# Carbon 14 testing and the age of the Earth



## PuritanCovenanter (May 15, 2008)

Does anyone know of any reliable articles refuting or confirming the testing method of Carbon 14 measurements?


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## reformedcop (May 15, 2008)

Doesnâ€™t Carbon-14 Dating Disprove the Bible? - Answers in Genesis


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## PuritanCovenanter (May 15, 2008)

That was what I was looking for. Thanks


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## Zenas (May 15, 2008)

It's quite amusing the faith science has in itself.


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## Backwoods Presbyterian (May 15, 2008)

Well said Zenas.


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## Iconoclast (May 15, 2008)

In the Beginning: Compelling Evidence for Creation and the Flood - index.html
Check this out, it is a really good online resource.


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## Abd_Yesua_alMasih (May 15, 2008)

My father is a scientist and I used to talk to him about this. He brought up what seems to be a common misunderstanding about carbon dating. It is all comparative. Actually they do not know if what they say is 10 million years old is really ten million years old, but what they can (hopefully) say is that something 12 million years old is older than 10 million years old. Thus they start to create their own timeline which is "good to work with" but not always acknowledged as 100% accurate.


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## Backwoods Presbyterian (May 15, 2008)

Interesting Fraser.


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## lwadkins (May 15, 2008)

Not to mention that the dating of an object can be affected by what conditions it has endured over the years.


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## PuritanCovenanter (May 15, 2008)

Iconoclast said:


> In the Beginning: Compelling Evidence for Creation and the Flood - index.html
> Check this out, it is a really good online resource.



This is a very interesting book also. Thanks.


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## Zenas (May 15, 2008)

As always, rather than questioning conclusions, they question evidence.


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## toddpedlar (May 15, 2008)

Abd_Yesua_alMasih said:


> My father is a scientist and I used to talk to him about this. He brought up what seems to be a common misunderstanding about carbon dating. It is all comparative. Actually they do not know if what they say is 10 million years old is really ten million years old, but what they can (hopefully) say is that something 12 million years old is older than 10 million years old. Thus they start to create their own timeline which is "good to work with" but not always acknowledged as 100% accurate.



To be fair, Carbon-14 isn't useful for anything older than a few thousand years (since its half-life is in that range). For dating things that are said to be millions of years old, other radioactive isotopes with much longer half-lives are used.


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## toddpedlar (May 15, 2008)

lwadkins said:


> Not to mention that the dating of an object can be affected by what conditions it has endured over the years.



Not sure what you mean by this, Lon. Conditions that something has endured can't (at least in any reasonable sense) impact the ratio of different isotopes in the substance. 

What is the dagger in the heart of dating methods, rather, is the assumptions made about "original isotope ratios" that are necessary in order to draw conclusions about current ages. Here I talk about things OTHER than the short half-life C-14 dating, which for what it can actually measure does a reasonable job (within the actual accuracy that it can claim - which usually involves quite large uncertainties). The million and billion year timeframes that are claimed for things rely on assumptions about 'original conditions' that aren't testable (unlike the 'original conditions' needed for C-14 dating, which are testable)


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## Backwoods Presbyterian (May 15, 2008)

Not to get to technical Todd but can you flush that out for us?


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## toddpedlar (May 15, 2008)

Backwoods Presbyterian said:


> Not to get to technical Todd but can you flush that out for us?



basically (and i need to get to bed soon or i won't get up in the morning sufficiently early ) it's this:

Lifetimes of radioactive elements are easily measurable by looking at the change of the rate of decay of a given sample of that substance. The decay rate changes according to an exponential function, so if you measure the rate of decays for identical short intervals over some period of time, you'll see the rate changing - and the function looks like Rate = Rate(t=0) * e^(t/lifetime). (here, e is the base of natural logs - 2.718blahblahblah) The quantity Rate(t=0) is something you don't know a priori, but it is a fact that the rate at any one time is proportional to the number of atoms of the radioactive isotope present. As these atoms decay, the number decreases - and hence so does the rate.

For carbon, there is a well known natural abundance of the radioactive isotope C-14, as compared to the normal isotope, C-12. I forget the actual number but it's something like 1 C-14 for every 10^18 C-12's. Don't panic - those aren't large numbers. 10^18 C-12 atoms is about the amount of C-12 atoms in 2 micrograms of carbon.

Anyway, in living organisms, this ratio is maintained as the organism eats, always taking in a fresh supply of C-14 along with the C-12 in its diet, and effectively balancing out the C-14 that is lost through decay. (you and I are radioactive - did you know that!?)

Now the organism dies. No more fresh C-14. The proportion of C-14 in the organism's body starts to decay away - from its mass, you can tell how much C-14 there was at "t=0" from the 10^-18 proportionality I mentioned. From its current rate of C-14 decays, you can then make the rate calculation Rate(t=now)/Rate(t=0). This ratio is just e^(-t/lifetime). Since we know the lifetime of C-14, we can from the ratio of rates find out what t, or the time since t=0; that is, the age of the organism since its death.

So far so good - for once living organisms, you have an easy way of dating them, and it's pretty reliable (though uncertainties might be significant, just due to the facts of scientific analysis which always have uncertainties).

For longer-timeframe measurements, the exact same method applies - the same radioactive decay laws (same form of the equation) holds. 

Difference is, though, we don't have a simple way to get the "original rate" of anything, because we don't have a simple way to get the original proportion of radioactive to non-radioactive isotopes in the object. 

But if we make assumptions - (you know what those do) we can get the original rate, and hence from an analogous analysis, the age of the object.

Problem is, those assumptions are grounded on - you guessed it, since I'm a card-carrying Van Tillian - PRESUPPOSITIONS.

Those presuppositions may or may not line up with the truth - and in fact if you don't make presuppositions in the case of long-timebase radioactive decay dating measurements, you can't do anything.

So there you have it... 

much too much detail, but finals have been over for a couple of days and I haven't lectured since last Thursday, so I was itching to do it, apparently


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## Backwoods Presbyterian (May 15, 2008)

Awesome Todd. Thanks a million.


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## Abd_Yesua_alMasih (May 16, 2008)

toddpedlar said:


> Abd_Yesua_alMasih said:
> 
> 
> > My father is a scientist and I used to talk to him about this. He brought up what seems to be a common misunderstanding about carbon dating. It is all comparative. Actually they do not know if what they say is 10 million years old is really ten million years old, but what they can (hopefully) say is that something 12 million years old is older than 10 million years old. Thus they start to create their own timeline which is "good to work with" but not always acknowledged as 100% accurate.
> ...


My bad. I was thinking of dating in general and applied it to carbon dating. From the post you can probably guess I am not a scientist.


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## aleksanderpolo (May 16, 2008)

Todd, thanks for the clarification. I have always wondered how one measure the half-life of something without taking measurement point that is at least comparable to its half-life. In my mind, it's like having a plot with x-axis spanning millions of year, with data point only spanning the last couple of hours, and try to measure the slope of this line and extrapolate it all the way to y-axis. I would like to see the actual plot of such measurement and its error estimation.

But it looks like from your explanation the R0 is an even greater uncertainy. What do you think of the RATE experiments that many site referenced? Are they being accepted as legitimate challenge, or are they just being laughed-off as old-wives' tale?


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## SRoper (May 16, 2008)

aleksanderpolo said:


> Todd, thanks for the clarification. I have always wondered how one measure the half-life of something without taking measurement point that is at least comparable to its half-life. In my mind, it's like having a plot with x-axis spanning millions of year, with data point only spanning the last couple of hours, and try to measure the slope of this line and extrapolate it all the way to y-axis.



You can make up for a long half-life by observing a large quantity of the isotope in question. It's really quite accurate if you think about just how many atoms are in a gram.

I find these discussions interesting because I'm hearing that a Christian worldview is the only worldview where science makes sense because we believe in a God that created an orderly universe where observation can make sense of things. However, it seems these same people cry foul when scientists take this well-ordered universe as a presuposition. "You're just assuming that decay rates are uniform throughout history," etc.


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## toddpedlar (May 16, 2008)

SRoper said:


> aleksanderpolo said:
> 
> 
> > Todd, thanks for the clarification. I have always wondered how one measure the half-life of something without taking measurement point that is at least comparable to its half-life. In my mind, it's like having a plot with x-axis spanning millions of year, with data point only spanning the last couple of hours, and try to measure the slope of this line and extrapolate it all the way to y-axis.
> ...



Getting a single measurement of rate is easy, but that does not give you the half-life. You still need to make observations that are separated in time - and the longer the half-life, the longer the separation needed between observations in order to get accurate results. More is always better, of course, but I just wanted to reiterate that you cannot determine halflife (without knowing the initial concentration that was in your sample) by a single rate measurement.


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## Semper Fidelis (May 16, 2008)

toddpedlar said:


> Backwoods Presbyterian said:
> 
> 
> > Not to get to technical Todd but can you flush that out for us?
> ...



I think you do a good job of noting some of the assumptions that go into some of our dating methods. Just to simplify for others, the half life of Carbon-14 is about 5000 years. That means that in 5000 years, you'll have 1/2 the Carbon-14 you had in your organic material that you did at the beginning of the period. As you note, Carbon-14 wouldn't really be a good way to determine that an object is several million years old but they have other isotopes for that.

One of the big problems they have, however, is being able to demonstrate two points:

1. That the amount of material they had in a rock or organic material is what they believed it was to begin with.
2. That the half-life of isotopes has not changed over the centuries.

For item 1, what if, when the earth was created, the Carbon-12 to Carbon-14 ratio was higher or lower naturally than it is now? Are scientists able to go back and _measure_ the ratio from 5000 years ago?

What about a rock formation with lead and U-238. How do they know how much of the lead was previously an isotope and how much was lead all along? How do they know there wasn't another isotope in the formation that decayed to lead.

For item 2, how do we know that the half-life of Carbon-14 has always been 5000 years? How do we know that the half-life of U-238 has always been 4 billion years? We cannot measure it.

The irony is that the naturalist has no emperical basis with which to even _begin_ to date an object. He can neither establish the amount of an isotope in certain objects nor can he state what the decay rate for isotopes where except for the past 100 or so years. He simply has a number of data points and then he extrapolates to the past by drawing a straight "best fit" line back to the past and says that the past has always been like the present.


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## Davidius (May 16, 2008)

SRoper said:


> aleksanderpolo said:
> 
> 
> > Todd, thanks for the clarification. I have always wondered how one measure the half-life of something without taking measurement point that is at least comparable to its half-life. In my mind, it's like having a plot with x-axis spanning millions of year, with data point only spanning the last couple of hours, and try to measure the slope of this line and extrapolate it all the way to y-axis.
> ...



Interesting point.  The ungodly have darkened minds and false presuppositions, so couldn't this effect their scientific conclusions?


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## aleksanderpolo (May 16, 2008)

Here is a simple calculation that I have done, please correct me if I am wrong.
Assuming a certain radioisotope has a half-life of a million year, assuming the rate equation to be:
A(t) = A(0)Exp(-Ln(2)*t/t(1/2))
After one day, the activity will be 0.999999998102 of its original activity, that is a change of 0.00000019% in activity.
After one year, the activity will be 0.999999306853 of its original activity, that is a change of 0.00006931% in activity.
So, even if the scientist take a whole year in measuring the change in activity, the difference is only 0.00006931%, I am wondering if this kind of accuracy has really been achieved, provide that radioisotopic decay is a random event (much like when you flip a coin 10000 times in multiple experiments, you will not get exactly 5000 head and 5000 tail in every experiment.) That's why I really would like to see the error bar associated with these kind of measurement, any relevant references?


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## toddpedlar (May 16, 2008)

aleksanderpolo said:


> Here is a simple calculation that I have done, please correct me if I am wrong.
> Assuming a certain radioisotope has a half-life of a million year, assuming the rate equation to be:
> A(t) = A(0)Exp(-Ln(2)*t/t(1/2))
> After one day, the activity will be 0.999999998102 of its original activity, that is a change of 0.00000019% in activity.
> ...



Any counting experiment has an uncertainty equal to +/- the square root of the number obtained.

So if you accumulate 100 counts, you have a 10% uncertainty, 100000 counts, 1% uncertainty, and so forth.

If you want to measure something with an uncertainty equal to 6.93 x 10^{-7} as you suggest, then you'll need to observe about 2.1 trillion decays.

Suppose you had a lump of 234 milligrams of U-234, which has a half-life of 245000 years. 

234 milligrams is 10^-3 moles, or 6.02 x 10^{20} atoms.

The rate of decays for such a sample would be equal to 0.693 * N / half-life,
or 5.41 x 10^{7} per second. 

Such a decay rate would be easily measurable with modern equipment. 

So, how long does it take to get to 2 trillion decays? about 38500 s.

That's half a day.

Of course no detector is 100% efficient, and whatnot, but a halflife of 250k years is pretty easily measurable with a small sample, and could be done in a day or so. Bigger sample, bigger rate, smaller time needed.

However... there are complications of course not least of which is that you can't get a perfectly pure sample like this very easily if at all; also, this isn't the way long-halflife isotopes' half-lives are determined - but I wanted to address only the question of whether it's possible to get such a precise result in a reasonable time, and the answer is yes.


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## Backwoods Presbyterian (May 16, 2008)

Fascinating stuff guys.


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## aleksanderpolo (May 16, 2008)

Thanks Todd, so at the end the biggest uncertainty is still A(0).


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## ChristianTrader (May 16, 2008)

SRoper said:


> aleksanderpolo said:
> 
> 
> > Todd, thanks for the clarification. I have always wondered how one measure the half-life of something without taking measurement point that is at least comparable to its half-life. In my mind, it's like having a plot with x-axis spanning millions of year, with data point only spanning the last couple of hours, and try to measure the slope of this line and extrapolate it all the way to y-axis.
> ...



Well ordered does not imply uniformitarianism. That processes can speed up or slow down does not argue against a rational ordered universe. This is besides the point that the dilemma that you seem to be setting forth here could be used to argue against miracles because such would imply that certain rates etc. have not been uniform from the beginning.

CT


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## Semper Fidelis (May 16, 2008)

ChristianTrader said:


> SRoper said:
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> 
> > aleksanderpolo said:
> ...



I agree. Entropy is a "law" of a well ordered universe after all.


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## SRoper (May 19, 2008)

ChristianTrader said:


> SRoper said:
> 
> 
> > aleksanderpolo said:
> ...



Without "uniformitarianism" what good is science? It seems any observations made only hold for the given experiment. The universe may be different tomorrow.

You are right, the dilemma may actually cut the other way. Could deism be a better foundation for science than Christianity?


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## Virginia Marine (May 19, 2008)

PuritanCovenanter said:


> Does anyone know of any reliable articles refuting or confirming the testing method of Carbon 14 measurements?



You may want to check out icr.org (link below)
Institute for Creation Research - A Christ-Focused Creation Ministry
They have a wide variety of articles on carbon 14 dating/age of the Earth/etc...
Hope this helps brother...
Semper Fi,
Jay


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## aleksanderpolo (May 19, 2008)

Virginia Marine, great profile picture! I used to stick the exact same picture outside my window when I was in grad school as a reminder of my "giftedness"!


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## ChristianTrader (May 19, 2008)

SRoper said:


> ChristianTrader said:
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> 
> > SRoper said:
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http://www.puritanboard.com/f60/wonderful-article-problems-uniformitarianism-32456/


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