Symmetry of parity: Mistake in the experiment?

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SUMMARY

The discussion centers on the Chien-Shiung Wu experiment, which demonstrates that parity is not symmetric by observing electron emissions from Co60 atoms with synchronized spin. A participant expresses confusion regarding the implications of this experiment, particularly in relation to mirror symmetry and the behavior of emitted electrons. A knowledgeable responder clarifies that the quantum mechanical property of "spin" differs fundamentally from classical rotation, and emphasizes that the analogy of a fan does not accurately represent the invariance under parity observed in the experiment.

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  • Understanding of quantum mechanics, specifically the concept of spin.
  • Familiarity with the Wu experiment and its significance in particle physics.
  • Knowledge of parity symmetry and its implications in physics.
  • Basic grasp of classical versus quantum analogies in physics.
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  • Read the Wikipedia article on the Wu experiment for a comprehensive overview.
  • Study quantum mechanics focusing on the concept of spin and its properties.
  • Explore the implications of parity violation in particle physics.
  • Investigate classical versus quantum analogies to better understand their differences.
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Students and researchers in physics, particularly those interested in quantum mechanics, particle physics, and the implications of symmetry in physical laws.

Whatif42
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According to an experiment of Prof. Chien-Shiung Wu parity is not symmetric. A thought experiment of mine contradicts her well proven theory. Where is my mistake?
Recently I saw this YouTube video from Veritassium about CPT -Symmetry:



In this video an experiment of Prof. Chien-Shiung Wu is presented, which has proven that parity is not symmetric, by observing the emmition of electrons from Co60 atoms with synchronised spin. After thinking about this for a while I am very confused, because either this claim an the results of the experiment are wrong, which I don't want to believe or I have made a fundamental misconception.

The video explains the events in a mirrorworld with a mirror. As explained correctly in the video a mirror does invert the z axis of an object (Min 2.54 in the Video). But why is the emmiting direction of the electrons not inverted as well on the z axis? Respectively the spin mirrorimaged?

Lets take a fan for visualisation and place it in front of a mirror and let's presume as well the spin of the fan resembles the spin of a radioactive Co atom in the experiment and the airstream resembles the emmited electrons.

These "electrons" would always flow in the direction of the mirror. No matter if you are in the mirror or the real world.

If I go further, away from the fan to a more theoretical assumption, from my point of understanding, time moves backwards in the mirrorworld as well. As a result of this, it seems obvious, that spin and particle flow are reversed in such a mirrorworld. The spin would be opposite and the electron would be attracted to the Ni60 and not emmited from the Co60.

I would be very happy, if somebody with more knowledge and a better understanding of this topic could reply and help me solve my problem.

Thank you in advance
 
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Whatif42 said:
lets presume as well the spin of the fan resembles the spin of a radioactive
That’s where you’re going wrong - the quantum mechanical property is called “spin” for historical reasons, but is nothing like the classical rotation of a macroscopic object.

You might want to give the Wikipedia article on this experiment a try: https://en.wikipedia.org/wiki/Wu_experiment
 
There a problem with your analogy, the fan is not invariant under parity, i.e. the "real fan" and the "mirror fan" are different and therefore, if I know the properties of the "real fan" and you send me a video of the fan, I can tell you whether I'm seeing the "real" or the "mirror" fan. This is not true for the spin in the Co atoms, so your analogy doesn't work. And is precisely this difference that is the main point of the experiment.
 

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