  Experimental evidence over a number of recent years has shown the density
parameter of the universe omega converging to the critical value of 1, which
defines a flat, Euclidean universe. No such calculations have defined a
critical value for the most significant component of omega, that for the dark
energy, omega lambda, but the new data provided by the Planck probe open up the
previously unconsidered possibility that a particular value with special
physical significance occurs at omega lambda = 2/3. If future observations
should converge on exactly this value, then we may have the first indication
that the explanation for this phenomenon lies in necessary constraints provided
by fundamental laws of physics on possible cosmologies for the universe.
