Photographing the wave function of the Universe

Abstract

We show that density fluctuations in standard inflationary scenarios may take the most general non-Gaussian distribution if the wave function of the Universe is not in the ground state. We adopt the Schrödinger picture to find a remarkable similarity between the most general inflaton wavefunction and the Edgeworth expansion used in probability theory. Hence we arrive at an explicit relation between the cumulants of the density fluctuations and the amplitudes or occupation numbers of the various energy eigenstates. For incoherent superpositions only even cumulants may be non-zero, but coherent superpositions may generate non-zero odd cumulants as well. Within this framework measurements of cumulants in Galaxy surveys directly map the wavefunction of the Universe.