…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.
From previous articles, I do believe it is consistent enough across different approaches and precise enough that there really seems to be more than one answer. How can that be?
We really don’t have a solid reason for the increase in expansion rate of the universe. Dark energy seems most straightforward and consistent with everything else but it’s not proven until we can identify and measure that energy. This lends weight to the idea that it’s not that simple
Suppose we come to establish that the expansion rate accelerated from 68 to 73 km per second / Mpc (in the lapse of, say, 80% the ~14 B. years age of U.) if this is so, so be it. Why oppose it ?
Or, if for the same period, we have two different rates … this is not acceleration. This is two methods yielding different results for what is supposed to be one sigle thing. So, one of the 2 methods doesn’t measure exactly the same thing as the other … whatever.
Obviously, observation and measurement have to be the basis for any hypothesis and for any explanation proposals. So, we should not say : “since we have no explanation, there should not be acceleration of the expansion”. - - But rather we should say : “since there is acceleration of the expansion, we should build some theoretical models around this reality”.
Anyway, you probably already know all of this.
Right. Theoretical models helped us get here, where we identify specific criteria to test. However two different answers don’t fit our current models of the universe. Something has to change: either the answers do not mean what we think or the universe evolves differently than we think
It’s fascinating how complex and wonderful it it is that every time we think we have something figured out, nature gets more complex
It’s a real life example of HGttG:
i love Douglas Adam’s trilogy in five books as well 😁