Multi-brane cosmology

5D warped extra dimension models with multiple 3-branes can naturally realize hierarchical mass scales which are ubiquitous in physics beyond the Standard Model. We discuss cosmological consequences of such multi-brane stabilized radions. It is confirmed that for temperatures below scale IR brane at end dimension, we recover ordinary expansion Universe, Hubble rate determined by sum physical energy densities on all where they localized. In addition, explore cosmology above intermediate and branes Universe described a spacetime replaced an event horizon. As temperature cools down, phase transitions expected to take place, come out from behind The Goldberger-Wise mechanism radion stabilization has well-known problem having supercooled transition, typically does not get completed time. This even more severe when introduced, whose well TeV, as corresponding much larger. circumvent employing alternative dark Yang-Mills fields, prevents long supercooling epoch, but still allows strong first order transitions. result, our predict stochastic gravitational wave background unique multi-peak signature, within sensitivity reach future space-based observers. also show there $N-1$ radions $N$ 3-brane set-up, unlike recent claim exists only one radion.