Pear Shaped nucleus could ruin time travel forever

https://www.sciencealert.com/physicists-discover-brand-new-nucleus-shape-time-travel-not-possible ; also, the size of the universe, both observable and invisible: https://www.forbes.com/sites/startswithabang/2018/02/23/if-the-universe-is-13-8-billion-years-old-how-can-we-see-46-billion-light-years-away/amp/