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Author | Topic: Assumptions involved in scientific dating | |||||||||||||||||||||||||||||||||||||||
Coyote Member (Idle past 2355 days) Posts: 6117 Joined: |
In the flood thread we have the following:
Coyote writes: And what scientific evidence would you use to dispute the time frame?
ICANT writes: The assumptions you have to use to begin with. I would like to use radiocarbon dating as the main subject, as that's the one I'm most familiar with. The primary assumption in radiocarbon dating that all organisms contained the same amount of C14 when they died. As atmospheric levels of C14 vary with cosmic radiation, and initial amounts of C14 can vary by a few percent, we need to calibrate our dates, and this is done quite successfully via tree-rings, varves and other annular data. And those seem to be all of the important assumptions! I've seen creationists' lists with up to nine assumptions that they argue make radioactive dating inaccurate, but for radiocarbon dating those are the main assumptions we rely on. Now, the job for ICANT and other creationists is to show that these assumptions lead to huge errors in radiocarbon dating. Simple denial is not good enough. A good basic reference for those who are not yet familiar with the subject:Answers to Creationist Attacks on Carbon-14 Dating Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.
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AdminAsgara Administrator (Idle past 2551 days) Posts: 2073 From: The Universe Joined: |
Thread copied here from the Assumptions involved in scientific dating thread in the Proposed New Topics forum.
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NosyNed Member Posts: 9011 From: Canada Joined: |
Another assumption is that the decay constant is and has been constant. There's no evidence to show that this is not correct. Is this really an "assumption"? Is it still an assumption when it has been tested and verified to a very high degree?
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Coyote Member (Idle past 2355 days) Posts: 6117 Joined: |
Is this really an "assumption"? Is it still an assumption when it has been tested and verified to a very high degree?
Creationists imply that the assumptions they don't like are nothing more than wild guesses. You are correct that this assumption has been tested and verified many times. That's the case for the majority of assumptions used in science. Most assumptions are far from "wild guesses."Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.
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Dr Adequate Member Posts: 16113 Joined: |
What they seem not to understand is the meaning of the words "assumptions". The assumptions of a method are the things that have to be true in order for the method to give the right answer. It does not mean "things scientists just assume to be true". On the contrary, they need to check carefully that they are true before they can apply the method ...
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JonF Member (Idle past 417 days) Posts: 6174 Joined:
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Part the first: "assumptions" (I prefer "premises") underlying radiometric dating
A. The amount of decay (daughter) product present at solidification must be known. It certainly is true that the amount of initial daughter must be known. It is not true that this is assumed. Only K-Ar dating (seldom used any more) is susceptible to error due to "excess argon" present at solidification, and we know that such is rare. (E.g. in 40Ar-36Ar Analyses of Historic Lava Flows Dalrymple found that one of 26 samples had significant excess argon, 18 did not have excess argon, and seven had a little excess argon that would be insignificant after a few million years, compared to the decay product.) The K-Ar method, beloved of creationists because it is possible for it to be fooled but not used much anymore, relies on the premise that the gaseous daughter product escaped from the liquid melt. Rational sample selection (e.g. avoiding the situations in which this is known to be problematic such as pillow lavas that solidified very quickly underwater) almost always leads to reliable dates, as shown by the excellent agreement of K-Ar dates with more robust methods (such as shown at Consistent Radiometric dates). Irrational and fraudulent sample selection, often practiced by creationists, can produce obviously false results; but this is a problem with creationists, not with the method. But the various methods in wide use today are not susceptible to such errors. Isochron methods use the chemical/mechanical identity of various isotopes of the daughter product to produce the initial quantity of daughter product as a result of the analysis, not a premise (Isochron DatingHelium Diffusion Rates Support Accelerated Nuclear Decay, pp 3-4:
quote: The widely used Ar-Ar method is similar to isochron methods in that it is not affected by any premises about the amount of initial daughter. A sample is irradiated to convert some of the 40K to 40Ar, and a known-age sample is irradiated at the same time to find the percentage of the 40K that was converted. The basic age determination could be made by back-calculating the amount of 40K and using the K-Ar dating equation... but there's another important wrinkle. The sample is heated by a laser, the 40Ar and 40K released is measured and used for dating, the sample is heated a little hotter, the 40Ar and 40K released is measured and used for dating, and so on until the sample is vaporized. It should be obvious that if there is no excess argon or argon loss all those dates will be the same. If we plot the heating step number on a horizontal axis and the date obtained from that heating step on a vertical axis we would get a horizontal line:
It is a fact that if there is excess argon the left side of the "plateau" will be higher than the middle, and if argon has been lost it will be lower. But if there is a significant plateau in the remainder of the plot it still indicates the real age. (Of course sometimes there's no plateau at all and the method fails). A good example of this is 40Ar/39Ar Dating into the Historical Realm: Calibration Against Pliny the Younger (free registration required), in which the Berkeley Geochronology Center dated lava from the 79 AD eruption of Vesuvius, which contained excess argon. Alas, they did not produce a plot similar to the one above. More detailed information on Ar-Ar can be found at Argon-Argon Dating: What is it Good For?. B. Relevant material must not be gained or lost after solidification. Again, K-Ar is susceptible to this kind of error, but we know it happens infrequently because K-Ar correlates so well with more robust methods. Other methods at least indicate the issue, and some can often produce a valid date if material has been gained or lost. Isochron methods (see reference above) will not produce a straight line if this issue arises. Ar-Ar dating and U-Pb dating also indicate when relevant material has been gained or lost (almost always lost). Ar-Ar can often produce a valid date if a plateau is present such as shown in the bottom plot below:
The argon lost over the years is indicated by the left side, where most of the loosely bound argon has already escaped and the indicated age is less than the real age.. U-Pb dating also indicates when relevant material has been gained or lost (almost always lost), and can often produce a valid date. There's somewhat technical explanations at Radiometric Dating, heading "The U, Th, Pb System" and The U-Th-Pb System: Zircon Dating. C. Constant decay rate. The RATE group concluded that the only viable explanation for radiometric dates in a young Earth is Accelerated Nuclear Decay (AND). They attempted to prove the existence of such. There are many refutations of their claims on the Web: I recommend RATE (Radioactivity and the Age of The Earth): Analysis and Evaluation of Radiometric Dating and Radioisotopes and the Age of the Earth. However, AND is easily disproven by the fact that we do not see the heat and radiation effects that would be produced by AND; a molten Earth and no life on it except perhaps for some thermophilic bacteria.. C.I. Heat Condensing 5E8 years of decay into one year or less would produce an immense quantity of heat. From the first RATE book, Introduction, page 8, Vardiman writes:
quote: Snelling quantifies this problem in Radiohalos in Granites: Evidence for Accelerated Nuclear Decay, page 183:
quote: Obviously if the Flood is taken to have occurred more recently, the numbers would be different but just as disastrous. The only hypothesis I've seen proposed to solve this problem is Humphreys' cosmic expansion theory, in which the Earth is cooled by the expansion of space. The problems with this hypothesis are discussed in detail at Nonexistence of Humphreys’ Volume Cooling for Terrestrial Heat Disposal by Cosmic Expansion and Flaws in a Young-Earth Cooling Mechanism. But without even considering whether the hypothesized mechanism is possible we can see a major problem with it. The cooling would have to be applied not evenly throughout the Earth, but very selectively: more cooling where there's more radioactive elements (e.g. rocks) and less cooling where there's fewer radioactive elements (e.g. oceans and living creatures). That just isn't going to fly. Humphreys acknowledges the problem in Young Helium Diffusion Age of Zircons Supports Accelerated Nuclear Decay, pp 73-74:
quote: Note that he's not really presenting a viable hypothesis, and note the reality of Biblical literalism overlying the false claim of scientific inquiry. C.II. Radiation Condensing 5E8 years of decay into one year or less would also produce an immense quantity of radiation. Again from the first RATE book, Introduction, page 8, Vardiman writes:
quote: Note that this assumes that the heat problem is solved, so there would be water remaining to shield Noah from the radiation from the rocks. I haven't looked into whether this shielding is realistic (there is uranium dissolved in sea water). I haven't seen any YEC quantifications of this problem, but it turns out it isn't difficult. There have been many studies of radiation dosage due to 40 K in humans, e.g. Assessment of the doses received by the Cuban population from 40K contained in the body: modelling based on a neural network, Body potassium content and 40K radiation dose to Iranian subjects, and Body potassium content and radiation dose from 40K to the Slovak population. Note that, for decay that produces beta radiation in a human body, 1 microGy = 1 microSv = 1 micro Sievert. All these sources agree that the radiation dosage in the human body due to decay of 40 K is in the range of 100-200 microSv/year, and I doubt that all the subjects were heavy banana consumers. Let's take 100 microSv/year for simplicity, and see what dosage would result from condensing 5E8 years of decay into one or less. It's pretty simple:
5E8 *100*1E-6 = 50,000 Sv Again a more recent flood would yield a different but essentially similar number. How bad a radiation dose is this? At Lethal dose (LD), 4-5 Sv is listed LD 50/30, meaning 50% of the people exposed to this die within 30 days. At How Much Radiation can the Human Body Safely Receive? the external background radiation on Earth is about 2.4 mSv, and an exposure of 6 Sv is equivalent to 90% death rate, increasing to 100% at higher levels. Obviously dosing Noah et. al. with 10,000 times the LD 50/30 would turn the ark into a casket of rotting flesh (or maybe zombies!!). The only solution I've seen proposed for this problem is that living things didn't have any 40 K in their bodies until after the Flood. In Summary of Evidence for a Young Earth from the RATE Project, page 765, Vardiman et. al. write:
quote: I would sure like to see some YEC try to defend this one! Of course there's a big fat pile of observations and analyses that establish that there has been no significant change in decay rates for many billions of years
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kbertsche Member (Idle past 2380 days) Posts: 1427 From: San Jose, CA, USA Joined: |
coyote writes:
Coyote, for calibrated dates (calibrated to tree rings, to give an actual calendar age), I would modify this a bit: I would like to use radiocarbon dating as the main subject, as that's the one I'm most familiar with. The primary assumption in radiocarbon dating that all organisms contained the same amount of C14 when they died. As atmospheric levels of C14 vary with cosmic radiation, and initial amounts of C14 can vary by a few percent, we need to calibrate our dates, and this is done quite successfully via tree-rings, varves and other annular data. And those seem to be all of the important assumptions!
For calibrated dates, that's it. The main assumption is (3), that we can count tree rings. Assumptions 1 and 4 are almost "givens". Assumption 2 can be (and has been) verified. For calibrated dates, we are essentially measuring the amount of radiocarbon in an unknown sample and comparing this to the amount of radiocarbon in the tree rings that were used for calibration. We find a match (accounting for the time difference between the calibration curve's measurement and the present--assumption 4), and count the rings (assumptions 2 and 3) to get the date. It does not matter that the original atmospheric concentration of radiocarbon changed in the past; it did so the same for both the unknown sample and the calibration sample. It would not even matter if the radiocarbon decay rate had changed in the past; it would have done so the same for both the unknown sample and the calibration sample. If we are trying to date something other than wood, it might have preferentially incorporated more or less radiocarbon than our calibration samples. But we can detect this and make accurate corrections by doing a delta-13 measurement."Science without religion is lame, religion without science is blind." — Albert Einstein I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously. — Erwin Schroedinger
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Coyote Member (Idle past 2355 days) Posts: 6117 Joined: |
I'm still waiting for ICANT or some other creationist to enlighten us on which assumptions they are having problems with.
Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.
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NoNukes Inactive Member |
I'm still waiting for ICANT or some other creationist to enlighten us on which assumptions they are having problems with. I highly doubt they are coming. Neither ICANT nor Faith have ever insisted on any particular answer to radiometric. ICANT is not YEC anyway and in general has no opposition to old ages. He does have some goofy beliefs about the earth being much smaller during the time of the flood... Under a government which imprisons any unjustly, the true place for a just man is also in prison. Thoreau: Civil Disobedience (1846) History will have to record that the greatest tragedy of this period of social transition was not the strident clamor of the bad people, but the appalling silence of the good people. Martin Luther King I never considered a difference of opinion in politics, in religion, in philosophy, as cause for withdrawing from a friend. Thomas Jefferson
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Coyote Member (Idle past 2355 days) Posts: 6117 Joined:
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This thread, for creationists to document why the assumptions used in radiometric dating are unfounded, has been open nearly a month.
In spite of all the creationist claims we see that radiometric dating is invalid because "assumptions," not one creationist has been willing to post their claims in detail here. So much for their claims...Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.
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Pressie Member (Idle past 224 days) Posts: 2103 From: Pretoria, SA Joined:
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Yeah, I was waiting for some creationist to come along. Especially with K-Ar dating, as one of my old lecturers (in the US they would call them Professors and he got his PhD in some area of Geochronology from Harvard many years ago), has been providing me with information on how he used to do K-Ar dating on some formations of the Barberton Sequence...in the 1980's. Since then he has been getting more accurate dates in his research with other methods.
Those mining companies are not stupid! They still pay him to date those rocks. They say more accurate dates (instead of 3.8 billion +- 50 million years) 3.8 +-20 million years will provide them with more accurate predictions on what will be found underground. I'm still waiting for some YEC to use YEC methods for exploration and mining... They don't seem to want to put their money where their mouths are.
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kbertsche Member (Idle past 2380 days) Posts: 1427 From: San Jose, CA, USA Joined: |
Back in the 1980s or so there were some YECs trained in geophysics, specifically in oil exploration. I think this was through the short-lived ICR graduate school. My friend Glenn Morton was one of the trainees; I've met at least two of his fellow trainees. The ones I met are all OEC or TE now.
I asked them how they could look for oil in a YEC context, and they said that the absolute dates are not very relevant. All that they need are relative dates and a knowledge of the underground morphology in which oil is found."Science without religion is lame, religion without science is blind." — Albert Einstein I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously. — Erwin Schroedinger
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Faith  Suspended Member (Idle past 1693 days) Posts: 35298 From: Nevada, USA Joined: |
I asked them how they could look for oil in a YEC context, and they said that the absolute dates are not very relevant. All that they need are relative dates and a knowledge of the underground morphology in which oil is found. Pretty much what I've been saying. It's insisted that specific old age dates are needed but that makes no sense. All the OE dates do is point to the relevant rock, and it's the relevant rock that points to the oil. ABE: Not the morphology, though, right? That would have to be discovered some other way in any case./abe But if they see a way to find oil as a YEC, why become OEC? Edited by Faith, : No reason given. Edited by Faith, : No reason given.
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Coyote Member (Idle past 2355 days) Posts: 6117 Joined: |
Relative dating is not the subject of the thread.
Have you any observations on the assumptions involved in scientific dating?Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge. Belief gets in the way of learning--Robert A. Heinlein In the name of diversity, college student demands to be kept in ignorance of the culture that made diversity a value--StultisTheFool It's not what we don't know that hurts, it's what we know that ain't so--Will Rogers If I am entitled to something, someone else is obliged to pay--Jerry Pournelle If a religion's teachings are true, then it should have nothing to fear from science...--dwise1 "Multiculturalism" demands that the US be tolerant of everything except its own past, culture, traditions, and identity.
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Faith  Suspended Member (Idle past 1693 days) Posts: 35298 From: Nevada, USA Joined: |
Relative dating is not the subject of the thread. Have you any observations on the assumptions involved in scientific dating? Sure: absolute or "scientific" dating is irrelevant if relative dating is all it takes to find oil or do other practical geological work.
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