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Carbon dating explained simply southern

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Posted by Paul Braterman. Radiocarbon dating only takes us back some 50, years. This makes it a much smaller threat to Young Earth creationists than, say, lead-uranium dating, which takes us back billions of years. So why do creationists single it out for attack? Because there are indeed problems with the most simple-minded application of the method, and it does not matter to the creationist that these problems have long since been solved.

Creationists think, and Carbon dating explained simply southern, more like lawyers than like scientists. In the courtroom, changing your story under cross-examination will destroy your credibility, and yet this is what scientists Carbon dating explained simply southern all the time.

Scientists accept that even the most well-established findings are subject to revision and refinement; lawyers, like theologians, Carbon dating explained simply southern certainty whether the data Carbon dating explained simply southern it or not.

I start with a simplified summary of the principles behind radiocarbon dating, without which the discussion would be meaningless. Most radiometric methods depend on measuring the amount of a parent radioactive isotope present in the sample, and the amount of the daughter into which it decays. Add up the amount of parent Carbon dating explained simply southern present and the amount of Carbon dating explained simply southern, and that gives you the amount of parent present initially.

You can determine the rate constant by taking a known amount of parent, and counting the number of decays per second, as measured with a Geiger counter or a more reliable and up-to-date instrument such as fluorescence counter. In the case of radiocarbon dating, the parent is carbon and the daughter is Carbon dating explained simply southern, which is lost from the sample.

This seems like a dead end, until we remember where carbon comes from. Carbon is formed in the upper atmosphere by the effects of cosmic ray bombardment on nitrogen, is rapidly converted to carbon dioxide, and then mingles with the rest of the CO2 in the atmosphere see Figure. If we assume a steady rate of bombardment, that Carbon dating explained simply southern we will have a steady rate of production of carbon, and a steady state abundance of carbon in the atmosphere, where the amount decaying each year Carbon dating explained simply southern equal to the amount being formed.

Now consider what happens during the life Carbon dating explained simply southern an organism, and after its death.

The Birth of Carbon 14

As long as it is alive and metabolising, it will exchange carbon with its environment, taking it in directly as carbon dioxide by photosynthesis Carbon dating explained simply Carbon dating explained simply southern a plant or indirectly as food for an animal. At this stage, the proportion of carbon present as carbon will be directly dependent on that in the atmosphere.

But as soon as it stops metabolising, it stops exchanging, and the proportion present starts decaying according to the radioactive decay law, with a halflife of years. So it looks as if we can just use the proportion present in the atmosphere right now as a measure of the initial proportion, and compare it with the proportion remaining.

But this is unrealistic, since the intensity of cosmic ray bombardment is known to change over time. Moreover, it could have been associated with an increase in the rate of carbon production, making pre-flood specimens look much older than they really are. With the exception of the first and last, all these objections have some degree of plausibility, but unfortunately for the creationists they have all long since been answered, many of the answers being set out by Willard F. Libby, inventor of the method, in his book on the subject.

If any of these had been different, we would not have had the same kind of physics and chemistry that we have today. But we know from their structure that ancient rocks were formed under the same rules as we have today, because they contain the same kinds of elements combined to make the same kinds of minerals. The creationists have published theoretical curves for Carbon dating explained simply southern in decay constants, but these have no basis in science, and are generated merely to make observations fit the biblical timeline.

This method works because all but the Carbon dating explained simply southern layers of a tree are metabolically inert, and out of circulation. The most recent calibration comes from organic debris in varves annual layers of Carbon dating explained simply southern deposited in a lake Lake Suigetsu, in Japan that happens to be free of turbulent inflows. Near doubling of atmospheric C14 in the Southern hemisphere, as the result of nuclear testing.

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One of the lies you were Carbon dating explained simply southern told at school is that all isotopes of the same element Carbon dating explained simply southern precisely the same chemical properties. This is not true, and generally speaking, heavier isotopes are slightly more sluggish in their chemical reactions.

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These North Ronaldsay sheep, which feed on seaweed, will show different isotopic Carbon dating explained simply southern from sheep fed on grass. This effect has been measured for photosynthesis. Carbon dioxide in plants is, as expected, slightly depleted in carbon relative to carbon, and the effect is far from Carbon dating explained simply southern around 27 thousands of carbon abundance for most kinds of plant.

It is retained as part...

We expect the effect to be twice as large for carbon, which, using the known year halflife of carbon, corresponds to years; not trivial when dating historical artefacts.

Carbon dating explained simply southern, exactly the same effect will Carbon dating explained simply southern to Carbon dating explained simply southern dating explained simply southern material used to set up the calibration, and the errors will systematically cancel out. Ideally, the fractional abundance of carbon should be measured, as well as that of carbon, to calibrate out any minor fractionation Carbon dating explained simply southern, and this Carbon dating explained simply southern less arduous than it sounds because nowadays carbon abundance is measured by direct counting in a mass spectrometer rather than, as in the original studies, indirectly inferred from sample radioactivity.

For plants, it is straightforward Carbon dating explained simply southern match like with like. Not so for material derived from animals, where the total amount of isotopic fractionation will depend on their diets, and also on what they have been eating.

However, as already Carbon dating explained simply southern, we now have direct calibration back to 52, years before present, beyond which the amount of remaining carbon is so small that using current techniques the method Carbon dating explained simply southern useless.

About Paul Braterman

If carbon had been buried in the flood, the appropriate amount of carbon would have been buried with it. And the ideas of a changed rate of Carbon dating explained simply southern or decay have been dealt with under 1 and 2 above.

I have discussed this before. And marine specimens will always contain less carbon than terrestrial specimens of the same age, because of the time it takes for mixing between the atmosphere and surface waters, and again between Carbon dating explained simply southern waters and the depths.

The first, and most difficult, thing is to realise that he is been perfectly sincere. He is certain that his reading of the Bible is true; but the facts of geology are also true; and it is therefore his mission to create an account that reconciles the two. If this means the mountains must have skipped like rams, then that is how they must have skipped.

He Carbon dating explained simply southern feel no more absurd Carbon dating explained simply southern this point, than the cosmologist feels in invoking a time when our Universe was smaller than a tennis ball and its temperature was trillions of degrees. Counter-arguments will be dismissed as so many minor anomalies that will no doubt be explained away in due course.

If the creationist repeats long-refuted claims, that is because he believes that there are refutations Carbon dating explained simply southern the refutation, even if he cannot immediately call them to mind, or does not have time to explain them properly. You and I of course would never do such things, but your friends might when it comes to defending emotionally precious but logically fragile beliefs; consider, for example, what passes for political discussion in your favourite pub or chatroom.

And what does this mean for debating with creationists? Such a debate, unlike a discussion between people willing to learn Carbon dating explained simply southern each other, is a zero-sum game.

He will project simplicity, sincerity, and certainty, and when you come to reply, you Carbon dating explained simply southern dating explained simply southern sound as if you are making excuses. He will present anomalies did I mention those year-old water snails? His followers will end up confirmed in their convictions, as will yours, and those in the middle will come away confirmed in their own initial conviction that there are two sides to the story, both worth hearing.

But does that mean that we can learn nothing from the creationists? Carbon dating explained simply southern both Leonard and I have learnt a great deal from examining the creationist claims. Be smart, and learn from everyone. There are standard techniques for doing this, for instance by measuring non-radiogenic isotopes Carbon dating explained simply southern the daughter material, and, these days, Carbon dating explained simply southern microsampling of single crystalline grains.

Lecture scene from Glasgow Skeptics in the Pub Facebook page. Atmospheric carbon diagram public domain, by Hokanomono via Wikipedia. Posted on March 25,in CreationismReligionScience and tagged carbon isotopescarbon datingisotopic fractionationLake SuigetsuphotosynthesisRadiocarbon datingRadiometric datingWillard Libby.

Reblogged this on Peddling and Scaling God and Darwin and commented: Another good article by Paul. Creationists have been misrepresenting radiometric age-dating for over 80 years and are immune to criticism.

Reblogged this on Patrick Mackie. I just sent this article to this bloke who is indeed impervious to criticism: Same final outcome, however arrived at. You are commenting using your WordPress. You are commenting using your Twitter account.

You are commenting using your Facebook account. Notify me of new comments Carbon dating explained simply southern email. Notify me of new posts via email. This site uses Akismet to reduce spam. Learn how your Carbon dating explained simply southern data is processed. Home About me Book: Leave a comment Comments 7. Paul Braterman March 25, at 8: I think you mean impervious. Patrick Mackie March 26, at 7: Paul Braterman March 26, at Duncan Booth March 26, at 2: Paul Braterman March 26, at 3: Ashley Haworth-roberts March 28, at Leave a Reply Cancel reply Enter your comment here Fill in your details below or click Carbon dating explained simply southern icon to log in: Email required Address never made public.

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