A different approach to the Hubble Tension

Pinball1970

Pinball1970

Valued Senior Member
This paper uses Gaia data from a selection of stars from the Milky way, to estimate the age of the Universe and therefore what the Hubble constant should be.
This was independent of cosmological models, just the Stellar ages were used.

The oldest Milky Way stars: New constraints on the age of the Universe and the Hubble constant | Astronomy & Astrophysics (A&A)

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
www.aanda.org www.aanda.org

It is worth checking out what Gaia actually did, it was launched 2013 and was decommissioned last year. L2 was getting a little crowded with JWST and Euclid there also.

en.wikipedia.org

Gaia (spacecraft) - Wikipedia

en.wikipedia.org en.wikipedia.org
 
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Pinball1970 said:
This paper uses Gaia data from a selection of stars from the Milky way, to estimate the age of the Universe and therefore what the Hubble constant should be.
This was independent of cosmological models, just the Stella ages were used.

The oldest Milky Way stars: New constraints on the age of the Universe and the Hubble constant | Astronomy & Astrophysics (A&A)

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics
www.aanda.org www.aanda.org

It is worth checking out what Gaia actually did, it was launched 2013 and was decommissioned last year. L2 was getting a little crowded with JWST and Euclid there also.

en.wikipedia.org

Gaia (spacecraft) - Wikipedia

en.wikipedia.org en.wikipedia.org
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What value, or range, does this method get? The last time I read about this, it was between 67 and 73 km/s/Mpc.
 
exchemist said:
What value, or range, does this method get? The last time I read about this, it was between 67 and 73 km/s/Mpc.
Click to expand...
There are two competing measurement ranges, with one suggesting between 67-68, and the other between 70-74, depending what types of measurement you go for.
No doubt a new one will be deliberately unhelpful and suggest the 68-70 range. So I'll go with it being 69, just to be contrarian. ;)
 
Sarkus said:
There are two competing measurement ranges, with one suggesting between 67-68, and the other between 70-74, depending what types of measurement you go for.
No doubt a new one will be deliberately unhelpful and suggest the 68-70 range. So I'll go with it being 69, just to be contrarian. ;)
Click to expand...
You cannot just average this out because they were using two completely different methods.
The Cosmic distance ladder seems to be the culprit as there is a lot more room for error there.
Not Kermos level error, science level error.
 
Pinball1970 said:
You cannot just average this out because they were using two completely different methods.
Click to expand...
I know - hence my first sentence which details the different range of values for each method.
My deliberately unserious guess for 69 is based on my second sentence.

It really shouldn't be that tricky. ;)
 
Pinball1970 said:
You cannot just average this out because they were using two completely different methods.
The Cosmic distance ladder seems to be the culprit as there is a lot more room for error there.
Not Kermos level error, science level error.
Click to expand...
Yes the CMBR would on the face of it seem the more direct method. So now I suppose the hunt will be for why the distance ladder method could be in error.
 
exchemist said:
Yes the CMBR would on the face of it seem the more direct method. So now I suppose the hunt will be for why the distance ladder method could be in error.
Click to expand...
The ladder is messy, it is measurements further further away and from what I have read lots of small errors could be adding up to the 10% we find.

Variations in Type 1a SN, dust, parallax calibration errors.

Spritzer, Webb and others are refining these measurements but they appear to be persisting so far, the tension remains.
There the question of Dark energy too, a recent study points to an expanding universe that is slowing down not speeding up.
 
Pinball1970 said:
The ladder is messy, it is measurements further further away and from what I have read lots of small errors could be adding up to the 10% we find.

Variations in Type 1a SN, dust, parallax calibration errors.

Spritzer, Webb and others are refining these measurements but they appear to be persisting so far, the tension remains.
There the question of Dark energy too, a recent study points to an expanding universe that is slowing down not speeding up.
Click to expand...
I’ve never looked into the distance ladder method. Didn’t we have something a while back that suggested early supernovae had a different composition due to infalling gas diluting the heavier elements? So maybe that alters the assumptions about them a bit.

As for Dark Energy, that’s just a placeholder concept anyway so if it goes by the board it would tidy things up, I’d have thought.
 
exchemist said:
I’ve never looked into the distance ladder method. Didn’t we have something a while back that suggested early supernovae had a different composition due to infalling gas diluting the heavier elements? So maybe that alters the assumptions about them a bit.

As for Dark Energy, that’s just a placeholder concept anyway so if it goes by the board it would tidy things up, I’d have thought.
Click to expand...
I floated it on PF and the reaction was lukewarm.

One question was regarding the way the stars were selected. Unfortunately I do not know enough about those models.

Edit: This, "Bayesian isochrone fitting code StarHorse." I will do a deep dive. A first quick search cited other major studies it has been used for. Basically it kicks out anomalous results and the Gaia data is a huge data set, the bigger the population size the better number was my understanding.
 
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This actually touches on something I’ve been exploring in another thread about structure, evolution, and observation being different aspects of the same system:

https://www.sciforums.com/threads/a...ience-different-aspects-of-one-system.167396/

What stands out here is that the different methods aren’t just measuring the same thing in the same way. CMB estimates relate to early-universe structure, while distance ladder methods depend on much later, locally evolved structures.

So it raises the question of whether we’re really dealing with a single fixed value, or whether what we call the Hubble constant depends on the structural context being measured.

If that’s the case, the tension may not just be a discrepancy to resolve, but a clue about how measurement relates to structure.
 
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