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Is there a discrepancy between the Oldest Galaxy and Age of the Universe

  1. Dec 2, 2011 #1

    How is the age of the Universe most accurately estimated and is it possible there is a discrepancy between the Oldest observed Galaxies and the estimated Age of the Universe?

    What are the implications for say a 1B year error in the age of the Universe on the Standard Model and the various Cosmology theories we have at present?

    How long do we estimate it takes for thinly spread gas to clump into stars and then for stars to clump together into a Galaxy powerful enough to be seen from 13.2B light years away?

    At the rate at which the limit for the oldest galaxies observed are being pushed back where is the curve likely to reach a limit value whilst using Hubble?
    How much further would the James Webb potentially see if Galaxies are actually there to be observed?
    Last edited: Dec 2, 2011
  2. jcsd
  3. Dec 2, 2011 #2


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    Current theory has no problem with the age of the oldest clusters and the time since the big bang. If you made the universe 1 billion years younger there would be a problem, but current estimates have a much smaller error bar.
  4. Dec 3, 2011 #3
    The latest full sky surveys (globular clusters), along with results of WMAP and the high Z-supernovae data show, within margin of error, that there is no inconsistency with the Age of the Universe, and the oldest stellar structures. Everything seems to be fitting nicely. Historically, this was not the case...but that was due to major errors in dating, going back to the original crisis when there wasn't an understanding of the difference between Population 1 and Population 2 stars.

    However, things have been pretty much rosy, at least since the mid to late 1960s. All subsequent data and observations have reinforced the fact that the Universe is older then the oldest observed structures (e.g. stars, galaxies, globular clusters, etc.).
  5. Dec 3, 2011 #4
    Thanks for replies. It will be interesting to see if older Galaxies are detected over the coming decades.
  6. Dec 4, 2011 #5
    Age of the universe we get several ways - expansion of the universe, lumpiness of galaxies.

    Big, big problems. Right now we think we can get the age of the universe to about 100 million years. If we saw a galaxy that was 15 billion years old, that means that we've seriously goofed up something.

    You can get a rough guess by something called the Jeans instability time, and that can happen pretty fast (i.e. on the order of a million years).

    We've long, long ago past that limit. Observationally there is nothing to keep us from seeing a galaxy 20 billion light years away. The fact that we don't, tells us something.
  7. Dec 4, 2011 #6
    In the early 1990's, there is a bit of excitement when there was the possibility that you had globular clusters that were older than the universe, but it turns out that that disappeared when people came up with better stellar models.

    There are a ton of things that "you just don't see" then you would expect if the universe were older than we think it is.....

    1) red dwarfs that are off the main sequence
    2) stars with very low amounts of hydrogen
    3) very cool white dwarfs

    In each of those cases, you end up with a good explanation of why you don't see these things by assuming that the universe is 13 billion years ago.
  8. Dec 5, 2011 #7


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    I agree with twofish, what we don't see speaks volumes about the age of the universe. An enormously ancient universe [hundreds of billion of years or more] would be dominated by the corpses of deceased stars. WMAP conclusively ruled out this possibility.
  9. Dec 5, 2011 #8
    Again thank you all for your replies and for helping in my understanding. I agree with the "what you dont see" statement.

    Could you please confirm again that Hubblle is capable of seeing galaxies with higher redshift and lower intensity even out to 20B light years. Did I understand this correctly? What then are the main aims of its replacement?
  10. Dec 5, 2011 #9
    No, Hubble deep field survey has imaged galaxies that are very high-Z, and correspond to a "Lookback" distance of 13 billion light years or so. But that is the distance travelled by the light from when it was first emitted to when it was received. In other words, the Look Back distance is 13+ billion years. This same galaxy was much closer when it first emitted it's light, and is now (at the time Hubble received the light) much, much further away, due to the expansion of space. The very farthest Lookback distance possible for any observatory (using E/M spectrum) is approx. 13.7 billion years, such as WMAP, which is seeing the CMB radiation from the surface of last scattering (recoupling), when the Universe first became transparent, approx. 100,000 years after the Big Bang.

    We cannot see anything farther back then the Age of the Universe (approx. 13.7 billion years). This is our Cosmological Horizon. Again, that is not to say that there are not objects that are "now" farther away. In fact, most of the high-Z objects are receding faster then the speed of light, and are (at present time) much farther away then 14 billion light years. The common stumbling block/misconception is when one confuses the distance of an object when it's light was first emitted, versus the distance of the object at the time of reception, versus the Lookback distance (time/distance the light travelled). Cosmologists and Astronomers typically use the last definition, i.e. Lookback distance/time, when giving distance measurements to distant objects. The current distance to a distant object (at this particular instant of time) is also known as the Proper Distance.
    Last edited: Dec 6, 2011
  11. Dec 6, 2011 #10
    If you had a galaxy with a lookback time of more than 13 billion years, we would have been able to see it with telescopes of the 1960's and 1970's. The fact that the number of galaxies goes down long before we hit detection limits, tells us that the universe is finite.

    One other interesting thing is that in the 1960's, one of the proposed explanations for the microwave background was that they were redshifted results of extremely distant galaxies that were there because of the "steady state model."

    One other interesting thing is that if the universe was really infinite, then the sky wouldn't be dark at night (see Olber's paradox). The fact that the sky is dark is largely because you can only see back to the beginning of the universe.

    Lots of things. There are things we understand. Things we don't understand. Once you get past the first moments, we have a pretty good idea of how the universe formed. We really don't understand how galaxies form. There is this period known as the "dark ages" that happened between the time that CMB formed and the first stars, that we really don't understand very well.

    One funny thing is that the formation of the universe is a surprisingly simple problem. There's a lot of symmetry, and other than the very first moments, the physics is well known. At the time of CMB, the universe consisted of hydrogen-helium gas at 3000K, and you can heat hydrogen-helium gas to that temperature to see what happens.

    You assume that one part of the universe is like another part, and the equations become very simple. Once you start forming galaxies, you no longer have this symmetry, and things get very messy.

    And then there is the really weird stuff. One thing that people are working on is to try to come up with models of what could have happened before t=0, with the hopes that you ought to seem some ripple effect that is observable.
  12. Dec 6, 2011 #11
    Just to be clear, this is because the universe is the way that it is, and not because of instrument detection limits. If we were living in a different universe that was 100 billion years old, or in an infinite steady state universe, our telescopes would be able to detect galaxies much, much further than what we see.
  13. Dec 6, 2011 #12
    Yes this is what I was getting at in my most recent question. Is the hubble telecope limiting our detection of even older galaxies (assuming they were there) eg. perhaps due to intensity or red shift beyond the instruments detectors.

    The reason I suggest this is that it still makes the news when the very highest red shift galaxies are detected and they seem to be only just detectedable so I wondered if perhaps instrumentation could be preventing us from seeing even older structures. Presumably there must have been some very violent supernovas in the first 500 hundred millions years are these observed?

    Twofish said "One other interesting thing is that if the universe was really infinite, then the sky wouldn't be dark at night (see Olber's paradox). The fact that the sky is dark is largely because you can only see back to the beginning of the universe."

    Well the sky isnt really dark we have all this CMBR which our eyes cant see. Before I signed on to the standard model I had often wondered if the CMBR could in some way be related to this paradox.
    Last edited: Dec 6, 2011
  14. Dec 6, 2011 #13
    Nope. It's not a detection issue.

    Part of it is a "needle in the haystack" issue. If you just take a picture of the sky, you see just a massive number of points of light. It takes some effort to go through all of those points, select the ones that might be distant galaxies, take spectrum, and then see what their redshifts are.

    The reason it makes the news when we see a really young galaxy is that young galaxies are just rare. The other problem is that right after the CMB, really young galaxies are just gas that we can't see because they don't shine. At some point the galaxies switch on so that we can start seeing them.

    People are trying to see population III stars. One mystery is that the oldest galaxies have some elements that couldn't have formed in the big bang, so the current idea is that there must have been a period of massive star formation. We're trying to see that.

    But if the universe was infinite then every spot should shine like the sun. The idea is that if the universe was infinite, if you look in any direction, you ought to eventually hit a star so the entire sky should be as bright as the sun.

    It is. The universe is finite age, and you can't see past the beginning of the universe. Also it's cool to go back in the 1960's and read alternative explanations for CMBR that didn't work out.
  15. Dec 6, 2011 #14
    Careful. You may be confusing the question of a Universe that is infinite in time, with a Universe that is infinite in space. We are 99.99999999% certain that our Universe is FINITE in time, i.e there was a beginning (Big Bang) approx. 13.7 billion years ago. In spatial extent, our Universe may very well be infinite. If the geometry is either Flat or Hyperbolic, it is infinite in extent. The most state-of-the-art measurements are pointing to a Universe with a flat geometry (i.e. infinite).

    The Olber Paradox is partially resolved by an expanding Universe...in that the more distant light E/M sources are more and more red-shifted...eventually to frequencies below visible light (e.g. microwave). The greatest contribution to the question why the Night Sky is dark, however, is due to the finite life-time of our Universe, and the finite life-time of stars. There has not been enough time or enough energy output from stars to make our night sky bright.
    Last edited: Dec 7, 2011
  16. Dec 7, 2011 #15


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    Olbers paradox applies to any universe that is both temporally and spatially infinite. An expanding universe does not satisfactorily resolve this paradox.
  17. Dec 9, 2011 #16
    Thanks for replies.

    Re Olbers paradox: I explain the darkness by saying that the observable universe is finite, including even the radius of the CMBR sphere which is the final obervable limit. I am not sure why Chronos says this doesnt satisfactorily explain the paradox?

    Can anyone speak to how the JWT would help with the deep field survey, beyond what Hubble is capable of?

    Yes I would like to see those very early population III supernovae, they seem to be an important piece in the puzzle.
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