Carbon 14

Carbon 14 atoms are almost identical to ordinary carbon atoms - which we call Carbon 12.  The difference between them arises because within the atomic nucleus Carbon 12 has six neutrons, whereas Carbon 14 has eight.  When the neutrons are added to the normal complement of six protons we get 12 or 14 particles totally in the carbon nucleus, hence the names.  Carbon 12 is by far the most common form of carbon on earth, with only about one atom in a million being Carbon 14.  There are other forms of carbon which differ in their neutron numbers, but they do not concern us directly here.

From a chemical point of view, and therefore from a life point of view, Carbon 14 only differs from the others in that it is radioactive.  That is to say, the atom has a tendency to spit bits out at random and to change into something completely different chemically.  Carbon 14 atoms are produced in the upper atmosphere by cosmic rays (neutrons) colliding with nitrogen atoms.  At some quite random point later each Carbon 14 atom 'decays' (breaks up), by throwing out a neutron, to become nitrogen again.  From the point of view of life there is no difference between the two.

In the normal way there is a constant flow of carbon through a living thing.  The carbon atoms in our bodies are constantly being 'swapped', so that all the carbon atoms, in common with all our atoms, are completely replaced over a period.  The effect of this is that while the organism is still alive the Carbon 14 is regularly replaced, and in theory is in 'steady state' in the organism.  The proportions of C14 and C12 will be similar to the proportions in our environment, which is mainly the atmosphere.  The carbon is present in the air as carbon dioxide.  There are other stores of carbon such as carbonate rocks which do not materially affect the argument.

However, when the organism dies this constant replacement ceases.  Because the Carbon 14 breaks down, its proportion in the total sum of the carbon atoms in the dead organism gradually becomes less.  Hence, if we have a means of measuring the relative proportion of Carbon 14 in the dead organism we also have, at least in theory, a means for measuring how long that organism has been dead.  In practice at the moment the Carbon 14 content decreases by half every 5500 years approximately.  If the Carbon 14 content is only one eighth of what we expect, then we have had three 'half lives', as they are known, and the time lag between when the organism died and the present is approximately 5500 x 3 years = 16500 years.  This is the theory.

Nearly all the methods of measuring date have problems.  The most important of these are factors which affect the apparent age of the sample.  Radioactive methods also have their fair share of these problems, some of which, it has to be said, are not really taken into account when calculating ages.

These include

1. knowledge of the stability of the breakdown rate;
2. an assumption that the starting conditions in any age are the same as they are today, or that, if different, the starting conditions are known or can be calculated accurately;
3. and that no material has been lost or gained.

There are more, but these will do to illustrate the difficulties.

To expand the problems:

1. The breakdown (radioactivity) rates have to be assumed to have always been the same, else there is no basis to make any calculations at all.  Unfortunately we simply have no means of testing this assumption.  We have been monitoring breakdown rates for less than 100 years, and we are extrapolating this, in some cases, back over millions if not thousands of millions of years.  As far as Carbon 14 is concerned we are, in the eyes of most scientists, working within the last 100,000 years, but there is still a factor of 1:1000 between our measurement time and the era to which we extrapolate.  If the rates have changed, even by small amounts, the cumulative effect could eventually be very large.

   Attempts have been made to calibrate the 'carbon curve' with other things, notably tree-rings.  As anyone who really knows about tree-rings will tell you, that in itself is an arcane science and full of assumptions which, while apparently reasonable, are no substitute for knowledge.  The simple fact is that all correlations of this kind are subject to error, which could all too often be serious.

2. There are two starting conditions in the case of Carbon 14 which are of concern.  One is the background Carbon 14 level in the environment.  This affects how fast Carbon 14 is taken up by living organisms, and it also therefore affects what proportion of Carbon 14 is actually present in a living thing when it dies.  The second is how fast Carbon 14 is being made at the moment.

   These are more serious problems than might appear from a cursory glance.  It is possible to calculate the rate of production of Carbon 14 in the upper atmosphere, given the concentration of nitrogen, the cosmic ray flux, and the chance of actual conversion should a cosmic ray collide with a nitrogen atom.  From this information we can then calculate what the background level of Carbon 14 should be.

   To understand exactly what is going on one has to imagine that there was a time at which there was no Carbon 14 on the Earth at all.  One then has to picture the 'take-off' of Carbon 14 from some arbitrary year zero, the Carbon 14 proportion rising on an ever-flattening curve to a steady level.  I'm not sure where the curve effectively levels out, but by all reasonable calculations it turns out that we are still on the rising part of the curve, and are nowhere near steady-state.  Melvin Cook points out that the present level is lower than it should be (i.e. the 'steady state' situation) by some 30%. (Cook)

   What this translates to in practical terms is that, at the present level of cosmic ray flux and nitrogen concentration, the atmosphere came into being no more than 16,000 years ago!  It also skews all the Carbon 14 dates, so that the calculated ages of materials telescope as one goes back in time.  The older dates are brought forward exponentially to a maximum of 16,000 or so years.  Scientists claim to have accounted for this one, but this is manifestly not the case, for they are still happily quoting Carbon 14 dates of 50,000 years, or more.  This is isn't science, whatever else it may be.

   Melvin Cook's book is well worth a perusal, even if one cannot hack the maths.  He is very thorough, and has some extremely interesting stuff on all sorts of issues related to creation.  He was a Professor of Materials Science at the university of Utah, and clearly knew his subject.

3. Material loss is also an issue, because carbon compounds can be lost from organic materials, but it is accepted by most that the error due to simple loss would be small.

   A particular source of worry here is confidence in the figures themselves, wherever they come from.  To illustrate this, there is a firm in the US called Geo-Chron, which performs Carbon 14 dating on a commercial basis.  The significant fact about this firm is that they will not, for money, commit themselves to dates greater than 3000 years.  They do not have the confidence in the Carbon 14 dating system to assign dates to material seemingly older than this.  This has nothing whatever to do with the accuracy or sensitivity of their equipment.  It stems simply from the uncertainties of the method.

   Academic scientists, in direct contrast to this, are quite happy to assign dates back to 50,000 years.  The reason that they can do this, pretty obviously, is that they are not accountable for their results in any meaningful way.  Geo-Chron are, hence the difference.  A commercial firm will not stake their professional reputation on ages greater than 3000 years for any sum of money.  It is a revealing comment on the validity of scientist's views, I think.

There are other snippets of interest here.  For example, for obvious reasons no substance older than about 60,000 years can contain Carbon 14.  However, we have identified some Carbon 14 in, e.g. samples of oil or coal, which means that coal and oil do not have to be anything like as old as some people would like us to think.  They must be of an age less than 60,000 years.  The immediate cry from the establishment here would be 'contamination', but great care was exercised when taking samples because it was realised that this would be an objection.

Again, comparison of Carbon 14 datings with those from other radioactive dating methods can reveal huge differences.  A skull found by Dr Leakey in Africa was dated by the Potassium-Argon method at 1,750,000 years.  Mammal bones in the same fossil bed were dated by the Carbon 14 method at about 10,000 years.  The subsequent reaction of Dr Leakey was that it must have been the bones of modern animal which fell into a crack.  In passing it must be said that Leakey was working in a volcanic area which had such fissures in abundance.  He was digging for paleontological remains.  A volcanic area is hardly one which can be reliably dated, as any genuine volcanologist will tell you, and to complain that some bones were of a modern animal that fell into a crack exposes that same scientist open to claims that the 'old' skull wasn't so old after all.  He wants to eat his cake and have it too.

Another similar incident, which could not be explained away quite so readily, was dealt with by not 'accepting' those figures, and more 'dates' being determined, which agreed better.  This is not untypical of the way dating is done, sadly.  This type of discrepancy is by no means unusual and serves to illustrate just how inaccurate the methods are.

The scientist who developed the Carbon 14 dating was Libby, for which he subsequently won a Nobel prize.  In private correspondence to Cook he admitted the problems inherent in the method.  He, better than any, should have known.  But he did not make those deficiencies known generally, and neither does anyone else in the main scientific establishment.  This does not encourage confidence in the claims of Leakey et al.

There are now better methods of using the Carbon 14 content of dead material to date specimens.  Mass spectrographic methods eliminate much of the uncertainties of measurement, and use very much smaller quantities of material into the bargain.  But the results are still merely a set of numbers (proportions of isotopes, basically), and these have to be interpreted.  The measurements are very accurate: interpretation is still an art subject to human whim.

References:
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Cook, M., 'Pre-History and Earth Models'