Ram Brustein

TL;DR: In this article, the authors consider whether current notions about superstring theory below the Planck scale are compatible with cosmology and find that the anticipated form for the dilaton interaction creates a serious roadblock for inflation and makes it unlikely that the universe ever reaches a state with zero cosmological constant and time independent gravitational constant.

TL;DR: In this paper, the authors explore various pitfalls and challenges in determining the equation of state (w) of the dark energy component that dominates the universe and causes the current accelerated expansion, and show that standard practices, such as assuming that w is constant or greater than ε(n), can also lead to gross errors in estimating the true EO of state.

TL;DR: It is shown that the method for determining precisely the current value and time variation of the equation of state, w, of the dark energy component responsible for the accelerated expansion of the Universe is fundamentally limited by the fact that luminosity distance depends on w through a multiple integral relation.

TL;DR: In this paper, the required sensitivity for detection of predicted gravitational radiation is estimated and a region of the parameter space is within reach for some of the planned gravitational-wave detectors, where a large class of string-cosmology backgrounds leads to a spectrum of relic stochastic gravitational waves, strongly tilted towards high frequencies.

TL;DR: In this article, it was shown that the Noether charge entropy is equal to a quarter of the horizon area in units of the effective gravitational coupling on the horizon defined by the coefficient of the kinetic term of a specific metric perturbation polarization.