Yanwen’s blog

10/30/2026

10/29/2026

On October 27, I wrote about belief while reflecting on Cai Zheng’s ambitious effort to build MUST, a telescope designed to advance China's spectroscopic survey to the front rank in the world.

As I wrote, I was reminded of a conversation I once had with my sister.

Her son also lives in the United States. When we decided to move from Kansas to the East Coast to be closer to our children, my sister asked whether I worried about the possibility of not getting along with my daughter-in-law. Perhaps it's better to keep a safe distance. She herself was concerned that she might have difficulty maintaining a good relationship with her son’s girlfriend.

I told her something along these lines: You have to trust your son’s judgment. You also have to believe in your own ability to get along with the people you meet in life. You have to believe that if you treat people with kindness and respect, they will most likely treat you in kind.

Of course, I had no way of knowing in advance how well I would get along with my daughter-in-law. But I could not let that uncertainty stop me from making a decision I believed was right for our family. I had to trust myself to build the relationship and to deal with whatever challenges might arise.

Looking back, I realize that this, too, was a kind of leap of faith—not blind faith that everything would go smoothly, but confidence that I could face the unknown.

Life is full of uncertainties. If we always wait until we know exactly how everything will turn out, we may never take the first step. Some things can only be understood through experience. We venture forward, learn as we go, adjust ourselves when necessary, and gradually discover what works.

As I reflected on this, a Chinese expression came to mind: 摸着石头过河 (Mō zhe shí tou guò hé)—literally, “crossing the river by feeling for the stones.” It describes moving forward step by step when the road ahead is not clear.

Perhaps this is what belief really means: not knowing for certain that we will succeed, but trusting ourselves enough to begin.

When we cannot always see the other side of the river, we have to take the first step and feel for the stones along the way. That is also how China opened its doors and embarked on reform.

10/28/2026

Yesterday, I came across an article titled “超低生育率的另一个解释：谁该带孩子？” (Chāo dī shēng yù lǜ de lìng yí gè jiě shì: Shéi gāi dài háizi? “Another Explanation for Extremely Low Birth Rates: Who Should Take Care of the Children?”). It caught my attention for two reasons.

Just last weekend, my sister in Beijing told me that her son’s girlfriend had made it clear that she did not want to have children. At the same time, I am helping my own son care for his newborn baby. These two experiences made the question in the article feel especially relevant to me.

The article discusses research seeking to explain why fertility rates have fallen so dramatically in South Korea and several other countries.

In 2006, David Coleman, a professor of demography at the University of Oxford, warned that if South Korea’s low fertility rate persisted, the country could eventually become the first to face the prospect of disappearing through natural population decline.

The warning may sound dramatic, but the underlying demographic problem is real. The total fertility rate estimates the average number of children a woman would have over her lifetime if current age-specific birth rates continued. A rate of about 2.1 children per woman is generally needed to maintain a stable population over the long term without immigration.

South Korea’s rate fell below 1.0 in 2018 and reached just 0.72 in 2023. It rose slightly to 0.75 in 2024, but remained far below the replacement level.

South Korea is not alone. Japan, Italy, Spain, and other countries have also experienced persistently low fertility, although the causes differ from one society to another.

The research discussed in the article offers an intriguing explanation: the problem may not be rising wages for women themselves, but the gap between women’s changing economic roles and society’s slower-changing expectations about childcare.

As women earn more and take on greater professional responsibilities, the opportunity cost of leaving work or reducing working hours to care for children increases. Yet in societies where traditional gender roles remain strong, mothers may still be expected to shoulder most of the childcare burden.

When fathers are discouraged from taking on a larger share of childcare, mothers bear a disproportionate cost in time, career opportunities, and personal freedom. For some women, the prospect of having children under these conditions becomes much less cheerful.

The researchers analyzed data from 62 economies between 1990 and 2019. They found that fertility tended to decline more rapidly where women’s share of labor income was rising quickly, particularly in societies with more rigid social norms. Their model, calibrated using South Korea’s historical experience, suggests that the mismatch between economic change and traditional childcare expectations can deepen the decline.

The researchers are not arguing that women’s economic progress is the problem. Rather, social expectations about who should care for children have not kept pace with that progress.

This raises an important question for families and policymakers alike: if both parents work, why should childcare remain primarily the mother’s responsibility? More equitable sharing of childcare, along with social policies that support working parents, could help reduce the conflict between career and family life.

Reading this article while helping care for my grandson has made me think about how much our expectations of parents need to change. Raising a child is not simply a woman’s responsibility. Perhaps it should not be a burden that families must manage alone.

If societies want more people to feel that having children is possible, they must do more than encourage births. They must make sharing the responsibility of childcare a realistic option.

10/27/2026

Yesterday, I read about the remarkable journey of Cai Zheng (蔡峥), a 40-year-old associate professor and vice chair of the Department of Astronomy at Tsinghua University. He is leading an ambitious project to build a powerful new telescope in western China.

The project is called MUST, short for the MUltiplexed Survey Telescope. I do not understand all the technical details, but what impressed me was the scale of the undertaking and the determination of the scientist behind it.

MUST is designed to do something special: observe a large area of the sky and collect detailed information about thousands of celestial objects at the same time. Unlike an ordinary camera, which mainly records how an object looks, a spectroscopic telescope also analyzes the light coming from it. This light can reveal information about an object's composition, movement, and distance.

In simple terms, MUST will help astronomers map the universe in much greater detail and investigate some of its biggest mysteries, including dark matter, dark energy, and how galaxies form and evolve. With a 6.5-meter primary mirror and thousands of optical fibers to collect light from different objects simultaneously, it is designed to survey the sky far more efficiently than existing facilities of its kind. Its first light—the moment it begins making astronomical observations—is planned for around 2029.

Once built, MUST marks China’s leap into leading large spectroscopic survey in the world. It will bring China into the front rank for this kind of cosmic mapping.

The telescope is being built at Lenghu, in Qinghai Province, on Saishiteng Mountain, at an elevation of about 4,576 meters. The site offers exceptionally dry, dark skies and stable atmospheric conditions, which are important for observing distant objects. But the same remote, high-altitude environment also makes construction and testing difficult.

The engineering challenges are beyond imagination. The project requires a giant, precisely shaped mirror, a sophisticated optical system, thousands of light-collecting fibers, and machinery capable of tracking celestial objects with extraordinary accuracy. Astronomers, engineers, and specialists from different fields must work together to make all these components function as one system.

The financial and professional risks are equally daunting. Cai has said that the project would cost more than one billion yuan and that, at the beginning, some experts doubted it could succeed. For a young academic, leading such a complex, long-term project is very different from conducting research and publishing papers. It requires not only scientific knowledge but also the ability to raise funds, build a team, coordinate different disciplines, and keep going when the outcome remains uncertain.

What touched me most was Cai's reflection on belief. He said, in essence, that from very beginning we must believe it can be done, work hard toward it, and persist in doing what is difficult but worthwhile.

“ 你必须相信这件事能办成.” (Nǐ bìxū xiāngxìn zhè jiàn shì néng bàn chéng.) You have to believe that you can make it happen.

I find this meaningful and inspiring far beyond science. Whether we are pursuing a career, raising children, learning a new skill, or working toward a long-term goal, we often face doubts—from others and from ourselves. Belief means believing that the goal is worth pursuing and that, through effort and persistence, success will become possible.

10/26/2026

Yesterday, I came across a quotation from Walter Lippmann, the renowned American journalist and political commentator:

The quotation appeared in Lippmann’s essay “Roosevelt Is Gone,” written shortly after the death of U.S. President Franklin D. Roosevelt. Lippmann’s point was that a truly great leader does not make himself indispensable. Rather than leaving behind a fragile system that depends on his continued presence, he stabilizes crises, builds durable institutions, and enables others to carry on successfully.

In other words, good leadership fosters independence rather than dependency. It builds for the long term rather than relying on one extraordinary individual.

This idea made me think about parenting and the Chinese saying “富不过三代” (Fù bú guò sān dài), often translated as “Wealth rarely lasts beyond three generations.” Perhaps one reason family fortunes are difficult to sustain is that passing down wealth is not the same as passing down the judgment, discipline, and abilities needed to manage it.

Good parents, like good leaders, do not need to be constantly present to solve every problem their children encounter. Their goal should be to prepare their children to handle challenges independently.

This means helping children develop good habits, sound judgment, problem-solving skills, and self-discipline. It also means creating routines and clear expectations that help them manage their responsibilities without constant reminders.

For example, instead of immediately intervening whenever siblings argue, parents can teach them a simple process for listening to each other, explaining their feelings, and working toward a solution. With practice, the children can use the same approach when their parents are not around.

Similarly, instead of reminding children every night to pack their schoolbags, parents can help them establish a checklist and a designated place for their school supplies. Eventually, the routine becomes a habit, requiring less parental supervision.

The goal is to build a structure that works even when parents are busy, tired, or away.

In the long run, the greatest gift a parent can give a child is the ability to stand on their own two feet.