But before we even consider the existence of life anywhere in the universe, it takes a precise balance of converging forces and phenomena to allow galaxies to form in the first place; and again to allow fusion to occur in stars, thus assembling the building blocks of life. And so on. The odds against us being here appear quite literally astronomical.
There are *many* things wrong with this line of argument.
1. We don't know that the constants *can* change. As of now, we have not detected any changes nor is there any good theory that describes how they could change.
2. If the constants *can* change, we don't know if there is a natural dynamic giving rise to the values we see now. In other words, the currant values might be an equilibrium state arrived at after some dynamics. Maybe the dynamics maximize complexity....
3. The argument assumes we have the right constants and that they are independent. The latter, especially, is doubtful. maybe the values we see are the result of fewer constants.
4. Related to this is the assumption that we have the right laws of physics (and thereby the right constants). I don't know of any physicists that would claim this at this point. For example, we certainly do NOT understand dark matter or dark energy.
5. Dark matter shows that either we don't understand gravity very well OR that we don't understand particle physics very well. Either way would have a huge impact on those constants.
6. Dark energy shows we don't understand much about the quantum aspects of gravity (ever hear of the prediction off by 120 orders of magnitude?). Again, as we learn more, we *expect* that the laws and underlying constants will be understood differently.
7. It is very much NOT clear what other values to the constants would lead to. We have to be very careful to not think the universe was made for *us* as opposed to us developing in this universe.
8. The argument is much stronger if the 'goal' is the production of stars and galaxies as opposed to thinking it is the formation of life. There are plenty of stars and galaxies, from even the earliest times (well, within the first few hundred million years). Life doesn't seem to have started until at least 10 billion years in. More of an afterthought, I'd say.
And I’m not sure the anthropic principle resolves anything. It reminds me of a British army drinking song, popular during postings to obscure places; “we’re here because we’re here because we’re here because we’re here…” Incontrovertibly true, but what does it tell us? Nothing we didn’t already know.
Yes, at one level it is rather vacuous.
Various multiverse theories do resolve the statistical improbability of our bring here, since in the context of a near infinite number of universes, the improbable becomes inevitable. But since all such theories are non-empirical and unfalsifiable, we’re in the realms of philosophy when we embark on such speculation; not a problem for me, I suspect it may be to you though.
Actually, it isn't the case that the theories are unverifiable. For example, most attempts we have made towards quantum gravity naturally lead to such a multiverse. If (and when) such theories are tested in *this* universe, if they work well enough, it would add to the acceptance of the overall multiverse description. This is still very much in the future, but is not at all unreasonable.
Most physical theories have aspects that are not directly testable, but are required for the theory to *be* testable in some aspects. it may well be that any workable theory of quantum gravity necessarily leads to a multiverse description. Time will tell.