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I Question on the particles that formed the Earth.

  1. Jul 1, 2017 #1
    Full disclosure, I am a creationist, but i want to know the finer points about the big bang and the creation of the universe.

    So we know that the formation of new rock from lava doesnt make them "day zero" rocks, ie they still would be considered aged when we do radiometric dating. So we know these changes dont change their "clocks" on how old they are, I think this is accepted among creationists and non creationists alike. So how do we know when the earth was formed by the particles of the big bang that the particles from the big bang havent aged on the way to the creation of the Earth assuming the particles from the big bang are "day zero" particles? Could being in the proximity of antimatter age or reverse age matter? So many questions regarding this but I'll stat here.
     
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  3. Jul 1, 2017 #2

    Orodruin

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    This is false. For example, potassium-argon dating is performed by comparing the potassium and argon abundances in the rock. The argon created by potassium decays while the rock is molten, but once it solidifies it traps the argon. The rock is therefore "day zero" due to not having any argon in it when it is formed and you can perform the dating by comparing the amounts of potassium and argon. For basic information on K-Ar dating, see the wikipedia page.
     
  4. Jul 1, 2017 #3

    mfb

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    All dating methods where one element can form a crystal but its decay product cannot form the same crystal start at zero age when the rock solidifies.
    All dating methods using radiation damage in solids start at zero age.
    Basically all dating methods for anorganic material rely on one of these two ideas. Not a coincidence, you need a well-known initial state.
    It was not.
    The big bang only produced hydrogen, helium and tiny amounts of lithium. Most of Earth is made out of heavier elements that formed in stars later.

    For things like the overall uranium isotope ratio (238 to 235; 234 is produced from 238 decay so that is special), what we see is indeed not the age of the Earth, it is the age of the uranium, and it is a bit older than Earth. This ratio on its own is not used for dating.
    No. And there are no relevant amounts of antimatter around anyway.
     
  5. Jul 1, 2017 #4

    Drakkith

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    Hi Damian79. Welcome to PF!

    Before we begin this discussion (which appears to have already started while I was typing this), I'd like to make it clear that ALL discussion should take place in the context of known science. This means that if someone tells you that X is true or Y is the way that something works, we are talking about those things as currently understood by the mainstream scientific community. There is no discussion of "absolute truth" here. I say this because I want to avoid many of the issues that often plague these conversations where criticism is given of the scientific view for not "truly" knowing what happened in the past or at large distances. We fully know and admit that we can't know any absolute truth and any statements or facts given here should always be understood as being part of a theory or model that is always being tested and verified to the best of our abilities. And rather than being a weakness of science, it's actually a strength in that it allows us to constantly ensure that our body of knowledge is as accurate as possible

    For starters, this is not how cosmologists and other scientists model and understand the formation of the Earth or anything within the universe. It would be beyond the scope of this post and probably this thread to give you the entire history of the universe as given in the standard model of cosmology (you can find a decent explanation on wikipedia), but we can talk about a few key points. Note that this is a very brief and general overview and is not intended to be an extremely accurate description.

    1. The big bang and subsequent evolution of the universe resulted in the formation of mostly hydrogen and helium, with a tiny smattering of lithium and a few other light elements (we're going to mostly ignore dark matter here, as it's not well understood yet and doesn't do much except provide extra gravity help form galaxies and galaxy clusters).

    2. These atoms eventually coalesced under gravity to form the galaxies and then the first stars.

    3. The fusion of light elements inside these stars created heavier elements like carbon, oxygen, nitrogen, etc. These first stars were very, very massive and eventually underwent supernova, spreading their heavier elements out into the universe to mix with the hydrogen and helium gas still out there. Galaxy and star formation continued, pumping out larger quantities of heavier elements over time.

    4. During subsequent star formation, the heavier elements formed what we call "dust". Now, dust is a very different thing that hydrogen and helium gas and has a profound impact on the events of star formation. With only hydrogen and helium (and perhaps trace quantities of lithium), the collapsing gas cloud tends to just get blown away once the proto-star becomes hot enough to emit lots of radiation and solar wind. There is no formation of rocky planets at this time because there are no heavier elements. However, once you add carbon, oxygen, nitrogen, iron, and the dozens of other heavier elements (including uranium) to the collapsing cloud of dust and gas, things change.

    Heavy elements are much denser than either hydrogen or helium and when the collapsing cloud of dust and gas forms a large, rotating disk surrounding the proto-star they tend to "stick together" to form molecules, dust grains, and small rocks that aren't simply blown away when the proto-star heats up. Over time, these rocks collide and merge with other rocks to form larger bodies, which then collide with more material, building up what are called "planetesimals". Further merging of these planetesimals results in the formation of proto-planets which eventually become full-fledged planets as they finally merge with the remaining material.

    5. Now, this is where a crucial part of dating the ages of rocks comes into play. At first, the proto-planets and newborn planets are very, very hot. So hot that they are essentially completely molten. Over time they cool down and the different elements are able to form solid rock. The particular composition of this rock is extremely important. We know that certain elements only bond in certain ways with other elements. For example, a particular type of rock is formed by silicon, oxygen, and zirconium and is known as Zircon. Zircon has the property that it readily incorporates uranium into itself, but it strongly rejects lead during its formation. So as the Earth cooled, zircon formed wherever there was sufficient quantities of oxygen, silicon, zirconium, and uranium.

    However, uranium is radioactive and has a half-life of about 4-billion years (experiments have verified this to a very high precision). Over time, part of the uranium that was taken up into zircon decays into various other elements, which themselves also decay into lighter elements. This chain of decay eventually stops at lead. As I said above, lead is strongly rejected by zircon when zircon is initially forming. So we can say with good confidence that any lead present inside zircon is the result of the decay of uranium. By looking at the ratio of lead to uranium, and knowing the decay rate of uranium and its decay products, we can reliably date the age of a sample of rock. Obviously things are more complicated than I've described them, but that's the general idea behind radiometric dating.

    Now, the reason I explained all of this was to give a very basic overview of how we date rocks and to show that much of the atoms making up the Earth were not formed directly via the big bang, but inside of massive stars and supernovae. When it comes to dating the age of the universe things get a bit more complicated and we have to use multiple methods that are very difficult to explain if you know very little about astrophysics. For example, I could tell you that we can date the age of a star cluster by looking at the type of stars remaining in the cluster (the ones that haven't undergone supernova yet), but you'd need to know about the details of how stars work to understand why that particular type of dating method works. And things only get more complicated from there.

    No. Antimatter is understood pretty well. It does not have any "mystical" properties that normal matter lacks. Antimatter works just like matter in all respects except that the sign of certain properties change (charge goes from positive to negative or vice versa as an example).
     
  6. Jul 1, 2017 #5
    I am a little confused by what you are saying. Do fresh lava rocks return a result of possibly zero days old when radiometric dating is done on them? Do you have a link that shows this?
     
  7. Jul 1, 2017 #6

    Orodruin

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    In molten rock, the argon escapes. When it solidifies there will therefore be no argon. If you make a measurement right after the rock has solidified, you will get an age of zero. Due to the long half-life of potassium-40, "zero" essentially means that you know that the rock is "less than 100000 years" as it takes some time for a measurable amount of argon to accumulate.

    I also suggest you read @Drakkith 's post regarding uranium-lead dating, which is based on a similar principle.
     
  8. Jul 1, 2017 #7
    Thank you for that primer Drakkith. So we get the dates from calculating the amount of material created by the original material? Or am I wrong here?
     
  9. Jul 1, 2017 #8

    PeterDonis

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    A good source on the general methods of radiometric dating is the Isochron Dating article at Talk.Origins:

    http://www.talkorigins.org/faqs/isochron-dating.html

    Potassium-Argon is one of the methods to which the general principles given in this article apply.
     
  10. Jul 1, 2017 #9
    I dont see any examples of fresh rocks coming up in the links of "potassium argon dating fresh lava rocks" that have low dates listed in the links. Perhaps my google search is borked because of my search history, so I can only see those dates from creationists which I know are contested.
     
  11. Jul 1, 2017 #10

    Orodruin

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    Yes, but you also need to know how much of the original material is left. Otherwise you cannot know the fraction of the original material that has decayed and, by extension, the age of the sample.

    Let us take a hands-on example with made up numbers. Let us say that your friend has a bunch of peaches and you know that every day your friend will eat half of the peaches that are left, leaving only the seed. If you only count the seeds, you have no way of knowing when the peaches were picked. However, if you see that there are 4 peaches and 28 seeds, then you know that
    • there were 8 peaches and 24 seeds 1 day ago
    • there were 16 peaches and 16 seeds 2 days ago
    • there were 32 peaches and 0 seeds 3 days ago
    and consequently the peaches were picked 3 days ago. Without the information of how many peaches there were or without the information on how many seeds there were, you would not have been able to obtain the information on when there was no seeds.

    Because of low accuracy for young rock, it is very impractical to use K-Ar dating on young rock (all it will tell you is that the rock is less than 100000 years). For young rock, it is much more interesting to use dating methods that employ nuclei that decay faster, since they will give more accurate results. Of course, you can try to do K-Ar dating on fresh rock, but it will just come out with zero argon abundance and this is not a very exciting result.
     
  12. Jul 1, 2017 #11

    Orodruin

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    To put this in a formula. The basic idea is based on having a number of nuclei ##N_0## of the parent nucleus and none of the daughter at time zero. A priori, you do not know ##N_0##. The number of parent nuclei after a time ##t## has passed will be given by ##N_P = N_0 2^{-t/t_0}##, where ##t_0## is the half-life of the parent. This also means that the number of daughter nuclei that have been produced are ##N_D = N_0 (1 - 2^{-t/t_0})## and consequently the ratio ##R = N_D/N_P## at time ##t##, which is what you can measure, is given by
    $$
    R = \frac{1-2^{-t/t_0}}{2^{-t/t_0}} = 2^{t/t_0} - 1 = e^{\ln(2) t/t_0} - 1
    $$
    and we can solve for ##t## as
    $$
    t = \frac{t_0}{\ln(2)} \ln(R+1).
    $$
    If you only knew ##N_D## or ##N_P##, you would not know what ##R## was. Note that there is no need to know the original number ##N_0##, you can make do with just things that you can measure today.
     
  13. Jul 1, 2017 #12
    I see.



    That is the issue I am currently having to accept all. I want to see a result that comes to 0.1 or less million years old. Has there been any tests done to prove the assumption that all the argon would leak out and give an almost zero day result? Has there been a study of the rate of argon leaving the rock? So at least I can be lead to believe that at the start, the age of the rocks would be zero?
     
  14. Jul 1, 2017 #13

    Orodruin

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    This will be difficult to find. Not because it is not possible, but because it is very basic and rather uninteresting to do such a study although it would in principle be very easy to do it. Just take some freshly formed rock and try to measure its argon content, you will get zero. I am not a geologist so I do not know the early publication history regarding radiogenic dating. It would however have made sense for early scientists to do such tests with known young samples.
     
  15. Jul 1, 2017 #14

    mfb

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    Pierre-Yves Gillot, Yves Cornette: The Cassignol technique for potassium—Argon dating, precision and accuracy: Examples from the Late Pleistocene to Recent volcanics from southern Italy
    2000 years is short enough to use well-documented volcanic eruptions.

    Table IV compares the measured ages with the actual eruption dates.
    Eolian islands: Eruptions 1400-1500 years ago, K-Ar measurements range from "0 to 4000 years ago" to "1200-2000 years ago" depending on the sample.
    Isle of Ischia: Eruption 715 years ago, K-Ar measurements go from "0 to 2000 years ago" to "300 to 1500 years ago".

    Random example, not the only such study.
     
  16. Jul 1, 2017 #15

    Drakkith

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    In addition to the above examples, note that it is a very, very well understand fact that gases in a liquid will diffuse from areas of higher concentrations to areas of lower concentrations if possible (perhaps "concentration" is not the right word. Partial pressures perhaps?).
     
  17. Jul 1, 2017 #16

    Orodruin

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  18. Jul 1, 2017 #17
    That about wraps it up for the questions from me. Thanks you for such quick responses. Sorry for the late reply, I had to do something.
     
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