From Sean Carroll, discussing his arXiv paper (a chapter in an upcoming book, Routledge Companion to the Philosophy of Physics) at Preposterous Universe:
It seems natural to ask why the universe exists at all. Modern physics suggests that the universe can exist all by itself as a self-contained system, without anything external to create or sustain it. But there might not be an absolute answer to why it exists. I argue that any attempt to account for the existence of something rather than nothing must ultimately bottom out in a set of brute facts; the universe simply is, without ultimate cause or explanation. More.
He adds,
[t]his kind of question might be the kind of thing that doesn’t have a sensible answer. In our everyday lives, it makes sense to ask “why” this or that event occurs, but such questions have answers only because they are embedded in a larger explanatory context. In particular, because the world of our everyday experience is an emergent approximation with an extremely strong arrow of time, such that we can safely associate “causes” with subsequent “effects.” The universe, considered as all of reality (i.e. let’s include the multiverse, if any), isn’t like that. The right question to ask isn’t “Why did this happen?”, but “Could this have happened in accordance with the laws of physics?” As far as the universe and our current knowledge of the laws of physics is concerned, the answer is a resounding “Yes.” The demand for something more — a reason why the universe exists at all — is a relic piece of metaphysical baggage we would be better off to discard. More.
Biophysicist Kirk Durston writes to say,
The word ‘suggests’ in a science paper is what I regard as a filler word to make up for the lack of actual data and results.
I don’t understand why Carroll is avoiding the problem of the universe having a beginning, unless he believes the universe is infinitely old, but that would conflict with the problem of traversing an actual countable infinite number of years before we could get to this one; we never would. I wonder if Carroll is failing to adequately distinguish between reality and mathematical models. I wrote a blog about his failure to do so a couple years ago here.
If Carroll is right, there is no science-based reason to consider a multiverse at all but how many cosmologists of his ilk would care to go there? Durston above assumes that modern cosmology will be expected to follow traditional rules of argument but, as post-modernism continues its trajectory, that may be increasingly contested.
Note: Carroll’s argument simply explained.
See also: Cosmologist Sean Carroll: A multiverse is “beyond falsifiability” – and that’s okay with him
Kirk Durston: Cosmologist Sean Carroll simply asserts “a conclusion with no supporting argument”
Durston and Craig on an infinite temporal past . . . (kairosfocus)
The Big Bang: Put simply, the facts are wrong.
and
Can the rot of naturalism be stopped? Relating information to matter and energy might help