In a recently posted interview with theoretical physicist Sean Carroll, atheist podcaster Alex O’Connor invites Carroll to give his opinions and criticisms of the fine-tuning argument for God. Not surprisingly, Carroll champions the multiverse concept as his candidate to account for the multiple physical parameters that have values within a finely tuned range necessary for life to exist.
With the multiverse hypothesis, a key supposition is that the physical parameters within alternative universes somehow vary over an undefined range, with the acknowledgement that most variants turn out badly for life. Our existence is therefore “explained” in that we landed in a “lucky” space, tautologically required for us to be alive, let alone to engage in philosophical debates.
How could anyone not be convinced by such a dismissal of the fine-tuning argument? As Carroll concludes, with his glib assessment of fine-tuning, “It’s a terrible argument.”
Sorely Lacking
Despite Carroll’s assertion that the multiverse explanation is scientific, it is sorely lacking in a foundational requirement of any scientifically founded concept — experimental or observational evidence. In almost the same breath, Carroll feints with the multiverse putdown to fine-tuning while admitting that scientific reasons for the multiverse are not “airtight,” but arise from “speculative” theories. But even if a multiverse did exist, there are reasons to discredit its utility as a defeater for the fine-tuning argument.
A scientific understanding of nature reveals that, given the constraints of the laws of nature (or given the way nature behaves), natural outcomes tend to fall within rather narrow ranges. For example, with about a trillion times 200 billion stars in our universe, every last one of them has properties within well-defined ranges, out of all imaginable values. The lowest mass star is about 0.08 of the Sun’s mass, and the most massive star tops out around a couple hundred times the Sun’s mass.
Not a Single Star
In our whole universe there is not a single star with a mass as low as the mass of Earth. Why not? Simply because the fixed laws of physics prohibit such a low-mass star. Given the values of the fundamental forces, with a mass as low as the Earth’s, the force of gravity could never compress that mass sufficiently to heat it to the point of igniting nuclear fusion. To paraphrase an old idiom, “That star won’t shine.” Even if this universe were a million times bigger or older, the range of observable star masses would not extend to Earth-mass stars.
Many other examples of the “sameness” of natural outcomes could be given. Consider how many naturally occurring elements have come to exist in the entire space and time of our universe — only 94, even counting extremely short-lived elements. Why not more? Because of the constraints of the laws of nature and its fundamental forces.
So, an honest inspection of how nature behaves casts doubt on the multiverse supposition that every combination of the laws of physics and fundamental parameter values would be instantiated in various universes. If our study of the nature of our own universe is any guide (and we have no observable basis to assume otherwise), whatever physical mechanism is responsible for generating alternative universes would most likely be physically constrained to produce outcomes within a narrowly defined range.
And so, even if a multiverse of universes exists, we are brought back to the original question of why the limited range of parameters within those universes includes the combination necessary for life to exist. We conclude that the multiverse concept, if it is valid, merely magnifies the conundrum of why any universe congenial for life came into existence.
Our “Necessary Luck”
Carroll and O’Connor nonetheless bravely evoke the multiverse to attempt to explain our “necessary luck” in finding ourselves in a universe finely tuned for life. Carroll even defends his approach with a reasonable appeal: “that’s just the way science does it.” But surely, a legitimate scientific explanation should not contradict what we have already learned from established science, nor should a proposed explanation be considered satisfactory if it only purports to explain part of the issue at hand.
In the discussion of fine-tuning, the main issue is the existence of life, including complex, multicellular intelligent life on planet Earth. To act as if the problem of the anthropic tuning of nature to allow life’s existence is solved by the multiverse is disingenuous. Even if our universe just happened to arise with physical parameters that allow life, this fortuitous physical outcome does nothing to explain the more pressing issue of accounting for the actual origin of life.
The functional complexity of living things, associated with their vast information content, lies across a gulf unbridgeable by any natural process of our finely tuned physical universe. An honest appraisal of all the evidence points beyond materialism to an intelligent mind, consistent with the biblical view of God, as the designer of the universe and life on Earth.