Читать книгу Planet Formation and Panspermia - Группа авторов - Страница 31

Without much of an approximation, we could consider that life as we experience it is powered by the Sun. The chemical elements that constitute both, living and other matter, are forged in stars. Also, the planets and their stellar hosts are condensed from gaseous matter that accumulated in galaxies. The conglomerates of galaxies are the building blocks of our universe. Within these clusters, the galaxies mutually interact and merge, which can heavily change their interiors. Galactic habitability would thus incorporate habitability phenomena between the level of individual stars/planetary systems and the cosmological level. The basic habitability features of these levels and their possible relation to the panspermia hypothesis are outlined, which, in essence, is a discussion of a potential for matter exchange. Figure 4.1 presents a sketch of these basic levels and their relations which are described in the remainder of this section.