…there are two different ways to measure this cosmic expansion rate, and they don’t agree. One method looks deep into the past by analyzing cosmic microwave background radiation, the faint afterglow of the Big Bang. The other studies Cepheid variable stars in nearby galaxies, whose brightness allows astronomers to map more recent expansion.
You’d expect both methods to give the same answer. Instead, they disagree—by a lot. And this mismatch is what scientists call the Hubble tension…Webb’s data agrees with Hubble’s and completely rules out measurement error as the cause of the discrepancy. It’s now harder than ever to explain away the tension as a statistical fluke. This inconsistency suggests something big might be missing from our understanding of the universe - something beyond current theories involving dark matter, dark energy, or even gravity itself. When the same universe appears to expand at different rates depending on how and where you look, it raises the possibility that our entire cosmological model may need rethinking.
The instrumental error bars are no longer overlapping. But if we imagine all the modifications one could make to Lambda-CDM, then there is still a huge “theory” error bar that subsumes all these.
Basically I’m saying the model is wrong, yes, but it can very much be fixed.
But could you make these modifications without diverging from other observations? If it were as easy as you put it, why have scientists been talking about it for decades?
Scientists have came up with countless ways to fix the Hubble tension. But all these modified theories so far are either