A paper regarding the Hubble tension using Gaia data

[pinball1970]

TL;DR

This paper uses measurements from the Gaia telescope on stellar data from the milky way, to estimate the age of the universe and the Hubble constant and points to the CMBR number.

This study uses data from the Gaia telescope launched in 2013 which measured stellar ages of stars greater than 12.5 gy.
This set a lower limit on the age of the universe, if there are stars >12.5 gy then the universe cannot be younger than this.

This impacts on the the Hubble constant, if the universe is older, the constant is lower.

That is my understanding from reading around (phys.org, wiki, Ai) but @Ibix @Bandersnatch @Orodruin and @Drakkith will have a professional view.

https://www.aanda.org/articles/aa/full_html/2026/03/aa57038-25/aa57038-25.html

 

[Jaime Rudas]

This impacts on the the Hubble constant, if the universe is older, the constant is lower.

Yes, the paper concludes that the age of the universe is:

$T_U \geq 13.8 \pm 1.0$ (stat) $\pm 1.4$ (syst) Gyr

According to the ΛCDM model, this would be equivalent to a Hubble constant of:

$H_0 \leq 68.3^{+5.4}_{-4.7}$ (stat)$^{+7.8}_{-6.4}$ (syst) km/s/Mpc

It should be noted that this value is compatible with both the Planck value ($H_0=67.4$ km/s/Mpc) and the SH0ES value ($H_0=73.3$ km/s/Mpc), although the latter is close to the upper limit.

 

[Ibix]

@Ibix @Bandersnatch @Orodruin and @Drakkith will have a professional view.

I haven't had a professional view on anything physics related for decades.

There is a lot of stellar modelling in that, and I don't know how robust any of that is. There's also a long process of carefully selecting the stars they're going to model. Both of those steps seem to me to require modelling assumptions, ones that must be quite hard to validate. Notice that the stellar model they use gives 18-19 Gyr ages for some stars (that end up excluded from their sample for other reasons, and they acknowledge that those are stars their model doesn't work for), so the result is clearly sensitive to how good those assumptions are.

So I think it's an excellent idea and another thread of measurements is always worth having. But this one stands on a lot of assumptions, the validity of which I don't know how to confirm.