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Does it makes sense to expect/hope that one day we will measure the age of the universe (in Earth's frame of reference for example) much more precisely, down to sub-year precision? Is there an absolute 0 for time (kind of like for temperature) that we could use instead of the year of our Lord or some other year?

Can we at least talk about a theoretical absolute age even if we might not be able to determine what it is? I'm thinking that even if we had perfect clocks counting seconds from the very beginning of the universe, due to relativity they might have readings that differ by years or more, making an absolute time impossible to set or maybe the expansion of the universe means this is a nonsensical question to ask. Is asking about absolute time like asking about absolute position?

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    The commonly accepted "+/- 40.000.000 earth years" error margin of $\Lambda$CDM should be taken with a grain of salt. The actual error margin could be much larger, of the order of 1B years due to the Hubble tension. See https://physics.stackexchange.com/questions/611740/is-the-commonly-accepted-universe-age-of-13-8b-years-really-accurate/611809#611809 and https://physics.stackexchange.com/questions/514882/why-is-the-planck-wmap-estimate-of-the-age-of-the-universe-preferred?rq=1. – MadMax Apr 26 '21 at 21:16
  • Age for who? Special relativity rears its ugly head. – FlatterMann May 16 '23 at 20:45
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    @FlatterMann that's what I said in the second paragraph isn't it? There's still surely some distribution of ages (of rocks on the surface of the Earth if we have to restrict it further) we could describe. –  May 16 '23 at 20:50
  • That's my point: you know the answer, already. "The age" is observer dependent, and so is "the shape". We could argue about whether the age of the universe is the same in the local rest frames of observers that see the universe as (nearly) isotropic, but that leads to the question whether the universe is homogeneous at scales larger than several (hundred) times the Hubble diameter. My religious bet is "no, it isn't", but then... I am not religious and I don't bet and the question lies firmly outside of what science can do. – FlatterMann May 16 '23 at 20:53
  • If every particle making up the Earth was a clock that we could read the value of, there is some shape of the distribution of those values that I would consider an answer in the affirmative to my to my question for my purpose of establishing a consensus age of the universe. –  May 16 '23 at 21:03
  • Every nucleus is, in some sense, part of a clock. Radioactive decay of geological samples agrees well with the age of the universe as estimated by other methods, for all I know. – FlatterMann May 16 '23 at 21:19
  • I meant that if each particle can have an absolute age, I would consider the distribution of those ages the absolute age of the universe. –  May 16 '23 at 21:23
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    In cosmology, we tend to use the comoving frame of the CMB, as mentioned in https://physics.stackexchange.com/q/495821/123208 (I have some info on the CMB frame in https://physics.stackexchange.com/a/411082/123208 ). – PM 2Ring May 16 '23 at 21:53

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Within our present model of the universe, the age of the universe is deduced from observational data :

Ancient light from the Big Bang has revealed a precise new estimate for the universe's age: 13.77 billion years, give or take 40 million years.

13.770.000.000 earth years +/- 40.000.000 earth years.

If we accept the claim that it is the best precision, (ignoring maybe larger errors due to models used),the error given is too far removed for your "sub year precision" for it to be attainable, imo.

anna v
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    Did you forget the famous Hubble Tension? The number you quote does not come directly from observational data, but from fitting it to the Friedmann cosmology, which is in an existential crisis as the worst theory of the mankind mismatching by whooping 95% the actually observed matter content in the universe. – safesphere Feb 27 '21 at 06:59
  • @safesphere the error is the important thing, which is experimental, no matter what the theory predicts. Take the ratio: you cannot get great improvement no matter what the theory predicts in billions of years. – anna v Feb 27 '21 at 07:03
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    The Hubble Tension is the difference between relatively direct measurements (which are still not geometry independent) and fitting indirect observations to the Friedmann model. This difference is much larger that the error you quoted. The actual uncertainty is in the range of a billion years. – safesphere Feb 27 '21 at 07:08
  • @safesphere can you give a link? – anna v Feb 27 '21 at 07:11
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    The Hubble tension is 67 to 74. With simple math this translates to about a 1.3-billion-year difference. – safesphere Feb 27 '21 at 08:08
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    We should stick to the present calendar(s) until the accuracy is improved. – my2cts Feb 27 '21 at 09:29
  • You didn't answer my question, you just said our current estimate is so impercise that you think it's physically impossible for humans to ever attain the precision that I'm asking about over the entire future of science. But my question is more abstract about whether it even makes sense to say that the universe has some specific, very precise age. Can you point to every point in space and say this spot has existed for exactly X seconds (or plank times)? Is there some sort of unavoidable noise floor for measuring the age of the universe which is much higher than +/- 1 year? –  Feb 28 '21 at 21:13
  • in relativity, if you take two close, synchronous clocks and move one really quickly far away and bring it back, the clocks will show different times, so that means different parts of the universe have different ages, potentially way more than a year, right? but I guess the difference can't be that high if we're using the Earth as the reference point? –  Feb 28 '21 at 21:19
  • One has to stick to a fixed inertial scale for the modelling of the universe, so accelerated clocks just confuse the issue. Our present model is theBig Bang and the time variable is from the rest frame of the solar system. In this model there is already inherent indeterminacy of time and space before the Planck time, and quantum mechanics , basically random, has been invoked. Planck time time intervals of around $10^{−43}$ s. See https://en.wikipedia.org/wiki/Inflation_(cosmology)#/media/File:History_of_the_Universe.svg , it is seconds, not years, in theoretical accuracy predictions. – anna v Mar 01 '21 at 05:32
  • That is why I thought you were asking about experimental possibilities – anna v Mar 01 '21 at 05:33
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Even assuming we have the correct cosmological model, the precision to which we can measure cosmological parameters is fundamentally limited by our vantage point. Our location in the universe is random, but every experiment we do is from the same random location. We can reduce instrumental error in measuring the cosmic microwave background, but we are always measuring the same inherently noisy pattern. This problem is called "cosmic variance".

In principle, we could discover a theory of everything that forces a certain value for certain cosmological parameters (perhaps the cosmological constant), allowing us to better fit the other parameters, or we could find maps of the microwave background from millions of years ago in the ruins of Atlantis and combine it with the current map to reduce the noise. Failing that, I think that future astronomical observations can only slightly improve the precision of the fit.

benrg
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The key concept in the question is. "Is it theoretically possible...?" This a distinctly different question than whether it is practically possible. As astronomical instruments get bigger, their precision will also get better. The biggest current instrument in recent times is the Hubble with a diameter of 2.4m, which has produced an error of about 40,000,000 years. One can imagine theoretically creating a telescope the size of the solar system with a diameter of about 22,000,000,000,000m. If such an instrument were to someday be created, it would not be too surprising to me that the precision of the age of the universe will very possibly become less than a year.

Buzz
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