  This Letter, i.e. for the first time, proves that a general invariant
velocity is originated from the principle of special relativity, namely,
discovers the origin of the general invariant velocity, and when the general
invariant velocity is taken as the invariant light velocity in current
theories, we get the corresponding special theory of relativity. Further, this
Letter deduces triple special theories of relativity in cosmology, and cancels
the invariant presumption of light velocity, it is proved that there exists a
general constant velocity K determined by the experiments in cosmology, for K >
0, = 0 and < 0, they correspond to three kinds of possible relativistic
theories in which the special theory of relativity is naturally contained for
the special case of K > 0, and this Letter gives a prediction that, for K < 0,
there is another likely case satisfying the principle of special relativity for
some special physical systems in cosmology, in which the relativistic effects
observed would be that the moving body would be lengthened, moving clock would
be quickened. And the point of K = 0 is a bifurcation point, through which it
gives out three types of possible universes in the cosmology (or multiverse).
When a kind of matter with the maximally invariant velocity that may be
superluminal or equal to light velocity is determined by experiments, then the
invariant velocity can be taken as one of the general invariant velocity
achieved in this Letter, then all results of current physical theories are
consistent by utilizing this Letter's theory.
