I've been exchanging emails recently with a seemingly more reasonable young earth creationist. I am more knowledgeable about evolutionary biology and while I should know radiometric dating and how it works like the back of my hand, after reading books on Paleontology and taking Physical Geology and Archaeology classes, I do not. I tend to forget those details.

So to make it easier for me and save some time, if any of you on the boards would care to help me out, and point out where the e-cquaintance is mistaken (or correct) that would be awesome. I do have a book by Eugenie C. Scott that might have answers to this, and I will refer to my Geology and Archaeology books, which I kept, but I may not find time for that until tomorrow or the next day.

Below is the email in spoilers for space and wrapped in a quote...

Quote:

I found this information that I have been using to support my arguments that tend to focus on radiometric dating.

It gives the assumptions that are made when analyzing different fossils and rock to find their ages or how old they are.

I'm going to list them as they are given and then give my own interpretation of what errors might be made if these assumptions are incorrect.

1. The Radioactive element decays at a constant rate

-If the specific decay and production rates vary throughout time and approach equilibrium, but have not yet reached equilibrium as is the case for Carbon-14 which would take a minimal 20,000 to 30,000 years as denoted in the error analysis section of Dr. Libby's work on Carbon-14 dating, how can we say that we can accurately measure the age of anything outside of our realm of knowing the average specific decay and production rates?

What I'm trying to say is that given the correct starting amount of carbon and the relatively current SPR and SDR then we can find the age of the material accurately. For material that is older than what we have known values for the SPR and SDR, then we have to assume that the SPR and SDR values are the same back millions or whatever large value of years are the same as they are today. Which I think if I worded that correctly, you would agree that these SPR and SDR values are constantly approaching equilibrium at different rates that are not currently understood. If this was the case, then maybe millions of years ago the specific rate of production was much less than the Specific rate of decay which would cause most of all radiometric dating not very scientifically accurate.

2. The rock/mineral being analyzed has not been contaminated throughout the years by the end product that is being analyzed in order to determine half-life.

-If you are looking to find that U-238 being radioactively decaying into U-236 over the known half-life of 4.5 billion years [which is based upon assumption 1. that the radioactive element decays at a constant rate determined by today's current value] and you find a specific amount of Uranium-236, you have to assume that at no point of time did uranium enter the rock/mineral and that all of the Uranium-236 that is found had decayed from Uranium-238.

Given 4.5 billion years of possible contamination, this could cause the results to be completely unrelated to today's value associated with radiometric decay which given assumption 1 and 2 are true so far, then radiometric dating by definition should work.

The question is, are these two first assumptions true? They both have to be true in order for radiometric dating to be accurate over a span of 4.45 billion years which could cause major changes throughout time with SPR and SDR and contamination of the rock/mineral being dated.

3. The rock/mineral being analyzed contained no end product when it was originally formed

-If a rock is dated based on the amount of end product which is used to determine a relative date, how can you know for sure that when the rock was originally formed that it contained no end product? If this is able to be determined, how can you be sure that you have an accurate amount of end product accounted for from the beginning? (not radioactively decaying)

Assumption 3 is important as well because if the rock/mineral is being tested for (let's stay focused) is the Uranium 236 from the Uranium 238, and it is supposed that all the uranium 236 came from the uranium 238, you are going to get a date much older than the true date. would you agree with this?

(It would take a lot longer for lets say 200 atoms of Uranium 236 to form than just 20 atoms from uranium 238, what if only 20 of the atoms of uranium 238 actually radioactively decayed to 236 and the rest was present at formation?)

4. Leaching of the parent element does not occur.

-If a rock has a date that is relative to both the end product and the radioactive material, then the date is measured by taking the amount of end product and comparing it to the amount of radioactive material and determining that the age by looking at how many atoms of Uranium 236 must have decayed from Uranium 238. If the parent material is almost completely non-existent, then we can safely say that all of the atoms have successfully radioactively decayed from the parent element right? What if the parent element exited the system? How do you know that this could not occur? given the Earth is an open system.

Assumption 4 is necessary to finding the values for the half-life of elements that measure dates back much further than carbon-14 can and according to the National Institute of Standards and Technology the dates can be measured with fair precision.

NIST is assuming that assumption 4 is true, which in open systems if often not the case. How can we be sure that when evaluating the standards that over 4.45 billion years, the sample has not released any parent product into the atmosphere and out of the mineral? (The effect of this assumption being wrong could make all measurements seem much older than they might actually be).

Something more easily observable within the Human life span (carbon-14) can still achieve accurate rates, but only relative to the time periods it is measuring. (obviously once you are measuring billions of years, a thousand years or so isn't going to make much of a difference) However, the way that carbon-14 can be most accurate is by knowing how old the product was and how much time the carbon-14 had to decay and then calculating in the SPR and SDR which are not known past our research from the last maybe 150 years.

Four assumptions don't seem like too many, but if you look at the effect they can have on the results, especially for radioactive materials that we have had less time to research, they could be completely innacurate. We could debate all our lives on whether or not each of these assumptions are true, but if they are wrong, then we could be spoonfeeding lies into the classrooms about the age of the Earth, something that you and I both know would take a long time to correct.