We often hear the argument, that if just one of the fundamental constants were slightly, very slightly different, we wouldn’t be here. There would be no stars, no planets and therefore no us.
I doubt that we have simulated a universe with a bit smaller gravity constant and a bit faster light, very deeply. Yes, I can imagine a sky with no stars! But I am not sure if a weaker gravity causes that. Maybe some bigger stars would still be there, producing some strange chemistry, even more suitable for complex molecules. We haven’t calculated that yet. Not thoroughly.
I don’t know. Maybe they would, maybe they wouldn’t. A weaker gravity could mean a weaker anti gravity (repulsion) and therefore a more stable universe than ours.
The fact is, we don’t know what would be if the fine constant were slightly different. Saying that only a small fraction of possible universes can harbor complex processes like life, is a jump to the unknown. Not to the known.
They talk like this Universe was full of life, and that this Galaxy alone inhabits at least a million civilizations. It seems as if they haven’t updated since Sagan. The Galaxy looks very much empty now, and the Universe not particularly friendly to life.
A small change in the set of fundamental constants would perhaps give us another universe, approximately as hostile as ours.
I don’t see a good reason for the so called Strong Anthropic Principle, which claims that other universes would be much less hospitable for life. We are already living in one very inhospitable Universe right now! There is little room for the worsening of life conditions.
Based on that, I reject the SAP.