  I consider a class of Grand Unified models, in which E8 is broken to
SU(3)xSU(2)xSU(2)xSU(2)xU(1)_Y, then to SU(3)xSU(2)_{diag}xU(1)_Y. The breaking
of (SU(2))^3 to SU(2)_{diag} reduces the SU(2) coupling constant, at
unification, by a factor of 1/\sqrt{3}, so that the ratio of the SU(3) and
SU(2)_{diag} coupling constants, at unification, is equal to the ratio observed
at about 1 TeV. By choosing a suitable alignment of U(1)_Y, and introducing a
generalization of the CKM matrix, the U(1)_Y coupling constants of the observed
fermions, at unification, can also be arranged to have the ratios, to the SU(3)
coupling constant, that are observed at about 1 TeV. This suggests a model of
Heterotic M-Theory, with a standard embedding of the spin connection in one of
the E8s, but with the visible sector now having the E8 that is unbroken at
unification. The universe is pictured as a thick pipe, where the long direction
of the pipe represents the four extended dimensions, the circumference
represents a compact six-manifold, and the radial direction represents the
eleventh dimension. The inner radius of the pipe is about 10^{-19} metres, and
the outer radius of the pipe is about 10^{-14} metres. We live on the inner
surface of the pipe. The low-energy generation structure and the high mass of
the top quark follow from the breaking pattern, and gravity and the Yang-Mills
interactions are unified at about 1 TeV. Parity breaking must occur
spontaneously in four dimensions, rather than being inherited from ten
dimensions. The stability of the proton might be correlated with the entries in
the CKM matrix.
