The resolution of the time- like cosmological singularity with orientifolds provides well defined boundary conditions, which are necessary to determine past/future transition amplitudes for quantum fields. In particular, we have considered the vacuum to vacuum amplitude. Assuming the trivial vacuum in the past, we have derived a thermal spectrum for radiation in the far future. A careful calculation shows that an observer in the far future will see a thermal spectrum with temperature T= ε / 2π a(τ), (4.1) as expected for radiation in a (d + 1)-dimensional cosmology. The new space-time global structure together with the orientifold singularity resolution, provide new venues of research in cosmology. In particular, one should revisit standard questions in cosmology by allowing for the possibility of the big-bang being replaced by a cosmological horizon.
展开▼
