Let me sum up, try to anticipate any questions, and move these results back into a discussion of general cosmology.
The whole giant digression involving QR took place because I wanted to take the proposition that God could not make a universe where 2 is not the successor of 1 to a higher level, on a road to what might even include all of mathematics, but at minimum enlarging the statement to God could make no universe where the statements of mathematics would be false, from at least the founding axiom through to somewhere beyond the law of quadratic reciprocity. Anything theoretically true here would be theoretically true in any other universe as well, and vice versa.
No such universe is imaginable, might be a less religiously provocative way of stating it. Now that I can state it, there is only to wrap up the discussion of QR and return to cosmology, where the above will be one of the postulates of my personal philsophy within cosmology--mathematical cosmology, I suppose.
A gem that comes out of this is that we have the capability to understand any universe, and any universe of any description, no matter how different from our own, would have the capability of understanding our universe. That capability, consisting of mathematics and its growing extensions, would remain invariant across universes, while retaining its elastic variability and variety.
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Eisenstein's P by Q rectangle must be viewed as a scaling object, just as if we had two gears intermeshing with radii corresponding to the lengths of the two 4n+3 primes, it expresses their ratio. I think his rectangle must be the simplest scaling object for this problem.
As I suspected a while back, the problem is a paucity of 2's when both primes are 4n+3. Once the rectangle is divided into four quadrants, there is no 2 left over, in other words, each quadrant contains an odd number of lattice points. That paucity of 2's forces the diagonal to cut the smaller rectangle of WAYX into two unequal halves of different parity.
The dimensions of the interior rectangle within ABCD containing only interior lattice points is
(p-1)(q-1).
This is none other than Euler's phi function Φ(p), the measure of how many numbers less than p are prime to it. There are sixty lattice points in the interior of ABCD. Points on the perimeter are not prime to one or other prime, so cannot be included. As usual, (mod 0) not allowed.
Once odd primes have the extra freedom of at least one more factor of 2, the problem is resolved, and the two primes are forced to act together, forced to the same parity because their smaller rectangle contains an even number of lattice points.
At the beginning, Eisenstein calculates the number of even lattice points in ABCD. He knows if they are aysmmetrical in the two halves of ABCD, so will the odd lattice points be, to make up for the discrepancy. The number of even lattice points in ABCD is of course thirty. His initial additive method was good enough for the parity of p, (-117), but not good enough to obtain q's parity.
(P-1/2)(q-1)/2) is indeed the total number of points in WAYX, 1/4 of the total points in ABCD, and 1/2 the number of even points.
-1(5)(3) is -1(60/4) or -1Φ(p)/4 after all. So Eisenstein's exponents are correct not only in their parity but they are also the "appropriate" exponents in that they are a factorization of the number of lattice points in WAYX. More importantly, (p-1/2) and (q-1/2) are the number of quadratic residues for each prime, we already know.
Now, that is everything about Eisentein's rectangle. Does it really prove quadratic reciprocity?
Yes, here is why I think so. Since (p-1/2) and (q-1/2) are a simple count of the number of quadratic residues for each prime, and their product is used as an exponent to count -1 back and forth from negative to positive, both are represented, and their product forms the dimensions for the rectangle of inner points of WAYX, and the exponentiation's result can only be negative when both (p-1/2) and (q-1/2) are odd.
For me that quite settles the issue, not only for 4n+3 prime pairs but for any prime pair, excluding 2, which I can recite the forumla for but have not yet reasoned out. My focus has been the 4n+3 primes, knowledge of which I hoped would illuminate the triggering mechanism for other prime pairs as well, which has happened for me.
4n+3 primes have to be the same thing in any universe. The only fundamental difference between 4n+1 and 4n+3 numbers is the degree of evenness when you subtract 1 from them.
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Now that we all know this fundamental fact of numbers and how it constrains universes, we can proceed with broader cosmology again.

