Implication of the Superstring theory on Astrophysics and Cosmology

Under the spirit of J. Polchinsky's introduction of D-brane in the string target spacetime (or 'bulk', for short), we consider the presence of both closed and open superstrings and coupling of their low-lying modes in the bulk. As a probe to explore the astrophysical and cosmological implications of the superstring theory at larger length scale or in low-energy dynamics, we construct the Yang-Mills monopole black hole solution and investigate its features. Our results exhibit that as a result of intimate interactions among low-lying modes, some cherished features of classical gravitation and cosmology break down. They are the violation of black hole no-hair theorem and the break down of cosmic censorship hypothesis. We learn from this lesson that these implications of fully developed superstring theory in classical gravitation and cosmology largely depart from our conventional wisdom signaling that the most current version of superstring theory is indeed the best candidate for quantum theory of gravitation.