Galactic traversability: a new concept for extragalactic SETI

Interstellar travel in the Milky Way is commonly thought to be a long and dangerous enterprise, but are all galaxies so hazardous? I introduce concept of galactic traversability address this question. Stellar populations one factor traversability, with higher stellar densities velocity dispersions aiding rapid spread across galaxy. The interstellar medium (ISM) another factor, as gas, dust grains, cosmic rays (CRs) pose hazards starfarers. review current understanding these components different types galaxies, conclude that red quiescent without star formation have favorable traversability. Compact elliptical globular clusters could "super-traversable", because stars packed tightly together there minimal ISM hazards. Overall, if major hindrance travel, increases time gas fractions decline. Traversability consideration extragalactic surveys for search extraterrestrial intelligence (SETI).