A Safe Beginning for the Universe?

Understand

When general relativity is augmented by quadratic gravity terms, it becomes a renormalisable theory of gravity.

• This theory may admit a non-Gaussian fixed point as envisaged in the asymptotic safety program, rendering the theory trustworthy to energies up to the Planck scale and even beyond.
• We show that requiring physical solutions to have a finite action imposes a strong selection on big-bang-type universes.
• More precisely we find that, in the approach to zero volume, both anisotropies and inhomogeneities are suppressed while the scale factor is required to undergo accelerated expansion.