  We study a continuous quantum phase transition that breaks a $Z_2$ symmetry.
We show that the transition is described by a new critical point which does not
belong to the Ising universality class, despite the presence of well defined
symmetry breaking order parameter. The new critical point arises since the
transition not only break the $Z_2$ symmetry, it also changes the
topological/quantum order in the two phases across the transition. We show that
the new critical point can be identified in experiments by measuring critical
exponents. So measuring critical exponents and identifying new critical points
is a way to detect new topological phases and a way to measure
topological/quantum orders in those phases.
