re: #108 Love-Child of Cassandra and Sisyphus

Many civilizations could have popped up in our own galaxy, and gone extinct, before our solar system even formed.

Unlikely. It takes two successive supernova events to make a lot of the higher-order elements we depend on for life and after that happened it has taken about a third of the lifespan of the universe from the Big Bang (about 4 billion years) for the Earth to form and stabilise to the point where life could develop. We may in fact be the first or nearly the first self-aware tool-using intelligent lifeform in this galaxy or indeed in the entire universe.