The only way to cross a galaxy from one end to other in human-life-span is to warp space-time to such extent that a small tunnel is generated that connects the two ends of the galaxy. It is still in the realm of science fiction.
However, seven circular structures deep in the dense forests of Sunderbans are the gateways of such tunnels. Nobody knows for sure but some believe that several such tunnels exist in different parts of the globe. It is claimed that Harppans, Ancestral-Puebloans, Minoans, etc migrated through these tunnels.
Mathematically these are commensurate with our neighboring planets.
Words ~ 100
Thanks for the prompt Rochelle Wisoff-Fields. SHALOM.