Taken from a .edu website. Here's what it says.

Scientists check the accuracy of carbon dating by comparing carbon dating data to data from other dating methods. Other methods scientists use include counting rock layers and tree rings.

When scientists first began to compare carbon dating data to data from tree rings, they found carbon dating provided "too-young" estimates of artifact age. Scientists now realize that production of carbon-14 has not been constant over the last 10,000 years, but has changed as the radiation from the sun has changed. Carbon dates reported in the 1950s and 1960s should be questioned, because those studies were conducted before carbon dating was calibrated by comparision with other dating methods.

Nuclear tests, nuclear reactors and the use of nuclear weapons have also changed the composition of radioisotopes in the air over the last few decades. This human nuclear activity will make precise dating of fossils from our lifetime very difficult due to contamination of the normal radioisotope composition of the earth with addition artificially produced radioactive atoms.

Question:
1) How do they know that the Sun has changed in the last 10,000 years?
2) They are only certain that radioisotope compositions have "only" changed in the last few decades?


Interesting thought to question those who are certain with carbon dating or any dating method for that matter.

Blessings!

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Just a couple elementary observations that initially stuck out to me. 1) They check the accuracy of the carbon dating method by comparing it to other methods. How are they sure the other methods are correct? 2) "Scientists now realize that production of carbon-14 has not been constant over the last 10,000 years, but has changed as the radiation from the sun has changed." This is an interesting comment to me because a Biblical worldview would seem to provide a cause for this change; a global catastrophe (the flood). 

I found the comment concerning the nuclear tests, etc to be interesting. I may need to explore that a litter further. Thanks for sharing this. 

1) How do they know that the Sun has changed in the last 10,000 years?

The only natural source for 14C in the atmosphere is high-energy solar rays striking atoms of 14N and changing them into 14C. Over time, 14C decays back into 14N. This creation and decay leads to an equilibrium ratio of 14C to 12C. Plants incorporate atmospheric carbon into their tissues while they're alive, so a living plant will have a ratio of 14C to 12C that closely matches the atmospheric concentration. When a plant (or part of a plant) dies, no new carbon is added to the tissue, so as the 14C decays to 14N at a constant rate, the ratio of 14C to 12C drops.at a constant rate. Assuming a fixed atmospheric ratio, the difference between 14C in the sample and 14C in the atmosphere will tell you how long it's been since the sample died. Conversely, we should be able to predict the ratio of 14C in a sample of known age.

In fact, when samples of known ages (tree ring sequences, layers of lake sediment, coral deposits) are measured, the amount of 14C differs from the expected amount and things of a particular age differ by the same amount (rings from one tree match trees from other parts of the world as well as sediment cores, coral, etc.) Furthermore, historical fluctuations match historical sunspot cycles, which are known to affect the amount of solar radiation reaching Earth. Since scientists have continuous samples (trees matched by ring width, unbroken layers of sediment from lakes, coral reef cores) that reach from the present to 10,000+ years ago and show these fluctuations, the conclusion is that the amount of solar radiation has been changing over time.

2) They are only certain that radioisotope compositions have "only" changed in the last few decades?

The changes are measurable. Changes in 14C curves match changes in atmospheric 14C that can be directly correlated to man-made nuclear sources. There are no similar changes in the curves prior to the 1940s that could derive from other sources, whether man-made or not.

This is an interesting comment to me because a Biblical worldview would seem to provide a cause for this change; a global catastrophe (the flood).

The changes that they're talking about are much more gradual and long-term than one would expect from the Flood. Also, the fluctuations increase and decrease over time. Since historic fluctuations match known sunspot cycles and prehistoric fluctuations fit the same pattern, it is assumed that these match prehistoric sunspot cycles.

The journal Radiocarbon has online archives at radiocarbon.org going back to 1959 and many of the papers deal with calibrating radiocarbon dating curves, if you would like some insight into how scientists have arrived at their conclusions.

Rubina---the AMS C14 test used by creationists in recent years at Arizona State is one of the most advanced processes known. Also this counts c12 which does not dissipate   Actual molecules are counted and reconstructed  and so the accuracy of these tests is pretty clear.  Recent dating (by Paleo-Christians) has concluded man, dinos, and mammoths under the same as contemporaoes of one another and the dating results is under 50,000 down to 16,000 years(allosaurus).  

Dr. Bumgarner said that he believes a tweak in one process if he is correct would bring those dates down even more.  I just want to say that I don't think we can compare the 1950's-60's C14 process with this current development.  At the worst these dates bode for young earth.  Creationist Paleo guys were not allowed to produce their information at some of the larger scientific meetings because their work challenged the norm....I see this as a feather in YOung Earth creationists hat???

I believe this test to be pretty reliable, and if you read up on the tests done with this form, you would also find that comparisons and known dates of certain objects and ancient materials were used to test its accuracy and it is very very, accurate... so I think your last comment about questioning any carbon dating may not exactly reflect accuracy.  

The old c14 tests and many of the other tests are still inaccurate, and we creationists know this, but this AMS process used on dino bones etc. were based on the prediction by Paleo creationists that DInos are not that old and that c14 still were to be found in the bones.  Up and to that point it was not done as evolutionary scientists believed that 65 million year old dinos would have no C14 in it knowing the length of the half life of c14.....

Their belief (creationists) that carbon 14 should be still exist if they were Young Earth.  This is exactly what was found, and with the advent others finding blood, tissue  and collagen ..it is clear these animals are young earth.  So I think we should be a little more graceful in posting facts that support young earth.... Its not perfect... especially if you only allow for a 6,000 year old earth, while the bible surely implies young earth by relationships back to Adam & Eve, if it was 12,000 or 20,000, this would still not be 65 million years old.....Cheers!!! 

 

I just recently submitted my research paper for my Nuclear Science course on Radiocarbon dating. I posted it if anyone cares to check it out. It covers a lot of the pros and cons of radiocarbon dating and discusses a lot of the points mentioned here in further detail.

http://matthew2262.wordpress.com/2013/02/18/examining-radiocarbon-d...

Matthew I am very interested in this subject as I think while there issues with it, I also think that creationists are finding this as a good tool to infer young earth, and so I am not so quick to have a negative view of c14 testing especially or specifically AMS.  I will download and read it.  Love this site because there are a lot of knowledgable people, interested in what you have to say.  Cheers!!!!

Is it true that c14 said that an organism is 4000 y old while it was alive ?!
Matthew Parker said:

I just recently submitted my research paper for my Nuclear Science course on Radiocarbon dating. I posted it if anyone cares to check it out. It covers a lot of the pros and cons of radiocarbon dating and discusses a lot of the points mentioned here in further detail.

http://matthew2262.wordpress.com/2013/02/18/examining-radiocarbon-d...

Abdurrahman Ibraheem said:

Is it true that c14 said that an organism is 4000 y old while it was alive ?!

 

Anything that incorporates carbon from a source other than the atmosphere will date as old as the source of carbon. Animals that eat land plants (which derive their carbon directly from atmospheric CO2) eat plants that are at most a few years old (so may date two or three years older than they actually are), but animals that get their food from deep water may date much older (recently dead penguins often date several hundred to several thousand years old, depending on what fish they eat). The deeper the water, the longer it's likely to have been since the CO2 in the local food web was in the atmosphere (this is referred to as "carbon reservoir"). There are published calibration curves for dealing with this problem. Shellfish (like the mussel in the cartoon) often incorporate carbon for their shells that is even older, originating in decaying material or underground limestone deposits that may be thousands of years old.

Does it give correct readings to materials we actually know the dates of?

Donald Smith said:

Does it give correct readings to materials we actually know the dates of?

 

It depends on what you mean by "correct". It gives consistent readings for particular materials of known ages, but the readings are slightly different than a simple 14C decay curve would predict and the older the materials, the more they diverge from the curve. The method scientists use to deal with this is to measure as many things with known ages as possible to calibrate the readings. If they measure a bunch of wood that is known to be 400 years old and it measures an uncalibrated 450 years old, for example, then unknown wood that measures 450 years old is "corrected" to 400 years old.

 

Lou, Mariana & Matthew: 

Are there any other documents that would help in the understanding of radiometric dating? Anything which you guys have helped publish or in the midst of publishing?

http://www.radiocarbon.com/carbon-dating-results.htm describes the BETA Analytic Final Report. Could someone explain what this report is?


Pretreatment Methods

Beta Analytic’s pretreatment methods are reported along with each radiocarbon dating result. All necessary chemical and mechanical pretreatments of the submitted material are applied at the laboratory to isolate carbon 14, which may best represent the time event of interest.

When interpreting the radiocarbon dating results, it is important to consider the pretreatments. Some samples cannot be fully pretreated, making their carbon 14 ages more subjective than samples that can be fully pretreated. Some materials receive no pretreatments.

AMS Dating Procedure

AMS carbon dating starts with the reduction of the sample carbon to graphite (100% C) along with preparation of standards and backgrounds. The graphite is then analyzed for carbon 14 content in an accelerator mass spectrometer. The final result is corrected for isotopic fractionation then converted into a calendar-calibrated date.

Radiocarbon Age and Calendar Calibration

The "Conventional Carbon 14 Age" is the result after applying carbon 13-carbon12 corrections to the measured age and is the most appropriate radiocarbon age. Applicable calendar calibrations are included for organic materials and freshwater carbonates between 0 and 42,000 BP. If certain calibrations are not included with a report, the results were either too young, too old, or inappropriate for calibration.

Beta Analytic started using the INTCAL09 database in September 2011 to calibrate radiocarbon age to calendar years. In previous years, the laboratory has been using the INTCAL04 database. If you need to have your results recalibrated, please email us at lab@radiocarbon.com.

Beta Analytic's calibration program takes into account the errors of each individual tree-ring measurement on the calibration curve and then employs a "spline fit" mathematics procedure to the data as per Mathematics use for calibration scenario - A Simplified Approach to Calibrating C14 Dates, Talma, A.S., Vogel, J.C., 1993, Radiocarbon 35 (2): 317-322)

Standard Deviation

Beta Analytic does not report standard deviations of less than +/- 30 BP for single measurements since this can lead to a misinterpretation of the accuracy of the results. The only time standard deviations of less than +/-30 years BP are reported is when the lab runs a unique sample fraction (e.g. a single twig, seed, bone, shell) 2 or 3 times on portions that have been pretreated, graphitized, and AMS counted independently of each other. This ensures that as much as possible, any sample, laboratory or counting bias is accounted for in both the accuracy and quoted sigma. Once 2 or 3 measurements have been made, the lab then performs a weighted average age and error calculation and reports those values.

The detection efficiency in particle accelerators is very high, as such extremely low sigmas are possible simply by measuring more reference standards and/or counting the unknown sample for longer periods of time. While this may produce a very small numerical sigma value, that value is strictly limited to the "determinate errors" associated with counting the 14C modern standard (oxalic acid), unknown sample, and chemical blank (background).

Quoted sigmas on radiocarbon dates, unfortunately, cannot take into account "indeterminate errors" such as sample homogeneity, chemistry, and to a lesser extent, detector stability. As good as AMS machines are, simultaneous measurements of the 14C modern standard, sample, and blank cannot be done so small shifts up or down in the detection efficiency of the AMS over the course of the run will affect the accuracy of the result, which at times are outside of the smaller quoted sigma values possible. This is why Beta Analytic only quotes smaller errors by going through the additional effort and cost of running samples multiple times.

Rubina said:

http://www.radiocarbon.com/carbon-dating-results.htm describes the BETA Analytic Final Report. Could someone explain what this report is?

 

If this company dates a sample for you, they send you this report that gives information about how they prepared and tested the sample. If the customer is a scientist writing a scientific paper, then this information would go into the "methods" section of the paper.

"Pretreatment" is the process of preparing a sample for analysis. The goal is to remove any contamination that might mess up the results. Wood, for example, is usually washed and then subjected to chemicals that dissolve everything but lignin (the structural portion of wood). If a sample can't be completely pretreated, then there's a higher chance that a result is altered by environmental contamination.

AMS stands for accelerator mass spectrometry and is one (very accurate) way to determine the ratio of 14C to 13C/12C in a sample. In AMS, individual graphite molecules are electrically accelerated down a long tube. Heavier molecules containing 14C atoms travel slower than lighter ones that don't, so the instrument can count how many 14C atoms are in a sample. Another way to count 14C atoms is to measure the number of radioactive decays from a sample of known size during a fixed time.

Age calibration is what I briefly wrote about in my last post. INTCAL09 is a collection of calibration curves for different materials, available here. The attached graph, for example, is for terrestrial materials (including wood). According to the graph, a piece of wood that gives an uncalibrated date of 10,500 years BP (before present) should actually be dated to 12,400-12,500 years BP, or 10,450-10,550 BC.

 

 

"Standard deviation" is a statistical term that boils down to how likely it is that the results are accurate and is based on the accuracy of the 14C measurement. One standard deviation (also referred to as "one sigma" or 1σ) is equivalent to ~68% and two standard deviations is ~95%. If the standard deviation is +/- 200 years, for example, that means that the sample is 95% likely to be within 400 years of the measured age. The paragraph about the standard deviation is saying that even if the sample is good enough that the standard deviation for the measured result is less than 30 years, there are sources of error outside the instrument that are +/- 30 years, so the lab can't get any more accurate than that no matter what.

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