HKU to cancel Astronomy and Maths-Physics Majors

The University of Hong Kong (HKU) is planning to cross out two majors from its list in Faculty of Science: Astronomy and Mathematics-Physics, starting from the academic year 2018/19. (Source)


One of my colleagues shared this news to me through an HK Podcast (Cantonese). As a Physics graduate, I could empathise what the students and alumni shared in the interviews. Based on what reasons should these two majors be cancelled? What would happen to the only Astronomy major offered in the whole Hong Kong?

HKU’s Dean of Science Matthew Evans explained to the students that “[they] are not choosing to enroll on these majors.” The low enrollment rate is the main reason cited. He also said that the efficient use of resources and academic time prompted the action. Such decision upset the students and alumni.

Lam Chiu-ying was one of the graduates from the HKU’s mathematics-physics major in 1971. He was also the former director of the Hong Kong Observatory. He thinks that a good university should not be chasing after fleeting trends and only focusing on subjects that brings in students. He likens such phenomenon to a supermarket – a place only offering popular items.

It kind of reflects how cut throat the competition in Hong Kong is. It is not unusual for a university to close unpopular courses, but HKU has a unique position: it is the only Hong Kong university that runs an astronomy major. According to Scival, University of Hong Kong has strong scholarly output in the field of Physics and Astronomy. The publications is increasing over the years, for example about 2,000 publications in the last 5 years. 20.6% of the works are in the top 10% most cited worldwide, and 37.0% of the publications are published in the top 10% journals worldwide as well.


We need to relook at the role of university. It is supposed to be the center of scholarly research and innovation, and at the same time the place where future generation gets advanced education. I think that HKU should put more thoughts in getting more students interested in such subjects instead of simply closing them down. By working with high schools and government authorities, the university can give more exposure to the astronomy and physics and ignite the passion among Hong Kong young generation.

Science Busking at NUS Open Day 2017

Here are my juniors at NUS Open Day this year! Hurray!

A Bucket Full of Science


Last Saturday students in our course* put up a wonderful performance during NUS Open day 2017, communicating science to public visitors in the form of busking!

Below is a short description and a mosaic of pictures to illustrate each busking activity.

Marshmallow Cannon

A marshmallow is in a hollow tube is ejected by one blowing into the tube. Participants are challenged to send the marshmallow flying as far as possible. Our science communicators then explain the physics of the moving marshmallow inside and outside the tube, and discuss the parameters affecting the distance traveled by the marshmallow (such as the dimensions of the tube and the angle of elevation).

Science of Coffee

The science behind a good cup of coffee is demonstrated by live brewing and coffee tasting. Visitors are invited to taste different samples of coffee made with different brewing parameters such as grind size and temperature, and…

View original post 223 more words

Endless energy generated by evaporating water on charcoal

No, not this way! (source)

Minor corrections: It is not endless (the generation needs constant water supply), and by charcoal I mean nano-structured carbon layers. Still, it is impressive to see how a simple physics phenomenon could give rise to an important application: producing electrical energy. A group of scientists from China published a paper on the topic in Nature Nanotechnology Letter last month.

Water molecule. (source)

Water is a molecule composed of 2 Hydrogen (H) and 1 Oxygen (O) atom, and collectively they behave slightly ionic – there are H+ and OH- ions in the system, for example a cup of water. When the water on the carbon surface evaporates, it will induce a force to pull water through the tiny channels in the carbon layers. An usual piece of carbon is hydrophobic, meaning it repels water and stops the action pretty much.

The scientists found out that by treating the carbon to heat and plasma, the surface will be a mixture of carbon and oxygen compounds, and turns into hydrophilic surface. That is, water-loving oxidised carbon. Hence, the water gets pulled through the channels and evaporates at the other end at a steady rate, provided the vapour pressures at both sides don’t change.

How does it produce electricity then? Remember we mentioned earlier: the water contains ions, and a stream of water in motion is a current, carrying minuscule but measurable electrical charge. Ta-da, we produced electricity!

The scientists further found out the voltage produced can reach up to 1 V (high enough to light up an LED), and can be turned on and off by opening and closing the box in which the experiment is contained. This cheap, controllable way of producing electricity from evaporation of water could lead to very practical uses in real life, such as power generation at rural areas or places with little sunlight.

Original Paper

A dream of seaduck

I dreamt of a constellation called Mergus last night. In the dream, I was learning to scull a sampan towards the West direction, navigating with the help of Mergus. All the stars in the sky were subtitled with their own names, sparkling in the dusk sky with magical dust.

I never come across the word, and Mergus the constellation does not exist in real life. However Mergus does exist – a genus of sea ducks.

This was one of the most magical dreams I had.


That’s not how it should have ended. All the research, all the hard work, all the time the team has spent in finding the truth culminated to an empty promise.

For a lack of better term, he was forced to walk the path alone now. His team has perished one by one in the name of discovery. He still remembered how the headlines reported the collaboration – “An All-Star Team Strive to Look for the Secret of the Universe”. The clash of intelligence will bring a spark in the darkness to cast a glimpse on the answer. Provided there is any, of course.

In the first few years, they got extraordinary results. With the particles colliding, the coffee brewing, the liquid helium cooling, the lasers focusing, the papers were being churned out day by day. He thought to himself they were getting closer and closer to the answer after every beer session.

And the progress halted. It was like a bullet train which decided to hit the “ABORT” button to hit a wall. For years, the team was stuck at what they had, puzzled and disappointed. They were the best the world could offer, the experts in their own fields, the cream of the crop in this big pot of seven billions people.

Three committed suicide, two killed each other in a fiery argument, and four lost their mind and ended in an asylum. They all went out like a candle, snuffled by an invisible hand one after another. He could not figure out why, but he almost felt that there was something not ought to be discovered. What if there were something greater, some ideas beyond human’s ability to comprehend? If sanity was defined by one’s ability to think and understand rationally, then the knowledge might exist outside the realm of sanity. An answer that couldn’t be explained at all.

Anticipation kills, he recalled his mentor’s words.

via Daily Prompt: Anticipation


She’s been waiting for this day for her whole life. A device that can slow the flow of time, stop and reverse its direction for a tiny weeny bit. It’s sort of like the superpower of heroes in videogames and movies, without all those flashy computer effects. Life is a movie without outstanding actors and momentous conflicts, only filled with unfinished plots and passable performances here and there.

She rubbed her eyes and took a deep breath. She put down her glasses carefully, aligning the rim with the edge of her workstation with high precision. She’s always annoyed by how people place their glasses – why not do things to the perfection if you have the chance so?! Her psychiatrist always tried to advise her to let things go more easily and not to hold any grudge. He always said that life is beautiful not for those perfect moments we achieve, but for those lessons we failed and learned. Wabi-sabi, he said, is a philosophy of recognizing and accepting those imperfections in life. Like a cracked teapot that is still used and appreciated for its earthly beauty.

Making tea? I’d put that under a compactor and drive across it. She sneered. I’m going to show him how these failures taught me to turn them into perfections.

Time for a final test. She’s tried a few earlier today, but nothing can be too sure. She put an egg yolk back to its shell without any crack, unwrote a few typos in her documents, stopped a bean from germinating and revived a rat whose head’s been severed. The device was able to reverse back the time by five to seven seconds, just enough window to eliminate the sources of errors. These irksome moments are soon to extinct in this world.

She took a scalpel and cut her left wrist. Twice. Blood started to ooze out, firstly bead by bead, slowly forming a tiny stream and then a small puddle under her left hand. One, two… she counted to five, and turned on the device.

She saw things reversing. Moments by moments like PowerPoint slides going back one by one with slowed animation.

Her blood flowing upwards against the gravity and back into her body;

The glass she smashed on her husband’s head, all the shards pieced back and flew back to her hand;

The first time he tried to kiss her, in which she walked too fast and he missed by an inch;

The typo she made during her high school exam, vanished and undone;

The bread her mum made for her, levitating from the ground back to her hand with the jam side up;

The gear was shifted back to N instead of R, while her father unknowingly stood at the back while her mum was too busy talking in the phone and starting the car.

These little regrets. These minor annoyances. These irksome moments. She decided that she had them enough before losing consciousness.

Her psychiatrist always said: “Babies couldn’t have learned how to walk without tripping on the floor, and planets couldn’t have formed without the matter from a dead star. Life is not a life if there were no pitfalls or mistakes.”

via Daily Prompt: Irksome

The Nobel Prize in Physics 2016: a cinnamon bun, a bagel and a pretzel

In our education system, science subjects have been always compartmentalized. Biology, Chemistry and Physics have been taught in isolation with each other, yet insights often comes after you take a step back and look at the big picture.

Condensed matter physics has been on fire recently (Not you, Galaxy Note 7), discoveries have been made here and there. This year, the Nobel prize committee has selected three physicists for their work in the field “for theoretical discoveries of topological phase transitions and topological phases of matter”.

To us, it sounds like a mishmash of alphabets. In order to understand this, we need to look at some old school concepts.

Phase transition (Or, in simple term, change of states)

2016-10-06_125911We are taught in elementary schools that matter has three states, i.e. solid, liquid and gas. The most common example is water, which
is a liquid and can transform into ice or vapor if we cool or heat it enough. The constituent atoms or molecules move randomly with different magnitudes.


In extreme cases, some other exotic states appear. For example, plasma is a hot ionized gas, and quantum condensate, a state where the atoms occupy the lowest energy levels. This study deals with the cold world – what happens if I cool things down enough?


Hall Effect

Let’s take a piece of metal and apply a voltage across two opposite ends (say, up and down). You will get a current flowing. Then when you apply a magnetic field at the right angle to the current, you will detect a voltage across the other two opposite ends (left and right). It is called Hall effect, named after the scientist Edwin Herbert Hall in 1879.

When you take an extremely thin metal sheet, and cool it down to near absolute zero, cool thing happens. When you do the same procedures as aforementioned, you will still get a Hall voltage, but the ratio of the current to the Hall voltage is always the same, no matter what material you choose.

The weirder thing is that if you change the magnetic field enough, the ratio will change as well, but only in integer steps. It doubles, triples and so on without taking any values. This quantum hall effect was not unexplained until David Thouless, one of the laureates, provided the answer using a field from Mathematics – topology.


Topology describes things that do not change when you transform it in a continuous manner, be it stretching, twisting or compressing. If one shape can transform to another shape with the said action, they belong to the same topological category. For example, a piece of paper can be folded into a paper crane, or a lump of clay can be molded into a bowl. If you punch a hole into an object, it belongs to another category, like a cup with handle is different from a cup without handle.


So, we can group things under categories of no hole, one hole, two holes etc. It always jump in steps (there is no one and a half hole!).

Linking two unlikely realms together, the scientists managed to explain why quantum hall effect only changes in integer steps, and based on this to explain exotic phase transitions.