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timtyler comments on Quantum Physics, CERN and Hawking radiation - Less Wrong
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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.
No. I am giving you the conventional view, which you do not understand.
I do not wish to appeal to authority, but since we are now arguing in terms of what is the conventional view, perhaps I can legitimately mention that I have a PhD in experimental particle physics. True, I'm not a theorist, but I do feel I have a reasonable grounding in these matters.
Which part of "CP symmetry is broken" is unclear to you? If antineutrinos and neutrinos have different masses, that breaks C symmetry and its discoverer will certainly get a trip to Stockholm. But this is not required for the argument I gave above to be correct. The breaking of CP symmetry is already known, and has been known since the sixties. It has exactly the same consequences as if neutrino and antineutrino masses are different, it's just a bit more difficult to visualise.