I'm studying parity for the first time but there is something I don't understand. I read that a system conserves parity if every experiment is the same in a mirror that is also $180^{\circ}$ flipped. When I look myself doing something in a mirror everything is the same and so I'm a system that conserves parity. But I also read that to conserve a parity a system must be symmetric (or antisymmetric) and I'm not, so how it's possible?


rubbish You are not a system that conserves parity. Maybe you need a more rigorous definition of a parity transform: https://en.wikipedia.org/wiki/Parity_(physics) /rubbish

Parity transform means that you mirror the system in three perpendicular planes. So lets see. First we mirroring: your left and right hands swap places, same goes for eyes, ears etc. Second mirroring: your nose goes to the back of your head etc. Third mirroring: your head goes to the follow, whilst your feet go up into the air. Now at that point you clearly do not look like you did initially, so you are odd under parity transform.

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  • $\begingroup$ Do you mean that i’m not the same after the transformation becouse for example if i have the right hand closed and the left open after the trasformation it’s the opposite? Then in this case observer can’t understand if he’s whatching the mirrored world or the real one $\endgroup$ – SimoBartz Mar 19 '19 at 7:03
  • $\begingroup$ Even simpler. You are upside-down after parity transform. This is what the observer will note first. $\endgroup$ – Cryo Mar 19 '19 at 11:17
  • $\begingroup$ It this case it sounds like parity conserved Is just a synonymous of symmetric (and anti symmetric). Is it true? $\endgroup$ – SimoBartz Mar 19 '19 at 21:55
  • $\begingroup$ :-) I think you are right. I was thinking about one thing and said another (now corrected). Parity conservation means that transformation does not change the parity of the system. For this to make sense, system should have definite parity. Either odd or even. You have odd parity, because your top is different from the bottom. Saying that you do not converve parity makes no sense. What does make sense is to say that you have odd, and probably inddfinite parity $\endgroup$ – Cryo Mar 20 '19 at 1:53

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