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Question: How does carbon-14 dating work?
Answer: Cosmic rays in the upper atmosphere are constantly converting the isotope nitrogen-14 (N-14) into carbon-14 (C-14 or radiocarbon). Living organisms are constantly incorporating this C-14 into their bodies along with other carbon isotopes. When the organisms die, they stop incorporating new C-14, and the old C-14 starts to decay back into N-14 by emitting beta particles. The older an organism's remains are, the less beta radiation it emits because its C-14 is steadily dwindling at a predictable rate. So, if we measure the rate of beta decay in an organic sample, we can calculate how old the sample is. C-14 decays with a half-life of 5,730 years.
Question: What specifically does C-14 dating show that creates problems for the creation model?
Answer: C-14 dates show that the last glaciation started to subside around twenty thousand years ago. But the young-earth creationists at ICR and elsewhere insist that, if an ice age occurred, it must have come and gone far less than ten thousand years ago, sometime after Noah's flood. Therefore, the only way creationists can hang on to their chronology is to poke all the holes they can into radiocarbon dating. However, as we have seen, it has survived their most ardent attacks.
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Taken from this webpage Assumptions of Radioactive Dating • Smilodon's Retreat:
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Radiocarbon dating must be calibrated. How do we calibrate it? Well, we take a carbon sample from a material of a known age and date that. Then we compare the two and adjust the radiocarbon date to the known date. By making thousands (if not millions) of these adjustments we get a very good idea of how old a piece of unknown material can be.
Yes, this is a range of possible dates. All radiometric dating systems are range. The 2004 calibration set is here. Basically, the calibration curves are off by no more than 16 years over the historical range (6,000 years or so) and no more than 163 years over the last 20,000 years. That’s less than 1% if you’re interested in that sort of thing. The 2009 calibration set extends the ‘well calibrated range’ to 50,000 years using the varves in a Japanese lake. Varves are cool. I just like saying ‘varve’. But this is already almost a thousand words and I’ve only done ONE! response to these clowns.
Long story short, scientists have always known that variations in C-14 concentration happen. This is unlike the creationists which think it happened, but can’t be bothered to check.
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Taken from this webpage Carbon Dating Gets a Reset - Scientific American:
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From Nature magazine
The carbon clock is getting reset. Climate records from a Japanese lake are set to improve the accuracy of the dating technique, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct.
Carbon dating is used to work out the age of organic material - in effect, any living thing. The technique hinges on carbon-14, a radioactive isotope of the element that, unlike other more stable forms of carbon, decays away at a steady rate. Organisms capture a certain amount of carbon-14 from the atmosphere when they are alive. By measuring the ratio of the radio isotope to non-radioactive carbon, the amount of carbon-14 decay can be worked out, thereby giving an age for the specimen in question.
But that assumes that the amount of carbon-14 in the atmosphere was constant - any variation would speed up or slow down the clock. The clock was initially calibrated by dating objects of known age such as Egyptian mummies and bread from Pompeii; work that won Willard Libby the 1960 Nobel Prize in Chemistry. But even he "realized that there probably would be variation", says Christopher Bronk Ramsey, a geochronologist at the University of Oxford, UK, who led the latest work, published today in Science. Various geologic, atmospheric and solar processes can influence atmospheric carbon-14 levels.
Since the 1960s, scientists have started accounting for the variations by calibrating the clock against the known ages of tree rings. As a rule, carbon dates are younger than calendar dates: a bone carbon-dated to 10,000 years is around 11,000 years old, and 20,000 carbon years roughly equates to 24,000 calendar years.
The problem, says Bronk Ramsey, is that tree rings provide a direct record that only goes as far back as about 14,000 years. Marine records, such as corals, have been used to push farther back in time, but these are less robust because levels of carbon-14 in the atmosphere and the ocean are not identical and tend shift with changes in ocean circulation.
Bronk Ramsey's team aimed to fill this gap by using sediment from bed of Lake Suigetsu, west of Tokyo. Two distinct sediment layers have formed in the lake every summer and winter over tens of thousands of years. The researchers collected roughly 70-metre core samples from the lake and painstakingly counted the layers to come up with a direct record stretching back 52,000 years. Preserved leaves in the cores - "they look fresh as if they've fallen very recently", Bronk Ramsey says - yielded 651 carbon dates that could be compared to the calendar dates of the sediment they were found in.
The recalibrated clock won't force archaeologists to abandon old measurements wholesale, says Bronk Ramsey, but it could help to narrow the window of key events in human history. "If you're trying to look at archaeological sites at the order of 30,000 or 40,000 years ago, the ages may shift by only a few hundred years but that may be significant in putting them before or after changes in climate," he says.
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From the webpage Radiocarbon Dating:
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Reliability of radiocarbon dating
Radiocarbon dating has been studied at great length over the past few decades, and its strengths and weaknesses are very well understood at this point in time. For instance, even in the 1950s, when Willard Libby first developed the process, it was recognized that the scheme assumes that the level of carbon-14 in the atmosphere is constant. But researchers have known at least since 1969 that the carbon-14 level has not been constant, so that the radiocarbon clock needs to be "calibrated."
As a result, various schemes are used to correct and calibrate radiocarbon dates, including:
- Dendochronology: counting tree rings.
- Measurements of coral or other carbonate structures such as stalagmites, corroborated using uranium-thorium radiometric dating.
- Optically stimulated luminescence dating. This is based on the fact that stimulating mineral samples with blue, green or infared light causes a luminescent signal to be emitted, stemming from electron energy that is proportional to the amount of background radiation the specimen has undergone since burial. This scheme can be used to date items between about 300 years to over 100,000 years, and thus can be used to double-check and calibrate radiocarbon dates [Optical2011].
- Varve sediments: Counting the alternating light and dark bands in glacial lake beds that record the annual passage of seasons.
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Conclusion
The amount of carbon-14 in the atmosphere is not constant. The carbon clock need calibration against objects of known age. So everything hinges on these objects, like the 70-metre core samples from the sediment from bed of Lake Suigetsu, assuming that "distinct sediment layers have formed in the lake every summer and winter over tens of thousands of years."
The Bible tells us that there was a great flood. What is the impact of this flood on the carbon-14? What were the conditions in the antediluvian world? What was the amount of carbon-14 in the pre-flood world? No scientist takes that condition into account because they assume that the flood had never happened.
In the six hundredth year of Noah's life, in the second month, on the seventeenth day of the month, on the same day all the fountains of the great deep burst open, and the floodgates of the sky were opened. (Genesis 7:11 NASB)
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