## The elegant beggarsJune 23, 2009

Posted by keithkchan in fun stuffs, Philosophy.

I am pretty busy these days, for no good reasons as usual. But I have to say something on this blog. This time let me say something I find totally ridiculous here in New York (or America).

The beggars people usually have in mind, at least I have in mind, are usually humble and pitiful. But this is not the case in New York. Beggars can be found everywhere here, particularly in the subway. I find it very annoying because I commute by subway everyday.

“Ladies and gentleman, sorry for disturbing you. My name is Peter. I am homeless, jobless. I am hungry. I have XYZ disease. Blah, blah, blah… I am grateful if you can give me some money or change.” Then the guy goes around the compartment to collect money when somebody is kind enough to give them money. The guy then goes to another compartment to continue his speech. The guy’s voice is loud and clear despite the fact that the guy claims himself to be “sick and hungry”. From the speech, I get the impression that the guy’s voice is energetic and confident, it sounds we have the responsibilities to pay him. Most of the time the beggars decently, sometimes they wear better than I do. In one occasion, the beggar wears a suit, isn’t it totally ridiculous? Should I call them gentlemen instead of beggars?

Most of the time I ignore them. But some people are “kind” enough to give them money. Let’s estimate how much money they make. From my observation, they get on average one dollar in each compartment in the train. Suppose this takes, say 5 minutes. So they make 12 dollars in one hour. Let’s assume they work 8 hours in one day. They make 96 dollars in one day. If somebody gets about 100 dollars a day, how likely that he suffers from hunger? That’s totally ridiculous. In fact, they make more money than I do! As a poor graduate student, I only get 70 dollars each day from the stipend. So I am poorer than a beggar!

So I will say those people who pay these beggars are not kind, but stupid. Almost all those people who ask for money are stronger and bigger than me, and have no apparent disabilities. OK, if they want to find a job in Wall Street, it can be difficult. I don’t think it is so difficult to get a job in McDonalds’ or in a pizzeria. They don’t do it because those stupid people keep on paying them money. This “job” as a beggar is easier and maybe more profitable than being a worker in a restaurant.

My observation is only limited to New York City. I don’t know if this is a local phenomenon, or it also occur in other parts of America. This is one of the ridiculous things I find in New York.

## Will Google take over the world?June 1, 2009

Posted by keithkchan in Philosophy.

Google has released a new product again, Google wave. Google’s products are usually innovative and free. Besides saying it is cool, I am not going to comment on it further.

So far I only use Google as a search engine. In fact I realized I use more than that, e.g. Youtube, maybe more. I still refuse to use Gmail although most of my colleagues use it now. The reason that I worry that Google has really a lot of momentum. In last few years or so, Google has released new products that kick other competitors’ ass. Google’s products are dominant in the market, everybody search using Google, email using Gmail, look for directions in Google map, watch videos on Youtube … It has the potential to eliminate all the competitors and take over the world.

But I now hesitate. Well, Google just makes our life easier. What do you want? The reason that everybody uses it simply because it is free and of high performance. This is just a demonstration of the survival of the fittest. The latest product Google wave is good for scientific collaboration. After all, Google seems very friendly to science so far. Google supports open software, which I personally admire.

Now I begin to question am I simply stupid pig headed, and making fuzz out of nothing? If Google is going to take over the world, the world may be of better shape than it present form.

## Comments on the experimental requirementsApril 23, 2009

Posted by keithkchan in Philosophy.

I haven’t updated this blog for some time. Today I had some discussions with my Mr Payam and Mr Mincer. I feel that I have pretty strong opinion that I want to blog about.

In our department, we have a rather perversive requirement — students have to fulfill some experimental requirement by either taking the experiment courses or doing an experimental project with a faculty member. This requirement has caused a lot of trouble for some of us. This is particularly bad for the theoretical students since most theorists don’t like doing experiments. I think I am a theorist but not a highbrow one, so I think I can give “relatively balanced” opinion.

The argument for the existence of this experimental requirement is that the department expects the graduates to know how real experiments are done, and give the students a chance to discover their potential in doing experiments.

Everyone enters the graduate school have already known the importance of experiments of physics. After all physics is an experimental science. We agree. Doing good experiments are hard. Need a lot of creative designs and careful planing, and a lot of practical skills. We agree that experimentalists are not stupid. When we apply for graduate school most of us already have well defined field of interests, taking the experimental course is not going to change anything. OK, doing experimental project may be able to shift their interest. But then the whole idea of having this requirements is to let the experimentalists to have more students. After all the lab can take up a lot of students, many of the lab procedures are tedious and labour-intensive.

So far I have been suffering a lot from from this requirements. Due some misguided thoughts, I tried to do a project with some guy in astronomy. After some time, it became so technical, time-consuming and more importantly boring, I quited the project. From that experience, I guess the most important thing I learn is that astronomy is boring.

My friend Mr Payam took the experiment course. He spent a lot of time doing those experiments and writing lab report, so it messed up his research.

I think this requirements should not exist at all. I have complained about to some people, but they insist on keeping it. Apparently, I am not the only one have this opinion. According to Mr Mincer, some theorists hold the same viewpoint as mine. Unfortunately, experimentalists and theorists can only agree that they disagree.

I certainly agree the importance of experiment to physics, but I disagree that theorists should be afflicted with the pains that the experimentalists suffer.

## The Art of Asking “Stupid” QuestionsMarch 21, 2009

Posted by keithkchan in Philosophy, Whatever.

These few days we tried to verified the approximation used in some guys’ paper, who claimed to have done what we have done. In their paper they used the spherical approximation, instead of solving the equations exactly. When I showed my advisor the results, he immediately said that it must be wrong since in the large scales the nonlinear effects should not matter. I then spent a couple of days to check if there were stupid mistakes that I have made. Indeed I did, but it was not related to the major problem. Although the conventional wisdom was that the linear regime should not be affected by the nonlinear effects, the equation we solved were highly nonlinear, this was not obvious to me. I went to press him, and we finally realized that in the spherical approximation the nonlinear effect in the high k can indeed influence the scale physics. Incidentally, this partially suggests the answer to my previous question if quantity is more important than quality. Those guys write many papers, quality may fluctuate a bit.

I often ask questions most of them are probably stupid. I think the real good physicists certainly know the importance of asking questions. Sometimes, some concepts may be so “obvious” to them they did not even think about it. Like in the case of my advisor who is regarded as an expert in this field, but he could still miss something sometimes.

I believe that if I keep on asking questions I will be able to good questions sometime. The most important thing is not to stop asking questions, even if they are are stupid. After all, it is not clear if it is stupid a priori.

## Publish or Perish; Quantity or Quality?March 11, 2009

Posted by keithkchan in Philosophy.

These days I am kind of impatient. I finished writing a paper two months ago and I gave it to my adviser t to review. Since he also has been writing a companion paper, and so far he has not yet had time to review it. This field I work on is rather hot. Two weeks after I finished writing, somebody put a paper on the arXiv, and they did some something quite good, and make our results less impressive. Yesterday, another guy puts another paper on the arXiv, at least from the title, they claimed that they have done something similar to what we have done. At the time when I was writing the paper, we were the first one to be able to do it, I am not so certain now and may need to modify the wording in the paper. Is it reasonable to feel pissed off now? Well I am not really pissed off. He is nice guy, and he teaches me a lot of things. It is just a bit “unfortunate” that his paper is unexpected long and time-consuming. Probably this kind of things happen between every student and their advisor. Perhaps I am more fortunate than other students already. The reason I spell it out simply because I like to bullshit every now and then. =)

Another thing that I am not so sure is should we write as many papers as possible? Of course it is excellent if one can write a lot of papers and all of them are of high quality. Here I assume that the product of quantity and quality (citation or in whatever sense) is roughly constant. If one writes a lot of papers it is more likely that the similarity among them is relatively high. I asked some professional guy who was a professor, he thought that quality was more important than quantity. If I recollect correctly, he told me that Alan Guth did not write any paper for first several years of his post-doc, and the only paper he wrote was the inflation paper.

However, I also think that the quality of a paper is not so clearly defined concept. If you write a lot of papers, some of them may fall into the category that the person who you want to please like it. And also for graduate students, it is quality not yet so important? After all, we don’t have (much) reputation yet. Of course you don’t want to get bad reputation from poor quality papers.

Any thought? I am still not so sure which way is the best way. I don’t think I will write many papers since my advisor is a very careful guy and he certainly thinks quality is much more than quantity.

Update: In light of the comments by my colleagues offline, I clarify that I am not unhappy about my advisor. We are in good terms. This post is meant to express my thoughts on publishing only.

## Counting TreesMarch 1, 2009

Posted by keithkchan in fun stuffs, Philosophy.

Today I tried to count the number of labelled trees. Let me make it clear what kind of trees I am interested in. Suppose there are are N points, and we want to connect these N points together using N-1 lines, which are called edges, only, so that there is a continuous path between any two points. Furthermore we have labelled the points with numbers. The question is that how many topologically different trees for N point. Actually, this problem arises in some tree level perturbative expansion, but that is not the point of the post.

Let me illustrate it using some examples. For N=2, there is only 1 topologically distinct configuration. For N=3, there are 3. For N=4, there are 16. Obviously it increases rapidly wiht N, for N=5, I did not even try. The claim is that there are $N^{N-2}$ for N points. I tried to show this formula. I thought it would not be very difficult, but after thinking for 1 hour, I still had no clue, and decided to give up. I later found that this is the Cayley’s theorem in graph theory. In one of the proof one maps the problem to something easier to count by means of the Prufer sequence. Any theorem has a name is unlikely to be very easy to prove, so I don’t bother to describe it here, interested reader can read this note.

In fact I now remember that I learned this before in my undergraduate graph theory course. At that time I took it just for fun and thought that it would not be of any use in physics. This is the first theorem in graph theory that I find useful in physics, unfortunate I forgot about it. In fact I took quite a lot of math courses, such as group theory, differential geometry, in undergraduate, but I could not appreciate their importance to physics at that time, and were not well motivated. Another point is that the level of difficulty of the combinatorics problem may not be easy to estimate.

## Happy Birthday Mr DarwinFebruary 12, 2009

Posted by keithkchan in fun stuffs, Philosophy, Whatever.
1 comment so far

I heard that this year is some anniversary of Charles Darwin for some time. When I look around other blogs, I learn that today is Mr Darwin’s 200 birthday. Although I am not a biologist, I love science, and Darwin’s evolution is a beautiful theory.

From my previous criticism on the stupid creationist, you may know that I believe in evolution. But I believe in evolution is not because Mr Darwin told us so, not just because we look like chimpanzee. This theory has been found to be in agreement with a lot of evidences. There are thousands of fossil records, which enable us trace out the evolution tracks of species. We have sequenced the genes of many species. For example, our genes are more than 90% similar to the chimpanzees. In medicine, we have seen the evolution at work many times, although this time it is undesirable. When we attack the virus or bacteria with some medicine, the medicine kill all those strains that are not resistant to the drug, and only the resistant strain survives. Technically it is said that a strong selection pressure is applied. Before other non-resistant strains are killed, they compete with resistant strains for food and mate. Since selection pressure killed the non-resistant strains, the resistant strain take over the whole species. The species becomes resistant to the drug. That is one of the reason why curing AIDS is so difficult.

When people see the complexity of the species in our world, which is beyond their imagination, so they cook up the stupid creationism. This stupid idea (note that it is qualified to be called a theory since it has no predictive power at all) has no foundations, well except those people believe in the Book written one thousand years ago by some people. If the universe if created by some intelligent stuff, which is usually called God, according to those creationists’ logic, God has to be created by some super-God, which may be created by Super-Super-God, blah, blah, blah. On the other hand, evolution is a very slow process, the species evolves adaptively based on the environment.

Those religious people often attacks evolution saying some of the links are not clear, for example from fish to reptiles. There are more and more fossils discovered. I think the complete picture will be possible soon. But if you think about those religious people’s attack, you will find it silly. Suppose there are two jigsaw puzzles, the one representing evolution has been filled say 70%, the one representing creationism is empty. The religion people then tell you to believe the Holy Book and the jigsaw has been filled completely although you can’t see it. They then say the evolution one is 30% not filled, it must be wrong. Which one do you believe? Surprisingly, they are quite a lot of people believe in religion one.

So if you want a satisfactory explanation of the Nature, evolution is only theory that you can trust. Of course evolution tells us that if somebody proposes another theory with better agreement with the evidences, we will accept that theory as the working theory. This is spirit of evolution, survival of the fittest. Happy birthday to Mr Darwin.

## Big Crunch and Academic Job ProspectiveJanuary 17, 2009

Posted by keithkchan in Philosophy, Whatever.

In the past I thought that the job opportunities were insensitive to the general economical environment. Now it seems to me that this is not true. The credit crunch in the financial sector has non-minimal coupling to the academic job market.

Now it is the season of post-doc hunting. Around this month, many institutes are selecting their prospective post-docs. It seems the competition for post-doc position is veeeery intense. Let me give you an example. There are 500 applicants for a post-doc position at NYU CCPP. A colleague here at Room 538 is also looking for post-doc. He told me that he applied for more than 10 post-docs. He have several papers already but so far he only got negative reply. He seems not so optimistic about his job hunting.

There are several reasons for the strong coupling between the financial sector and the academic market. First the money in the academic sector shrinks. Many positions are in the academic sector are funded by some endowments, foundations, or government agencies. The returns from the sources is dramatically reduced after the the economy turns bad. Many institutes have started to reduce costs. For example, MIT is making 5% cut in expenditure. One of the easy ways to cut cost is to reduce the number of new openings.
A common path for the graduate students from theoretical physics is the financial sector since it offers much higher salary and the numbers of opening are much more. However, ever since the big crunch, the competitors from MBA, laid-offs from the other financial companies have increased dramatically. The financial market path also becomes very difficult. Some graduates may then think it would be better to stay in the academia in this difficult financial situation. The increases the number of applicants for the post-docs. Since many people have anticipated the bad situation, they try to maximize the chance of success by applying as many as possible. These cause the huge number of graduates fighting for a job.

I still have several years to go, and by the time I graduate the economic situation will probably have recovered. If possible, it is better to stay in the current, for example delaying the graduation. For the friends who are applying for post-docs or whatever jobs, good luck, Nature bless you.

## The Joy of Astronomy?January 10, 2009

Posted by keithkchan in Philosophy.

There is some reasons for my long silence. First I expected Mr Eyal would help me to keep the blog updated. It seems I am too optimistic. Another reason is that I am kind of in a dilemma, but I am not going to talk about it explicitly here.

OK, let me turn to the topic of the post. From various sources, I got some impressions of astronomy. I would like to comment on it. First, if you like me check out the Bad Astronomy regularly, you may got the impression that astronomy is really cool. Astronomers takes tons of beautiful pictures of galaxies, nebulae, quasars, etc. That’s the final product, not the whole story. Real astronomy is boring!

Astronomers spend a lot of time on telescope, various observation instruments. From my point of view, that’s engineering, and engineering is dirty and boring.

Some astronomers do not directly involve in observations, instead they analyse the observed data. One of my colleague is working on some of a big observation project, and he mainly works on data analysis. He told me that in last few days, he spent all the time to download the data and change the data format. I also know some guy works on a project involving analyzing images. He told me that the work need to done is very technical, and there was not many useful things would be learned. I don’t think there is anything can be learned from doing this kind of work. In particular there is no physics. You may counter argue that because it is astronomy, not physics. Well you may say that such tedious work happens in every research project. But it seems to me this kind of work is the day job of astronomers.

My observation is that in astronomy, when you get into details, it becomes very technical, tedious, and you don’t feel there is much physics involved.

Sorry for saying so many negative things about astronomy. These negative observation probably stems from the fact that I am not interested in this kind of work. If there are some readers who disagree with me, feel free to argue with me. But be careful, not to confuse astronomy with astrophysics.

Update: This year is the International Year of Astronomy, but the conclusion of my post remains unchanged.

## Exam is overDecember 18, 2008

Posted by keithkchan in Philosophy.