Archive for Tsung Dao Lee

Lessons from Physics and Biology

Posted in Sport, The Universe and Stuff with tags , , , on August 6, 2024 by telescoper

As I’ve mentioned before on this blog, one of my English teachers at school would occasionally give us exercises in creative writing inspired by `Only Connect’ – the epigraph of the novel Howard’s End by E.M. Forster. We were given two apparently disconnected things (usually news items), asked to think of a possible connection between them and write an story joining them together. From time to time when trying to think of something to write about I’ve resorted to playing the same game and am going to do it today.

This time, I thought I would connect two of my own recent blog posts, one about the case of female boxer Imane Khelife and the other about about the death of theoretical physicist TD Lee. What could the connection be?

Tsung-Dao Lee’s most famous work – for which he won the 1957 Nobel Prize with was on parity violation, which was detected experimentally by Chien-Shiung Wu in 1956. Parity is a conserved quantity in classical physics (e.g. in electromagnetism and gravity) and it was believed until the mid-20th century that it would be conserved in the quantum theory of nuclear interactions too. Wolfgang Pauli, for example, criticized Hermann Weyl’s suggestion of a two-component weakly interacting massless particle because it implied parity violation.

The experimental proof of parity violation in some weak interactions led to a much deeper understanding of fundamental physics, including the the idea of chiral gauge interactions, and the development of the standard model of particle physics. Parity is violated in some strong interactions too. Our simple-minded view of how things are changed as a result of an exception to a widely-held assumption. That’s how progress happens.

You might think now that I’m going to write about the fact that double-helix structure of DNA is right-handed, i.e. that it exhibits a form of parity violation, but that’s not it. Or only a little bit. You see, not all DNA is right-handed…

What does this have to do with Olympic boxing? Well, much of the furore about about Imane Khelif is about the (unproven) assertion that she has XY chromosome and is therefore male and should not be allowed to box in the women’s competition. A ‘biological’ female would have XX chromosomes.

It is true in the vast majority of cases that men have XY chromosomes and women have XX chromosomes, but if you read any reasonably modern book on human biology, the statement that ‘females have XX chromosomes’ is preceded by a “usually” or “in most cases”. But there exceptions: some women have XY chromosomes and some men have XX chromosomes; there are also individuals who have an extra chromosome and are XXY.

How can a person be said to be female if they have XY chromosomes? Well, that is because there is a very long journey between the information encoded in genetic material and the expression of that information in form and function. That entire process determines whether an athlete may nor not have an advantage over another. In a rare, sensible article about the Imane Khelif case I found this

Alun Williams, professor of sports and exercise genomics at Manchester Metropolitan University, said that when considering if a person had an unfair advantage it was necessary to look at chromosomes, levels of testosterone and other hormones, as well as the body’s response to testosterone.

“That then is a clinical assessment, which is really very invasive,” Williams said. “Simply looking at someone’s sex chromosomes … is incomplete.”

In most cases individuals with XY chromosomes develop “male” characteristics and those with XX chromosomes develop “female” but there are exceptions. For example, there are women – with ovaries, a uterus and no male sex organs – who have XY chromosomes. These are biologically female, even if their karyotype indicates otherwise. There is much more to biology than genetics, just as there is much more to physics than electromagnetism and gravity.

I don’t know whether Imane Khelif has XY chromosomes or not, and frankly I don’t care. The fact is that she was assigned female gender at birth, has been raised as female, and her gender is female as on her passport. She is a woman. I won’t use the phrase biological woman, because it is silly: every human being is biological. Caster Semenya is female too.

You might not care about this case and prefer top stick to the rigid definition that XX=male and XY=female. I don’t think that’s appropriate in sports: chromosomes don’t compete in sports, people do. I’ve also been accused of being ‘unscientific’ for accepting that the exceptions to a rule. On the contrary, I think such exceptions are how our understanding improves, not only in scientific terms but also in our respect for our fellow human beings.

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R.I.P. Tsung-Dao Lee (1926-2024)

Posted in R.I.P., The Universe and Stuff with tags , , , on August 5, 2024 by telescoper

T.D.1.jpg_copyI’ve just heard the sad news of the death at the age of 97 of TD Lee (shown left) who, together with CN Yang, won the Nobel Prize for Physics in 1957 for his work on parity violation in particle physics. I always find it difficult on occasions like this to find ways of describing the work of people of such eminence in fields other than my own, but in this case it turns out I have a personal connection of a sort. Way back in 2006 when I was at Nottingham, the University decided to award Prof. Lee an honorary degree and I was chosen to deliver the oration at the graduation ceremony before spending some time chatting to him with some students. I remember that it was a very hot day and I was wilting under the graduation robes, but he took it all in his stride despite being 80 years old. Anyway, here is the text that I prepared for that occasion, which I hope will serve as a fitting obituary.

 

 

 

 

PROFESSOR TSUNG-DAO LEE

ORATION DELIVERED BY PROFESSOR PETER COLES

ON MONDAY 17 JULY 2006

Chancellor, Vice-Chancellor, Ladies and Gentlemen, it is both a pleasure and a privilege to present Professor Tsung-Dao Lee for the award of an honorary degree.  Professor Lee is a distinguished theoretical physicist whose work over many years has been characterized, in the words of Dr J Robert Oppenheimer, by “a remarkable freshness, versatility and style.”

Tsung-Dao Lee was born in Shanghai and educated at Suzhou University Middle School in Shanghai.  Fleeing the Japanese invasion, he left Shanghai in 1941.  His education was interrupted by war.  In 1945 he entered the National Southwest University in Kunming as a sophomore.  He was soon recognized as an outstanding young scientist and in 1946 was awarded a Chinese Government Scholarship enabling him to start a PhD in Physics under Professor Enrico Fermi at the University of Chicago.  He gained his doctorate in physics in 1950 with a thesis on the Hydrogen Content of White Dwarf Stars, and subsequently served as a research associate at the Yerkes Astronomical Observatory of the University of Chicago in Williams Bay, Wisconsin.

Astronomy is a science that concerns the very large, but it was in the physics of the very small that Professor Lee was to do his most famous work.  After one year as a research associate and lecturer at the University of California in Berkeley, he became a fellow of the Institute of Advanced Study in Princeton and, in 1953, he accepted an assistant professorship position at Columbia University in New York.  Two and a half years later, he became the youngest full professor in the history of Columbia University.  During this time he often collaborated with Chen Ning Yang whom he had known as a fellow student in Chicago.  In 1956 they co-authored a paper whose impact was both immediate and profound.  Only a year later, Lee and Yang were jointly awarded the Nobel Prize in Physics.  Professor Lee was thirty-one at the time and was the second youngest scientist ever to receive this distinction.  (The youngest was Sir Lawrence Bragg who shared the Physics Prize with his father in 1915, at the age of twenty-five; Werner Heisenberg was 31 when his Nobel Prize was announced, in 1932, but he did not receive the prize until the following year.)

It is usually difficult to explain the ideas of theoretical physics to non-experts.  The mathematical language is inaccessible to those without specialist training.  But some of the greatest achievements in this field are so bold and so original that they appear, at least with hindsight, to be astonishingly simple.  The work of Lee and Yang on parity violation in elementary particle interactions is an outstanding example.

Subatomic particles interact with each other in very complicated ways.  In high energy collisions, particles can be scattered, destroyed or transformed into other particles.  But governing these changes are universal rules involving things that never change.  The existence of these conservation laws is a manifestation of the symmetries possessed by the mathematical theory of particle interactions.

Lee and Yang focussed on a particular attribute called parity, which relates to the “handedness” of a particle and symmetry with respect to mirror reflections.  Physicists had previously assumed that the laws of nature do not distinguish between left- and right-handed states: a left-handed object when seen in a mirror should be indistinguishable from a right-handed one.  This symmetry suggests that parity should be conserved in particle interactions, as it is in many other physical processes.  Unfortunately this chain of thought led to a puzzling deadlock in our understanding of the so-called weak nuclear interaction.  Lee and Yang made the revolutionary suggestion that parity is not conserved in weak interactions and consequently that the laws of nature must have a built-in handedness.  A year later their theory was tested experimentally and found to be correct.  Their penetrating insight led to a radical overhaul of the theory of weak interactions and to many further discoveries.  Physicists around the world said “Of course!  Why didn’t I think of that?”

This classic “Eureka moment” happened half a century ago, but Professor Lee has since made a host of equally distinguished contributions to fields as diverse as astrophysics, statistical mechanics, field theory and turbulence.  He was made Enrico Fermi Professor at Columbia in 1964 and University Professor there in 1984.  With typical energy and enthusiasm he took up the post of director of the RIKEN Research Center at Brookhaven National Laboratories in 1998.  He has played a prominent role in the advancement of science in China, including roles as director of physics institutes in Beijing and Zhejiang.

Professor Lee has received numerous awards and honours from around the world, including the Albert Einstein Award in Science, the Bude Medal, the Galileo Galilei Medal, the Order of Merit, Grande Ufficiale of Italy, the Science for Peace Prize, the China National-International Cooperation Award, the New York City Science Award, the Pope Joannes Paulis Medal, Il Ministero dell’Interno Medal of the Government of Italy and the New York Academy of Sciences Award.  His recognition even extends beyond this world, for in 1997 Small Planet 3443 was named in his honour.

Chancellor, Vice-Chancellor, to you and to the whole congregation I present Professor Tsung-Dao Lee as eminently worthy to receive the degree of Doctor of Science, honoris causa.

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Oratorio

Posted in Biographical, The Universe and Stuff with tags , , on July 16, 2009 by telescoper

T.D.1.jpg_copyBlogging about graduation ceremonies yesterday, I was reminded that a few years ago I had to deliver an oration on behalf of a very famous physicist who was awarded an honorary doctorate at the University of Nottingham. The recipient was TD Lee (shown left) who, together with CN Yang, won the Nobel Prize for Physics in 1957 for his work on parity violation. I thought you might find it interesting to  read the text of the oration, which I just found on my laptop this morning:

PROFESSOR TSUNG-DAO LEE

ORATION DELIVERED BY PROFESSOR PETER COLES

ON MONDAY 17 JULY 2006

Chancellor, Vice-Chancellor, Ladies and Gentlemen, it is both a pleasure and a privilege to present Professor Tsung-Dao Lee for the award of an honorary degree.  Professor Lee is a distinguished theoretical physicist whose work over many years has been characterized, in the words of Dr J Robert Oppenheimer, by “a remarkable freshness, versatility and style.”

Tsung-Dao Lee was born in Shanghai and educated at Suzhou University Middle School in Shanghai.  Fleeing the Japanese invasion, he left Shanghai in 1941.  His education was interrupted by war.  In 1945 he entered the National Southwest University in Kunming as a sophomore.  He was soon recognized as an outstanding young scientist and in 1946 was awarded a Chinese Government Scholarship enabling him to start a PhD in Physics under Professor Enrico Fermi at the University of Chicago.  He gained his doctorate in physics in 1950 with a thesis on the Hydrogen Content of White Dwarf Stars, and subsequently served as a research associate at the Yerkes Astronomical Observatory of the University of Chicago in Williams Bay, Wisconsin.

Astronomy is a science that concerns the very large, but it was in the physics of the very small that Professor Lee was to do his most famous work.  After one year as a research associate and lecturer at the University of California in Berkeley, he became a fellow of the Institute of Advanced Study in Princeton and, in 1953, he accepted an assistant professorship position at Columbia University in New York.  Two and a half years later, he became the youngest full professor in the history of Columbia University.  During this time he often collaborated with Chen Ning Yang whom he had known as a fellow student in Chicago.  In 1956 they co-authored a paper whose impact was both immediate and profound.  Only a year later, Lee and Yang were jointly awarded the Nobel Prize in Physics.  Professor Lee was thirty-one at the time and was the second youngest scientist ever to receive this distinction.  (The youngest was Sir Lawrence Bragg who shared the Physics Prize with his father in 1915, at the age of twenty-five.)

It is usually difficult to explain the ideas of theoretical physics to non-experts.  The mathematical language is inaccessible to those without specialist training.  But some of the greatest achievements in this field are so bold and so original that they appear, at least with hindsight, to be astonishingly simple.  The work of Lee and Yang on parity violation in elementary particle interactions is an outstanding example.

Subatomic particles interact with each other in very complicated ways.  In high energy collisions, particles can be scattered, destroyed or transformed into other particles.  But governing these changes are universal rules involving things that never change.  The existence of these conservation laws is a manifestation of the symmetries possessed by the mathematical theory of particle interactions.

Lee and Yang focussed on a particular attribute called parity, which relates to the “handedness” of a particle and symmetry with respect to mirror reflections.  Physicists had previously assumed that the laws of nature do not distinguish between left- and right-handed states: a left-handed object when seen in a mirror should be indistinguishable from a right-handed one.  This symmetry suggests that parity should be conserved in particle interactions, as it is in many other physical processes.  Unfortunately this chain of thought led to a puzzling deadlock in our understanding of the so-called weak nuclear interaction.  Lee and Yang made the revolutionary suggestion that parity is not conserved in weak interactions and consequently that the laws of nature must have a built-in handedness.  A year later their theory was tested experimentally and found to be correct.  Their penetrating insight led to a radical overhaul of the theory of weak interactions and to many further discoveries.  Physicists around the world said “Of course!  Why didn’t I think of that?”

This classic “Eureka moment” happened half a century ago, but Professor Lee has since made a host of equally distinguished contributions to fields as diverse as astrophysics, statistical mechanics, field theory and turbulence.  He was made Enrico Fermi Professor at Columbia in 1964 and University Professor there in 1984.  With typical energy and enthusiasm he took up the post of director of the RIKEN Research Center at Brookhaven National Laboratories in 1998.  He has played a prominent role in the advancement of science in China, including roles as director of physics institutes in Beijing and Zhejiang.

Professor Lee has received numerous awards and honours from around the world, including the Albert Einstein Award in Science, the Bude Medal, the Galileo Galilei Medal, the Order of Merit, Grande Ufficiale of Italy, the Science for Peace Prize, the China National-International Cooperation Award, the New York City Science Award, the Pope Joannes Paulis Medal, Il Ministero dell’Interno Medal of the Government of Italy and the New York Academy of Sciences Award.  His recognition even extends beyond this world, for in 1997 Small Planet 3443 was named in his honour.

Chancellor, Vice-Chancellor, to you and to the whole congregation I present Professor Tsung-Dao Lee as eminently worthy to receive the degree of Doctor of Science, honoris causa.

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