What are the assumptions that must be enacted while using radion-carbon dating?

Question

I went to the Creation Museum (no bashing please!) and in the intro, they mentioned how that method of dating was innaccurate and that it was based on many assumptions. All it mentioned was that the decay rate was different in the past. Then in a different part of the museum said that this method was used to date rocks from the Most recent Mt. St. Helen's explosion 300,000 years old. How is that possible?

Emphasis on the second question.

Answer 1

With as little "bashing" as possible here, they are being intentionally dishonest. They are well aware from being told many times by many sources why their claims are bogus and misleading.

Just Google any portion of their claim and you will get numerous rebutals to their claims, many from experts. Do a little research into the expertise of the creationists making the claims, and which side would benefit the most from being dishonest about radiometric dating.

Answer 2

Radio-carbon dating is used to calculate the age of a formerly living fossil by measuring the amount of the carbon-14 isotope remaining in it.

Most carbon on Earth is the more stable carbon-12. Carbon-14 is created in the upper atmosphere when nitrogen absorbs stray particles from the solar wind and is transmuted: n + N-14 -> C-14 + p. Carbon-14 is not stable like carbon-12,; it will breakdown over time. The rate of this breakdown is very well know, so the age of an organic item can be calculated by comparing the ratio of carbon-14 to regular carbon-12.

The two assumptions that make radio-carbon dating work are: 1) the amount of carbon-14 created on a daily basis stays the same over time and 2) the item in question stopped absorbing carbon of any kind from the environment once it died.

The rate at which carbon-14 decays is not among the assumptions.

It should be noted the radio-carbon dating has its limitations. 1) Carbon-14 has a half-life of about 6000 years; it can only be used to date objects up to 30,000 years old. 2) It is accurate, but imprecise. Dates are reliable give or take 50 years. 3) It only works on an organic fossil, something that used to ingest carbon on a daily basis when it was alive, i.e. animals and plants. 4) Due to the amount of fossil fuels used in the last century, this method does not give accurate results when trying to date anything newer than 200 years.

For the record, radio-carbon dating is never used to date rocks. For that, geologists use radiometric dating of elements with much longer half-lives, such as argon and strontium.

Answer 3

Decay rates can fluctuate, but not very much. Because decay is based on the nucleus decaying, very little outside interactions are strong enough to effect the nucleus.

Look, i would love to bash creationism for 14 paragraphs, but I'll try not to be mean. Carbon dating is the MOST scrutinized science in the world. I did a presentation on how the machines work. And the scientists are not allowed to use glassware that's been used ever, and they have to report where they buy everything and there is so much scrutiny on it. The reason why is because it's based on things that people don't understand very well and creationists can use that to try and twist it.

Like it's based on probability. During a half life there is a 50% chance of a decay in every nucleus. And so with lots of nuclei you end up losing 50% every half life. Well technically you could lose only 49% or something else, but what people don't grasp is the sheer volume of these things.

It'd be like a casino going out of business because people gambled luckily every time all the time. It just doesn't happen that way.

Furthermore, there are a lot of good sciences that validate radioactive dating. For example, Uranium decays into Thorium, which turns into Radium, which turns into Radon.
And you can mine a sample and measure the amounts of all of them and they all tell the same date. it's a very solid form of science.

Answer 4

The biggest assumption is that radioactive substances decay according to the unproven "half-life" principle.

Someone has measured the amount of carbon-14 in an item at time zero, and again at time zero plus X, and extrapolated to say that it would take 5730 years for the original sample to lose half its carbon-14.

Two problems with this method:

The major problem: It assumes that the process(es) measured will continue at the same rate, forever. No one can prove that. Since no one has been around long enough to measure the carbon-14 in a sample until it loses exactly half its original amount, no one can be sure if the calculated figure is equal to what would be measured if we waited 5730 years.

The minor problem: It assumes exact measurements. Let's say we start with ten grams of a substance. We might actually have 9.999 grams or 10.001 grams, as our measuring equipment is only accurate to 0.001 grams. When we take our second reading, a year later, we measure 9.995 grams. It might be anywhere between 9.994 and 9.996 grams, due to our equipment's tolerance.

We say that the sample lost 0.005 grams in one year; but the truth is, it could have lost anywhere from 0.003 grams (9.999 - 9.996) to 0.007 grams (10.001 - 9.994). The second figure (0.07% per year) is more than double the first (0.03% per year). The first figure results in a "half life" of 2310 years; the second, 991 years. That's a huge difference for having "only" a +/- 0.01% tolerance in measurements.

The people who use other dating methods are dealing with starting amounts in the neighborhood of micrograms, but using measurements that are not appropriately more accurate. In other words, the variance in the what they measured is far more, percentagewise, than the 0.01% that I used in my example. That would make the range of the calculated "half life" vary by even more than my example.

That's why "half life" measurements of assumed age using any radioactive isotope method are at best, inaccurate, and at worst, a farce.

Answer 5

The assumption that the decay rate of the isotope Carbon 14 is constant is the key to carbon dating.

We have only been studding radioactive material for the last 70 years or so, we have known about it longer than that, but not what it was. At no time has the decay rate of a radioactive substance changed in an unpredictable manner. The decay rates are constant.

What the heck is Carbon 14 dating? It is a method used to determine the age of something and since all living things have some sort of carbon inside of them it can be used to determine the age of anything that was once alive.

Radioactive substances are natural and occur often, but in predictable amounts. Also radioactive substances are throwing pieces of themselves off and so they decay and fall apart into something else. The rate of this decay is well known and studied and is the reason why nuclear waste is so dangerous. The decay time can be thousands of years for some things.

If you are alive then you take in carbon in some form. It is either in the food, or the air, or parts of you. This is true for anything that lives on this planet or any form of life that we have discovered so far.

When you die you stop taking in carbon. If you had a certain amount of naturally radioactive carbon in your body at the time of your death then if you get a bone or something that doesn't decay the amount of that radioactive carbon will remain constant. Therefore the radioactive decay rate of the naturally occurring carbon (Carbon 14) will be an indicator of the things age.

Carbon 14 dating is not that accurate, but we are getting better and currently have it down to plus or minus 30 years. Due to the amount of carbon 14 needed we are limited to dating substances between 58,000 and 62,000 years old or about 10 half-life’s.

When you die and stop taking in carbon the existing radioactive carbon starts to decay at a known rate called a half-life. If you have 2 lbs of a radioactive substance then in one half life you will have 1 lb of radioactive substance. In two half lives you will have 1/2 lb of radioactive substance and so on. As time passes you will have a decreasing amount of radioactive material, but you will almost always have some radioactive material because the rate of decay is a geometric function that approaches zero, but never quite reaches zero. Of course as some point it will be so small that you can’t measure it any more.

If you know the rate of decay, then you know how long that carbon 14 has been present in the sample. The error in decay rate, statistics, sample errors and other errors are included in the 30 year figure I quoted. If I know how much carbon 14 was present at a time in the past then if a sample has the same amount of carbon 14 in it then it is as old as that point. When the earth was young it had more radioactivity so there was a higher amount of carbon 14 present, as time passes the amount of carbon 14 decays away at a steady rate based on its half life. Therefore based on this time you can make a very close estimate to the age of the material. This is how scientists use Carbon 14 dating to determine the age of something, especially dinosaurs.

Now pieces of dinosaurs are rare, very rare. The bones you see in museums are mostly fossils. A fossil is a mineral deposit that replaces bone. However, there will be some original bone that survives. If not then the mineral deposit would hold that same carbon 14. If you take a fossil and try to carbon date it then you are going to have a large error period because you can’t predict how the action of water and minerals replaced the bone. But, if you have actual dinosaur bone then you can get very accurate.

We do have some dinosaur bone and some dinosaur material. In fact Jurassic Park is not too far from the truth. Amber is actually tree sap that hardens to stone. If you have a mosquito inside a piece of amber then it will be unchanged since the moment it got stuck. If that mosquito had bitten a dinosaur then it would have dinosaur blood inside of it. This has happened, and the blood has been harvested. Where the movie fails to meet reality is when they scientists take the dinosaur DNA and reconstruct a living creature. The DNA in the movie was mostly complete and filled in with frog DNA. In reality the DNA is a mess and it is very hard to make any sense of it. But DNA contains carbon. So it can be carbon dated. That means the blood from a dinosaur bitten by a mosquito that got sealed in amber can give us the age of that dinosaur. As is often true in Science Fiction; a scientist saw Jurassic Park and laughed saying it can’t be done, until he tried to do it. It has been done; someone has got dinosaur blood out of a mosquito. In this case you can carbon date that blood sample to within 30 years. You may not be able to make sense out of the DNA, but if you study it enough you can find DNA markers. These markers are what makes the difference in DNA samples. Reptiles and dinosaurs have DNA markers that other creatures don’t. So we may not know exactly which dinosaur was bitten, but we know it was a dinosaur.

The actual bone fragments will yield a carbon 14 dating sample and that will be accurate to within 30 years. Even if you can’t get a fragment, by the amount of carbon 14 in the mineral fossil you can arrive at a figure that is accurate to within a few thousand years.

The decay rate; half lifes of radioactive substances are best explained with quantum mechanics, but they are constant, and don’t change. That means that a carbon 14 dating system is very accurate. When a carbon 14 dating claims that a dinosaur lived a few million years ago that is a big difference from a claim made at the Creationist Museum that dinosaurs only lived 10th of that time; the science doesn’t back the claim of the Creationists.

Okay, the amount of radioactive material on the planet could change. An increase in cosmic rays could create more radiation and turn more carbon into carbon 14. In this case the measurement of carbon 14 dating would be off; it would be too young.

For the science to work the amount of radiation has to decrease at a faster rate than it is possible. There is no way to speed up decay rate and there is no way to make something that is radioactive not radioactive. It has to decay away first. There is no way to fudge the carbon 14 dating to agree with the bible. Logic says that bumble bees can’t fly, they don’t have enough wing surface. They fly because they turn their wings to grab more of the air. What isn’t known now can be later explained and verified.

Sloppy science could date the Mt. St. Helen's to 300,000 years old. Also a 300,000 year old sample could do the same. Mt. St. Helens hasn’t just erupted one time. It is part of a super volcano system and has erupted before and will erupt again. The heat of a volcano is as hot as nature can get on our planet, and it can pretty much dissolve anything, but it can’t change the decay rate of a radioactive substance.

The sample errors that the Creationists are showing are like a dozen compared to 100s of carbon dating samples that are verified. It may be hard to date Egyptian artifacts, but we have a written history that can be used to verify carbon 14 dating on material like mummies which still contain once living matter. This is an independent way to prove carbon 14 dating works.

Answer 6

I agree with Boots McGraw's accurate assessment....in the post before me.

For more....Read here for a great article on the unreliability of decay rates and radiometric dating methods.
http://www.trueorigin.org/dating.asp