God built rivers and mountains. Humans can build only bridges. This is the Pont du Gard near Avignon, France. This water bridge was built by Romans during the period of Julius Caesar. I was there in 2015 to get inspired.

    As His best gift, God gave me this empty land between these two Towers.

    Let us build a bridge between them.

    What do they say about me? Click here.



Lifetime Achievements

  • Young Suh Kim

    Professor Emeritus
    Department of Physics
    University of Maryland
    College Park, Maryland 20742, U.S.A.

    In 1999, I was on a train from Naples to Rome (Italy). Italy is a beautiful country. I was wondering how the world would appear if the train's speed becomes comparable with the speed of light. I am a physicist who loves to think like Einstein.

    If this world is too complicated, let us choose a simpler object. The hydrogen atom is bound state of an electron circling around the proton.

  • One hundred years ago, Niels Bohr was worrying about the electron orbit of the hydrogen atom which cannot be exlained within the framework of Newtonian mechanics. This became the beginning of quantum mechanics.


      Albert Einstein was interested in how things appear to moving observers. This became the beginning of his theories of relativity.

      Bohr and Einstein met occasionally to discuss physics. However, there are no written records to indicate that they ever discussed moving hydrogen atoms.

      If they did not talk about this problem, there is a good reason. There were and still are no observable hydrogen atoms moving with relativistic speed.

    I am not the first person to recognize this blank spot. Paul A. M. Dirac wrote three important papers on this subject. How did I know?

  • In 1962, I was appointed as an assistant professor of physics at the University of Maryland. In the same year, Paul A. M. Dirac (Nobel 1933) visited the University for one week. Since I was the youngest faculty member, I was assigned to be his personal assistant.

      We used to say "baby sitting" for this kind of departmental duty, and I was the babysitter.

    This gave me an excellent opportunity to learn his physics directly from him.

  • Dirac is well known for his Dirac equation for electrons and positrons, but his life-long interest was in understanding localized objects in Einstein's world. The hydrogen atom is not a point particle, but is localized standing wave with a space-time extension. Dirac published three important papers on this subject, in 1927, 1945, and in 1949. They are

    1. Dirac (1927). The Quantum Theory of the Emission and Absorption of Radiation, Proc. Roy. Soc. (London) A [114], 243 - 265 (1927).

    2. Dirac (1945). The Quantum Theory of the Emission and Absorption of Radiation, Proc. Roy. Soc. (London) A [A183], 284 - 295 (1945).

    3. Dirac (1949). Forms of Relativistic Dynamics, Rev. Mod. Phys. [21] 392 - 399 (1949).

    However, these papers are not well known among the present-generation physicists. The reason is very simple. His papers are like poems with beautiful formulas, but they do not contain figures. After many years of struggle, I was able to translate his poems into cartoons. Then it is then very easy to synthesize those three papers into one picture, as shown here:

    I am very proud to say that I learned the mathematics of squeezing the circle into an ellipse during my high-school years in Korea.

  • What does this figure have to do with the moving hydrogen atom? The moving hydrogen atom means the moving bound state. According to Gell-Mann's quark model (1964), the proton is a bound state of the quarks, sharing the same quantum mechanics as the hydrogen atom. Thus, the quantum bound state went through the following evolution.

    Unlike the hydrogen atom, the proton can be accelerated, and its speed can become very close to that of light. Then how does the proton appear? In 1969, Feynman obsered that it appears like a collection of infinite number of light-like particles with a wide momentum distribution. These particles are called Feynman's partons.

    The question is whether Gell-Mann's quark model (for the proton at rest) and Feynman's parton picture (when it moves fast) are two different ways of looking at the same object.


    This figure allows us to resolve the quark-puzzle issue of Gell-Mann and Feynman, and the Bohr-Einstein issue of the moving hydrogen atom.

    This result allows us to extend Einstein's E = mc2 to the internal space-time structure of the particle in Einstein's relativistic (Lorentz-covariant) world.

    This table is contained in my PRL paper published in 1989. I am primarily responsible for the three arrows given in this table. The details of this table is given in one of my earlier bio pages.

    This table can be translated into the following genealogy of Princeton:


  • In 163, Dirac published another paper with a strange result. He starts with two coupled oscillators. He then concluded that the symmetry property of this two-oscillator system is like the Einstein's system of space and time. The only difference is that there are two time variables. The mathemtics for this system is known as the O(3,2) deSiiter group, generated by ten five-by-five matrices. We can then convert the second time variable into four space-time translations, using the technique known as the group contraction.

    In his 1949 paper, Dirac stated that the construction of quantum mechanics in Einstein's Lorentzian world is essentially construcion of a representation of the inhomogenous Lorentz group, generated by ten five-by-five matrices. The question then is whether it is possible to derive this inhomogenous Lorentz group from the O(3,2) system. Both systems are generated by ten five-by-five matrices.

    The question then is whether it is possible to convert the ten generators of the deSitter group into the ten generators of the inhomogneous Lorentz group. Among the ten generators of the deSitter, only four of them contain the second time variable. If we flatten this coordinate by fixing this variable to be one, then the ten generators of the deSitter group becomes those ten generators of the inhomogenous Lorentz group. This procedure is known as the group contraction, as illustrated in this figure:

    Click here for a published paper on this subject.

  • Let us look at this table.

    I synthesized Dirac's three papers (1917, 1945, 1949) into the same mathematical base of the inhomogeneous Lorentz group, which is also the mathematical base for quantum field theory for scattering processes. Thus, both the scattering and bound states share the same mathematical base. This is quite acceptable to everybody.

    However, quantum mechanics and special relativity are known to be two separate subjects. People would say I am crazy if I tell Einstein's E = mc2 is derivable from quantum mechanics.

    Being called "Crazy?"
    The most rewarding aspect of the life as a scientist.



Let me explain my personal life. How much did I accomplish?

Childhood (1935-1946)

      The Sorae Church. I went to this church during my childhood years.
      Click here for the history of this church.

  • I was born in 1935 at a Korean village called Sorae, where Koreans set up their first Presbyterian church in 1884. Horace Underwood was the first American Presbyterian missionary who came to Korea in 1885. Upon hearing about this church, he went to Sorae and noted that this village is near a beautiful scenic beach called Kumipo. He built his house there. Then, many other Americans came to Kumipo to build their summer houses.

    My grandfather was one of Underwood's trusted Korean friends. He was a well-to-do landlord, and took care of Underwood's properties at Sorae and Kumipo while he was busy in the capital city of Seoul. Underwood set up a Christian college in Seoul which became one of the leading universities in Korea, called Yonsei University.

    I attended this Sorae church when I was a child, and grew up in the thoroughly Christian environment.

  • Unfortunately, Korea became divided in 1945 after World War II, and the village of Sorae is now under the control of the North Korean regime which was installed in 1948 by Joseph Stalin of the Soviet Union. My family moved to Seoul in 1946.


Teenager (1946-1954)

  • In Seoul, I finished my elementary school, and I spent six years in a Korean high school (1948-54), before coming to the United States] with a student visa.

  • Alas, the Korean War broke out in 1950 and lasted until 1953. The school campus was damaged and we had to study at temporary places until the cease fire was signed in July of 1953. During these war years, Korean high-school boys had to go through a thorough military training. I learned how to operate infantry rifles and how to throw hand grenades.

    Click here to expand this photo.

  • In this photo of 1954, I am shaking hands with General Maxwell Taylor who was the commander of the U.S. Forces in Korea. Under him were more than 300,000 combat-ready American troops.

    General Taylor was a scholarly man and was keenly interested in Korea's educational system. He wanted to visit the best high school in Korea. He asked his Korean secretary which school to visit. The Korean secretary told Taylor about the high school he attended. He is also in this photo (far left).

  • I liked mathematics during my my high school years. You have seen above that my physics ideas were based on circles and ellipses. There is a good reason:


Undergraduate Years (1954-1958)

    Click here to expand this photo.

  • In September of 1954, I came to the United States to become a freshman at the Carnegie Institute of Technology (now called Carnegie Mellon University) in Pittsburgh, Pennsylvania.

    The life was not easy for me, but I worked hard enough to get excellent grades.

  • On March 12, 1958, I received a letter from Princeton University telling me I was one of twelve students admitted to the graduate program in physics. This was the happiest day in my life. Going to Princeton meant working with Albert Einstein, even though he died in 1955, three years before 1958.


Princeton Years (1958-1962)

  • In July of 1958, I went to Princeton for my graduate study. Thanks to my solid high-school and undergraduate backgrounds, I completed my PhD degree in three years, but I was asked to stay there for one additional year as a post-doctoral fellow.

    In this photo of 1961, I am making preparations for my third paper to be published in the Physical Review, the standard journal of the American physical Society.

    Indeed, my Princeton background shaped up my research carrier. I went to Princeton in 1958 in order to meet Einstein, even though I knew he left us in 1955. Yet I was able to meet Eugene Wigner (Nobrl 963) there. I was able to explain Wigner's work in terms of Einstein's E = mc2. I was then able to explain the quark-parton issue or Bohr-Einstein issue in terms of Wigner's 1939 paper on his little groups, as shown the two tables given above. I am thus justified to the genealogy shown above.


My life at the University of Maryland since 1962

    Click here to expand this photo.

  • In July of 1962, I became an assistant professor of physics at the University of Maryland, near Washington, DC. This is a photo of the physics faculty taken in the spring of 1963, and I am the youngest person in this photo. 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.

  • This is a human nature which can be described as Herod Complex. Among my colleagues, there were several people who got turned down from Princeton and went to other good graduate schools. Those people were extremely nasty to me. 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.

    What is the job of the youngest faculty member? In September of 1962, Paul A. M Dirac (Nobel 1933) visited the University of Maryland at the invitation of John S. Toll, the chairman of the Department of Physics. Toll assigned me to serve as the personal assistant to Dirac. This gave me the valuable opportunity to learn physics directly from him. Click here to see what learned from him.

  • The most rewarding aspect of my life at the University of Maryland is that the campus is near the city of Washington, DC.

    There are many politicians in the Greater Washington area, but there are far more scientists in this area. They are providing necessary wisdom to the government. Here are the photos from this interesting city.


Construction of my own Family

  • In Korea, the school year starts in March, while it begins in September in the United States. Thus, I spent one freshman semester at the Engineering College of Seoul National University, right after my high school graduation until I started my freshman year at the Carnegie Institute of Technology (in Pittsburgh. USA) in September of 1954.

    At that time, Koreans did not trust female engineers. There were not many girls going to engineering colleges. In 1954, my freshman class consisted of 360 students, but there were only 15 girls. Among those girls, one of them appeared attractive to me.

  • The following photos show the engineering college and the girl who attracted my attention.

  • I met this girl again in 1963 in Washington. By that time, she needed a husband, and I needed a wife. We got married. We had our son in 1965, and he went to Princeton as a freshman in 1983. He got married in 2003. We now have two grandchildren.

  • This is our family photo of 1966.

  • In 1969, we bought a new house, and we still live there. This house is about six km from the campus of the University of Maryland. I could go to my office during the evening hours.

    1. Our neighbors are nice people. They help us whenever we need helps. We once invited them to a Korean restaurant in the Washington area.
    2. There is a treed area near the house, and we see sometimes un-invited guests like this in our backyard.
    3. Click here for more house photos.

  • In 1983, our son went to Princeton for his undergraduate study, and grduated in 1987. He then went to Harvard for his graduate degree. He is a Harvard PhD.

  • In 2003, he married a medical doctor. We now have two grandchildren. Their parents (our son and his wife) are doing well. In 2020, they bought a Steinway piano for our grandchildren. We are proud of all four of them.

  • My two grandchildren will go to colleges in coming years. My grandson wants to go to Princeton because his father and grandfather went there. My granddaughter does not want to go to Princeton because the life there will be too competitive.

    In any case, college tuitions are high these days, and becoming higher every year. When I was a freshman at Carnegie Tech in 1954, the tuition was $580 for one year. These days, the standard figure is $20,000, and it is rising every year. Their parents are asking me to pay.

  • Let me conclude. In my main job as a research scientist, I am singing Einstein these days, and people are beginning to listen. Financially, I reached the level of average Americans. I own a home, travel around the world, and ready to pay college tuitions for my grandchildren. I came to the United States in 1954 with a student visa. The United States has been very nice to me.

Life after 2007

I am a life-time student.
I love students, and they love me!

    Princeton's undergraduate students.
    Princeton's graduate students.
    Physics graduate students in Strasbourg (France).
    Physics graduate students in Vienna (Austria).
    Russian students in Moscow.
  • In 2007, I became a professor emeritus at the Univ. of Maryland. This could mean a retirement from professional life.

    To me, however, it was a 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.

    1. I am free to say whatever I want to say. You may be interested in the books and articles I published in recent years. Click here for my publications.

    2. Since there are no scheduled duties, I have been free to travel around the world and take photos.
      Click here for the photos I took from many different countries.

    3. I am now free to talk about Albert Einstein. Talking about Einstein and other big names used to upset my colleagues and departmental administrators in the past.

      I am now free to talk about Einstein as a philosopher. Then, where is his coordinate among the well-known philosophers? Click here.

  • I realized that the most important aspect of my research has been and still is to find out about myself, not necessarily about Einstein and others.

    1. Work Habit. Connect the existing lakes to build a big canal. Paul A. M. Dirac wrote many papers in order to make quantum mechanics consistent with relativity. But he never attempted to combine them to make one big paper. It was a profitable business for me to combine them into one paper. How could I do what Dirac could not do? Dirac wrote beautiful sentences, and his papers are poems. I translated his papers into cartoons (figures). Then it is easy to combine them into one picture

    2. Where do I stand in Physics? After many years of struggle (before 2000), I found out where I stand in physics.

    3. I then became more ambitious. I could integrate physics.

    4. During the 20th Century, scientists developed quantum mechanics (via Bohr and Heisenberg) and relativity (via Einstein). The question is whether these two theories can be derived from one basket of equations. I am writing papers and books on this unthinkable problem. Click here for my recent articles books.

  • As a cultured man, I pretend to know about art and music. I can now say that physics is an art of Harmony and Integration (Tao and Hegel). Let us see harmony and integration in art and music.


      Thomas Jefferson Memorial
      in Washington, DC. USA.


      post card from the Beethoven Museum
      in Bonn, Germany.
    1. Harmony in Architecture and Harmony in Physics. Let us look at the Jefferson Memorial in Washington, DC (USA). It is harmony and synthesis of Greek columns and Roman dome. This building was John F. Kennedy's favorite art piece.

    2. Harmony in Music and Harmony in Physics. You are invited to my Beethoven page, Go to his String Quartet No. 4. You will appreciate how important "harmony" is in music.

    3. Feynman's One Physics. Feynman is my hero in physics. Like him, I believe in one physics. Richard Feynman was a great American physicist. He received his PhD degree from Princeton in 1942. I maintain a webpage dedicated to him. Click here. Feynman is also a very interesting individual.

  • Why am I so crazy about webpages? Click here.

    1. Passion for communication. 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. The internet technology is God's best gift to me.

    2. How do I take photos?

    3. One crazy webpage.

    4. Another crazy webpage. People seem to like crazy webpages.