depict allowed regions for a variety of experimental measurements whose results depend on the weak mixing parameters $\rho,
\eta$, in the Wolfenstein parametrization of the CKM matrix. There is a consistent determination, and no evidence for physics beyond the standard model, in the region of overlap. Figure \[F2\]a is the contemporary situation; Figure \[F2\]b assumes the same data, but with the theoretical precision improved by a few teraflop-years of computation. You can see the value added.

Fantasies
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### Pinning Down $(g-2)_\mu$

Another recent heroic, beautiful, and outstanding achievement in experimental physics is the precision measurement of the anomalous magnetic moment of the muon, $(g-2)_\mu$, reported by the Brookhaven $g-2$ collaboration. In this case too, the significance of this result would be greatly enhanced if we could do a better job on the QCD ingredients, here low-energy vacuum polarization and light-by-light scattering. Our inability to do these calculations brings home the general point that the existing technology of lattice gauge theory is quite fragile, in the sense that it can be used to calculate a few things very well, but most others essentially not at all. So my fantasy here is of techniques that degrade more gracefully.

Actually, in the 