This is all a misconception, though. Look carefully at the theorem you mention, and I expect that you will see that it is quite compatible with what I have been saying.
Would you care to do me (and other readers) the courtesy of explaining what misconception you think I’m actually suffering from, and what about the CPT theorem you think I’ve failed to look at carefully enough, and what specific things it says that would make what you say look sensible?
Would you care to do me (and other readers) the courtesy of explaining what misconception you think I’m actually suffering from, and what about the CPT theorem you think I’ve failed to look at carefully enough, and what specific things it says that would make what you say look sensible?
You don’t seem to understand how a model can lack CPT symmetry and be consistent with theory and observations. You should be aware that others besides Fredkin have seriously proposed this:
The Feynman proposal has the consequence that the electric field flips sign under time reversal, and that the magnetic field does not but it, too, has the consequence that the theory is time reversal invariant.
If I don’t understand how that can happen, then perhaps the problem is either (1) that it can’t or (2) that how it can is a subtle matter which hasn’t been explained well enough for me to understand it. So far, in this discussion, you’ve offered no reason to think #2 more likely than #1, and in any case you haven’t made any attempt to explain how it could happen.
The PDF does not appear to contain the sentence you purport to quote from it. (More specifically, it does not appear to contain the word “flips”. (Neither does the abstract.) In any case, its proposal seems to amount simply to redefining “time reversal”. If all you’re saying is that if you use “T symmetry” to mean what everyone else calls “CPT symmetry” then physics is likely to be T-symmetric but not CPT-symmetric, then (duh!) I agree, but I’m not sure why that’s supposed to be interesting.
The PDF does not appear to contain the sentence you purport to quote from it. (More specifically, it does not appear to contain the word “flips”.
Section 2.4 page 32. Searching for “flips” doesn’t work here either. Copy-n-paste into a text editor shows why—fi and fl are weird ligatures in this PDF.
In any case, its proposal seems to amount simply to redefining “time reversal”. If all you’re saying is that if you use “T symmetry” to mean what everyone else calls “CPT symmetry” then physics is likely to be T-symmetric but not CPT-symmetric, then (duh!) I agree, but I’m not sure why that’s supposed to be interesting.
To quote from the article:
We have articulated the `geometric’ notion of time reversal implicit in Malament’s work, according to which time reversal consists in leaving all [other] fundamental quantities alone, and merely flipping the temporal orientation.
It’s plainly proposing T symmetry. Does that help you to see how such a thing might be possible?
Aha, of course. (I did search for some other substrings, though I forget what. Presumably they also contained ligatures. D’oh.)
plainly proposing T symmetry
… in Malament’s proposal, which is not the same as the Feynman one you cite earlier. The purpose of the paper is to argue for a definitional change whereby we call “T” what is currently generally called “CT”. Everything in the paper is concerned with classical, not quantum, electrodynamics. The paper does not argue that T symmetry (as generally understood or with a revised definition) is plausibly true in quantum electrodynamics.
Does that help you to see how such a thing might be possible?
It would make this discussion more pleasant for me if you’d be less patronizing. Whether you care about that is, of course, up to you.
Would you care to do me (and other readers) the courtesy of explaining what misconception you think I’m actually suffering from, and what about the CPT theorem you think I’ve failed to look at carefully enough, and what specific things it says that would make what you say look sensible?
You don’t seem to understand how a model can lack CPT symmetry and be consistent with theory and observations. You should be aware that others besides Fredkin have seriously proposed this:
For example, according to the PDF of Spacetime symmetries and the CPT theorem Richard Feynman proposed much the same thing:
If I don’t understand how that can happen, then perhaps the problem is either (1) that it can’t or (2) that how it can is a subtle matter which hasn’t been explained well enough for me to understand it. So far, in this discussion, you’ve offered no reason to think #2 more likely than #1, and in any case you haven’t made any attempt to explain how it could happen.
The PDF does not appear to contain the sentence you purport to quote from it. (More specifically, it does not appear to contain the word “flips”. (Neither does the abstract.) In any case, its proposal seems to amount simply to redefining “time reversal”. If all you’re saying is that if you use “T symmetry” to mean what everyone else calls “CPT symmetry” then physics is likely to be T-symmetric but not CPT-symmetric, then (duh!) I agree, but I’m not sure why that’s supposed to be interesting.
Section 2.4 page 32. Searching for “flips” doesn’t work here either. Copy-n-paste into a text editor shows why—fi and fl are weird ligatures in this PDF.
To quote from the article:
It’s plainly proposing T symmetry. Does that help you to see how such a thing might be possible?
Aha, of course. (I did search for some other substrings, though I forget what. Presumably they also contained ligatures. D’oh.)
… in Malament’s proposal, which is not the same as the Feynman one you cite earlier. The purpose of the paper is to argue for a definitional change whereby we call “T” what is currently generally called “CT”. Everything in the paper is concerned with classical, not quantum, electrodynamics. The paper does not argue that T symmetry (as generally understood or with a revised definition) is plausibly true in quantum electrodynamics.
It would make this discussion more pleasant for me if you’d be less patronizing. Whether you care about that is, of course, up to you.