Archive for the ‘Science’ Category

Where does Taiwanese air pollution come from?

Wednesday, December 16th, 2015

Conclusion: The pollution now (December) is from China, the pollution in November was locally generated.

Earlier this year, there was a bout of posts about whether the air pollution in Taiwan came from China. The air is apparently pretty bad right now, and this time I think it’s clear that it’s from China. I just pulled this screenshot from


Screen Shot 2015-12-16 at 2.02.24 PM

Observe that the pollution in Yilan Country, southeast of Taipei, is not that different from Taipei itself. This is what you would expect if the pollution came from far away. Compare this to the map from November (



Notice the huge disparity in homogeneity. Also, if I remember correctly, back then the wind was also unusually still. I think based on these facts, I would conclude that the pollution in November was locally generated and the pollution now is from a far away source, probably China. (Disregard the low pollution directly to the West, the wind doesn’t come from there. Also, there could be a time lag, so even the pollution levels in the direction of the wind source at the same point in time are not immediately relevant.)

If I had all the historical data in a csv, could probably do a better analysis than two snapshots, if anyone could point me to a source I’d be happy to do that.

How to Study

Thursday, April 19th, 2012

The veritasium guy talks about the importance of independent thought to learning. I think that often when you mention independent thought, people immediately see it in terms of creativity and expression and other artsy concepts. As Derek explains in this video, however, independent thinking has benefits that go beyond originality Рit is also a great source of efficiency in learning, as constructing a coherent and consistent worldview in your head means that many things get checked and re-iterated every time you come across a new fact.

Truly impressive science education videos

Wednesday, April 18th, 2012

If you were to ask people to name some science popularizers, they might name Stephen Hawking or Neil deGrasse Tyson. Veritasium impresses me a lot more.

The thing about the types of questions that Hawking or Tyson raise is that they are not the types of questions that people think of themselves as being able to answer. Yes I am made of stardust, sure, but knowing that fact doesn’t change anything I do in real life, and wasn’t something I thought I could answer in the first place.

The Veritasium videos, on the other hand, are full of simple surprises:

I’ve tried to amuse other people with these videos and been disappointed to find them un-amused. I suspect this is largely because to appreciate these things you need to have had expectations to begin with.

Children are easy to amuse because they are actively learning about the world, and have a constant cycle of assumption formation and surprise and learning going on; as people grow older, they come to accept that they can’t know about everything.

There are many different ways of not knowing, however. The attitude imbued by scientific training is a very constructive one, where ignorance is recognized as being transient and resources can be invested if a piece of knowledge is deemed valuable enough.

The most unfortunate attitude I’ve come across is cynical resignation and almost total lack of curiosity — such people are often also beset by what they see as injustices big and small as they are buffeted by the world in directions which, through their ignorance, they see as random and unchangeable. Many of them turn dualist / spiritual, and in an effort to avoid being wrong resort to beliefs that are not even wrong.

Quantum Riddle

Tuesday, May 22nd, 2007

Question: Of the bound hydrogen atom eigenstates, which has the highest kinetic energy?

Answer: The lowest energy state.

Ain’t that curious? Kepler’s laws helped me understand this one. Oh, and this holds for all molecules – I leave the proof as an exercise.

State Counting in Thermodynamics

Saturday, March 3rd, 2007

Let’s say you have a box full of particles, and each of those particles is independently in one of N states. Each state has a probability of occuring. Let us further suppose that none of these probabilities are the same – if so, then there is one state with the highest probability. If there are then properties E and V which are diagonal and have a 1-1 correspondence to each other amongst all the states, then the most common E and most common V definitely are related to each other by E=MV^2/2.

Examine the Speed and Energy distributions of the ideal gas. The modal values of these two distributions do not correspond to each other via the E = MV^2/2 relation. Paradox?



Monday, February 19th, 2007

I’ve been reading What is Thought? by Eric Baum, a book on the mind by an AI researcher.

For part of the book, Baum describes solving Blocks World problems with a computational economics model. The problem is called Hayek, and it is described in this article. I will just describe the part that is most interesting to me.


RG in Biology

Thursday, December 14th, 2006

Professor Chakraborty described some work identifying what is essentially an analog-to-digital circuit in the immune system. One thing he mentioned was the future use of renormalization group theory to study these systems.