Undergrad Star cluster in the Milky Way appears to be as old as the Universe

[Tom.G]

One of the oldest known objects in the universe is wandering around the Milky Way.
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:
Using a computer, the team created 20,000 synthetic stellar populations for M92, each for a different possible cluster age. They then compared the colors and brightnesses for each of these populations with Hubble Space Telescope observations of M92 and calculated the age that fit the collection best.

https://www.sciencenews.org/article/star-cluster-milky-way-old-universe

https://doi.org/10.48550/arXiv.2306.02180

Cheers,
Tom

 

[Vanadium 50]

I haven't had time to go through this, but they actually report that these stars are older than the universe, by about 1%, That begs the question of how good the modeling is - 1%? 5%?

 

[hutchphd]

They report an uncertainty of +/-.75 Gyr which is 5% yes? Did not dive in far enough to understand that number though.

 

[Ken G]

Also, one must bear in mind that there are two very different types of uncertainty, a distinction that often gets overlooked when assessing the significance of some conclusion. One type is random in nature, the other, systematic. Random errors normally emerge from the unavoidable uncertainties in the observations, and although they can be somewhat straightforward to quantify, they also can be hard to pin down precisely (an example being the infamous 2011 OPERA superluminal neutrinos). So most random errors are what you know you don't know, based on your understanding of the limitations of your instruments, though you might be missing some.

Systematic errors are what you don't know you don't know, in your logical chain of reasoning. These are often from incorrect assumptions being made in the analysis somewhere, and do not necessarily require new physics, just more complete application of the physics we have, or a fairer assessment of the idealizations being made. So even had they quoted their uncertainty as less than 1 percent, so an age older than the universe, we would still not be able to conclude there is some missing physics or error in our cosmology, it could still be undetermined observational error they aren't including, or a systematic error from some assumption they made in their chain of logic. (Personally, I'd be pretty skeptical that even a five percent uncertainty encompasses all the possible sources of uncertainty here. They seem to assume our knowledge of stars and how they evolve is pretty secure, but there are still many aspects of stars, such as rotation and magnetic fields, that still introduce significant systematic uncertainties.)

 

[DaveC426913]

A quote I am finding more and more widely-applicable as we move further into the 21st century:

".. there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns—the ones we don't know we don't know."
- Rumsfeld, 2002.

 

[Bombu]

I haven't had time to go through this, but they actually report that these stars are older than the universe, by about 1%, That begs the question of how good the modeling is - 1%? 5%?

Sorry, but please don't say " begs the question." Look it up. It is virtually always misused. It really refers to a mist candidates logic error.

 

[Ken G]

Actually, the argument could be made that @Vanadium 50 is using the correct logic meaning, of "assumes the conclusion." One can say that "begs the question" is in a sense dodging the key question, while replacing it with something easier to prove. So when someone says "it is a problem that this star is older than the universe", they are really doing just that, because they are making it seem like the key question is a comparison of two ages, when in fact, the key comparison is the two ages along with their uncertainties. So if I correctly take the meaning, the point @Vanadium 50 is making is that the important question there (the uncertainty ranges) is being "begged" (assumed away as not relevant), and replaced by a question that is easier to state (the age comparison), but is actually not the relevant issue at all. So I think "dodges the key question" and "assumes the conclusion" are really quite similar, in either case it is about which question you are framing as the one that needs to be answered, and which questions do you think are unimportant (i.e., which "conclusions have been assumed").

 

[Vanadium 50]

I looked at it more carefully.

Based on cosmology, M92 should be 13.2 +/- 0.3 Gy old. This paper says it's 13.8 +/- 0.7. The difference is 0.6 +/- 0.8.

I fail to see the problem.

 

[Vanadium 50]

A different way to present the same numbers:

M92 gives us an estimated age of the universe of 14.3 +/- 0.8 Gy. Cosmology gives is 13.7 +- 0.2 Gy. These are perfectly compatible.

 

[Ken G]

And those numbers also show that the "problem" involves using a conclusion with a much larger uncertainty to cast doubt on one with a much smaller uncertainty, making worse the error of ignoring that the two intervals overlap. One should be more likely to nod and say "yup, another result consistent with the standard picture." Oh the difference an error bar makes....

 

[Tom.G]

Oh the difference an error bar makes....

Now THAT is hittijng the nail on the head!!

 

[PeroK]

A different way to present the same numbers:

M92 gives us an estimated age of the universe of 14.3 +/- 0.8 Gy. Cosmology gives is 13.7 +- 0.2 Gy. These are perfectly compatible.

Not to a science journalist!