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EvC Forum Science Forums Dates and Dating

# 14C Calibration and Correlations

Author Topic:   14C Calibration and Correlations
dwise1
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 Message 16 of 59 (580843) 09-11-2010 5:24 PM Reply to: Message 13 by faith2409-11-2010 4:04 PM

 I am confused about the half life thing. Can someone please explain what that is?

It applies to the decay of all radioactive materials. Basically, there's a probability that the nucleus of any given radioactive isotope will decay, but we can't really predict when that will happen to a particular nucleus. Rather, we can work out statistically how long it takes for half the nuclei in a sample to have decayed. That time is the half life of that isotope and we have found that each isotope's half lives are constants -- ie, each isotope has its own particular half life and each half life is a constant.

Here's a resource that will explain it better and help you learn: Radiometric Dating: A Christian Perspective by Dr. Roger C. Wiens at http://www.asa3.org/ASA/resources/Wiens.html. He also covers different kinds of decay and even isochrons, the methodology for dating rocks.

With all due respect, not being able to know what you do and don't already know, if necessary you should brush up a bit on atomic theory first. Such as the number of protons in the nucleus being what determines which element that atom is. And that there are normally an equal number of neutrons in the nucleus, but an isotope is when there's a different number of neutrons. Some isotopes are unstable, making them radioactive. And when an isotope decays, part of the nucleus breaks away, including some protons; the loss of protons changes that isotope to a different element, called a daughter element. Certain isotopes have particular daughter elements, which can also be radioactive isotopes that will decay their own daughter elements. These decay chains are part of what nuclear physicists study.

One of the benefits of creation/evolution are these opportunities to learn something.

 This message is a reply to: Message 13 by faith24, posted 09-11-2010 4:04 PM faith24 has not yet responded

RAZD
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 Message 17 of 59 (580845) 09-11-2010 5:29 PM Reply to: Message 13 by faith2409-11-2010 4:04 PM

Hi faith24, and welcome to the fray.

 There is very little C-14 to begin with that can be calibrated back to a few 6-10k years based on historical data.

Which the limitation of the historical record, not the 14C (or other dating) record(s).

See Message 1 for the correlations that extend back to the theoretical limits of the 14C method, correlations that are actual annual counts from several different systems that all agree on the age in question. This is how dating methods are calibrated to improve their accuracy.

Note that these calibrations all show that the age measured by 14C is consistently too young, so using uncalibrated ages is conservative.

 I guess i would have to say the correlation is only as good as your guess assuming the decay rate is a constant.But somehow people will say " oh but it is constant"!

It has been measured and tested and tested and measured and there is no evidence of any significant change in decay rates. Uranium halos are a great demonstration of this, as they take hundreds of millions of years to form, and if the decay rate changed the halos would not form.

See Are Uranium Halos the best evidence of (a) and old earth AND (b) constant physics? for further discussion of this.

 I am confused about the half life thing. Can someone please explain what that is? This is confusing.... it is like playing chess - it takes time to learn each pieces have certain moves and all the number of possible moves you can make.

It is what education is like, learning things that form a basis for additional learning.

Half-life is a way of describing an exponential decay curve. This kind of decay curve occurs a lot in nature, not just in radioactive decay. It is a particular element of the curve that the time it takes for quantity {A} of element {X} to reach 1/2{A} is the same as the time it takes 1/2{A} to reach 1/4{A} and for 1/4{A} to reach 1/8{A}, etc etc etc.

The basic formula is:

N = N0(1/2)(t/HL)

Where:
N = amount, N0 is the original amount
t = time, in years
HL = half-life, in years

This is what half-lives are, and why they are used.

An example is a bucket of water with a hole in the bottom. The flow out of the hole is related to area of the hole and the pressure of the water at the hole, which is a function of the depth of the water over the hole.

When the bucket is full, the pressure is maximum and the flow rate is maximum, when the bucket is half full the pressure is 1/2 maximum and the flow is 1/2 maximum. If we go through the mathematical derivations we will end up with a flow decay curve that is exponential with a "half-life" for the time it takes to reach half full from full, quarter full from half full, etc.

The thread that coyote was referring to on another thread Age Correlations and An Old Earth, Version 2 No 1, parts of which have been excerpted for Message 1

Enjoy

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 This message is a reply to: Message 13 by faith24, posted 09-11-2010 4:04 PM faith24 has not yet responded

JonF
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 Message 18 of 59 (580850) 09-11-2010 5:47 PM Reply to: Message 15 by faith2409-11-2010 5:16 PM

 I still don't see how it is a constant? How do i determine what is constant and what is not?

Physicists understand radioactive decay very well. They can predict what we would see today if radioactive decay rates varied in the past. Since the physics of atomic nuclei is a very fundamental part of how our universe works, it turns out that there are lots of things we would see today if radioactive decay rates varied in the past. We've looked really hard for those things, and they aren't there. We conclude (we do not assume) that radioactive decay rates have been constant for 13-ish billion years.

 This message is a reply to: Message 15 by faith24, posted 09-11-2010 5:16 PM faith24 has responded

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faith24
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 Message 19 of 59 (580859) 09-11-2010 7:20 PM Reply to: Message 18 by JonF09-11-2010 5:47 PM

quote:
Physicists understand radioactive decay very well. They can predict what we would see today if radioactive decay rates varied in the past. Since the physics of atomic nuclei is a very fundamental part of how our universe works, it turns out that there are lots of things we would see today if radioactive decay rates varied in the past. We've looked really hard for those things, and they aren't there. We conclude (we do not assume) that radioactive decay rates have been constant for 13-ish billion years.

What does the constant decay rate has to do with the age of the earth? What if the decay rate change, then what happen?

 This message is a reply to: Message 18 by JonF, posted 09-11-2010 5:47 PM JonF has responded

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crashfrog
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 Message 20 of 59 (580863) 09-11-2010 9:05 PM Reply to: Message 15 by faith2409-11-2010 5:16 PM

The Carbon Cycle
 Hrmm... So the assumption is based on the amount of C-14 in the atmosphere is the same found in plants/animals.

It's not an assumption. We know it's the same because of the carbon cycle - the carbon present in organisms is ultimately coming from, and going back into, the atmosphere. Photosynthetic organisms are fixing CO2 into sugars, which are consumed by other organisms and incorporated into their structure; organisms are respirating and breaking down sugars into CO2 for energy and exhaling it into the atmosphere.

That's the carbon cycle, in a nutshell, and it ensures that carbon is cycling through the biosphere so fast that the isotope ratios in living things will always be the same as the atmosphere. It only stops when the organism dies. And when it stops, the ratio of carbon-14 begins to drop due to radioactive decay. Therefore we can measure the time elapsed since an organism died, subject to the ability of our instruments to measure C14 and its decay products.

 This message is a reply to: Message 15 by faith24, posted 09-11-2010 5:16 PM faith24 has not yet responded

JonF
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 Message 21 of 59 (580865) 09-11-2010 9:19 PM Reply to: Message 19 by faith2409-11-2010 7:20 PM

 What does the constant decay rate has to do with the age of the earth? What if the decay rate change, then what happen?

If decay rates changed, it would cause the radiometric dating methods that tell us about great ages to be wrong. If radioactive decay rates sped up the ages we would get would be older than the real age. If the Earth is really around 10,000 years old that would require speeding up radioactive decay rates so much that the Earth would melt and everyone would be fricaseed by the heat. And the radiation would fry 'em too.

Another fact is that there are many different ways that radioactive elements decay. If our methods give us the wrong answers than all those differnt ways would have to change in just the right way in a coordianted manner. Otherwise dating methods based on different modes of decay wouldn't agree so often.

 This message is a reply to: Message 19 by faith24, posted 09-11-2010 7:20 PM faith24 has not yet responded

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 Message 22 of 59 (580873) 09-11-2010 10:43 PM Reply to: Message 13 by faith2409-11-2010 4:04 PM

 I guess i would have to say the correlation is only as good as your guess assuming the decay rate is a constant.But somehow people will say " oh but it is constant"!

Well ... it is. This is one of the first things that was checked --- by the Curies, whom I presume you've heard of --- right back when radioactive isotopes were first discovered. They looked to see if the decay rate was affected by any environmental influences such as temperature or pressure. They drew a blank.

Throwing the sample into a nuclear reactor might skew your results, I guess ...

Besides which, we can check radiocarbon dating against dendrochronology and the formation of varves in proglacial lakes. In order for radiocarbon dating to be wrong, they'd have to be wrong too, which would mean that three totally unrelated processes would have had to go wrong in lock-step with one another.

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faith24
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 Message 23 of 59 (580874) 09-11-2010 10:45 PM Reply to: Message 18 by JonF09-11-2010 5:47 PM

quote:
Physicists understand radioactive decay very well. They can predict what we would see today if radioactive decay rates varied in the past. Since the physics of atomic nuclei is a very fundamental part of how our universe works, it turns out that there are lots of things we would see today if radioactive decay rates varied in the past. We've looked really hard for those things, and they aren't there. We conclude (we do not assume) that radioactive decay rates have been constant for 13-ish billion years.

Whether it is constant or not, that can be debatable. But either way you will have to choose one or the other based on the evidence you believe to go right where it leads you.

Edited by faith24, : No reason given.

Edited by faith24, : No reason given.

Edited by faith24, : No reason given.

 This message is a reply to: Message 18 by JonF, posted 09-11-2010 5:47 PM JonF has responded

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Coyote
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 Message 24 of 59 (580877) 09-11-2010 11:27 PM Reply to: Message 23 by faith2409-11-2010 10:45 PM

No, not debatable
 Whether it is constant or not, that can be debatable. But either way you will have to choose one or the other based on the evidence you believe to go right where it leads you.

The only ones who dispute the decay constant are creationists, who do so for religious reasons rather than scientific ones.

The evidence, when you actually follow it, leads to the conclusion that the decay constant has been constant for billions of years.

The key points of the book can be summarized as follows:
1. There is overwhelming evidence of more than 500 million years worth of radioactive decay.
2. Biblical interpretation and some scientific studies indicate a young earth.
3. Therefore, radioactive decay must have been accelerated by approximately a factor of one billion during the first three days of creation and during the Flood.
4. The concept of accelerated decay leads to two unresolved scientific problems, the heat problem and the radiation problem, though there is confidence that these will be solved in the future.
5. Therefore, the RATE project provides encouragement regarding the reliability of the Bible.

They RATE study produced evidence which showed science was right, but they refused to accept their own findings!

Pertinent to your position, if the decay constant changed to permit radioactive decay that was sufficiently fast so as to accommodate a young earth, the heat and radiation produced by that accelerated decay would have cooked the earth and irradiated anything on it.

The RATE boys had no answer to this problem, and fell back on a priori religious belief that some solution would be found at some unspecified date in the future.

Sorry, that's not doing science. That's religious apologetics.

Even though the RATE boys spent over a million dollars of creationist money, they were unable to come up with any evidence to support their position.

So no, this question is not debatable--at least not within science. The debate, if there is one, is between scientific evidence on one side and religious beliefs which are contradicted by scientific evidence on the other.

Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.

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 Message 25 of 59 (580878) 09-12-2010 12:15 AM

Incipient topic drift (maybe) happening

Revised message - Just a caution.

Please remember that this is a Carbon 14 themed topic. Carbon 14 only used for up to ~50 thousand years back and is not relevant for datings of millions or billions of years. If you find that messages are heading towards millions or billions of years considerations, then you need to find a topic elsewhere.

Or something like that.

Short version: Let's continue to keep things Carbon 14 connected.

This revision is a result of this message, for which I thank Coyote.

Edited by Adminnemooseus, : Hid original message and toned down subtitle. Did revised message.

Percy
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 Message 26 of 59 (580900) 09-12-2010 9:46 AM Reply to: Message 23 by faith2409-11-2010 10:45 PM

 faith24 writes:Whether it is constant or not, that can be debatable.

Sure it can be debatable. If the evidence for a constant decay rate were equivocal then the conclusion that the decay rate is constant would be debatable. But the evidence for a constant decay rate is unequivocal. Even the RATE group discovered that it is unequivocal.

In case it wasn't clear from Coyote's post, the RATE project was a creationist research effort conducted under the auspices of the Institute for Creation Research and the Creation Research Society.

--Percy

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kbertsche
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 (1)
 Message 27 of 59 (580973) 09-12-2010 6:11 PM Reply to: Message 19 by faith2409-11-2010 7:20 PM

 What does the constant decay rate has to do with the age of the earth? What if the decay rate change, then what happen?

First, I agree with those who say that the decay rate has not changed; we have good experimental and theoretical evidence for this.

Second, even if it had changed in the past (e.g. a hypothesized "accelerated nuclear decay"), this would not affect calibrated radiocarbon dates.

Why is this? Let's consider how radiocarbon calibration is done. We start with tree species which have pronounced annual rings (e.g. N. American Bristlecone Pine, Irish Oak). We both count the rings (to get a calendar date), and radiocarbon date them assuming a constant radiocarbon ratio in the atmosphere and today's decay rate (to get an "uncalibrated" date). This gives us a calibration curve, allowing us to convert uncalibrated dates to calendar dates.

Now suppose you find a piece of old wood and have it dated. How is this done? First, a date is calculated assuming a constant radiocarbon ratio in the atmosphere and today's decay rate (exactly the same way that the calibration curves were done). Then, we use the calibration curves to get the actual calendar date.

How would a change in decay rate (perhaps due to a hypothesized "accelerated nuclear decay" about 5000 years ago) have affected the situation? It would have changed the uncalibrated dates, both for our unknown sample and for the calibration curve. Thus the calibration curve would be different. But after calibration, the date for the unknown sample would come out the same. In essence, the calibration procedure cancels out any changes in decay rate or in atmospheric radiocarbon concentration. A calibrated date depends only on two assumptions:
1) the atmospheric concentrations of radiocarbon were the same at the unknown wood and at the trees which were used for calibration
2) tree rings are annual and we can count them accurately.

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JonF
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 Message 28 of 59 (580989) 09-12-2010 7:23 PM Reply to: Message 23 by faith2409-11-2010 10:45 PM

 Whether it is constant or not, that can be debatable

Well, it could be debatable; it was; but it is no more. The debate is long over. Radioactive decay rates have been constant for 13-ish billion years.

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chenchen21621
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 Message 29 of 59 (601372) 01-20-2011 3:32 AM Reply to: Message 15 by faith2409-11-2010 5:16 PM

Spam - Content deleted

Edited by AdminPD, : Removed spam

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RAZD
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 Message 31 of 59 (690399) 02-12-2013 5:46 PM

Bump for CoolBeans
Welcome to the fray CoolBeans

 http://www.dinosaurc14ages.com/carbondating.htmIm not a creationist I just want to clear some doubts. Some of the dinosaurs dated have been fairly recent.

Half this article is misinformation, and half is bogus, the remaining half has just enough truth to make the article seem to be a genuine discussion of 14C dating.

 Im sorry. im new in here. Some of their points is that their results agree with each other. They specifically criticize carbon dating at the begining giving the results of dating living animals. They are not published in any journal but they claim censorship. Thir work was presented at a convention, but their work has been deleted. I dont trust this people. Some of them are ver well known. Hugh Miller and Carl Baugh are part of this. They sent their samples to Geochron and other facilities to test them. The paper is in the website. So if you are interested in it, read it.

Let me predict that one of these living animals is a seal at McMurdo Sound.

See Message 1 of this thread for the evidence on 14C accuracy, and also see Radioactive carbon dating and fossils and carbon dating.

Enjoy

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