LAUSR

I show that a generic quantum phenomenon can drive cosmic acceleration without the need for dark energy or modified gravity. When treating the universe as a quantum system, one typically focuses on the scale factor (of an FRW spacetime) and ignores many other degrees of freedom. However, the information capacity $\mathcal{S}$ of the discarded variables will inevitably change as the universe expands, generating a quantum correction [Phys. Lett. A 382, 36, 2555 (2018)|arXiv:1707.05789] to the Friedmann equations. If information could be stored at in each Planck-volume independently, this effect would give rise to a constant acceleration $10^{120}$ times larger than that observed, reproducing the usual cosmological constant problem. However, once information capacity is quantified according to the holographic principle ($\mathcal{S}=\mathcal{S}_\mathrm{h}$) cosmic acceleration is far smaller, and depends on the past behaviour of the scale factor. I calculate this holographic quantum correction, derive the semiclassical Friedmann equations, and obtain their general solution for a spatially-flat universe containing matter and radiation. Comparing these $\mathcal{S}_\mathrm{h}$CDM solutions to those of $\Lambda$CDM, the new theory is shown to be falsifiable, but nonetheless consistent with current observations. In general, realistic $\mathcal{S}_\mathrm{h}$CDM cosmologies undergo phantom acceleration ($w_\mathrm{eff}<-1$) at late times, predicting a Big Rip in the distant future.