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I was confused because of how he said it... I am not familiar with half life dating... I have heard of it. I was pointing out that radiometric dating is unreliable and inaccurate which I firmly believe.
This is Why, I read this from Interactive Bible Home Page www.bible.ca
Hmmm... radiometric dating is based on the half-lives of radioactive material. Thus Percy's ( I believe ) challenge still stands. You are convinced that radiometric dating doesn't work but you don't know scat about it. That is shameful.
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This would seem to imply that the problem of radiometric dating has been solved, and that there are no anomalies.
You need to get over the creationist 'all or nothing' mindset. There ARE problems and anomalies. Some methods and materials are very problematic. This doesn't mean they give meaningless dates. It means that you have to be careful with the sample and use the appropriate method for the material. Think about taking a set of fingerprints from a piece of glass. There are a hundred ways you could mess up the sample. This doesn't invalidate fingerprinting. I watched an investigator look for fingerprints on a laptop that had been dropped on the sidewalk as the thief fled the scene. The officer decided it wasn't even worth trying because of the texture of the plastic case. Fingerprints wouldn't be obtainable or reliable if some trace were found. This doesn't invalidate fingerprinting either. Yet, creationists will use the wrong methods and claim to invalidate radio-dating. Creationist also complain when scientists toss unreliable data-- such as the officer would have obtained had he dusted the laptop for fingerprints.
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So if we take a lava flow and date several minerals for which one knows the daughter element is excluded, we should always get the exact same date, and it should agree with the accepted age of the geological period. Is this true? I doubt it very much.
You DOUBT it? You haven't bothered to check? Sorry, but we do get the same dates, within a margin of error. Not only that but various different methods are used where possible and these also agree, within a margin of error. Some features can be identified all over the planet. These too agree. If the dates turn out to be odd, then geologists have a problem to solve. Contamination? Well, test a new set of sample collected with extreme paranoia.
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If the radiometric dating problem has been solved in this manner, then why do we need isochrons, which are claimed to be more accurate?
Why would you not want something more accurate? A ruler that measures centimeters is great until you try to measure bacteria. It is unbelievable that you are using the attempt to get even better data as a criticism.
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But are dates from mica always accepted, and do they always agree with the age of their geologic period? I suspect not.
Maybe you should stop suspecting and actually learn about these things?
Dates are not always accepted. Why? Consider: You and nine friends walk for an hour each counting his steps. At the end of the walk, nine of you agree within a hundred paces, but one of you is a thousand steps off. Which count do you accept? The average of the nine plus/minus 100? Or the thousand pace anomaly?
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1. The decay constant and the abundance of K40 must be known accurately.
No evidence suggests that the decay rates change. In fact, for decay rates to change 99% of our understanding of physics would have to be wrong.
As for the second statement, I am pretty sure that the absolute value for K in the newly formed sample is not necessary. The method works on ratios, not absolutes. Somebody smart can correct me if I am wrong.
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2. There must have been no incorporation of Ar40 into the mineral at the time of crystallization or a leak of Ar40 from the mineral following crystallization.
Correct. The original K-Ar method assumed zero argon in the newly formed sample. Most-- two-thirds-- of the time this is a valid assumption. In the remaining few cases the trapped argon gives slightly older date than than it should. When dating old rock, this is acceptable. It may give 51mya instead of 50mya. Yes, contamination is a problem. Geologists are careful to choose samples which are most likely to be uncontaminated.
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3. The system must have remained closed for both K40 and Ar40 since the time of crystallization.
Basically the same objection as #2.
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4. The relationship between the data obtained and a specific event must be known.
What? This doesn't make sense.
( Your three unreferenced quotes are in violation of forum guidelines. )
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It is known that neutrinos interact with atomic nucleii, so a larger density of neutrinos could have sped up radioactive decay and made matter look old in a hurry.
It is also known that trillions of neutrinos pass through the earth and don't hit a thing. Do you have any idea how rarely a nuetrino hits something? Read up on neutrino detectors a bit.
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a. In the lead-uranium systems both uranium and lead can migrate easily in some rocks,
So you don't date those rocks.
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and lead volatilizes and escapes as a vapor at relatively low temperatures
Yup... relatively low-- 327.5 C. Kinda rules out most places on earth. In other words, this problem is easily avoided.
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It has been suggested that free neutrons could transform Pb-206 first to Pb-207 and then to Pb-208, thus tending to reset the clocks and throw thorium-lead and uranium-lead clocks completely off, even to the point of wiping out geological time.
It has been? What are the details?
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Furthermore, there is still disagreement of 15 percent between the two preferred values for the U-238 decay constant.
Ahem....
Scroll down to the bottom of the page and you will discover that this edition is copyrighted 1998. It might come to as a surprise to anyone unfamiliar with creationist deceit that when one checks Kofahl’s endnote one finds that his documentation for this is dated 1974. Kofahl is using a nearly three-decades old reference to support the statement what is current status of this question. This is a good example of creationist deceit. They know that the vast majority of ordinary people do not read the endnotes and thus will not notice how utterly inadequate the reference really is.
No webpage found at provided URL: http://members.cox.net/ardipithecus/evol/lies/lie022.html
It took ten seconds to find that. Try harder, maybe?
Besides, even 15% off gets nowhere near a 6000 year old Earth.
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Furthermore, the value of the decay constant is still disputed, although the scientific community seems to be approaching agreement.
As of 1991 at least, the rates were known to within 1%.
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Historically, the decay constants used for the various radiometric dating systems have been adjusted to obtain agreement between the results obtained. In the potassium/argon system another adjustable "constant" called the branching ratio is also not accurately known and is adjusted to give acceptable results.
Wrong. Both the decay rates and branching ratios can be measured directly. Dating methods, which are more complicated-- ie. there are more variables involved-- than the decay rates and branching ratios are used to cross-calibrate one another much as you might use several different clocks to calibrate your watch.
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In general, if lava was heated after the initial flow, it can yield an age that is too young.
No kidding? That is how the method is supposed to work. The clock is set by temperature. Reheat == reset.
'K. That is all I can stand of this cut-n-paste. Bye now.
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No webpage found at provided URL: www.hells-handmaiden.com
{Fixed 1 quote box - AM}
[This message has been edited by Adminnemooseus, 08-11-2003]
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