The Cambias Digression

We've brought ourselves up to the present day in the evolution of the Earth, life, and human civilization. My estimates for the various filters we've passed through indicate that there ought to be around fifty other civilizations in the Milky Way. The principle of mediocrity suggests that a good half of those fifty should be…

In my previous posts on the topic of Great Filters, I've looked at all the hard science limits on life and intelligence on other worlds. Those limits left us with a ballpark figure of 5,000 intelligent species in the Milky Way. Now we're shifting to the "softer" sciences, with a focus on history and archaeology.…

I finished up last week's post on Great Filters by looking at the Galaxy according to the numbers I've cooked up. It produced the surprising figure of lifebearing planets every 50 light-years or so. In cosmic terms that's right next door. It means that in the near future we have a pretty decent chance of…

Having considered how uncommon Earthlike worlds are, now we're going to look at potential Great Filters in the history of life itself. The first is more of a meta-filter, and affects some of the possible stellar and planetary filters already discussed. It's simply this: what is the range of potential forms of life in the…

I've discussed galactic and stellar-scale Great Filters. Now it's time to look at them on a planetary level. The first is the question of how stable planetary systems are. This is a problem which goes back to Isaac Newton. When Sir Isaac compiled his great work the Principia, he was bothered by one implication of…

The first set of potential "Great Filters" I'm going to discuss are those which operate at the level of stars and galaxies — things which might make most galaxies, or most star systems, unsuitable for the development of life. But first, a digression. In science, especially in cosmology, the number 1 is a very funny…

Two weeks ago, during the world's first CYBER WorldCon, I participated in a panel discussion called "COVID-19: A Great Filter?" The panelists were myself, writer and Coronavirus expert Vylar Kaftan, and astrophysicist Valentin Ivanov. Our topic was the concept of the "Great Filter" and whether a plague like the current Coronavirus outbreak could qualify.         …