The Big Bang Theory: laughter, inspirations and more

 

I have worked as a post-doc researcher in physics in the UK for two and a half years. After finishing my daily research work, I would arrive home alone without the companionship of my family and my then-girlfriend, now wife. It was then that I started watching the American sitcom, The Big Bang Theory. The TV show is a hilarious, comedy show that revolves around two genius physicists, a theoretical physicist and an experimental physicist, their beautiful street-smart neighbour who lives across the hall, and their aerospace engineer and astrophysicist friends. It made me cry tears of laughter, literally laughing away the boredom of being alone in a foreign country.

The comedy series was stunningly successful. Aired between 2007 and 2019, it constantly topped national ratings and attracted large audiences. One of the main characters Dr Sheldon Copper has inspired many young people to leap into the study of physics. Jim Parsons who plays the Caltech theoretical physicist Sheldon received four Primetime Emmy Awards for outstanding lead actor. As a physicist and physics educator, I am excited that an entertainment show featuring physicists as its main characters has achieved such success. It proves that apart from laying down the foundation for natural science research, physics can also bring laughter to people.

Apart from the laughter, the TV drama prompted me to think about more deeply about what physics is and what physicists are pursuing. In one episode, Penny, the street-smart girlfriend of the experimental physicist Leonard, Sheldon’s roommate, asks Sheldon to help her understand what Leonard does so that she can have more topics to talk with him. Instead of explaining Leonard’s work, Sheldon, who is so eager to educate Penny, tailor-made an introduction course for her. He says that physics comes from the ancient Greek word “physika” which means the science of natural things and it was there in ancient Greece that the story of physics began. He continues to teach Penny that physics began on a warm summer evening around 600BC when people looked up at the night sky and noticed that some of the stars seem to move so they named them Planetai, the Greek word for wanderer.

Sheldon’s very short introduction to physics moved quickly from physics’ first appearance in ancient Greece to Newton’s second law of motion of F=MA — force is equal to mass times acceleration. Having no knowledge in physics, Penny, of course, couldn’t follow Sheldon’s crash course. Ignoring Penny’s nonchalant responses to his teaching, Sheldon uses an example to test whether she really understands Newton’s equation. Penny, who has absolutely no idea who Newton is and what F=MA means, just throws out irrelevant dummy remarks to Sheldon’s question. It ends with Sheldon mocking her, “Have you suffered from a recent blow in the head?” The pair then lock horns as usual again.

The main character Sheldon possesses the stereotypical eccentric personality traits of a physicist that are often portrayed in movies. While he is exceptionally intelligent, his obsession with presenting his arguments in a scholarly and objective manner and the lack of empathy makes him unable to connect with others. His stubbornness of doing things his way and sarcastic comments put him in constant conflicts with his friends. Audiences could not help but laugh when Sheldon’s singular ability and rich knowledge in physics is placed side by side with Penny’s total ignorance on the subject. This is one of the setups that works like magic in making the audiences laugh throughout the whole series.

While the genius-layman setup made me laugh, I came up with an idea of screening this scene in the first lesson of my physics courses to stimulate my students to think about what physics is. Indeed, “What is Physics?” is always the foremost question I want to pose to my students. I hope, in the very least, the TV programme could grab my students’ attention and engage them in the lesson. Judging from the continual bursts of laughter from the class, the experiment is a success.

So what is physics? Simply put, physics is the study of fundamental principles about the physical world. When talking about physics, people often mention mechanics, electricity and magnetism, relativity theory, and quantum mechanics. I think physics is much broader than this clichéd understanding. When I studied for my PhD, my research focus was in the field of statistical physics, a discipline of physics that provides enormously powerful tools to explain phenomena outside the realm of traditional physics. During my PhD research, I spent most of my time in applying theories of statistical physics to analyse financial markets and transportation networks. Not only ordinary people think that these topics are unrelated to physics, even other research students from my year raised similar doubts about their relevancy.

In the beginning of my PhD research, I also asked myself whether such interdisciplinary research is physics and struggled to give my peers a positive answer. However, after all these years of research works and teaching, probably also because of the inspirations from the TV show, The Big Bang Theory, I can now tell them with confidence that the interdisciplinary research I work on is physics. What’s more, statistical physics should be regarded as a core component of physics just as other well-known branches of physics. Research breakthroughs in this field carry the same fundamental nature as discoveries found in quantum mechanics or astrophysics. So, how did my changes in attitude come about? Before answering this question, perhaps I should first talk about “What is statistical physics?”

Not many people are aware that every single moment they are alive, they are breathing in huge numbers of air molecules. By doing a little math, we know that the number of air molecules in one cubic metre of air amounts to at least 10²³ . It is an astronomical number with 23 zeros.

By applying physics concepts we learn from high schools, we can easily predict the motion of an individual air molecule. But when we are interested in understanding physical properties like temperature and air pressures of a particular space, it is the collective picture of all the molecules that matters. It is the aggregate of how all the individual molecules are flowing in space, not their individual motions, that truly affect such physical quantities. And this is where statistical physics comes into play. By using statistics, classical physics and quantum mechanics, statistical physics bridges the two worlds between microscopic motion of air molecules and the macroscopic physical quantities such as air pressures.

Then, why is the study of transportation networks also considered as physics? Let’s imagine ourselves driving a vehicle on a highway. As a driver, we act in response to nearby vehicles. When the road is not congested, we follow the car in front at a reasonable speed within a safe distance. But when the situation changes from free flowing to congestion, we need to slow down, queue on and off, and move forward only when the car in front moves. If we want to understand what has caused the changes, knowing how an individual vehicle moves doesn’t help. Instead, we need to know about the collective movements of all vehicles in a congestion. The relationship between individual vehicles and overall traffic condition is similar to that between air molecules and air pressures. Like in the study of air molecules, statistical physics can fill up the gap to connect the microscopic motion of individual vehicles to the macroscopic phenomenon such as traffic congestion.

As quantum mechanics or relativity provide numerous imaginations for works of popular culture like manga and movies, they shape how physics is perceived by the general public. Physics research, however, should not be limited to these realms. There are scholars and researchers, including those working in my area of statistical physics, working diligently in other fields of physics. They make as much contributions as theoretical physicists in quantum mechanics and relativity do to our understanding of the natural world. In the end, the goal of physics is to find a way to explain natural phenomena.

People who walk towards this goal, who dedicate themselves to understand nature, including the study of patterns of physical objects large or small, individually or collectively, should legitimately be called real physicists. And they should be called so even though they work outside the traditional realms of physics. It is with this belief that I regard the studies of financial market behaviour and transportation networks through the lens of statistical physics is on a par with other classical studies of physics. And this is how I understand physics and physicists now.

Humanity’s persistent quest to uncover the ground truth of the natural world fascinates me. When I teach classical mechanics or nature of science, I always use Galileo as an example to illustrate human’s insatiable quest for knowledge and truth. As many of us know, Galileo Galilei (1564 - 1642) lived at a time when Geocentrism, which means the earth is at the centre of the Universe, was the dominant theory. Before Galileo, the Italian astronomer Nicolaus Copernicus (1473 – 1543) proposed an astronomical model that the sun, instead of the earth, is at the centre of the Universe with other planets revolving around it. Based on his own observations, Galileo, found that Copernicus’ heliocentric model was more correct.

The Roman Catholic Church at that time adopted Geocentrism as a doctrine. Galileo knew that championing Heliocentrism would be considered a challenge to the Church, and this would bring dire consequences to him. Galileo was finally condemned to house arrest by the Church and forced to recant his Heliocentrism theory. Despite these setbacks, he still found a way to attract others to continue to study and find new evidences that support Heliocentrism. As more and more observations were made in support of Heliocentrism, the Church finally abandoned the dogma of Geocentrism almost two hundred years after Galileo’s death.

When Galileo paid dearly for his advocacy of Heliocentrism, he earned a household reputation for his experiment done at the top of the Leaning Tower of Pisa. Before Galileo, people believed that heavier things fall faster. The legend is that Galileo dropped objects of different weights from the top of tower and showed that all objects, regardless of their weights, hit the ground simultaneously. Although this story has been dismissed by many scholars as apocryphal, it has captured attention from generations of scientists, engineers and explorers. During the Apollo 15 mission to the moon in 1971, astronaut David Scott used a feather and a hammer to verify Galileo’s proposed theory of equal gravity. Scott’s experiment showed that objects fall at the same speed on the moon in the absence of air resistance. Scottt's tribute paid to Galileo for his contributions to science came more than 300 years after the death of the Italian polymath.

Another example showcasing human’s persistence in truth seeking is the discovery of Higgs Boson, the so-called “God particles”. A group of physicists including the British theoretical physicist Peter Higgs (1929-2024) proposed the presence of Higgs field and Higgs particles as early as in 1964 to explain why some particles have non-zero mass. Almost 50 years have lapsed when Higgs particles were proven to exist in 2012, after a series of experiments done at the Large Hadron Collider at CERN in Geneva. Higgs was awarded the Nobel prize for Physics in 2013 for his pioneering work in 1964. Higgs, who lived a very long life, has just passed away in April 2024, aged 94.

The study of Higgs Boson is part of humankind’s endeavour in fundamental physics research. Back in mid-1950s, a number of European countries established CERN (Conseil Européen pour la Recherche Nucléaire) to facilitate collaborations among countries in high-energy physics research to find out what constitutes the Universe and how it works. The discovery of Higgs Boson is the biggest achievement CERN has ever made to date. It tells a remarkable story about how the quest for understanding and proving a fundamental physical law lies deep in the human heart. The desire for truth is so huge that we are willing to spend more than US$4.7 billion and 10 years to construct the Large Hadron Collider at CERN.

From the greatest scientific minds like Galileo, Newton, Einstein, Higgs to the TV character Dr Sheldon Copper who finally received a Nobel Prize in Physics on the TV show, physicists aim to find out the fundamental laws governing our physical world. Their battles for truth are endless: from the structure of matters to the basic principles governing how physical objects interact with each other, and to why there are traffic congestions. It is their unquenchable curiosity and persistence to reveal these fundamental mechanisms that define them as physicists.

As such, I always stress to my students that physics is not only about completing the exercises they are asked to work on during classes. It is not even about carrying out mathematical calculations accurately. While modern day’s physics heavily relies on mathematics, the primary task of physicists should be the investigation of fundamental principles. It is their passion for finding the truth that has slowly advanced the frontiers of human knowledge. This is the main take-home message I would like my students to get from my physics courses.

I joined the Department of Science and Environmental Studies of this university in 2013 shortly after coming back to Hong Kong from the UK. The Big Bang Theory continued to be my favorite choice on my nighttime entertainment menu. It took me away from the hustle and bustle of my intensive teaching and research work. As a physicist, I always wonder how much truth is there in the stereotypical geeky, nerdy image of scientists as seen in the TV comedy. As stereotypical as the characters of the TV series might be, the TV drama has made physics more approachable to ordinary people. That said, many people still see physics a discipline that has little connection with the real world and physicists as unsociable beings living a cloistered life of research in the ivory tower.

But when you know that in reality, physicists like me study things like transportation network, you will know how far this preconception is from the truth. At the Nobel Prize ceremony on the show, Dr Sheldon Copper put aside his formal acceptance speech and said, “I was under a misapprehension that my accomplishments were mine alone. Nothing could be further from the truth. I have been encouraged, sustained, inspired, and tolerated not only by my wife but by the greatest group of friends anyone ever had.” I like this episode very much for it reminds me that physicists are part of the bigger family of humankind as physics part of human civilisation. I hope that the TV series inspires you like it does to me.

Note: Dr Bill Yeung Chi-ho holds a PhD in Physics from the Hong Kong University of Science and Technology (HKUST). His main research interests include statistical physics, physics of disordered systems, modelling, transportation networks, complex systems, social networks and STEM education. Dr Yeung shows great interest in advancing science education, in particular in the application of information technology on science education and STEM Education.

(Dr Bill Yeung collaborated with Tam Siu-man on this piece.)