Scale invariance in cosmology and physics

The fundamental laws of physics are required to be invariant under local spatial scale change. In 3-dimensional space, this leads to a variation in Planck constant \hbar and speed of light c. They vary as \hbar ~ a^(1/2) and c ~ a^(-1/2), a is the local scale. A direct consequence is that the expanding universe progressively alters the values of c which in turn affects the evolution of the universe itself. Friedmann eqns violate scale invariance and neglect to account for the scale dependency of c. We build a cosmological model which is fully consistent with scale invariance and respects Lorentz invariance. This model leads to a universe different from the ones depicted in Friedmann model. We apply our model to resolve a series of observational and theoretical difficulties in modern cosmology: "runaway density parameter" problem, budgetary shortfall, horizon problem, eg. Our model does not resort to inflation hypothesis. We derive a modification to the Hubble law and Hubble constant, and a new brightness-redshift relationship for Type Ia supernovae: (a) Hubble constant has been inadvertently overestimated by a factor of 9/5; so has the critical density by (9/5)^2; (b) Our new photometric distance-redshift relationship d_L=2c/(3H0)*(1+z)^(5/6)\ln(1+z) with one parameter H0=37 fits to the high-$z$ objects as equally well as the traditional relationship does with three parameters H0=70.5, OmegaM=0.27, OmegaL=0.73. We draw two conclusions: (i) With H0=37, the critical density is only 0.28 time the value previously thought; dark energy is absent. (ii) H0=37 restores the age estimate to 17.6 Gy (via t_0=2/(3H0)). They also raise the possibility that the universe expansion is not accelerating, but rather a result of c progressively adapting to new spatial scale as the universe expands. Finally, we discuss an array of implications of scale invariance in the larger context of physics.