The previous chapter ended with a civilization trying to keep enough room for the future. This chapter asks what that room might eventually be used for. Humanity can remain confined to its birthplace, or it can begin the long work of establishing durable homes beyond Earth.
The stars are not a near-term forecast. Even the first independent settlement elsewhere in our solar system lies beyond anything we have built. Following the path seriously reveals why population matters: exploration can be performed by a crew, while expansion requires generations. We begin with the reason to attempt it at all.