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RolfAndreassen comments on Quantum Physics, CERN and Hawking radiation - Less Wrong
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No. Start with a left-handed neutrino. Reverse T under your assumption. It is now a right-handed antineutrino going the other way; reverse space as well to restore the original direction, if you like, although the argument does not depend on this. Because CP is broken, right-handed antineutrinos do not behave exactly as left-handed neutrinos do. Therefore you can tell how many times T has been reversed. You don't get the full symmetry back except by applying CP another time.
Yes.
A parity flip, I presume you mean.
That is indeed true.
Well you only said you reversed it once - and then you flipped P, but not C, leaving things in a bit of a mess - and then you tried to make out the mess was something to do with me.
Reversing T an odd number of times changes everything. Reversing it an even number of times changes nothing. You can't distinguish between reversing T different numbers of times beyond that - under the hypothesis that reversing T automatically reverses C and P.
Ok, leave the parity flip out of it. If this is true:
then you do not have T symmetry. Done.
It makes time run backwards. Those in charge may not think that this is such a null-op.
If you pressed the "rewind" button, you would normally expect to see some changes!
Ok, there's your problem: You don't understand what is meant by 'symmetry'.
At this stage, I don't really see why you are continuing to comment :-(
To convince you that you are wrong about CPT violation and T violation. Why are you posting?
Once more. Start with a left-handed antineutrino. T-reverse under your assumption that this also reverses CP. You now have a right-handed neutrino. Because of CP violation, it does not have the same physical properties that it started with. Therefore, T symmetry is broken. Which part of this argument do you disagree with?
The "Therefore". Reverse the universe, and a left-handed antineutrino turns into a right-handed neutrino travelling in the opposite direction. Everyone agrees about that. Its different properties don't prevent the universe from retracing its steps - rather they are essential for that to happen correctly.
No; wrong. Its different properties will, precisely, cause the universe not to retrace its steps exactly. The rate for X\to e^+ \nue is different from that for e^- \bar\nue \to X; this is what CP violation means. Therefore, when you have reversed time, the antineutrino will not precisely retrace the steps the neutrino took.
Do you realise that what you are claiming is pretty unconventional? Here is the conventional view:
Investingating to see if I could see what you are talking about found some claims that the symmetry between neutrinos and antineutrinos is violated:
In the highly unlikely case of any such asymmetry being confirmed, that would break CPT symmetry - and serious revisions of fundamental physics would be needed.