Meet an alien from another planet

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    Alien Planet
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Discussion Overview

The discussion revolves around the hypothetical scenario of meeting an alien from another planet and determining whether the alien is made of antimatter without physical contact. The conversation touches on theoretical concepts related to particle physics, specifically CP violation.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant suggests that comparing the rate of CP-violated processes could indicate whether the alien is made of antimatter.
  • Another participant humorously proposes throwing something at the alien as a method of testing.
  • A further contribution explains that CP violation implies different reaction rates between particles and their antiparticles, suggesting that observing these rates could theoretically help identify the alien's composition.
  • Another participant mentions that the teacher's point may reference a joke from Feynman's lectures, prompting others to look up specific pages for context.

Areas of Agreement / Disagreement

The discussion includes a mix of serious theoretical exploration and humorous suggestions, with no clear consensus on the practicality of the proposed methods for determining the alien's composition.

Contextual Notes

There are unresolved assumptions regarding the feasibility of measuring CP violation in a practical scenario involving an alien. The reference to Feynman's lectures suggests a potential misunderstanding or miscommunication about the original point made by the teacher.

Soff
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Suppose you are going to meet an alien from another planet. How can you make sure that the alien is not build of antimatter without touching it?

My teacher told me that I have to compare the rate of the C-P violated processes. I didn't understand this point.
 
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Throw something at him ;)
 
if CP is a good symmetry between particles and anti-particles, then CP violation means that reaction rates between set of particles will be different from those rates generated by a set of anti-particles. so by observing the rate of CP violating processes generated by these aliens you can tell (in principle, not sure this is practical) whether they are made of anti-matter.
 
Your teacher was referring to a joke that Feynman had in his famous lectures. Go to the library and look up Feynman's lectures on Physics Volume one pages 52-10 to 52-11.
 

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