Abstract Using arguments from holography we propose that the deviation of cosmological spectral index $$n_S$$ n S scalar fluctuations unity may be controlled almost entirely by critical exponent $$\eta $$ η $$d=3$$ d ...

(Abridged) Does inflation have to happen all in one go? The answer is a resounding no! All cosmological problems can be solved by sequence of short bursts cosmic acceleration, interrupted epochs decelerated expansion. spectrum perturbations will still match the CMB and LSS if earliest stage last ${\cal O}(50)-{\cal O}(60)$ efolds at least O}(15)$ long. Other stages considerably shorter. But as ...