A new theory of the universe

by Neil Turok

Wednesday 29 Mar 2023, 11:30 → 13:30 Europe/Zurich

4/3-006 - TH Conference Room (CERN)

Observations of the universe on very small and large scales have revealed a surprising economy in its basic laws and structure. In this light, we have simpler solutions to cosmology’s central puzzles. Instead of postulating a pre-hot big bang period such as inflation, we extrapolate the observed universe all the way back to the singularity. Instead of adding new particles and forces, we assume only the Standard Model (including right handed neutrinos) and improve it to maintain local scale symmetry. With this improvement, the hot plasma does not “see” space shrink away at the singularity, which becomes a kind of mirror. Our picture makes the simplest-yet proposed dark matter candidate -- a stable, right handed neutrino -- viable.  We calculate the gravitational entropy for realistic cosmologies, with radiation, matter, lambda and space curvature and find it favours flat, homogeneous and isotropic universes like ours, with a small positive cosmological constant. We show that dimension zero fields - which have a nontrivial vacuum as their only physical state - can cancel the vacuum energy and trace anomalies in the SM, at leading order, provided there are three families of elementary particles. They also provide a new explanation for the primordial density fluctuations. Subject to two key theoretical assumptions, the amplitude and spectral tilt are calculable in terms of Standard Model couplings and agree with the observed values, with no free parameters. In principle, all features of the LCDM model are thereby explained without the need for inflation or any new particles. (See arXiv:2302.00344 and references therein).