Noether and Symmetry
Emmy Noether
1882 -1935
Jack and Mark talk about how certain "big ideas" in physics, called conservation laws, are built upon deep symmetries that are found in nature and in the laws that describe nature. This connection was first discovered by German mathematician Emmy Noether. Listeners will hear how symmetry and violations of symmetry help scientists understand the universe, perhaps explaining why there is more matter in the cosmos than antimatter. In other words, the assymmetry may be related to the the question, "Why is there something rather than nothing."
Podcast length: 1:03:08
Show Notes:
Selected Awards and Publications associated with Emmy Noether:
1932 Alfred Ackermann–Teubner Memorial Award for the Promotion of Mathematical Sciences
July, 1918 article (page 1) in which Noether's Theorem is proven.
Video by Dr. Don Lincoln (of Fermi Lab) on Emmy Noether
Discussed in the episode:
Use of Noether's Theorem to show how symmetry of translation in space implies the conservation of momentum. Click here to download a .pdf of this document.
Other items of interest related to this podcast:
Chien-Shiung Wu
Figure 1
Figure 2
Chinese-American Physicist Chien-Shiung Wu conducted the 1956 experiment that exhibited the violation of parity conservation (P-Conservation) for the weak interaction which controlled beta-dacay.
The conservation of parity was already established as being upheld for electromagnetic and strong nuclear interactions. When P-Conservation is exhibited, the mirrored-version of an experiment (one which shows reflection symmetry, where right in the non-mirrored experiment is left in the mirrored experiment and visa-versa) will behave as the mirrored-version of the non-mirrored experiment. If P-Conservation is found, there is no way to operationally define the concept of left and right without reference to the human body. However, if P-conservation is violated the notion of left and right can be operationally defined. This experiment was prompted by two other Chinese-American physicsists, Tsung-Dao Lee and Chen-Ning Yang who won the Nobel prize in physics for their ideas in 1957.
Two better understand this idea, look at the two clocks in figure 1. The clock on the right is a mirror image of the clock on the left. It also runs as a mirror image of the clock on the left. These clocks exhibit the symmetry associated with P-Conservation.
However, in figure 2, the mirror image runs in the same way as the clock on the left. This is a symmetry violation in which parity is not conserved.
This is a photo of Chen-Ning Yang and Roberts Mills. It was generously given to Jack by Dr. Mills' granddaughter, Katie (a student in Jack's AP Physics class). The Yang-Mills theory describes the behavior of elementary particles and is a very important foundation for the Standard Model of particle physics.
Chen-Ning Yang
Tsung-Dao Lee
Matter and anti-matter show symmetry through charge conjugation. If this type of symmetry is found in the universe, there should be as much matter in the cosmos as anti-matter. But there is actually very little anti-matter compared to matter.
Emmy Noether's gravesite and marker. On the campus of Bryn Mawr College in Bryn Mawr, PA.
Albert Einstein wrote her obituary for the New York Times on May 4, 1935
