Can Cosmology Provide a Test of Quantum Mechanics?

Inflation predicts that quantum fluctuations determine the large scale structure of the Universe. This raises the striking possibility that quantum mechanics, developed to describe nature at short distances, can be tested by studying nature at its most immense -- cosmology. We illustrate the potential of such a test by adapting the simplest form of the inflationary paradigm. A nonlinear generalization of quantum mechanics modifies predictions for the cosmological power spectrum. If we assume that the nonlinear parameter $b$ is a comoving quantity observational cosmology, within the context of single field inflation, is sufficiently precise to place a stringent limit, $b\leq 3\times 10^{-37}$ eV, on the current, physical size of the nonlinear term.