Can science prove how old the earth was?

Discussion in 'Earth Science' started by Mind Over Matter, Aug 16, 2011.

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  1. Mind Over Matter Registered Senior Member

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    Some scientists claims that the age of the earth is between 4.4 and 4.6 billion years old.

    What physical evidence to support that claim?
     
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  3. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    Good question.
    I didn't know the answer before looking it up.
    It's amazing how often just because you see something written down that you accept it without question.
    Here's the answer.

    Radiometric Dating.
    In some parts of the world the mineral Zircon was formed in the presence of Uranium. Zircon is able to include the metal Uranium in its structure as an alternative to the metal Zirconium, but not Lead.
    The atoms of Uranium bound in the mineral slowly turn to lead.
    By measuring the amount of Uranium against the amount of lead in a crystal of Zircon, the age of the crystal can be measured.
    The decay, though random, proceeds at a calculable rate, which gives a highly accurate result.

    Uranium-lead dating is often performed on the mineral zircon (ZrSiO4), though it can be used on other materials, such as baddeleyite.[19] Zircon and baddeleyite incorporate uranium atoms into their crystalline structure as substitutes for zirconium, but strongly reject lead. It has a very high closure temperature, is resistant to mechanical weathering and is very chemically inert.
    http://en.wikipedia.org/wiki/Uranium-lead_dating


    Sounds good to me.
    Any particular reason why you ask?
     
    Last edited: Aug 16, 2011
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  5. leopold Valued Senior Member

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    the age of the earth cannot be directly measured like for example a tree and its rings.
    with any indirect method comes assumptions.
    assumptions are things we take for granted but actually we have no proof of, that's why they are called assumptions.
     
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  7. wlminex Banned Banned

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    . . . .Yes radiometric age-dating om zircon (and other minerals) works well. . . . but remember that we are dating the age of the 'zircon' (when it crystallized). If the host rock has been 'recycled' (e.g., metamorphosed, etc.) or the zircon has re-crystallized, or otherwise the U-Pb ratio 'reset' . . . the original host rock may actually be older than indicated. Also, there are arguments made that 'loss' of radiometric components may indicate a younger age Maximum age of the earth is determined by finding (and reporting) the radiometrically-'oldest' (via U-Pb) zircons. We perhaps need to look at zircons, etc. in some meteorites?

    wlminex
     
    Last edited: Aug 16, 2011
  8. wlminex Banned Banned

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    Leopold99 quote: "assumptions are things we take for granted but actually we have no proof of, that's why they are called assumptions."

    You MEAN, we take these things (assumptions) on "FAITH"? . . . I've seen that word in some theological posts (tee hee!)

    wlminex
     
  9. Ophiolite Valued Senior Member

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    Assumptions are not taken for granted. Taking things for granted is not science. (But then you have never displayed much of an understanding of what science is, despite years spent on this forum.)

    Assumptions are starting points of a sequence of tests that either validate the assumptions, require them to be modified, or lead to their rejection. The assumptions that lead to the estimates of the age of the Earth have been validated from a number of independent directions to the extent that it would be wholly unreasobable to seriously doubt the broad ages ascribed to the Earth.
     
  10. leopold Valued Senior Member

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    i thought i was on your ignore list.
    put me back on it and keep me there.
    report the post if you have any problems with it.
     
  11. Ophiolite Valued Senior Member

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    I have no intention of reporting the post.
    I have every intention of stating what the problem with the post is.
    I have done so.

    I shall continue to do so with each post you make until either I get bored, or you start talking intelligently.

    Now, do you deny that your understanding of 'assumptions' in a scientific context is flawed? If not, justify your understanding.

    If you choose not to respond to that request you reveal yourself as being even more messed up than I generally believe you to be.
     
  12. Trippy ALEA IACTA EST Staff Member

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    As Ophiolite and wlminex have pointed out, your use of 'assumption' in the scientific context is flawed.

    The only assumption made in such measurements is that the earth continues to behave in much the same way it always has, and we have good proof to support that assumption.

    The rest (eg including Zircon dating) comes from observations that can (and have) been verified in a laboratory by direct observation.
     
  13. Trippy ALEA IACTA EST Staff Member

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    However, the TP history of the rock can be inferred from observations of which metamorphic facies are present, and from observations of discrepancies between various clocks (which have different reset temperatures).
     
  14. Me-Ki-Gal Banned Banned

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    I pretty much except the earth is 4 billion years old , or maybe 5 . I take it on Faith as scientist that seem to know what they are talking about tell Me this . I trust there judgment, After all they look for the evidence like good detectives that they are .
     
  15. leopold Valued Senior Member

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    really?
    what proof is there that says radioactive decay always proceeded at the rate it is now? we are talking about zirconium and its compounds.
    that's assumption 1.
    that is also what you stated in the above quote, you are assuming things have always been the way they are now which may or may not be correct.
     
  16. spidergoat Valued Senior Member

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    ...astrophysical observations of the luminosity decays of distant supernovae (which occurred far away so the light has taken a great deal of time to reach us), for example, strongly indicate that decay rates have been constant (at least to within the limitations of small experimental errors) as a function of time as well. (wikipedia)
     
  17. Trippy ALEA IACTA EST Staff Member

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    There's what Spidey siad (included below):

    There's also things like Oklo Fossil Reactors.

    But equally, as with all models, if the underlying assumptions were wrong, it would introduce anomalies - discrepancies between prediction and observation. And there aren't really any. We've even been able to infer some quite amazing things about the history of our solar system as a result.
     
  18. billvon Valued Senior Member

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    Physics and the inherent "time travel" given to us by the speed of light. We can see what happened billions of years ago - and nuclear reactions proceed at the same speed now as they did back then.
     
  19. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    The atoms of Uranium that exist now, have existed since they were created.
    Their physical decay is not affected by light or heat or pressure.
    We can't go back in time to check, but it is reasonable to assume that the laws of nature were the same 3,000 or 3 Billion years ago.
    Why should you think otherwise?
     
  20. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    That won't work against this type of argument.
    You are making assumptions.
    That the speed of light is a constant.
    That the laws of nature do not change.
    That space and time have always been the same.


    If people are determined to believe that the world is a few thousand years old, they will concoct theories to suit their beliefs, and you will never convince them otherwise.
     
  21. leopold Valued Senior Member

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    2 words quantuum mechanics, and more specifically the uncertainty principle.
    when an experiment depends not on physical laws but whether an observer is present then all bets are off.
    you really can't be too sure of anything under those circumstances.
     
  22. Captain Kremmen All aboard, me Hearties! Valued Senior Member

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    That's a cleverer argument.
    Yes according to quantum physics, until the crystal is looked at all the atoms of Uranium are in a state of possibly having turned to lead.

    But, if you knew how old the crystal was, you could still predict the proportion which would have turned to lead.

    Similarly, once you look at the crystal, you can tell the amount of time which must have passed to make that proportion of Uranium turn to lead.

    Unless the laws of physics were different in the past.

    You are back to your original argument.
     
  23. Trippy ALEA IACTA EST Staff Member

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    Here's the thing though. Nowhere does it say that the observer has to be intelligent.

    In this instance, the crystal itself counts as an observer.
     
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