Parity violation on macroscopic scale

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Discussion Overview

The discussion revolves around the concept of parity violation and its potential implications on a macroscopic scale. Participants explore whether parity violation, typically associated with weak interactions at a microscopic level, can influence macroscopic phenomena or if the macroscopic world remains parity symmetric.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant asserts that parity is violated only by the weak interaction, suggesting that there is no parity violation on a macroscopic scale.
  • Another participant proposes that macroscopic properties are influenced by microscopic events, questioning if parity violation could "leak" into the macroscopic world.
  • A participant argues that any experiment detecting parity violation serves as an example of such leakage, noting that experimental apparatuses are macroscopic and exhibit different behaviors under parity violation.
  • There is a mention of the Wu experiment involving cobalt-60, suggesting that while theoretically possible, the probability of significant macroscopic effects from parity violation is extremely low.
  • Another participant brings up theories linking homochirality in biological systems to parity violation, referencing experiments related to this topic in the context of the Rosetta comet landing mission.

Areas of Agreement / Disagreement

Participants express differing views on the influence of parity violation on macroscopic phenomena. While some argue against the possibility of such effects, others suggest that there are theoretical frameworks and experimental evidence that could indicate a connection.

Contextual Notes

The discussion highlights the complexity of linking microscopic and macroscopic behaviors, emphasizing the role of statistical mechanics in making such connections. There are unresolved questions regarding the conditions under which parity violation might manifest in macroscopic systems.

Who May Find This Useful

Readers interested in the intersections of quantum mechanics, statistical mechanics, and biological implications of physical laws may find this discussion relevant.

tzimie
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a question which is bugging me...

Yes, I know that parity is violated only by the Weak Interaction, which is very short range. So I would answer "no, there is no P violation on macroscopic scale"

However, many macroscopic properties are the results of what happens on the microscopic level. So can P violation somehow "leak" into the macroscopic world? Or, If you insist on the answer "No", is there a solid proof that macroscopic world is P symmetric?
 
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tzimie said:
However, many macroscopic properties are the results of what happens on the microscopic level. So can P violation somehow "leak" into the macroscopic world? Or, If you insist on the answer "No", is there a solid proof that macroscopic world is P symmetric?

Any experiment that successfully detects parity violation is an example of leakage into the macroscopic world - the experimental apparatus is macroscopic and behaves differently when parity is violated.

However, you are probably looking for something a bit more exciting than just a few needles reading different values... Like say a big lump of cobalt-60 (google for "Wu experiment parity") blasting gamma radiation and electrons in different directions? There's no reason why such a thing could not in principle be assembled, but the probability of it happening is so low that in practice it will never happen.

Similar considerations apply to even the more prosaic examples of macroscopic properties emerging from what happens on the microscopic level. A macroscopic dropped brick will pretty reliably fall to to the ground - but in principle all the air molecules underneath it might just randomly happen to be moving up at the same time and then it would float. Generally any time that you want to make a connection between microscopic and macroscopic behavior you have to apply the methods of statistical mechanics.
 
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Some theories to explain the fact that we only observe L-Aminoacids and D-sugars (homochirality) in living beings try to trace this back to the parity violating terms in the hamiltonian. I think that even some experiments in the Rosetta comet landing mission where dedicated to explore this.
See,
http://www.acadeuro.org/fileadmin/user_upload/publications/ER_Symmetry_supplement/Cline.pdf
 
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Interesting, thank you
 

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