Evidence for the big bang is about measuring redshift of galaxies throughout universal history, homgeneity and thermal equilibrium of the universe and CMBR, which could only be explained by it all having been in a compressed location where it could reach thermal equilibrium at some point in the distant past.
None of that is challenged by the Webb observations about very young supermassive black holes.
In fact, the existence of supermassive black holes themselves has basically always been an unsolved problem even before Webb. The only known possible explanation (stellar collapse -> accretion -> supermassive black hole) could be ruled out even before Webb on theoretical and experimental grounds, we just have stronger evidence against it now. (To wit: if supermassive black holes form from stellar black holes by growing, you would expect to see lots of intermediate mass black holes. We see almost none. Furthermore, the process of accretion is extremely energetic, so IMBHs would be the most visible objects in the night sky. The fact we see none is doubly damning)
The mainstream position now will be big bang + some kind of primordial black hole formation during the very early stages of the universe. Work of Hawking/Penrose shows that black holes can form under generic conditions in solutions to the EFE equations. We have a general understanding of how they could come about from certain dense matter layouts in a standard GR cosmological model.
This led to the development of cosmic inflation [2], which is what largely drove me from a doe eyed young astronomy enthusiast to a highly skeptical old fart. It solves the problem in an ad hoc fashion. Just have the universal expansion go into overdrive for a bit shortly after the big bang, then slow down, then start accelerating again - and then at the end we finally get something that looks like what we see - a homogeneous system in this case.
It made some highly accurate and improbable predictions which led to widespread adoption but then ran into numerous issues requiring further ad-hoc solutions. And this process has been repeated multiple times since its original formulation, to the point that there's a library of different inflation theories now a days, all getting ever more fine-tuned. If non-casually connected regions of space acted like they were non-casually connected then all would be fine, but the homogeneity that we do have is a big problem for the big bang.
Acoustic distortions. The universe was small and dense enough for sound to travel through ‘space’, which was filled with plasma. The theory is that inflation blew up these tiny distortions to the scale of the structure we see in the universe.
• Big Bang: we can only see back to surface of last scattering, i.e. the CMB, extrapolating backwards goes "???" at much the same point as it did a few decades back because we still have not unified quantum mechanics and general relativity
• CMB should only have isotope distribution of Big Bang nucleosynthesis, that hasn't changed in the last decades, dunno if that's what you meant by "various non-uniform gases were scattered around"?
• Variations in density of CMB do exist, key phrase is "Baryon acoustic oscillations", while they're very small magnitude they're also massive in distance scale, so they're how galactic clusters formed (that scale rather than stars directly): https://en.wikipedia.org/wiki/Baryon_acoustic_oscillations
https://www.youtube.com/watch?v=PPpUxoeooZk
https://www.youtube.com/watch?v=LRUTnoveZs8
• Re: "Perhaps the expansion of space wasn't uniform either": I heard about specifically "Timescape Cosmology", but a quick search says that's part of a broader category of inhomogeneous cosmologies: https://en.wikipedia.org/wiki/Inhomogeneous_cosmology#Timesc...
https://www.youtube.com/watch?v=SXg6YVcdOcA
https://www.youtube.com/watch?v=JlNVZz5D6WE
• Re: "and when space expands or contracts, energy is generated": no, general relativity does not in general conserve energy, and it is related to the curvature of spacetime. Simple example is that the photons in the CMB have much less energy to us than they did to the atoms they were emitted from**: https://www.youtube.com/watch?v=04ERSb06dOg
* I assuming I'm correctly judging the level and attention to detail they're providing, given the detail they put in and references to specific research publications. My degree is Software Engineering.
** There's also a Veritasium video about this, but to me Veritasium feels like a BBC 2 evening popular science show, so I'm not as confident about recommending it.
I don't know what conditions were like before that stage, but like Eric Idle says, nothing can come from nothing.
Dark energy is a horse shit name for a theory that was horse shit to begin with. The Universe is probably just inhomogeneous, like your intuition is saying.
It’s like a comment in your code like \\ TODO…
I don’t see why that’s that hard, or why we’d expect to instantly be able to figure everything out.
I still recall how neutrinos and black holes “couldn’t” be candidates.
To physicists, this means stellar neutrinos and blackholes (and galaxy centers). To lay persons, any category such as cold neutrinos or primordial black holes also qualify.
The sheer amount of vitriol and—I can’t think of a better term than this—“smugness” was off putting.
Before the internet, this was fine when locked away in their labs and classes; but I don’t think you understand the scale of damage neurodivergent scientists and its fans have done to the science community once they started to participate directly.