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Crisis in cosmology? Or just tweaking models? (self.science)

submitted 8 months ago by DelightfullyDivisive to c/[email protected]

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I have read several articles like this one.

https://www.livescience.com/space/cosmology/james-webb-telescope-confirms-there-is-something-seriously-wrong-with-our-understanding-of-the-universe

They all seem to be saying that there is a "crisis in cosmology", where different measurements can't reconcile what the value of the hubble constant is.

Then I watched this video last night that seems to be saying it's all just tweaking different models.

https://youtu.be/2pux7v9qJ58?si=ux3zBSHR-vvsz9qY

I'm not entirely sure if they're talking about two slightly different things. (Hubble's constant, and the predicted age of the universe.) Or if the "crisis" is really just a misunderstanding, or just clickbait tactics. Any informed opinions on the subject?

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[–] [email protected] 7 points 8 months ago (1 children)

For what I can tell, after the clickbaits and the sensationalisms, there is an actual unexplained discrepancy in the values of the Hubble constant measured with different methods. This means that something is not right in one of the methods (perhaps both), or that we are missing something else.

And yes, the Hubble constant is closely related to the age of the universe, so it's basically the same issue.

This is actually a good thing, because the "crisis" can be the first clue to discovering some new exciting science! Just look at how the "ultraviolet catastrophe" kickstarted the field of quantum mechanics a century ago

[–] DelightfullyDivisive 1 points 8 months ago (1 children)

The video (you can skip to the last five or 10 minutes of it to get the gist of what I'm talking about) says that the discrepancy isn't unexplained. It's point is that the different models depend on a large number of variables, and one of those variables is the size and brightness of the first generation of stars in the early universe. Tweaking that part of the model can explain the discrepancy. (According to the video.)

[–] [email protected] 2 points 8 months ago

OK, I've actually watched the video this time (the last part, as you suggested). It seems that the author decided to leave out the debate about the Hubble constant and talk about other phenomena in the early universe, which also have their uncertainties.

As far as I can tell, the Hubble tension is still a thing, and JWST only confirmed the measurements of the Hubble telescope. See for example this recent article on ars technica.

[–] [email protected] 4 points 8 months ago

The Hubble Tension is certainly real. The Hubble Constant can be estimated from a number of completely independent astrophysical phenomena. There is a significant difference in the value computed from 'local' phenomena, and distant phenomena. It is often referred to as the "5 sigma" tension, because that is the statistical significance of the disagreement. This has been know long before James Webb, but as the article says, these observations just lowered the uncertainty on one of the probes. But we were fairly certain already that this tension is real.

Whether it's a crisis or not is up to the individual. Things not agreeing in science

especially astrophysics/cosmology

is just part of the process. I don't know anyone that is 'worried', so much as looking for ways to solve the problem.

[–] Carrolade 2 points 8 months ago

Dr Becky will get you fixed up:

https://youtube.com/playlist?list=PLd19WvC9yqUf5TRqYoMYxEwjT6JIDW4Zn

Go in chronological order if you want the full picture, but it's not really necessary.

I'd describe it as a faux-crisis. It's not like astronomy as a field is going to end if we don't get it sorted by next week. It is annoying though.