BDanielMayfield wrote:Then the modern Big Bang theory, as modified to account for accelerating universal expansion, is a theory that explains observations, but it does so with another major, fundamental unknown plugged in, which is dark energy. As you stated yourself Chris, dark energy’s “actual nature remains very unclear.”
I fear that even the scientifically literate tend to misunderstand what science is all about, sometimes.
Every theory is simply a mechanism designed to explain observations. Most non-trivial theories have undergone revisions with time as increasingly rich observations revealed previously unrecognized details.
Dark energy isn't a fundamental unknown. It is an observation, and by adjusting our cosmological model to account for it we are able to make other sorts of predictions that we couldn't before, and about more than simply the observation of increased universal expansion. That's one thing that results in increased confidence that our model is improving.
What does it even mean that some fundamental thing like dark energy is "unknown", or "unclear"? What isn't? We know nothing about what electric charge "really" is. We know nothing about what gravity "really" is. We know nothing about what any of the fundamental forces "really" are. Each of these things is just like dark energy: mysterious "forces" (even that word is applied as a simplification) which we can only describe or explain by using abstract theories that appear to describe the behavior we observe.
Fundamentally, dark energy is no more mysterious than electric charge or gravity. The only difference is that we don't yet have as richly developed a theory for it, we don't yet have as many independent observations of its effects.