Solving the Bohr-Einstein Issue of the Moving Hydrogen Atom | Dr. Young Suh Kim

Albert Einstein’s theories not only transformed the way we think about science, but also had a profound effect on our collective understanding of the universe. Growing up, physicist and professor emiriturs Dr. Young Suh Kim felt inspired by the scientist. Years later, he would go on to bridge the gap between Einstein’s theory of relativity and physicist Neil Bohr’s model of the hydrogen atom.

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Dr. Young Suh Kim Physicist

There is no more recognizable name in the history of science and physics than Albert Einstein. Ask any pedestrian on the street in any country, and chances are that they will have heard about the German scientist, often associating him with the title of “genius.” However, many people would be surprised to know that the scientist had somewhat of a tumultuous upbringing. 

Einstein had unusually slow speech development during his childhood, so much so that his parents took him to a physician to get examined. Known for questioning the established path and paving his road in uncharted lands, Einstein stood out among his peers. Many of his scientific breakthroughs can be attributed partly to his rebellious nature towards authority figures. 

One headmaster told him he would not amount to anything, while another expelled him from school. In a bittersweet way, a curiosity about the world around him accompanied his delayed verbal development. His father gave him a compass when he was five years old, and he started to ponder the phenomenon of magnetic fields at that young age. 

Uniquely, the renowned scientist thought in pictures instead of words. His scientific discoveries often resulted from mental experiments that replicated the visual experience of actual laboratory procedures. 

At 16, he envisioned what it would be like to ride along a light beam. Moving at the same speed, would the waves seem stationary? He wrote, “I should observe such a beam of light as an electromagnetic field at rest.” But this outcome was not allowed by scientist James Clerk Maxwell’s current equations describing electromagnetic waves. 

Maxwell “was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and light as different manifestations of the same phenomenon.” 

Einstein could also picture mathematical equations as literal representations of natural phenomena because he understood that mathematics is the language nature uses to describe her marvels. The special theory of relativity resulted from his ten years of toiling over this thought experiment.

Through his accomplishments and grit, this zany scientist inspired a young student across the world to chase that same dream. Dr. Young Suh Kim is a renowned physicist and emeritus professor known for bridging the gap between Einstein’s theory of relativity and scientist Neil Bohr’s model of the hydrogen atom. Basically, Dr. Kim connected quantum mechanics to the theory of relativity.

Dr. Kim’s success in physics can be traced back to his educational roots in his home country. He credits the mathematics he learned in high school as foundational to his lifelong journey in physics. Dr. Kim went to Seoul High School in the 1950s during the Korean War. The tumultuous environment affected how Korean children were taught. In such a time of upheaval, students often learned their daily lessons in roofless classrooms.

“During the Korean War (1950-53), Koreans had to move from one city to another to avoid communists. From 1951 to 1952, my high school classes were held at an open space on a mountain side.” 

Dr. Kim learned about Einstein in his youth and immediately felt a kinship with him. He was always talented in analytical sciences, and the possibility of someday meeting his lifelong idol drove Dr. Kim to pursue the sciences more seriously. 

He attended Carnegie Mellon University in Pittsburgh, Pennsylvania, first seeking a degree in engineering. When Einstein passed away in 1955, Dr. Kim felt compelled to obtain a degree in physics instead. He earned a bachelor of science in physics in 1958.

In 1958, he received a letter from Princeton University informing him that he was one of 15 students admitted to its physics doctoral program.

“This was the happiest day of my life. Going to Princeton meant working with Albert Einstein, even though he died in 1955, three years before 1958.”

Symbolically, Dr. Kim felt that attending Princeton would be the closest he would get to be in the presence of Einstein. Einstein frequented an office in the school’s mathematics building in the 1930s. The ability to walk into the same buildings his idol once did galvanize Dr. Kim to work even harder.

While he was a student there, he was also able to study under Nobel prize winner Eugene Paul Wigner. Professors in the physics department told Dr. Kim that Wigner was totally isolated from the rest of the scientists. Out of curiosity in trying to understand the scientist better, Dr. Kim studied one of his papers on the Lorentz group, which proved beneficial down the road in Dr. Kim’s career. He interacted with Wigner often. Now, Dr. Kim is considered one of Wigner’s youngest students during his time at Princeton. 

“During the early years of my life at the University of Maryland, I restarted studying this paper. It was a frustrating experience because people did not know how to use this mathematical formalism for understanding physics.” 

The more he read, Dr. Kim felt that there was a gap in the history of physics discovery. 

“I also noticed a blank point in history. During the early years of the 20th Century, Niels Bohr was worrying about the hydrogen atom, while Einstein was interested in how things appear to moving observers. They met occasionally to discuss physics. If they talked about moving hydrogen atoms, there are no written records on this issue.”

The crux of the issue that interested Dr. Kim was whether the Bohr-Einstein issue of the hydrogen atom could be interpreted in terms of the scientific language Wigner constructed in 1939. This connection had never been formed before, and Dr. Kim started taking his first steps in solving this gap in history.

Einstein believed that quantum mechanics did not fully describe the universe. Because quantum mechanics is based on probabilities and uncertainties, he concluded that it did not provide a useful basis for the entirety of physics. Einstein believed that discoveries required predictions and direct observation.

He believed that since individual quantum interactions could not be observed directly, quantum physicists could only predict the probability that events would occur.

Einstein spent the latter half of his career trying to incorporate the ideas of quantum theory into a unified theory that would restore predictability and certainty to the physical sciences. Although he was ultimately unsuccessful, his solitary and tenacious pursuit teaches us a lot about him and his curiosity.

In three years, Dr. Kim received his Ph.D. in physics. After staying as a postdoctoral fellow in 1961 and 1962, Dr. Kim became an assistant professor of physics at the University of Maryland, making him the youngest faculty member among the physics staff. 

“The life was not easy for me in the highly competitive academic world, where everybody is afraid of his/her colleague becoming more famous than himself/herself. However, I always got help from appropriate persons whenever I was in difficult positions. The point is that I pursued my own research line strange to others.”

Like Einstein, Dr. Kim was not afraid to chase after what he believed was worthwhile. Dr. Kim credits the competition among faculty to something he has dubbed a “Herod Complex.”

“If you are the No. 1 [student in your class], can you afford another No. 1 in your class? This is the psychological burden you should carry throughout your life. I call this Herod Complex.”

Though this drive to accomplish more than those surrounding you is stressful, Dr. Kim believes this complex can serve as an excellent source of motivation. 

“Indeed, the word ‘Herod Complex’ can settle many quarrels among physicists. If you have your own Herod complex, it is yours to enjoy.”

He was promoted to associate professor and then full professor before retiring from teaching in 2007. He is now a professor emeritus at the University of Maryland. 

However, in academia, Dr. Kim started publishing his papers decades earlier, in 1961, while he was a postdoctoral fellow. In September 1962, Paul A. M. Dirac, a Nobel Prize-winning physicist, visited the University of Maryland. The chairman of the physics department, John S. Toll, assigned Dr. Kim to be Dirac’s assistant. 

“This gave me a valuable opportunity to learn physics directly from him.”

Dirac helped steer Dr. Kim towards pursuing what eventually became one of his most significant accomplishments, bridging quantum mechanics and relativity. 

“I was fortunate enough to spend 30 minutes alone with Dirac. I asked him what I should do in physics. He said American physicists should spend more time to understand Einstein’s Lorentz covariance. This was a totally unexpected answer to me.”

Wondering what Dirac meant by ‘American physicists,’ Dr. Kim realized Dirac might have been talking about specific scientists. 

“It was not until after reading some of Feynman’s papers to realize he was talking about Feynman. Dirac was right, Feynman or his students could have studied Lorentz transformations more carefully. For instance, his 1971 paper with his students contains many new physical ideas, but it is a total mess from the mathematical point of view. They could have done much better job if they had studied Wigner’s papers on the Lorentz group. Only after I read Feynman’s papers, I realized Dirac was talking about Feynman when he said ‘American Physicists.'”

Dirac wanted to make quantum mechanics consistent with the theory of relativity. His 1963 paper “constructed, from two harmonic oscillators, the lie algebra of the Lorentz group applicable to 3-dimensionsional space with two time variables.” This pursuit inspired Dr. Kim once more to solve the question himself.

Dr. Young Suh Kim Physicist

(Figure A)

“It is easy to find out the strengths and weaknesses of other people, but it is very difficult, if not impossible, to find out about oneself. I was not an exception. Indeed, I had to struggle during the early years of my professional life. I was not happy to follow bandwagons. I started finding out myself in 1965. At that time, quantum-bound states come from the poles in the complex energy plane or from ‘bootstrapping’ processes. Wave functions had nothing to do with physics, according to the bandwagons. I was not able to accept this view.”

Dr. Young Suh Kim Physicist

(Figure B)

Dr. Kim said that Dirac wrote in beautiful sentences and that his “papers are like poems, but there are no figures in his papers.” Additionally, Dirac would not quote his own earlier papers, making it difficult to follow the progression of ideas. Dr. Kim thought to draw those figures on his own and realized that the visualizations made it easy to integrate Dirac’s papers into one. Something about the drawings made these complicated theories click together in Dr. Kim’s mind (see figure A).

The harmonic oscillator is the “language of quantum mechanics,” while the Lorentz group is the “language of Einstein’s special relativity.” This initial bridging of the two concepts helped Dr. Kim explore whether special relativity is derivable from quantum mechanics.   

In the midst of studying this complex problem in physics, Dr. Kim met the woman who eventually became his wife. 

“I had to get married and had to build my family. In 1963, I met the girl whom I met during my freshman year in Korea (1954). In Korea, the college year starts in March, instead of September in USA. I spent one semester at a university in Korea before becoming a freshman at Carnegie Tech (in September 1954). Marrying a girl you met during the freshman year. How else can you get married?”

Despite how hard Dr. Kim worked, some aspects of his background made navigating politics within academia difficult. His colleagues treated Dr. Kim differently because he was born and raised in Korea.

“In 1965, the physics world was all excited about Dashen’s calculation of the neutron-proton mass difference. Roger Dashen, a young physicist of my age, became elevated by Princeton to the genius class. I was unhappy because of my Herod complex.”

Around that time, the physics world “had and still has a belief that the proton and neutron have the same mass, but their mass difference comes from an electromagnetic perturbation.” In Dashen’s Ph.D. thesis, he came up with the value of this mass difference using “the perturbation formula derived from S-matrix theory.” Dr. Kim scrutinized this paper, eager to share his findings with other scientists, but they were reluctant to listen.

“In 1965, I published a paper showing Dashen’s perturbation formula is based on one non-localized wave function, and thus his calculation is wrong. However, people did not believe what I was saying, because Dashen was a genius and I was something else (perhaps someone from an underdeveloped country). Some people told me they would not accept my result because I was using wave functions instead of the S-matrix.”

This move required a lot of bravery on Dr. Kim’s part.

“At that time, I did not have a permanent tenure, and my position was in danger because of this paper. I was looking for a job and had to give seminars at other institutions. While answering questions, I came up with a figure (see figure B). To make a long story short, this figure saved my position in the United States. This figure also has a history from my undergraduate years at Carnegie Tech. The United States has been very nice to me since I came to Pittsburgh from Korea in 1954.”

Dr. Kim found that pictures, diagrams, and visualizations helped him scrutinize other scientists’ findings or discover his own. Dr. Kim describes this newfound love for pictures as “a great revelation” in his physics life. Since then, Dr. Kim constructs a set of figures whenever he writes a paper. The rest of those papers also consist of figure captions. 

“In physics, we draw cartoons to convey abstract ideas. Abstract ideas in turn are formulated from what we observe in the real world. Then digital cameras should play roles in formulating abstract ideas. These days, we have a very serious environmental problem. Fresh air and fresh water are disappearing. Physicists should worry about this problem. We can photograph these environmental problems.”

Around these years, Dr. Kim recalled when he initially studied Wigner’s papers. In 1978, he published a paper revolving around the issue of how the hydrogen atom appears to moving observers, interpreted through Wigner’s papers, finally bridging the two ideas together.

“In 1978, with my younger colleagues, I published a paper saying that Wigner’s 1939 paper plays an essential role in studying moving quantum bound states, like the hydrogen atom or the proton in the quark model. I submitted this paper to the Journal of Mathematical Physics in late 1978, and it appeared in the Journal in early 1979.”

In 1986, he published a paper with younger colleagues containing a table stating that “Wigner’s little group unifies the internal space-time symmetries for both massive and massless particles, as Einstein’s.” e=mc^2 unifies the energy-momentum relation.”

After these accomplishments, Dr. Kim approached Wigner with these publications more than twenty years after leaving Princeton and Wigner was pleased with Dr. Kim’s work. He recognized the promise in Dr. Kim’s work, and he asked him to publish new papers. Together, the two published seven papers.

“In 1986, I told Professor Wigner he deserved one full Nobel prize for his 1939 paper, after showing a table that marked his contribution is as important as Einstein’s E = mc^2. Wigner became very happy, and I published a number of papers with him.”

“During the five years (1985-1990), I went to Princeton frequently to seek guidance from Eugene Wigner. I was like a graduate student working on his thesis research under Wigner’s guidance. When I was a ‘real graduate student’ (1958-1961), I was afraid of him.”

 Dr. Kim believes that this established himself in the physics discovery “genealogy” of Einstein since Wigner once worked alongside Einstein. Now, Dr. Kim felt that he was even closer to Einstein. Dr. Kim always admired Einstein for his independent thought, and emulating his way of life helped Dr. Kim achieve what he had. Dr. Kim sees Einstein not only as a scientific genius but also as a philosopher. In fact, he questions how philosophers can engage in their quest for truths without considering physics.

“While he was a high-school student, Einstein studied the books written by Immanuel Kant. According to Kant, one thing could appear differently depending on the observer’s environment. This is why Einstein worried about how things look to moving observers.”

Einstein’s thought process was often quite colorful. His philosophical interpretation of physical sciences helped him create scenarios to question existing theories. For special relativity, he imagined, for example, lightning striking a train from both ends. A bystander on the embankment may have the impression that the strikes occurred simultaneously, but a passenger on the moving train would see things very differently. Light from a strike at the front of the train would reach him a split second before the light from a strike at the back of the train due to the train’s forward motion. That led him to the conclusion that there is no such thing as absolute time because simultaneity depends on your velocity. This deduction led to the development of special relativity.

While constructing the theory of general relativity, Einstein imagined a person falling off a roof, elevators in free fall, and blind beetles crawling on curved surfaces. He also debated with scientist Niels Bohr on the true nature of reality. The scientist devised imaginary devices to show how the Heisenberg uncertainty principle might be evaded. In the space of quantum mechanics, he contemplated two particles interacting and then flying apart so that their states are correlated. This exercise anticipated the phenomenon known as quantum entanglement. 

These thought experiments ran in a loop inside Einstein’s head, driving him to answer his own questions. This constant thirst for finding the truths held in nature about our universe inspired Dr. Kim to do the same. Dr. Kim is proud of never abandoning his principles or straying away from trying to answer the questions he thought were important. 

By finding how quantum mechanics and relativity were interconnected, he achieved his lifelong dream of finding his place in Einstein’s genealogy, both in thought and physical proximity (see figure C).

Some of Dr. Kim’s scientific publications include “Covariant Harmonic Oscillators and the Parton Picture” in the Physical Review, “Gauge Transformations as Lorentz-boosted Rotations” in Physical Letters, “Representation of the Poincare Group for Relativistic Extended Hadrons” in the Journal of Mathematical Physics, and “Observable Gauge Transformations in the Parton Picture” in Physical Review Letters. 

Dr. Kim has also co-authored several books, including “Theory and Applications of the Poincare Group” in 1986, “Phase Space Picture of Quantum Mechanics” in 1991, “Physics of the Lorentz Group” in 2015, “New Perspectives on Einstein’s E=mc2” in 2018, and “Mathematical Devices for Optical Sciences” in 2019. 

After becoming an emeritus professor in 2007, Dr. Kim has not stopped in his pursuit of knowledge. 

“In 2007, I became a professor emeritus at the University of Maryland. This could mean a retirement from professional life. To me, however, it was the beginning of a new life. This means that I have no teaching and other scheduled duties. Thus, I became a full-time researcher, and I now publish books and articles with complete freedom. In addition, I could travel to interesting places in the world.”

Dr. Kim still maintains an office at the University of Maryland and publishes papers and books with the university address. Dr. Kim also travels the world and takes photographs for recreation. He has a son who followed in his footsteps, attending Dr. Kim’s alma mater. He hopes his grandchildren will do the same.

“Our son was born in 1965. We sent him to Princeton in 1983. We now have one grandson and granddaughter. They also live in the Washington area, and the six of us meet often for dinner. I like to send my grandchildren to Princeton. We shall see.”

One hobby Dr. Kim especially cherishes is writing for his extensive webpage cataloging his life and those of scientists he admires. Communication with the rest of humanity is something that Dr. Kim cherishes deeply.

“I had a shortwave radio when I was a high-school student (1951-1954) in Korea. While listening to the world, I became eager to talk to the world. Today’s internet technology is God’s best gift to me.”

Dr. Young Suh Kim Physicist

(Figure C)