### C.N. Yang

February 27, 2017

Physicist,

Chen-Ning Yang, who is usually identified as "C.N. Yang" in the

scientific literature, was the recipient of the 1957

Nobel Prize in Physics which he shared with fellow physicist,

Tsung-dao Lee, for their prediction of

parity non-conservation in processes that involve the

weak nuclear force. The weak nuclear force is one of the four known

fundamental forces of nature that include the

strong nuclear force,

gravitation, and

electromagnetism.

The weak force and electromagnetism are now thought to be manifestations of a single force, the

electroweak force, that will be evident at very high

energies (about 100

GeV). The weak force mediates

nuclear reactions that involve

beta decay or

alpha decay. Before Yang and Lee's

theory, it was thought that such reactions would appear the same when viewed in a

mirror. This parity-inversion

symmetry is one of the many symmetries seen in

physics. I wrote about symmetries in an

earlier article (CPT Symmetry, October 29, 2015).

Parity-inversion symmetry is nearly always seen in beta decay, so you need to look long and hard to find the few

counterexamples. A

1956 experiment involving the beta decay of

cobalt-60 by physicist,

Chien-Shiung Wu (1912-1997), revealed the non-conservation of parity. Non-conservation of parity means that it's possible to have an

experiment distinguish

left from right. One use for this would be to distinguish

left from right in

communication with an

extraterrestrial civilization.

While it was proven that parity is not always conserved, there was hope that a combination of symmetries involving both

charge (C) and parity (P) might still hold, but

James Cronin and

Val Fitch found

CP violation in

neutral kaon decay in 1964. The reason why

our universe is made of matter, and not an equal mixture of

matter and

antimatter, might be explained by CP violation.

Presently, it appears that adding

time-reversal (T) symmetry into the mix for a combined

CPT symmetry is a valid symmetry. The consequence of CPT symmetry is that an antimatter universe (C) that's a mirror image of our own (P) in which particle

momentum is reversed (T) would have the same

laws of physics that we observe. CPT has been confirmed in all experiments to date; but, as can be imagined, such experiments have become much more difficult than Wu's 1956 experiment that demolished P symmetry.

Yang, who was born on born on October 1, 1922, was a

young man in his mid-30s when he

published his theory of the weak interaction, and he did much interesting work after that. On the occasion of his 90th

birthday in 2012, he was presented with a black "

cube" of dimensions 8

cm x 8 cm x 6.6 cm

engraved with a birthday congratulation, two lines in

Chinese from

Tu Fu (712-770), "A piece of

Literature is meant for the

millennium, but its ups and downs are known already in the

author's heart," and a list of his thirteen significant contributions to

statistical mechanics,

condensed matter physics,

particle physics, and

field theory, ordered by date (see figure).[1]

Just posted on

arXiv is a copy of a paper published in honor of that occasion by Yu Shi in a 2014 issue of the

International Journal of Modern Physics A.[2] Here's the list of Yang's 13 significant contributions, as engraved on the cube, listed by topic area and year.[1]

**Statistical Mechanics**

1952-Phase Transition

1957-Bosons

1967-Yang-Baxter Equation

1969-Finite Temperature

**Condensed Matter Physics**

1961-Flux Quantization

1962-Off-Diagonal Long-Range Order

**Particle Physics**

1956-Parity Nonconservation

1957-T, C and P

1960-Neutrino Experiment

1964-CP Nonconservation

**Field Theory**

1954-Gauge Theory

1974-Integral Formalism

1975-Fiber Bundle

While I'm not skilled in particle physics and not comfortable reading papers that are

mathematically dense, I did work in the field of

superconductivity for a time. In this area of condensed matter physics, Yang and co-author,

Nina Byers, explained the

magnetic flux quantization in superconducting

rings observed at

Stanford University (Stanford, CA) by

Bascom S. Deaver and

William M. Fairbank.[3-4] In such rings, the

magnetic flux is

quantized in units of

**hc/2e**, where

**h** is the

Planck constant,

**c** is the

speed of light, and

**e** is the

electric charge. The

quantum of magnetic flux is 2.0678 x 10

^{-15} weber.

One important feature of this

equation is the factor of two. The

BCS theory of superconductivity, published in 1957, predicted that

supercurrent is carried by

electron pairs, called

Cooper pairs. While this theory explained many unusual features of superconductivity, such as the

isotope effect, flux quantization very dramatically provided evidence for Cooper pairs.[5]

The quantum of magnetic flux can be measured to great precision using

Josephson junction devices. Combining such a measurement with the

quantum Hall effect allows a very accurate estimate of the Planck constant. The quantum Hall effect gives a value for an

electrical resistance **R**_{K} called the

von Klitzing constant,

**R**_{K}=h/(e^{2}). It's interesting that there's a quantum of electrical resistance, ≈25812.80756 ohms, but it's more important that a combination of precise measurements will yield an excellent calculated value for

**h**.

### References:

- Yu Shi, "Beauty and Physics: 13 Important Contributions of Chen Ning Yang," arXiv, February 7, 2017.
- Yu Shi, "Beauty and Physics: 13 Important Contributions of Chen Ning Yang," International Journal of Modern Physics A, vol. 29, no. 17 (June 13, 2014), Article No. 1475001 (10 pages), DOI: 10.1142/S0217751X14750013.
- N. Byers and C. N. Yang, "Theoretical Considerations Concerning Quantized Magnetic Flux in Superconducting Cylinders," Phys. Rev. Lett., vol. 7, no. 2 (July 15, 1961), pp. 46-49, doi:10.1103/PhysRevLett.7.46.
- Bascom S. Deaver, Jr., and William M. Fairbank, "Experimental Evidence for Quantized Flux in Superconducting Cylinders," Phys. Rev. Lett., vol. 7, no. 2 (July 15, 1961), pp. 43-46, DOI:https://doi.org/10.1103/PhysRevLett.7.43.
- David Lindley, "Focus: Landmarks—Superconductor Quantizes Magnetic Field," Physics, vol. 8, no. 102 (October 23, 2015).