For the sake of other readers, what is being alluded to is the old drum I and others keep banging, to the effect that science makes models of reality that work, insofar as predicting further observations, but can never be taken to be final or definitive "truth".
This is not to put science and religion in the same category. Unlike religious ideas, the models of science are tested against objective observation of nature (or as near to that as we can get) and are continually adapted and refined accordingly. But we do in science happily use for convenience models we know are incomplete and thus in a strict sense at least partly "fictional", so long as they work*.
Also, among the more aesthetic tools used to evaluate the plausibility of a 'theory', theoretical physicists consider such things as "
explanatory power", "
elegance", "
simplicity" (i.e. Occam's Razor) and even "
beauty" (in terms of mathematical beauty, I mean):
Elegant Science
Elegance is a prized quality in science that is associated with simplicity and explanatory power. This essay considers the qualities that make a scientific model, experiment, method, or theory “elegant,” with a focus on the life sciences. We propose a definition of elegance that includes clarity, cleverness, correctness, explanatory power, parsimony, and beauty. The pursuit of elegance can improve the quality of science, but elegance must be pursued with caution, as the truth is sometimes inelegant.
Obviously, testability and empiricism are foremost (and this differentiates scientific models from religious frameworks, that they can - or rather
should - make testable predictions about reality).
But - and this is something of a related but distinct topic - recently there has been a
tendency among a number of physicists (and a somewhat worrying one, arguably) as a result of the failure of high-energy particle accelerators to find exotic new physics (and the concern that we might be reaching the limits of what we can viably experiment at our present energies), to
divorce science - or at least particle physics - from the criterion of testability.
The inflationary, cosmological multiverse arising from a “string landscape” (for instance) is an example of this 'trend'. Now, its possibly compelling if viewed as a speculative hypothesis. After all, it has explanatory power and might make good sense of the data - so there is a logical possibility of us living in an ever expanding megaverse of unlimited physical possibilities, which might explain why the cosmological constant has an unnaturally small, knife-edge value in our universe.
However, does it make any testable scientific predictions within the observable universe? Nope. Professor Sean Carroll vigorously supports the validity of “
non-empirical confirmation”, or rather the idea that the multiverse has explanatory power and solves otherwise intractable fine-tuning problems in relation to the vacuum energy and hierarchy conundrum, which means it should therefore be accepted as a scientific theory even though it is incapable of making any testable predictions and is itself predicted by other frameworks that are likely to be untestable, such as superstrings.
At present, the string-landscape multiverse is fundamentally beyond the realm of empirical test (just like God), with no possibility of direct or indirect testability (given that the "
bubble collision" idea in the CMB appears to be a false hope).
Here's Carroll talking about it:
Edge.org
"…2014 : WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT?
Sean Carroll
Theoretical Physicist, Caltech; Author, The Big Picture
Falsifiability
…Modern physics stretches into realms far removed from everyday experience, and sometimes the connection to experiment becomes tenuous at best. String theory and other approaches to quantum gravity involve phenomena that are likely to manifest themselves only at energies enormously higher than anything we have access to here on Earth. The cosmological multiverse and the many-worlds interpretation of quantum mechanics posit other realms that are impossible for us to access directly.
Some scientists, leaning on Popper, have suggested that these theories are non-scientific because they are not falsifiable.
The truth is the opposite. Whether or not we can observe them directly, the entities involved in these theories are either real or they are not. Refusing to contemplate their possible existence on the grounds of some a priori principle, even though they might play a crucial role in how the world works, is as non-scientific as it gets.
It’s the “empirical” criterion that requires some care. At face value it might be mistaken for “makes falsifiable predictions.” But in the real world, the interplay between theory and experiment isn’t so cut and dried. A scientific theory is ultimately judged by its ability to account for the data—but the steps along the way to that accounting can be quite indirect...
But in the real world, the interplay between theory and experiment isn’t so cut and dried. A scientific theory is ultimately judged by its ability to account for the data—but the steps along the way to that accounting can be quite indirect."
Here’s his words above with only a few point modifications, to illustrate how an apologetic theist might argue using similar logic to Professor Carroll:
“Some scientists, leaning on Popper, have suggested that these theories [about God] are non-scientific because they are not falsifiable.
The truth is the opposite. Whether or not we can observe Him directly, the Creator involved in this theory is either real or He is not. Refusing to contemplate His possible existence on the grounds of some a priori principle, even though He might play a crucial role in how the world works, is as non-scientific as it gets.
It’s the “empirical” criterion that requires some care. At face value it might be mistaken for “makes falsifiable predictions.” But in the real world, the interplay between theory and experiment isn’t so cut and dried. A scientific theory is ultimately judged by its ability to account for the data—but the steps along the way to that accounting can be quite indirect.
The Creator might be inaccessible to us, but He is part of the theory that cannot be avoided”
For a competing perspective from Carroll's, by two physicists defending the integrity of the traditional scientific method:
Scientific method: Defend the integrity of physics
16 December 2014
Attempts to exempt speculative theories of the Universe from experimental verification undermine science, argue George Ellis and Joe Silk.
This year, debates in physics circles took a worrying turn. Faced with difficulties in applying fundamental theories to the observed Universe, some researchers called for a change in how theoretical physics is done. They began to argue — explicitly — that if a theory is sufficiently elegant and explanatory, it need not be tested experimentally, breaking with centuries of philosophical tradition of defining scientific knowledge as empirical. We disagree.
Chief among the 'elegance will suffice' advocates are some string theorists. Because string theory is supposedly the 'only game in town' capable of unifying the four fundamental forces, they believe that it must contain a grain of truth even though it relies on extra dimensions that we can never observe. Some cosmologists, too, are seeking to abandon experimental verification of grand hypotheses that invoke imperceptible domains such as the kaleidoscopic multiverse (comprising myriad universes), the 'many worlds' version of quantum reality (in which observations spawn parallel branches of reality) and pre-Big Bang concepts.
These unprovable hypotheses are quite different from those that relate directly to the real world and that are testable through observations — such as the standard model of particle physics and the existence of dark matter and dark energy. As we see it, theoretical physics risks becoming a no-man's-land between mathematics, physics and philosophy that does not truly meet the requirements of any.
The issue of testability has been lurking for a decade. String theory and multiverse theory have been criticized in popular books1, 2, 3 and articles, including some by one of us (G.E.)4. In March, theorist Paul Steinhardt wrote5 in this journal that the theory of inflationary cosmology is no longer scientific because it is so flexible that it can accommodate any observational result. Theorist and philosopher Richard Dawid6 and cosmologist Sean Carroll7 have countered those criticisms with a philosophical case to weaken the testability requirement for fundamental physics.
Instead of belief in a scientific theory increasing when observational evidence arises to support it, [Dawid] suggests that theoretical discoveries bolster belief. But conclusions arising logically from mathematics need not apply to the real world. Experiments have proved many beautiful and simple theories wrong, from the steady-state theory of cosmology to the SU(5) Grand Unified Theory of particle physics, which aimed to unify the electroweak force and the strong force. The idea that preconceived truths about the world can be inferred beyond established facts (inductivism) was overturned by Popper and other twentieth-century philosophers.
Increasingly, the 'string landscape' theory - "
an elaborate proposal for how minuscule strings (one-dimensional space entities) and membranes (higher-dimensional extensions) existing in higher-dimensional spaces underlie all of physics" - and the particular variant of the multiverse theory dependant upon these speculative string vacua, is looking more and more like metaphysics rather than physics as the criterion of testability / empirical evidence is downplayed in favour of the sheer explanatory power, elegance and beauty of the "theory" itself.
The appeal of 'religious' explanations is not entirely dissimilar - people find a certain creation myth or metaphysical narrative especially 'elegant' or 'beautiful' in its explanatory power, over other ones (even if we cannot make a testable prediction from it).