[idi banashapan]

Well, that’s a fascinating point, and it touches on some of the fundamental aspects of relativity and cosmology. But let’s break it down carefully.

You're absolutely right that analogies, while useful for simplifying concepts, don't alter the fundamental laws of physics. They help us build intuition, but ultimately, the universe follows mathematical principles that don;t depend on our human need for simplification.

Now, regarding the speed of light, yes, the Doppler effect, or more specifically the redshift of light, is strong evidence that the speed of light is constant. This is central to Einstein’s special relativity, which tells us that the speed of light in a vacuum is the same for all observers, regardless of their motion or the motion of the source of the light.

As for the accelerating expansion of the universe, this is where general relativity comes into play. Space itself is expanding, and that’s not the same as objects moving 'through' space. When we talk about galaxies receding from us faster than the speed of light, we’re not violating relativity because it's not the galaxies themselves moving at superluminal speeds through space; rather, the space between us and them is expanding. This means that light from these galaxies will nevre reach us, because the fabric of space is stretching too quickly for the photons to make headway.

So, in a way, we have a sort of observational horizon, the so-called 'cosmic event horizon'. Beyond this, light from galaxies can’t reach us because space is expanding too fast. This is a direct consequence of the universe's expansion being governed by what's called 'dark energy', which is driving this acceleration.

Now, your intuition that we still have a lot to work out is absolutely correct! We don’t yet fully understand what dark energy is, or why the universe’s expansion rate changed over time. But the mathematical framework of relativity does an incredibly good job of describing what we 'can' observe. But there's nothing to say that what we can see is everything that is there.

So yes, there’s definitely a lot of bottoming out still to be done, but people far more clever than myself making good progress, I should think.