
The two readings give different answers. In a frozen slice the class alternates along a worldline, as
Ref. [4] concludes. In the D
4
slices it is conserved. The next result decides between them.
Proposition 6 (The reading of the time slices) Suppose every time slice were the same FCC
lattice. Then each of the twelve time-mixed D
4
bonds, starting from an atom, would end on an
octahedral site, not on an atom. Every D
4
root joins two vacuum nodes only if consecutive slices are
the two FCC cosets.
The series treats all 24 roots of D
4
as bond directions of the vacuum [5]. The migration rule of Ref. [4]
also depends on them: a hop is a time-mixed D
4
bond, so every hop carries one tick. Both require
the D
4
reading, and the frozen slice does not describe physical worldlines. Under the D
4
reading
the class is conserved at every hop. A defect at rest oscillates between two adjacent voids [4], and
it keeps one class at every tick. The only dynamical input is the propagation rule of Ref. [4]: each
update advances the worldline by one D
4
bond. That rule is a postulate there. So class conservation
rests on that postulate, not on a choice of reading. It holds for the six edge channels, which are
the migration channels of Ref. [4]. A move along a purely spatial bond would flip the class, but
no migration channel is of that kind. [established; conservation is conditional on the propagation
postulate of Ref. [4]]
By the previous subsection, the sign of the spin–hop coupling is then conserved too. So each worldline
carries a fixed class, and parity reverses it. This revises one conclusion of Ref. [4], which argued that
the class cannot carry a conserved label because it flips at every hop. The class still cannot be
the matter–antimatter label: voids that are neighbors in one slice have opposite classes, so bound
matter would annihilate [4]. Instead it is a conserved label that parity reverses, the natural carrier of
handedness. The time orientation ε of the worldline remains the matter–antimatter label [4]. Charge
conjugation combined with parity then reverses both labels, just as CP relates left-handed matter
to right-handed antimatter in the Standard Model. [conditional]
A.8 Directed growth selects one class
Proposition 7 (Growth distinguishes the classes) Take the growth direction
ˆ
g = [111]. The
subgroup of the FCC point group that preserves
ˆ
g is C
3v
, of order 6. It maps each void class to itself.
Every element of the point group that exchanges the classes reverses
ˆ
g.
So in a crystal that grows along
ˆ
g, the two classes are not equivalent. One class points its apex along
the growth direction. The other points it against. This agrees with Proposition 3, because
ˆ
g is itself
the flip-odd ingredient. [established]
Trapping at a growing surface. In the growth picture of Section A.2, a remnant node of the
frozen foam is trapped when the growing crystal covers it. Suppose growth proceeds layer by layer
in one direction. Below we assume this holds across our observable universe, a patch far from where
growth began. Before the next layer arrives, a remnant node on the surface can rest only where the
surface holds it (Figure 3).
Proposition 8 (Surface trapping) Take a growing (111) surface, and keep a remnant node at
least 0.612L from every atom, its closest approach in a void. The node has three bonds in each of
the two kinds of three-fold hollow, at a depth of a quarter of the layer spacing. Atop a single atom it
has only one bond. When the next layer arrives, a node in the hollow that the layer covers ends in a
tetrahedral void whose apex points along
ˆ
g. A node in the hollow that the layer leaves open ends in
an octahedral void. This holds for both stacking choices of the next layer. A tetrahedral void whose
apex points against
ˆ
g is centered above a single atom of the grown layer, where no node can be held.
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