  We suggest that behind the black hole information paradox is a new and
universal radiation mechanism, Gravity Induced Spontaneous Radiation, or GISR
hereafter. This mechanism happens to all kinds of compositional objects and it
requires only their microscopic structure as the basis. It's always accompanied
with such inner structures' variation and allows for explicitly hermitian
hamiltonian description. For black holes, by Wigner-Wiesskopf approximation we
show that such a radiation has a thermal spectrum exactly the same as hawking
radiation; while through numeric integration, we show that the variation of the
radiation particles' entropy exhibits all features of Page curve as expected.
We also provide exact and analytic solutions to the Einstein equation
describing microscopic structures required by the GISR of black holes and show
that, after quantisation the degeneracy of wave functions corresponding with
those solutions are consistent with the area law formula of Bekenstein-Hawking
entropy.
