures and the pace of the class. In contrast, when I cannot prepare and read ahead, I do much worse than other members of the class. Last semester was such a disaster; I was forced to take an optics class where I was unable to read ahead and solve problems.

Some physics topics captured my interest long before I took the required coursework. On such happy occasions, I read ahead and solve problems. Sometimes, I do the preliminary reading and problem solving months or semesters before taking the course where that topic is discussed. But to do that, I need a good source on what textbooks to use.

This is where MIT's Open Course Ware comes in. It's a website offered by the Massachusetts Institute of Technology containing course materials used by their Professors. Aside from the course descriptions, you can also find the syllabus, the reading assignments, homework and exams, and lectures or lecture notes. Sometimes the relevant pages will contain the schedules of topics discussed each meeting. This gives me an idea of what the pace is in that school.

Not all of the courses will have OCW pages, nor will all courses have all of the above. For example, some courses, such as Professor Lewin's physics course, 8.01 (the introductory physics course) contains videos of the lectures, while other course pages will have no multimedia content. But enough is provided to get a flavor of the course, and the most important information is the choice of textbooks, and the problem sets. For a student in a developing country, this is important, since it allows me to compare what is offered here with what the rest of the world has to offer. I learned from OCW what is expected of a typical undergraduate or graduate student.

When I first wanted to study general relativity, I got wrong-headed advice from a friend on what the best textbook was. (The recommendation, by the way, was Weinberg's text.) I couldn't learn it from that book because there were no problems for solution; it was also a textbook for graduate students, so it was at the wrong level. I had to go through a sequence of books before I found a good one at the right level . This was Bernard Schutz's A First Course in General Relativity. Although it provided some formalism, I felt that my ability to see the results at a glance was still in need of remediation.

It was at around that time that I first learned of OCW. To remedy the lack I felt, I looked up the introductory relativity course, 8.224 . I organized a study group with some fellow undergraduates. We obtained copies of Taylor and Wheeler's textbook Exploring Black Holes, and we worked through it. ( I still have my solutions to all of the questions filed away, in case I get to teach an undergraduate course in relativity.) My current research is an outgrowth of the things I learned from 8.224 and the graduate level course 8.962.

Sometimes, I wander around the other archived courses. I've used materials from the complex variables course, 18.04, when teaching methods to undergraduates. I'm happy that the methods we learn is standard, although we go more into the theory of gamma functions instead of studying integral transforms (which is taught anyway in the regular methods courses).

I've read the biographies of some well-known scientists, and many of them are good at learning things on their own. But without knowing the necessary books, self-study may be doomed to failure. A sequence of lucky accidents is required before it works. I know of cases of otherwise intelligent people who were just unlucky; Without mentors, without access to online resources (this was years ago, before internet access became something taken for granted), they were lost from the world of theoretical physics. Their talent was wasted.

My collaborator is luckier than I am because OCW gives a good list of introductory general relativity texts. No more wandering around the library shelves. (Although this has its own disadvantages!) As a result, general relativity can be understood by a well motivated sixteen year old. Compare this to Eddington's time when it was claimed that only few people understood general relativity!

Monday, December 27, 2010

firecracker bans and prostitution

(First, credit where it is due: I owe the ideas to Steven Landsburg, and the book I read was The Big Questions: Tackling the Problems of Philosophy with Ideas from Mathematics, Economics and Physics. I do not necessarily endorse all of his views, but the questions -- if not the answers-- should provide a decent amount of distraction. )

Every New Year's Eve, the streets of my country become a war-zone. The tradition is to use firecrackers ranging from sparklers to rockets and simple explosives called pla-pla, superlolo, etc. Every year it seems, we have kids on tv saying "Hinding-hindi na ako magpapaputok." ("I will never use firecrackers again."), while displaying a mangled hand or foot or worse.

I don't have any sympathy, by the way, for those kids. Even though it's politically incorrect, I cannot help but feel some amount of Schadenfreude. In fact, I would rather that they had blown-up their gonads so that they won't propagate their stupidity to the next generation. (This actually happened to an idiot playing with explosives; he is the only living recipient of the Darwin awards. ) I ride a bicycle, and such explosives are a hazard. There is a ban on the use of firecrackers that pose danger to life-and-limb, and these idiots still persist in going against the law.

That said, one of the futile ways of discouraging the use of firecrackers is to ban the sale. This is akin to what happens when prostitution is banned, because bans have never worked. One need only look at Prohibition in the United States to see that. What will develop, instead, is a healthy blackmarket.

My modest proposal, therefore, is to have the sale legalized and the use penalized. I think it would do better at reducing firecracker use. I'd even recommend inhumane punishments like sticking lighted pla-pla on the gonads of the offender and then letting it go off. That way, the clever can earn money at the expense of the stupid, the stupid pay twice, and maybe, reduce the propagation of stupidity unto future generations. :-)


Sunday, December 26, 2010

addenda

Something I found hilarious. Compare the fine and the illegal profits. All this with no admission of wrongdoing. No wonder Mr. Goldfield is happy.

Research with wikipedia vs primary sources

I'm a big fan of wikipedia, and it's one of the websites I regularly visit. When I want to learn something, I use it as a first step, because the references of a well-edited wiki entry can be a good second step.

Wikipedia entries are not the end, especially if you are doing academic research. When I read undergraduate research papers, a wikipedia entry (or worse, if the whole paper is cut-and-paste from wikipedia!), as sole reference would most assuredly draw my ire. Many undergrads (and a few graduate students!) who use wikipedia probably do not understand the limitations of wikipedia.

There is a nice entry in wiki itself on how to use wikipedia for research, but it's too many clicks away from the main page. To get there from the main page, I clicked on help, and then on Browsing Wikipedia, after which, I then clicked on Doing Research Using Wikipedia. Most regular users, I suspect, would skip the help pages. After all, you just plug in the search box, and then wikipedia will give a list of entries that may be relevant.

One of the reasons to be cautious when using wikipedia as a primary reference, is, paradoxically, because it is an encyclopaedia. Encyclopaedias are not meant to be the last word; they may act as a quick reference, but the meat is in the original or primary sources. A good scholar will track the primary works because the primary sources will be much more careful than secondary sources (of which Encyclopaedias are an example). Primary sources are much more likely to explain the limitations of the study, and will be less likely to contain outrageous claims.

Even within research articles, there is a tendency to be lazy when it comes to citing primary sources. I remember reading an editorial in Nature Cell Biology 11, 1 (2009) where the editors asked that authors be more careful with citations. Sometimes, researchers will just copy and paste the references used in papers they cite, even though the references themselves may be irrelevant, and then because of page-number limitations, forget to cite the true pioneering work.

Second, Wikipedia is editable by anyone with online access. Sometimes, there will be people with sinister agenda who re-edit pieces to suit their beliefs. This means garbage can be created at-will, and some time may pass before another venturesome soul will decide to create a more balanced account. After that, there may be some back-and-forth editing before a consensus view emerges. Even then, we cannot really be sure that the consensus view is correct. This will inevitably bring us back to a search for primary sources.

Third, there will be hoaxes. One of the best ones I know of is the Brahmanical See, a former wikipedia entry in which it is claimed that Hinduism has its own equivalent of the Pope. This entry lasted for approximately three and a half years before it was caught by a zealous editor who could find no supporting documents. Which brings us back to to the gospel of looking for primary sources.

There are a lot more reasons (of which I am too lazy to state), so I'm linking (ironically) to two entries in wikipedia: Why Wikipedia is Not-So-Great, and Wikipedia is Failing.

Thus, one should look for the primary sources. After that, one needs to know if the primary sources can be trusted. Arnold Arons, a physicist I admire, has always emphasized the questions "How do we know?" and "Why do We Believe?", and these questions should always be your company when sifting through primary sources. These questions, by the way, form the foundations of epistemology, and answering those questions, in turn, is surely a story for meant for another day.


Saturday, December 25, 2010

random christmas greetings and seven things about myself

I received text messages today wishing me a Merry Christmas. For the life of me, I do not know the senders. One of the senders identified himself/herself(?) and just to make sure, I used my online stalking powers to check on the sender's identity. I don't know who that person is.

So what to do when that happens? Since I did not want to be a churl, I texted back, "Merry Christmas to you and your family."

******
I don't really go around the blogosphere much-- the blog entries that I do read are my friends' blogs, and the blogs that turn up while doing google searches. So I was surprised when a friend, Helen, decided to give me an award. So I'd like to thank Helen first.

My interpretation: seven things (about the self) and seven blogs.

Unfortunately, there are only two blogs that I actually visit (on a semi-regular basis). The first one, of course, is Helen's A Quarter For My Thoughts and Beyond, and the second one is Nath's Imprints of Philippine Science, a science related blog.

As for my seven things:

(1) I try to be minimalist. A (dead) mathematician I admire, Paul Erdos, has said "Some French socialist said that private property was theft … I say that private property is a nuisance." Although I cannot carry minimalism to the extremes he took it (living out of two suitcases), I share the notion that owning too many things is no good because things need to be maintained; you have to spend time and money maintaining property.

This is also one reason I dislike knick-knacks (especially souvenirs whose only purpose is to be a souvenir): they take up space without any purpose. My version of hell is an infinite collection of knick-knacks (from Boracy, Vigan, and other tourist spots) and being made to dust them through eternity.

(2) In spite of my efforts not to own tangible things, I love books, and buy too often. My thesis adviser and I share this love of books; since he earns more, he buys more books than I do. (I suppose this is good for me, because our reading overlaps.) Bookstores are moneytraps for me; even though my only mission is to buy school supplies, I sometimes end up buying books. I've decided to use electronic books to keep our house spacious, but it's hard to resist actual paper.

(3) I'm trying to save money for intangibles (stock, bonds, etc.). While I was an out-of-school youth, I read Benjamin Graham's The Intelligent Investor and got interested in personal finance. I went through a finance phase (reading various popular books and selections from Investments-related textbooks), and learned about the need for a good portfolio.

(4) I'm a procrastinator. Although I know what I should be doing (saving money and investing, writing papers, etc), I spend a lot of time randomly surfing the web. There's a comic strip I read; you can find there Newton's Three Laws of Graduation. The First Law applies.

(5) I'm a skeptic. Repeated exposure to crazy stuff (Bulalo is good for hypertension being the most recent example.) has made me doubt many of the things people take for granted. I find it hard to take things on faith; if there's a statement in a math or physics book, I try to figure things out from first principles just to make sure that I have firm foundations for belief (that is, construct a proof). When I do take things on faith, I try to remember that I took it on faith, and that eventually, there ought to be a reckoning.

For example, interchanging the order of two limiting processes in mathematics is something physicists perform without much ado, but somewhere in the back of my mind, I know that I need to justify the step. Religion is also another thing taken on faith, and I have thought carefully about what I believe. Also, I believe in continuously improving my bullshit detector.

(6) I'm a dabbler. I'm interested in a lot of things: physics, math, finance, fiction, etc. A physicist's career depends on concentration, and dabbling in many things is dangerous in an era of specialization. The spread of my interests means it's hard to know everything. Even one subfield of theoretical physics can consume a lifetime, and dabbling reduces the time I ought to be spending on specialization. One advantage though of being interested in many things is I'm never bored. There's always something new under the sun.

(7) I like reading biographies of famous mathematicians and physicists, and I am drawn to people who were good teachers. There are ongoing efforts to improve the teaching and research environment in my country, and I take inspiration from people like John Wheeler, Lev Landau and Enrico Fermi whose own efforts helped create the environment I desire. I dream of a time when Filipinos with PhD's from the Philippines can be proud of the fact. A few decades ago, graduate education in physics here in the Philippines was like being cast-away in the middle of nowhere. I hope that, like the physicists and mathematicians I admire, I can do my part in improving physics teaching and research here.

random thoughts on christmas day

During Christmas Eve, the custom here is to prepare a feast to be eaten at midnight. Strangely enough, that's also the time when I least want to eat. I was ill yesterday, and all I wanted to do was sleep. Right now, I can't even work up an appetite, so there's a lot of food still in the refrigerator.

I'm planning to go on a bike ride later. It's been a few days since I last took out my bike, and I worry that I'll eat too much food and have too little exercise. Going to school is out since the faculty was reminded that school will be closed from the 22nd of December to the 2nd day of January. It's a pity since the trip from here to school and back will consume 2 hours. Maybe I'll go to Luneta or go along the bayside.

I have two bicycles; my road bike and a japanese one with basket and lights that I use for shopping. Although the japanese bike has a mudguard, rack and basket, it has the disadvantage of being hard to fix when during times when I get a flat tire. The rim is larger than the one on my road bike, and the interior (27 by 1.38) is hard to find in bike shops. The rear wheel is also hard to unmount, you need a screwdriver to undo the brakes and a 13" wrench. My regular wrench (the one I bring with me to school) doesn't match the nut on the rear bolt. I have an adjustable wrench but it's too big to bring. Aside from the difficulty with unmounting the rear wheel, I also need to fix the front light because the dynamo isn't working properly.


Friday, December 24, 2010

toilets and euphemism treadmills

While I was at the hospital, I was reminded of bedpans, and I've wondered, now and then, how people actually use them. A google search gave me some images, and I was finally satisfied. I read about bedpans in wikipedia, and I got to wandering through the toilet related entries.

It's really interesting what people, before modern plumbing (sometimes even after the invention of modern plumbing!), had to put up with. I learned for example, of outhouses; you built a small wooden house with a hole in the ground. The idea was to dig a very deep hole, and then drop your waste there. Worms and other aerobic organisms then broke down the waste. Eventually, the pit would fill up, and then you covered the hole with soil and then move the outhouse elsewhere.

I also read about commodes. Originally, a commode was a cabinet with a washstand, a pitcher and basin for washing. The cabinet was supposed to hold a chamber pot where you deposit your waste. Since there were no flush toilets then, one had to make do with a pot. A vestige of this era can still be found in the term "potty training".

While I was wandering through the entries in wiki, I was led to a link on euphemism treadmills. Steve Pinker invented the term to describe how some terms evolved. You can see how the various toilet related entries can serve as an example of the euphemism treadmill: some words were originally used as euphemisms; once these euphemisms gain currency, they become impolite to mention in company, and another euphemism is born.

Another example of the euphemism treadmill is the various terms people have used for African-American. think of Negro, Black, Nigger etc. There are a lot more examples out there.

Today is Christmas Eve, and I'm feeling extremely lazy. I'll think of something simple to cook, and I plan to go to bed early. Maybe later I'll start working on math. There's a chapter in Ablowitz's Complex Variables book that I plan to incorporate in the methods tutorials. The sections on asymptotics in Arfken is too skimpy, while Bender and Orszag would be overkill for undergrads. I'm still looking for a good reference for undergraduate methods..

Sunday, December 19, 2010

changes

My Aunt left for England this afternoon, so this will be the first day we'll be spending the night without her help. I greatly appreciate what she has done for us; without her, we would have been quite lost. My mother's relatively rapid recovery is due to my Aunt's care; she also made sure that my Mom followed doctor's orders.

Starting tonight, there will be a lot of changes at home. I'll need to be at home by 7pm, so I'll be losing whatever nightlife (not a lot actually) I had. I'll also need to sleep near my mom, in case she needs something at night. We'll have to make sure that lights off will be by 9pm, to ensure that both of us will wake up early.

Our help will be here from 7am to around 7pm. Since it's Christmas break, I won't need to worry about having to be at home early, since I don't need to go out of the house except for bike rides for fitness, and shopping. I do need to go to school tomorrow to get some papers for marking, but no more than that. The next time I'll go to school will be after New Year's day.

My Mom has made a lot of progress. The therapist was pleasantly surprised that my Mom could stand on her own, and she can now walk with some help. We'll be buying a quad-cane (the kind with four legs) so that she'll have more practice walking. If all goes well, she should be able to do without it after a few months.

Although I know some of the principles of physical therapy, I know that a professional will still do better. The idea is easy enough; my Mom is training both her left brain and the right side of her body to work together. The neurons she lost due to the stroke have to be compensated for by other neurons in her brain. So therapy has to be done while she's awake so that her other neurons will form the needed connections.

My Mom will also need to make sure that she doesn't lose her flexibility and that her muscles stay balanced. Among the consequences of not having therapy is losing the ability to move her arms and fingers. There are stories of people who cannot stretch their arms; the arm keeps folding back in place because one set of muscles has grown much stronger compared to another set.

Lights off will be at around 10pm. I'll wake up early to get some work done.

Sunday, December 12, 2010

Unmasking charlatans with fake scientific credentials

One of the downsides of having the internet is that anyone can post all sorts of claims. If you happen to believe in strange claims, (such as miracle cures, ways to make a thousand dollars every hour, etc.) there will be websites just for you. I think that this is hard on the elderly, since a lot of them have not developed enough filters to separate the true from the crap.

If you go to the websites of charlatans (I have a certain "doctor" in mind), you will find lots of things. If the charlatan claims to be an expert, then he will have to produce a C.V., and that is the best place to start. Do not read his claims; instead, check out his credentials.

The C. V. should contain where he had his schooling, his listed refereed publications, his work experience, and other information that should support his claim of expertise. A charlatan will pad his C. V. because he must make an effort to look like an expert. A real expert's C. V. will have all of the above and more, so on the surface, it will be hard to distinguish the real from the fake.

This is where google comes in; if he claims to have received an outstanding research fellow award from a Newton Hall Foundation, then type "Newton Hall Foundation" in the google search field. Include the quotation marks to indicate that google should search for the whole phrase. Without the quotation marks, it will search for each of the keywords, and the webpages produced may contain only two out of three, or one out of three of the keywords.

If you try doing it, you will (as of today) generate only two hits from google. (If I happen to be unlucky, it may rise to three after this posting.) From the hits I generate, I can easily conclude that the said foundation exists only in the imagination of the charlatan. An imaginary honorary degree should raise warning bells. If he can lie about this, then he may be lying about other things as well.

If an Oxford College of Applied Science is listed, anyone familiar with the Oxford and Cambridge university system will know that a College in Oxbridge is more like a dorm than what we think of as a college in my country. A College is not a degree-awarding body in Oxbridge. (In the Harry Potter universe, Hogwarts would be analogous to Oxford University, while the houses such as Gryffindor and Slytherin would be analogous to the colleges). So an honorary degree from an "Oxford College of Applied Science" is also a warning signal for the knowledgeable. A simple google search with keywords "Oxford College of Applied Science" will produce only two lists of webpages.

Another test is to look for scientific publications. It's not enough to claim that clinical studies have been made. Anyone can claim that. Instead look at the research papers that he cites. Do the said papers actually exist? Does the journal actually exist? Use google to check. If the journal exists, another filter is to check if it's in the list of academic journals compiled by ISI (Institute for Scientific Information), a citation indexing service. You can also check out the papers cited; if the paper has been refereed and is being read by other experts, then it should be cited in other academic papers.

Articles from newspapers (even major broadsheets!) are insufficient. Many journalists do not have scientific training, and I suspect that many of them do not understand the difference between scientific papers from crap. Of the two hits produced by a search for "Newton Hall Foundation" (with quotation marks), the first one is from the website of that imaginative doctor, while the second one is from a major broadsheet. The journalist involved should have at least verified that the so-called foundation actually exists!

Why the emphasis on refereed articles in scientific journals? A scientific paper must go through a process. After the paper is written and submitted to a journal editor, it must go through peer-review. The paper is read by other experts known to the journal editor, and the claims are checked. Only after the paper is approved by the referees will the paper be published.

Although the process may still allow crap to go through, it does reduce the amount. Referees are often overworked, and it is difficult to replicate everything, especially if the paper reports experimental results. A large number of citations by other scientists should increase your confidence that the paper is correct. (Unless, of course, it is cited by papers on scientific misconduct.)

If the paper's results are replicated by many other groups, then your confidence in the correctness of the paper should rise. Conversely, if other groups are unable to replicate the results, then you should doubt the results. This is the mechanism through which scientific misconduct can be discovered; fabricated data will be impossible to reproduce. As an example, Schon's papers were eventually retracted because other researchers could not reproduce his work. (Schon was eventually found guilty of scientific misconduct.)

Testimonials are the least reliable basis for scientific belief. Memory is faulty, and a lot of people are unable to distinguish between causation and correlation. There are a lot of reasons for doubting testimonials, too numerous to go into here. (Maybe a separate blog post?) For example, religious belief is based on the most part on testimonials; if testimonials were reliable, there would be no multiplicity of religions in the world.

So check and recheck. There is a lot of crap on the net; one should always upgrade one's bullshit detector. A defective bullshit detector is dangerous to your health.

Friday, December 10, 2010

Wednesdays and Fridays

My Wednesdays and Fridays are fully-loaded. My first class is from 7:30-8:30. Although I have no classes or teaching duties from 8:30am to 10 am, I have to update my class records and then have breakfast.

There are no nearby canteens-- the physics building is probably the most isolated building on campus-- and I have to walk for a few minutes to get to a nearby petrol station, where they have various restaurants and shops (Jolibee and Chow King being the least pricey). The only available food is fast food, and I'm getting tired of having the same thing everyday.

After a heavy breakfast (to make sure that I don't go hungry until 1:30 pm), I attend a quantum field theory class by Professor P from 10 am to 11:30 pm. The pace is outrageous-- the text that we're using is Mandl and Shaw's book, and we've reached the halfway point.

As of today, we've covered the quantization of spin 0, 1/2 and 1 free fields, and we're (rather the Professor) is now deriving the Feynman rules for quantum electrodynamics. Wick's theorem went by too fast for me, so I gathered my courage and explained that the pace was too fast, and that I would like to slowly work through the details. Happily, the professor agreed to do so.

I don't have time for lunch because immediately after (from 11:30am to 1:30pm) is a lab class I'm teaching. I can't just sit there and let the students do all the work. I have to walk around asking questions and providing help when needed. This means I get to have lunch around 2pm; I have to hurry because I would be meeting one of the theory apprentices for math methods supervisions. This is usually from 2:30 to 4pm, after which I have to attend a mathematical methods class on asymptotic approximation methods.

The asymptotics class is a lot of fun because I'm learning new methods of approximating integrals and I find that complex variable methods are of great use here. In fact, I'm planning to include some of the material I learn there to the math methods supervisions. I was impressed by the Mellin transform method for getting asymptotic series; you get the Mellin transform, perform an analytic continuation in the transform space, and then use a Bromwich like integral to get the inverse Mellin transform. The series comes from moving the contour of integration to the left or right, depending on whether you're interested in the behaviour near the origin or on the behaviour at infinity of the original function.

Alas, even though the spirit is willing, I still fall into micro-naps because by 4pm I feel tired. I've tried taking a short nap immediately after lunch, but it's not enough. I even drink coffee before going to class but I still fall asleep. I am thankful though that I don't have a class from 5:30 to 7 pm; that would probably break the camel's back. I'll try to see if sleeping earlier would help.

Monday, December 6, 2010

Spacetime Physics

The first physics book to hold my interest was the first edition of Edwin F. Taylor and J. A. Wheeler's Spacetime Physics. (Our university library still doesn't have a copy of the 2nd edition.) I was a sophomore when I first encountered the book at the hangout of the theory group. (My memory may have failed me here-- the only other possibility is after a random walk down the library shelves.

It was at the right level for me, and when I seriously started working on it (near the end of the sophomore year or was it the beginning of the junior year?), I fell in love with it. Although I tried reading other books, I disliked them. The usual approach is an algebraic one; in other books, one had to endure algebra without being able to see, at a glance, what one was working towards.

I did not understand, before Spacetime Physics, what an inertial observer was. The careful description of a latticework of clocks and rods freed me from the belief that an observer was a person stationed at the origin. Due to this misconception, I had trouble with Lorentz transformations. I also laboured under the belief that things like time dilation, length contraction and so on were consequences of the finite speed of light.

Spacetime physics had an unusual emphasis on spacetime diagrams and the geometric interpretation; this geometric interpretation, coupled with algebraic methods, gave me a better grasp of what relativity is about. I remember many later problem sets ---my classmates would struggle with lengthy algebra, and I would get the desired result in a few lines.

Later, when I was assigned to teaching a modern physics course for engineers, I chucked out the usual books and substituted Spacetime Physics for the relativity portion of the course. Since that part of the course relied mainly on the first chapter, we used an electronic copy of the first edition. (You can download the first chapter, with exercises, from Edwin Taylor's website .). The feedback I get is that relativity is the most enjoyable part of the course.

I've even had fun with the undergraduates of the theory group. I had two of our best undergrads take the special relativity exam; the exam was a 45 item multiple choice exam, and I told them that I would give a peso for every correct answer. I also appealed to their self-respect: would they really allow engineers to claim that they knew special relativity better than physics majors? (They've had the modern physics course for physics majors, so I teased them that they ought to have an advantage over "mere engineers". They used another book for relativity though. )

The result? The engineers had them beat. They scored in the early thirties range, while a "mere engineer" was able to get over 40 items right. The average engineering student was able to get around 30 items right, so I teased them without mercy afterwards.

The summer after that, our undergrads sat through the relativity portion of the course I taught, read Spacetime Physics, and solved problems I assigned. They did a lot better this time around; most of them got 40 items or more. (Appealing to self-respect is a good teaching strategy!)

Starting this year, all our undergraduate apprentices are required to sit-in during the relativity portion of the engineering modern physics course. They are also required to take the exam; self-respect should take care of the rest. I'm hoping to get some changes to seep in from below; Our students will eventually replace us, and I hope that when that time comes, the spacetime approach will become a standard part of the undergraduate toolkit.

Sunday, December 5, 2010

gigapedia is moving

I often visit gigapedia when looking for books. Although a google search with appropriate keywords will get you links for downloads, gigapedia provides a one-stop search. I don't know why gigapedia is moving (litigation? piracy issues?), and I'm sad that the website is moving.

Gigapedia is moving to a new portal http://library.nu/, and it provides the same functionality. There is no registration yet, so you can freely access its search engine without having to log-in. I've tried it, and it operates like gigapedia. For example, putting in "Gravitation" in the search field gives a list of books in library.nu pages; each page in turn contains more information about the listed book and links for download.

For people in developing (what a crazy description! developing?) countries, gigapedia has been a boon to book-lovers. Most students in developing countries find books unaffordable. As an example, a copy of Resnick, Halliday, and Walker would probably cost a fifth of the minimum monthly wage. A lot of us really care about the books, and we would be willing to buy them if they cost less.

Libraries do not provide enough here-- when budgets are cut, new acquisitions to public libraries are the first to go. (Our local officials would rather construct basketball courts and hold beauty pageants than subsidize libraries. ) For now, gigapedia's successor will definitely fill a need here in our islands.

update: you're now required to register before you can perform a search. The registration is easy enough. You are only asked for your email address, and once you get the activation email, you're ready to go.

Saturday, December 4, 2010

Older programs, Maple 8 and Windows 7

One of the difficulties of dealing with a new operating system (even if it's Windows!) is getting older programs to work. I have an installer of Maple 8 -- a symbolic computation program-- and I wanted it to work on my new machine. I tried installing it but couldn't make it work, because it was developed for Windows XP. I didn't want to buy the newer version because of the cost; and I also preferred the older version (the latest version is Maple 14).

I did a Google search. The first hits I obtained suggested installing a virtual machine and then running the program within the virtual machine. But that was nuts: given the limited capabilities of a netbook, adding a virtual machine would probably make the system unstable.

After refining the search, and using keywords "windows 7 compatibility older software", I got a hit for getting older programs to work on Windows 7. It's a support page from Microsoft and among the things it said was "To change compatibility settings manually for a program, right-click the icon for the program, click Properties, and then click the Compatibility tab." The tab will then contain things that you can manually adjust to make the program work. After fiddling with the settings, I was able to install the program and get it running on my netbook. :-)

math methods and saner schedules

When I first joined the theory group, as an undergrad, I was a walk-in. In other research groups, you had to write an application letter, go through an apprenticeship period, and then, if they liked you, to full membership. The apprenticeship was a series of tasks; depending on the group, it could be a series of programming problems to solve, or menial tasks essential to the continuing work of the lab.

At that time, people in the theory group did not have as much respect as they do now. There was a perception then that the theory group was the place to go if the other labs rejected you; although there were a few who went into theory because they preferred theoretical work. The people who were running the group at that time were ronin; they were PhD students with nominal advisers. Except for the undergraduates who were taken in by a PhD (this was rare at that time), the undergraduates were left at sea.

My own adviser was at that time a PhD student; so was the other theorist who took in undergraduates. They had few or no publications in journals, although this was to change later on as they got their PhD's. Since they had little experience advising, they took in anyone who asked to join their groups.

We had to invent our application process; walk-ins would prove unsustainable. The change in character of our group started with the time we were flooded with applicants (ten juniors applied) and we had no rejection policy. At that time, there was a voluntary math methods tutorial session (I set it up with the consent of my adviser) and we expected them to join it as we knew that everyone needed remediation.

This didn't mean our applicants weren't smart; a lot of them went on to get latin honors. We did notice that they emerged from the math methods courses with little or no understanding of basic methods (of the kind you can read in Arfken's book, Mathematical Methods for Physicists). My adviser tried a methods seminar, where each week a participant was supposed to discuss a given topic. That didn't work. After that, I set up tutorials for them once a week.

The tutorials are problem-solving sessions; I assigned Arfken problems and made each attendee write coherent solutions. My job was to critique the solution-- find errors in reasoning, giving tips on how to make the explanations coherent. I even wrote a style manual based on David Mermin's rules of writing. I also help with difficult problems; when I learned math methods, I had to learn it on my own, and it took waaay longer. I remember problems that stumped me for a year before I eventually figured them out.

We noticed that attendance fell as time went on, and it eventually stopped. This was bad because these methods were the keel of the thesis projects; a broken keel meant bad sailing or a sunken ship. We did not want cases where the supervisor was the one who did the work.

So as time passed, we made changes. We instituted an entrance exam that was meant to check mastery of calculus up to the first course in differential equations. If you did not pass this exam, then it would be impossible to cope with methods. It was also meant to scare away people who thought that being a member of the theory group meant less work.

We also found that we had to require attendance because after passing the entrance exam, some undergraduates never completed the math methods sequence my adviser and I designed. Later, we added a post-methods sessions exam; full membership and thesis mentoring would happen only after passing the post-methods exams. If an apprentice did not pass the post-methods exams, then the apprentice had to go look for another research group to join.

Although the post-methods exams seem to be harsh (the post methods exams would probably scare most undergrads), passing the exams is doable because the exam will be from the set of problems assigned during the tutorials. All you need is to actually attend the sessions and do the problems. The post methods exams are designed to get rid of absentees, as well as to ensure that every member of our subgroup met a minimum standard when it came to mathematical methods.

The methods sessions usually takes three-fourths of a year. Since our course was a five year course, we give out entrance exams during the third term (summer) of the sophomore year. The methods sessions are done during the third year; this means anyone we reject, or opts out, has the chance to apply for membership in other research groups.

We work through all of the problems in chapters 6 to 8 of Arfken's book. The coverage was complex variable methods up to contour integration and the method of steepest descent (chapters 6 and 7), and then an intensive study of the gamma function, as an application of all the methods (chapter 8). My experience is it takes the average undergraduate of the theory group three-fourths to a full year to achieve mastery. Again, these are very intelligent students (and I think this description applies to the average physics major)-- so my experience lends me to doubt the utility of the mathematical methods course that's actually required by our institute.

The math methods course required by the institute uses Arfken as the main text. To see how insane the pace is, what takes us almost a year to master during the methods sessions is covered in the first exam of the second course in math methods. This means the usual student is supposed to learn the same content in a month and a half during their sophomore year. In fact, math majors in my university would need to take about three courses during their senior year to cover the same amount of material. No wonder that as soon as the average physics major finishes the methods course, he or she is in need of remediation.

At first, there was only a single post methods exam. But I found that, as in the methods course, a single exam inadequately samples how well our apprentices understand the material. Compare a single exam (as is the case with the required course) with six post methods exams. After passing all the exams, (and I chose the five most difficult questions for each exam!) I am therefore not surprised at the disparity in performance of the average member of our subgroup compared to other people whose only experience with methods was through the required coursework.

During the last few semesters, the methods sessions were held once a week, every Saturday, from noon until 5 pm. I've changed it this semester to what I hope is a saner schedule; I now meet one-on one with each apprentice an hour every week. I ask about their progress and provide mathematical assistance when needed. I found that the Saturday sessions took a toll on me: I was unable to get my own research done; and I need to do that to get my PhD. I'm hoping that this new arrangement will work, and I'm relying on apprentices asking for help from older members who have passed the exams. I'm keeping my fingers crossed; it's time to take care of my own work as well.