Are there still rooms left for us?

This year the planet Earth reaches its landmark human population, 7 billion! And projected to be 8 billon in year 2030 and 9 billion in year 2050. Homo sapiens perhaps consist of the largest mammal population in the earth. The topic was highlighted by the January 2011 issue of National Geographic, which showed a tremendous acceleration of human population growth in the past millenium of the 20th century. The number of mega cities with population exceeding one million has increased from a mere 3 in 1800 (Beijing had 1.3 million then together with Tokyo and London) to a staggering 442 in year 2010 with Asia having most crowded cities. Population growth was in no doubt one of the central focuses of the media this year. Many media sources discussed the consequence and solutions to accomodate increasing number of humans. Building vertical cities become a future trend given that it’s after all a reality.

(Figure adopted from

With the advent of industrialization and advance of medicine, human life style morphed from nomadic and periodic migration to modern city dwelling. The former life style was at the mercy of mother nature and gradually phases out in most human society. The latter provides a long-term residence but in the meantime features more frequent and more damaging pattern of short-term human travelling for business and pleasure as well as trading transportations in air, land and ocean.

Aggravating the situation, consumption culture imposes much more stress on the environment. Mass consumption as a vehicle drives the global economy, labor market and international trading, and large-scale consumption is also a determinant for policy making, a pressure for foreign relations and a motivation for scientific and engineering research.

How much pressure the Earth can uptake for our consumption desires? Is there a tipping point that leads to a catastrophe?

Feel free to breath the dirty air

The infamous Beijing smug stroke again a few days ago. The situation was so dire that even some Chinese official acknowledged that China should adopt a better standard to measure the air quality and to report the results to the public. However, air pollution is not something new to ordinary Chinese as well as the lack of government effort to protect citizens from such hazard.

This time the authority was embarrassed by data released from the Beijing Embassy of the United States. The Embassy has installed meters on a roof to measure the level of fine particulates PM2.5 (particules smaller than 2.5 micron) and updated the information hourly via a Twitter thread. Instead, the Chinese government only reports the level of PM10, particulates bigger than 10 micron, and conveniently omits the PM2.5. It’s scientifically well known that PM2.5 particulates penetrate deeply into the lung beyond the protection by cilia, and presumably do much sever damage to human health. Health complications of inhaling PM2.5 particles might include pulmonary and cardiovascular disease such as asthma and bronchitis. More science still needs to be done to differentiate the effects of different types of PM2.5 particles.

In response to the data from the US Embassy, Chinese official asks the public not to trust the readings from the US embassy roof (I know the existence of this device perhaps more than two years ago from reading James Fallows blog at

A more interesting report emerged from New York Times. China’s high authorities in Beijing are protected from breathing the dirty air by some extravagant air purifiers.

NASA published a satellite data map about PM2.5 pollution worldwide from year 2001 to year 2006 (see below). At anywhere in the world, you might inhale numerous PM2.5 particles per breath. According to the satellite image, the number stays several fold higher if you happen to be living in China which has some highest readout in the map.

Total solar eclipse on July 22

We are expecting to observe a total solar eclipse (TSE, 全日食) on July 22, a rare event that can be seen in many areas in east Asia and in some Pacific islands. One can see the above figure (from NASA website containing much detailed information about this TSE event) for the projected TSE path that spans from east India into Pacific Ocean (the band indicates areas where TSE can be observed). NASA has also published on its website a projected TSE path through China (see figure below). People in major cities including Shanghai, Wuhan, Chongqing and Chengdu will have the chance to watch it. Places closer to the central line of the band have longer TSE time. Shanghai has about 5 minutes. Partial sonar eclipse (PSE) can be observed across much large areas.

Question: can we actually see the Sun on July 22 here in Shanghai?
Given that pollution and cloudy weather might block the clear sky, we
could only experience a dark period on July 22 without directly seeing
the TSE process. According to a weather forecast, Shanghai will have a T-storm or rain-shower with a 100% chance of precipitation on Wednesday. It’s not clear to me how this is going to affect the observation.

Predicting ethnic violence

Much to my surprise, a quantitative model built at New England Complex Systems Institute (NECSI) in Boston can predict where an ethnic violence may happen. The president of NECSI, Yaneer Bar-Yam, talked with Seed Magazine that their model was able to predict ethnic conflicts in India and former Yugoslavia with appreciable accuracy. This was a very interesting outcome. I am curious to learn whether the model can be applied to analyze the recent ethnic outbreaks in Tibet and Xinjiang. It is not certain to me whether the editor and Bar-Yam were aware of the Xinjiang riots when producing this piece.

This serves as another demonstration that science can provide a guide for policy making that might impact public and personal lives. The article can be downloaded from the institute’s website here.

You CANNOT drive on Chinese soil

Sorry, you cannot drive in China

I was working on getting my US driver’s license changed to a Shanghai one. I’ve heard terrible stories that all said getting a driver’s license here is largely an ordeal. You have to take a driving class and bribe your teacher even if you already pay all the fees, and stuff like that. In the US (for example, in Texas), you pay 20USD and take a test, and that’s about it.

Life is much easier if you already have a license from another country,  which might save you loads of troubles. Basically you get your license translated into Chinese by a certified agent (50rmb), then go to the police department that is in charge of processing driver’s license applications, pay all the required fees (photo taking 60RMB and health check 40RMB, health check for a driver’s license? anyways), take a written test (I did not get to this far), and then you are done.

For my case on last Wednesday, everything went quite smoothly as planned, at least for the earlier part. But…., after the health check found me "color blind", I was out. Yes, out! for my life time to be a driver in my own country. Well, I was not surprised that I have color deficiency. Specifically, I have subtle trouble in distinguishing red-green mixtures in some conditions. I will come back to the pop science of color vision below. I knew this since I was a child. In fact, it’s an inherited deficiency, from my mom who is color blind as well.

However, I was upset (still unsurprisingly) by the fact that one cannot drive just because that he/she is color blind. The society provides no room to accommodate you. Well, in this country, this reality is not a big deal and it is just the way of life. For example, you can be deprived of education opportunity if you have a hepatitis (it happened to a graduate applicant to our institute last year) or a heart condition (it happened to my cousin more than twenty years ago even after he passed the entrance exam, twice). You have a problem? You eat it. Sorry, no social help for you. The mindset goes like "you are the problem for the society and you should feel ashamed", and never like "the society should do better to help you to develop"

Human vision of color

So, what is color blindness? Can you tell the number buried in the following color diagram? If not, you are perhaps color blind. I can tell there is a 2 (red color) to the left, but cannot tell the number to the right.


Color blindness is a strong and disproportional term, which is often
misleading. Most color-blind people like me only have a certain degree of
deficiency in color perception, not a complete loss. It’s not true that we can only see black and white. That’s totally not cool! You can only find one such case in 10 million people, meaning that there are perhaps two people in Shanghai who can only see black and white.

The science behind color vision is technically called "trichromacy", which is a complex mechanism that human eyes use to percept color. In short, retina contains four types of cells — rod cells and three types of cone cells. Each type of cone cells has a light absorption spectrum that spans a certain wavelength different from the other types. The combination of three spectra from the three types of cones spans the entire visible light spectrum such that human can distinguish color based on the wavelength sensitivity of cone cells and color intensity received. The plot below shows absorption spectra of human cone cells (for details, see this wikipedia entry). Letters ‘S’, ‘M’ and ‘L’ indicate short, medium and long wavelength, respectively. The black curve is the spectrum of rod cells which can assist in color perception at a low light condition. The closeness between the M (green-sensitive) curve and the L (red-sensitive) curve explains why most color-deficient patients are green-red deficient because the distance between these two curves can be obscured by relatively minor disruptions.


The majority of people with color deficiency are born to it, indicating it is mainly a genetic disorder. Color blindness is also sexually disproportional. Among Asian population, near 5% of all males are color blind, compared to only 0.4% of all females (so, my mom is very special with regard to this fact). The explanation has to resort to recessive gene inheritance in X chromosome. I am not going to get into the details of this. Go studying some basic high school genetics if you are interested. Or, go to to check it out.

OK. So, can you drive if you are color blind?

A more relevant question is "Can color-blind people drive?" The short answer: yes. In fact, most countries issue driver’s license to people regardless of their color perception. There are a few countries that still decline driving rights to color-deficient people, like Singapore (a collective society, no wonder).

The major concern for color deficiency is the ability of accurately recognizing traffic lights. Again, as I mentioned above, the majority of color-deficient people
have little problem in telling the differences of plain colors, which
is actually the case for traffic lights. Also, traffic lights almost always go in fixed orders with red on top, yellow in the middle and green at the bottom, or red to the right, yellow in the middle and green to the left.  This actually eliminates drivers’ the reliance on color. Traffic lights can be distinguished by its intensity as well. Finally, it can be also a design issue. In places in Canada, traffic lights not only show green, yellow and red, but are also in different shapes, which help people with color deficiency to properly recognize signals.