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Hmm...challenging the error margin of a specific calculation result of a specific model based on confirmed inconsistencies is regarded as "opinion-based". Interesting. Just curious, is the rationale of closing a "opinion-based" question also "opinion-based"?


According to the calculation of the cosmological standard model $\Lambda CDM$, the age of the Universe is 13.8B years old. This claim is more or less supported by observation of oldest galaxies/stars in the universe.

But is 13.8B really accurate as inferred by $\Lambda CDM$?

Recently there were alarming inconsistencies turning up regarding the Universe's late-time history at low redshift, evidenced by the contradicting numbers of Hubble constant ($H_0$) measured by supernovae/cepheid variable ladders with what is predicted by $\Lambda CDM$ which is calibrated from CMB (Cosmic microwave background) observations and BAO (Baryon acoustic oscillations) constraints. This contradiction is called Hubble tension, or even "Hubble crisis" according to some cosmologists.

If the Hubble tension turns out not to be a systematic measurement error, it could have real implications on the accuracy of dark energy density ($\Omega_\Lambda$) and the true age of the Universe. The standard cosmology model $\Lambda CDM$ has been known as the "concordance model". Given the "Hubble tension" and other inconsistencies (e.g. the controversy surrounding $\sigma_8$), are we sure $\Lambda CDM$ is a "concordance model"?

Shall we take $\Lambda CDM$'s calculation of the Universe being 13.8B years young with a grain of salt? Should we put a much higher error margin on the claimed age number? In other words, I am questioning that when the Hubble tension is eventually resolved, a new value for the age might exceed the bounds of the commonly agreed +/- uncrtainty error that accompanies the 13.8B value.


Added note: see a related question here.

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    $\begingroup$ I think this question is impossible to answer, since almost by definition we don't know the source of the Hubble tension, not to mention any unforeseen new physics which could alter the calculation of the age of the universe. $\endgroup$
    – Javier
    Feb 1, 2021 at 19:24
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    $\begingroup$ Not qualified to answer, but this might point you in a helpful direction: livescience.com/…. $\endgroup$
    – Tony
    Feb 1, 2021 at 19:58
  • $\begingroup$ @Tony, thanks for providing the link! By "It is 13.77 billion years old, give or take 40 million years", did they factor in the "Hubble tension"-related uncertainties when they say "give or take 40 million years"? $\endgroup$
    – MadMax
    Feb 1, 2021 at 20:04
  • $\begingroup$ I don't think the estimate factors in the Hubble tension. It provides more evidence that the CMB measurements are not subject to measurement errors, but as the article says there could still be problems with the theoretical approach used to go from measurements to age. $\endgroup$
    – Tony
    Feb 1, 2021 at 21:14
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    $\begingroup$ Although not involved in the decision, I believe the question was closed as "opinion-based" because it referred to "the Universe" rather than "our local universe", "the local universe" or "the multiverse": Some persons may feel that the capitalization makes that clear, but the usage, in English, is generally to capitalize the larger, more important, or more generally-accepted of two entities: For instance, the deity of monotheistic religion ("God") is capitalized, but the word with the same spelling is not capitalized when it's describing any individual deity in pantheistic religions. $\endgroup$
    – Edouard
    Feb 2, 2021 at 12:07

2 Answers 2

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The significance of the tension is not that the age measurement is off by much, but rather such a tension strongly suggests that we have not yet correctly understood all the relevant physics. So the most likely outcome is that the physics gets understood better and all the age measurements turn out to be roughly right, just not quite as accurate as has been estimated on the basis of the models used so far.

I am not working directly in this area, so I cannot give an estimate of what the range of uncertainty might be. But it is clear from the publications that the Planck collaboration published measured values of cosmological parameters based on assumptions which included, among others: that if there is any spatial curvature, it is negligible; that if there is any local flow or other such inhomogeneities in the cosmic fluid, then its effects are negligible; that the dark energy has the form of a cosmological constant; various things to do with neutrinos and lensing which I don't claim to know much about. As soon as one allows that things like this cannot necessarily be assumed, one will get bigger error margins. So it seems to me that the error margins published by them are indeed a bit misleading, but I am not able to assess what would be a fairer statement. I note that Di Valentino, Melchiorri and Silk (2015) published a comparison of a 6-parameter model and a 12-parameter model. The error margin in the baryon density parameter in the 12-parameter model is twice what it is in the 6-parameter model. The error margin in the cosmological constant in the 12-parameter model is about 4 times larger than in the 6-parameter model. The error margin in the Hubble parameter in the 12-parameter model is $4.8$ times larger than in the 6-parameter model. Yes that's $4.8$ times.

So this indicates the kind of thing that can happen. More work has been done since then, of course.

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  • $\begingroup$ Thanks for the answer. Could you please elaborate on how "not quite as accurate as has been estimated". In particular, what is the error margin of the universe age if the uncertainties related to the Hubble tension is taken into account? $\endgroup$
    – MadMax
    Feb 2, 2021 at 4:05
  • $\begingroup$ @MadMax I added a paragraph; that's about the sum of my knowledge. $\endgroup$ Feb 2, 2021 at 11:42
  • $\begingroup$ Thank you Andrew! I am accepting your answer. $\endgroup$
    – MadMax
    Feb 2, 2021 at 18:05
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With $H = 73 km/s/Mpc$, the age of the universe is about 13.4 billion years, a number still comfortably above the age of the oldest globular clusters.

Caveat: this estimate was obtained by taking the inverse of the Hubble constant, which is a cruder way of estimating the age of the universe since it doesn't take into account the density of matter, radiation & dark energy. It is still a reasonable estimate however, and illustrates how much changing the Hubble constant might change the age estimate.

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  • $\begingroup$ Thanks for providing a rough estimation of the universe age based on the local measurement of the Hubble constant. According to Wikipedia, the universe age is "13.787±0.020 billion years within the Lambda-CDM concordance model as of 2018". So is the estimation of "about 13.4 billion years" outside the error margin of the concordance model? $\endgroup$
    – MadMax
    Feb 2, 2021 at 4:57
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    $\begingroup$ @MadMax yes. What exactly is your question though? It should be obvious that 13.4 is outside the error margin of 13.787 +/- 0.02. $\endgroup$
    – Allure
    Feb 2, 2021 at 4:58
  • $\begingroup$ Do you have any reference to the latest age estimation (as of 2018 or later) of the oldest globular clusters? In addition to the age estimation, I am interested in the error margins as well. $\endgroup$
    – MadMax
    Feb 2, 2021 at 5:12
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    $\begingroup$ @MadMax I'm finding your questions tedious and so will not be answering them anymore. If you really do not know how to tell if 13.4 billion is within the error margin of 13.5 billion +0.16 -0.14 +/- 0.5, ask a new question. $\endgroup$
    – Allure
    Feb 2, 2021 at 5:25
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    $\begingroup$ Of course I know the answers to these questions to you. The point is for the benefit of the other readers interested in the same question, so that they know what has been discussed. In your answer text, could you please make a conclusion by comparing your estimation with the error margins of the Lambda-CDM model (which is outside the error boundary) and globular cluster estimation (including the link), respectively. After that, I will accept the answer. I understand it might be "obvious" and sometimes "tedious" for your highness, but it is for the the benefit of the other readers. Thanks! $\endgroup$
    – MadMax
    Feb 2, 2021 at 6:00

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