What baffles me is how someone could use this argment (even if true) and go from "carbing daying may be flawed" to "therefor the biblical timelime is correct."   What a leap.

I've also run into arguments against carbon dating, and therefore evolution. I've tried reading up but I still didn't understand all of it. Theists seem to claim c-14 dating has been disproven, therefore evolution is false. For instance they will say 'Scientists tested an object they knew to be 100 years old, and c-14 dating put it at 5,000 years old, therefore it is not a valid test means'

A thing to remember here is even if c-14 is proven to be unreliable, it doesn't present any more evidence for the existence of their god. Heck, even if all of evolution was false, it doesn't automatically mean god exists.

OK, your friend is probably just repeating an old canard about accuracy in science. The fact is that any measurement is going to have defined error bars where we simply cannot be absolutely certain. In the case of carbon 14 dating, it is simply not possible to date an object to say 13 October 8354 BCE at 10:04 a.m.

Allow me to explain a bit further.

Carbon 14 has a known radioactive halflife which is a matter of quantum physics. What make it useful is the fact that at the moment that a specific plant or animal dies, it stops participating in the environment and the level of carbon 14 is fixed at that point. By analyzing the amount of carbon 14 present, it is possible to get a decent idea of when it died. Past that, you should also know that the half life of carbon 14 is close enough to 5730 years and we can measure it accurately for about ten half lives before there is no longer enough to work with. Here is where the rub is:

If carbon 14 is produced in the environment at a steady rate, then we can use it for dating with a high degree of confidence. Mostly this is correct. However, there are slight variations in the rate of formation of carbon 14. The primary source for carbon 14 is when cosmic rays in the upper atmosphere interact with nitrogen 14 (which is stable). However, that process is not perfectly constant.

1. In our galaxy, there is a supernova about twice every century on average and that will cause a temporary increase in the level of cosmic rays coming in from space.

    

2. Also, the earth's magnetic field changes slowly with time and this throws a small uncertainty into the works.

    

3. If that is not enough, changes in the level of sequestered carbon entering the atmosphere also contribute to the uncertainty in carbon dating (forest fires, methane hydrate in permafrost being released by climate change, the industrial revolution for example).

So just how can we even use the carbon clock at all? Well, the fact is that it is not the only clock that we have which can be used on the same time scale.

For example, we can check the carbon 14 level in tree rings. Since we know when tree rings were made to an accuracy of about one year going back a few thousand years, we can get the first part of the carbon clock down pretty accurately. Past that, we can line those dates up with other dating systems, such as varves (annual deposits of sediment in rivers and lake beds) and ice cores from the arctic. Generally, we can use carbon dating to get dates accurate to between 30 and 50 years when they are compared to other sources of dating information.

There are tons and tons and tons and tons of problems with C-14 dating. Luckily we have found work around to these problems. First a little piece of trivia. In the 1940's Willard Libby and James Arnold calculated the half life of radiocarbon (C-14) to be 5568 years. This value was used thought to be correct and used in radiocarbon dating experiments for quite some time. We now know that is 5730. However, because it would be confusing to change over to the correct value the original half life of 5568 years is still used even today. Is this a problem? Nope, its not off by enough to make a difference, once we account for all the other problems with C-14 dating.

Radiocarbon is produced in the earth's atmosphere when radiation hits nitrogen. I'm not a chemist and I don't know exactly how this happens so bare with me. Now, if the sun emits a constant rate of radiation then C-14 should be produced at the same rate. If this is true then we should see a build up of C-14 until it reaches critical mass and the amount of material decays at the same rate as it is produced. This is at about 62T. However, as we all know, the sun has periods of high and low activity. For this reason scientists have created calibration curves that were calculated by dating objects of known age (pieces of wood dated by dendrochronology, objects from tombs with written dates, etc...). What we can now do is compare the number calculated from a radiocarbon experiment to these charts to calibrate the age. It should be noted that this is only needed for objects more than 2500 years old (before 500 BCE).

Another problem is the deep ocean. The ocean exchanges carbon with the atmosphere. Sometimes carbon (and C-14 with it) can get trapped in the deep ocean, where it can remain for hundreds and thousands of years. While in the deep ocean, radiocarbon will decay. When water from the deep ocean wells up and ultimately rejoins the rest of the carbon exchange cycle, it dilutes the C-14 content with C-12 (regular carbon). This is also taken into consideration with the calibration curves.

Next we get to local problems. Rocks, like the deep ocean, can also act as carbon sinks. When rocks are formed carbon is trapped in them. The C-14 part of this carbon decays. When rocks erode by rain (or other forces) they expel their carbon into lakes and rivers. This, of course, dilutes the C-14 with C-12. For this must be taken into account when calibrating the age and can be done so by measuring. Also, C-12 diffuses over over plant leaves easier than C-14 (because its lighter, C-14 has 2 extra neutrons). When animals eat the leaves they dilute the C-14 in their body. This travels up the food chain and charts must be made for each species.

There are also problems with contamination. This can be avoided by good lab practices and by dating the insides of objects (the inside is less likely to be contaminated because its protected from the outside world).

Also, where funding permits, it is better to send two samples, each to different labs. If the results are the same then it is much more likely that there was no contamination or other complications with the experiment.

Sorry, I don't have any sources. I took a course on archaeology and the physical sciences and I'm just repeating what is in my notes. Hope this helped!

Kent Hovind has more to worry about prison dating than carbon dating.

Thanks again, everyone!

Conor

There is no hope for believers.

There is NO reconsideration of the decay rate, period. End of that discussion.

C14 is produced by cosmic rays. The more C14 the younger. About fifteen years ago there was some speculation that a nearby nova/supernova might have increased the cosmic ray flux and made some old things appear younger. Any such event would work in favor of creationists. To make things appear older there would have to be a decrease in cosmic ray flux. There is no conceivable mechanism by which this could have occurred.

The reality is C14 dating is used almost exclusively to date human activity. At the time this suggestion was made C14 dating was only good for about 16kyr and it might have explained why the sudden appearance of human artifacts 6kyr ago. That is things over several thousand years might appear to be bunched into a younger date. This has since been discarded. It explained nothing. Other dating methods are reasonably consistent with no increase in C14 in the atmosphere.

There is more to it than this but these are the fundamentals.

Introduce him to potassium argon dating and all the rest of the methods and he has no argument. Like somebody else said, there are many other methods.