This is material intended to teach science, most likely at the high school level, and it looks like we have some rather simplistic presentation as a result. For instance this does not discuss possible corrective measures at all.
Not sure I would call the Non-Destructive Testing Resource Center an impeccable source for information.
Are or are there not some assumptions that come with this process? For example, nobody was around billions or millions of years ago to observe what the earth was going through at the time or what these samples went through as far as how they were affected by any sort of catastrophic event, and in discussing millions or billions of years, there's a good chance they went through quite a few catastrophic events, not just one.
An excellent resource for information on all the various radiometric dating methods is:
is C14 dating only good for geological samples or also for biological samples,...
Carbon-14 is primarily for biological samples, though it's also good for stalagmites sometimes. What 14C dating measures is essentially the amount of carbon-14 that was in the air, as carbon dioxide, at some past time. The carbon dioxide got pulled out of the air by a plant (or alga) or by reacting with calcium and water to make limestone, so that we now have something solid to date.
And twigs are more common than stalagmites, so they get used more often.
Are or are there not some assumptions that come with this process? For example, nobody was around billions or millions of years ago to observe what the earth was going through at the time or what these samples went through as far as how they were affected by any sort of catastrophic event, and in discussing millions or billions of years, there's a good chance they went through quite a few catastrophic events, not just one.
Carbon 14 dating only goes back some 50,000 years or so. Some labs are experimenting with older ages, but those are not ready for prime time yet.
We do use assumptions in C14 dating, but fewer than you might expect. The primary one is that the decay constant has been constant. The other assumptions are generally things we can check on (see below):
One example, how do we know for certain what the initial amounts were to begin with? Isn't that an assumption? Has the rate of decay changed at all during time? How can anyone know that for certain?
The initial amounts for C14 dating are those in the atmosphere at a given point in the past, and we can test for those by dating tree rings, glacial or lake varves, or corals, etc. That allows us to correct for the atmospheric variation.
One last question that I have that doesn't pertain to assumptions is, is C14 dating only good for geological samples or also for biological samples, or in an idiot laymen's terms, for dead animals, plants, leaves, ect??? Thanks in advance for the responses.
Carbon 14 dating only works on things that contain carbon, such as any living organisms, as well as bone, shell, charcoal, etc. Soil, the atmosphere, and water contain carbon as well, and can also be dated.
quote:Are or are there not some assumptions that come with this process? For example, nobody was around billions or millions of years ago to observe what the earth was going through at the time or what these samples went through as far as how they were affected by any sort of catastrophic event, and in discussing millions or billions of years, there's a good chance they went through quite a few catastrophic events, not just one.
As I said in Re: Guess??? (Message 74), the main assumption is that we can count tree rings. Any catastrophic events that affected the radiocarbon levels in the atmosphere would have been reflected in the tree rings used for calibration.
Some YECs have theorized that a global flood would have made a large change in the carbon balance and could affect our radiocarbon dates. But if this is true, we should see an abrupt slope change in the calibration curve. We do not see this over the last 45,000 years or so.
quote:One example, how do we know for certain what the initial amounts were to begin with? Isn't that an assumption?
For Libby's original method, this was a necessary assumption. But with tree ring calibrations it is not--any changes in initial amounts are accounted for in the tree rings used for calibration.
quote:Has the rate of decay changed at all during time? How can anyone know that for certain?
We understand nuclear physics well enough to believe that radioactive decay rates are fixed, constants that depend only on the nuclear structure. But if they are not, this would also be reflected in the tree rings used for calibration.
The bottom line: for samples of wood that are no more than about 12,000 years old (the length of the tree ring portion of the calibration curve), the tree ring calibrations remove most of the assumptions.
quote:We do use assumptions in C14 dating, but fewer than you might expect. The primary one is that the decay constant has been constant. The other assumptions are generally things we can check on (see below):
Yes, this is true for uncalibrated dates. But since the same assumption is used in deriving the calibration curves, any changes in decay rate should be reflected in the calibration curves as well, and the changes should cancel out for calibrated dates.
I suppose we make an assumption that the atmospheric concentration was uniform around the globe, but this is a fairly good assumption for each hemisphere of the earth. There is a slight latitude dependence, and possibly a slight regional dependence. But we also have multiple calibration curves (N America, Europe, and Near East), so we can make these slight corrections if necessary.
quote:This site, BiblicalChronologist.org has a series of good articles on radiocarbon dating.
And the YECs should note that Gerald Aardsma, who runs this site, is a fellow YEC who was formerly on staff at ICR. But he was trained at a leading radioisotope laboratory (IsoTrace--the same lab that ICR uses for their samples), he understands radiocarbon, and he believes it is accurate.
I have been having an on-line discussion with a YLC who brought up Snelling's test on fossilised wood in old deposits. A google check for radiocarbon in fossil wood only turned up Snelling's reports for the relevant age formations. I see the possible sources of error mentioned. Is it known whether anyone has done tests to refute Snelling? I understand that no significant C14 is expected in deposits millions of years old, so it is not likely anyone would bother. I was helped to an understanding of the age of the Earth by EvC Forum, especially Razd's excellent Correlations thread, and Daniel Wonderly's "Neglect of Geologic Data by Creationists" which I heard of here. So thanks to all!
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