Thank you for writing and commenting, Mike!
- You’re right in questioning this. Just like most of the other variables, this one includes a lot of bias. In the case of Earth, we consider any large populace that is somehow organized and separate from other groups (geographically, ethnically, etc.) to be a civilization. But at what point do we consider all the people of Earth to belong to the same civilization? It seems we are getting to that point.
- Definitely. Every time we are able to look deeper into the sky and with more detail we find more stuff.
- Very good point here. There may be only a short window of time in which a planet is randomly sending signals outward into space, as well. But if they are curious like we are, then perhaps they will continue to do so just as a calling card.
- Here I would guess that the closer to the center of a galaxy would be far less hospitable, since the increased density of stars would mean a lot more gamma ray bursts, supernovae and probably space debris/asteroids/comets. There would be more planets, since more stars = more planets, but they would be getting pummeled. So where Earth is, in one of the outer spiral arms, is probably in the “zone” for a galaxy.
- Exactly. And as a science fiction writer I’m sure you have read about or imagined numerous other modes of communication, some of which may be more or less possible, such as via worm holes other dimensions. Our galaxy, let alone the universe, are simply too big for us to ever assume we know any significant portion of what’s possible.