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originally posted by: peter vlar
Because Lead 206 does not occur naturally. It only exists as the end result of radioactive decay of that specific isotope of Uranium. No other element, nor their isotopes, decay into Lead 206. It can NOT exist until U 238 begins to radioactively decay.
I've asked before, do you have any data suggesting that this is not true?
originally posted by: Phantom423
Therefore, we can assume that the entire lead content of the zircon is radiogenic.
originally posted by: cooperton
originally posted by: peter vlar
Because Lead 206 does not occur naturally. It only exists as the end result of radioactive decay of that specific isotope of Uranium. No other element, nor their isotopes, decay into Lead 206. It can NOT exist until U 238 begins to radioactively decay.
I've asked before, do you have any data suggesting that this is not true?
The burden of proof is on the one making the claim. What is the evidence that lead-206 does not exist besides the radioactive decay of uranium? There should be a paper focusing on such because it is integral to accurate dating, but I cannot find such a paper.
originally posted by: Phantom423
Therefore, we can assume that the entire lead content of the zircon is radiogenic.
That's my point^
originally posted by: Phantom423
Let's go over the definition of an isotope: an isotope is a DERIVATIVE of an existing element. The isotope of an element has the same number of protons, but has a different number of neutrons. Therefore, the isotope is unique to that element. Hence, Pb206 can only come from uranium. There is no other way it can be produced.
originally posted by: Phantom423
Regarding my zircon comments, again you're using the word "assume, assumption" in layman's terms.
originally posted by: cooperton
originally posted by: Phantom423
Let's go over the definition of an isotope: an isotope is a DERIVATIVE of an existing element. The isotope of an element has the same number of protons, but has a different number of neutrons. Therefore, the isotope is unique to that element. Hence, Pb206 can only come from uranium. There is no other way it can be produced.
Phantom I'd expect you to know more about radioactive decay. Alpha decay involves the removal of 2 protons and 2 neutrons. This causes decay of the nucleus and can result in a different element. I'm also confused with what you're saying - Lead is not an isotope of uranium.
originally posted by: Phantom423
The decay product is unique to the element - there is no other way that the product can be formed. I misused the isotope example - but the concept is the same - the decay product is unique to an element.
If you're suggesting an exotic process which would produce Pb206, then you have to describe that process. That question was raised many times over the course of a century and each time the answer was the same: Pb series can only be derived from uranium.
Regarding my zircon comments, again you're using the word "assume, assumption" in layman's terms.
I didn't use the word assume, the paper you quoted admitted that it was an assumption.
originally posted by: cooperton
originally posted by: Phantom423
Let's go over the definition of an isotope: an isotope is a DERIVATIVE of an existing element. The isotope of an element has the same number of protons, but has a different number of neutrons. Therefore, the isotope is unique to that element. Hence, Pb206 can only come from uranium. There is no other way it can be produced.
Phantom I'd expect you to know more about radioactive decay. Alpha decay involves the removal of 2 protons and 2 neutrons. This causes decay of the nucleus and can result in a different element. I'm also confused with what you're saying - Lead is not an isotope of uranium.
originally posted by: Phantom423
Regarding my zircon comments, again you're using the word "assume, assumption" in layman's terms.
I didn't use the word assume, the paper you quoted admitted that it was an assumption.
originally posted by: Phantom423
The decay product is unique to the element - there is no other way that the product can be formed.
originally posted by: cooperton
originally posted by: Phantom423
The decay product is unique to the element - there is no other way that the product can be formed.
How are you so sure? when uranium was formed, perhaps lead is formed alongside it.
"The Earth's uranium was produced in one or more supernovae"
How do you know lead was not formed in supernovae as well?
originally posted by: Phantom423
It wouldn't make a difference. There's enough data which demonstrates that the half life calculation works. If it didn't work, every nuclear engineering development would be invalid -
So unless you can come up with some exotic process or hypothesis, the current model stands as being valid.
originally posted by: peter vlar
a reply to: cooperton
Do you have any evidence at all that there is a separate, magical process to create these other lead isotopes?
originally posted by: cooperton
originally posted by: Phantom423
It wouldn't make a difference. There's enough data which demonstrates that the half life calculation works. If it didn't work, every nuclear engineering development would be invalid -
So unless you can come up with some exotic process or hypothesis, the current model stands as being valid.
I was never arguing half life calculation. I am saying you cannot with certainty determine the initial ratio of the sample. As your source said, " we can assume that the entire lead content of the zircon is radiogenic".
originally posted by: Phantom423
Then it would be an equal assumption that it wasn't.
And as I said, it makes absolutely no difference as to what is being sampled and tested today.
originally posted by: DarkvsLight29
I also believe in evolution.
originally posted by: SeaWorthy
originally posted by: DarkvsLight29
I also believe in evolution.
Just because something is created to evolve doesn't mean it wasn't created.
originally posted by: cooperton
originally posted by: Phantom423
Then it would be an equal assumption that it wasn't.
So you, (and many of the papers you posted), admit that you have to assume a particular initial concentration ?
And as I said, it makes absolutely no difference as to what is being sampled and tested today.
It absolutely does. If I have a sample with 1g of uranium, and I know the half life, I still cannot determine the age of the rock without knowing the initial concentration of uranium. Do you understand?
originally posted by: Phantom423
originally posted by: cooperton
originally posted by: peter vlar
Because Lead 206 does not occur naturally. It only exists as the end result of radioactive decay of that specific isotope of Uranium. No other element, nor their isotopes, decay into Lead 206. It can NOT exist until U 238 begins to radioactively decay.
I've asked before, do you have any data suggesting that this is not true?
The burden of proof is on the one making the claim. What is the evidence that lead-206 does not exist besides the radioactive decay of uranium? There should be a paper focusing on such because it is integral to accurate dating, but I cannot find such a paper.
originally posted by: Phantom423
Therefore, we can assume that the entire lead content of the zircon is radiogenic.
That's my point^
Let's go over the definition of an isotope: an isotope is a DERIVATIVE of an existing element. The isotope of an element has the same number of protons, but has a different number of neutrons. Therefore, the isotope is unique to that element. Hence, Pb206 can only come from uranium. There is no other way it can be produced.
Regarding my zircon comments, again you're using the word "assume, assumption" in layman's terms. If you read the article (which I see you didn't), you would understand how many samples are tested, analyzed and the final result is calculated mathematically. These calculations are within a standard deviation.
You don't read the articles or you would be asking more intelligent questions.
originally posted by: cooperton
originally posted by: Phantom423
The decay product is unique to the element - there is no other way that the product can be formed.
How are you so sure? when uranium was formed, perhaps lead is formed alongside it.
"The Earth's uranium was produced in one or more supernovae"
How do you know lead was not formed in supernovae as well?
originally posted by: cooperton
originally posted by: peter vlar
a reply to: cooperton
Do you have any evidence at all that there is a separate, magical process to create these other lead isotopes?
When uranium was formed long ago, how do you know it was formed with concentrations of lead in a ratio of 100/0 Uranium/lead?
You assume this to be true, yet there is no empirical evidence that this is true - it is an assumption.
originally posted by: HiddenWaters
a reply to: cooperton
There is a misunderstanding here, the dating method described here using uranium and lead does not rely on environmental ratios of lead or uranium, not in the past and not now. The most common mineral tested is zircon-due to chemical properties, when zircon forms, it can incorporate uranium, but CANNOT incorporate lead into its structure, so it starts out with ZERO lead and possibly a certain amount of uranium, I come along 3 billion years later, find a zircon crystal and analyze that crystal and get a ratio of uranium to lead-since I know the half life of uranium,and I know the current ratio of lead to uranium, I can work out how old the zircon crystal is (ie. when it was formed). The lead in the zircon crystal can only come from the decay of the original uranium in the crystal when it formed.
What ever the ratios are outside the zircon crystal, they are irrelevant to the crystal itself.
I believe I have this more or less correct, if not, I'm sure the smarter ones in the crowd will correct me.