> Allen:
> > One of the assumptions of all radiometric dating is that the rocks are
> >old enough to be measured by whichever of the radio-isotope pairs (or
> >more) you choose. Since you must first assume old rocks, the dates
> >acquired by measuring the radio-isotopes cannot be used to prove the
> >rocks old. You can use all the physics you want, but it still won't get
> >around this fact of logic: You can't prove what you assume.
{Susan}
> I'd wonder where you got this nonsense, but I know it is widely spread
> around creationist websites and books. Please read:
> http://www.talkorigins.org/faqs/dating.html
> The assumption underlying radiometric dating is that isotopes decay at a
> steady rate and that rate is measurable.
I read the TO article and it does not address the point I am making. The assumption I am discussing is so basic that it appears that few people have thought much about it. Five other important assumptions (including the ones you make) are listed in McDougall I. and Harrison, T.M., 1988, Geochronology and Thermochronology by the 40Ar/39Ar Method, Oxford Monographs on Geology and Geophysics No. 9., pp. 11, 12. Of interest are assumptions 3 and 5 listed below: [My notes are in []s and color coded if you email reader shows Rich (HTM L) Text.]
[The assumption] 3. The radiogenic argon measured in a samaple was produced by In situ decay of 40K in the interval since the rock crystallized or was recrystallized. [Reality] Violations of this assumption are not uncommon. [Rationalization for using radiometric dating anyway] Well-known examples of incorporation of extraneous 40Ar include chilled glassy deep-sea basalts that have not completely outgassed preexisting 40Ar*, and the physical contamination of a magma by inclusion of older xenolitic material. Further examples will be discussed later, as the 40Ar/39Ar method allows the presence of extraneous argon to be recognized in some cases.
[The assumption] 5. The sample must have remained a closed system since the event being dated. Thus, there should have been no loss or gain of potassium or 40Ar*, other than by radioactive decay of 40K. [Reality] Departures from this assumption are quite common, [Rationalization for using radiometric dating anyway] particularily in areas of comples geological history, but such departures can provide useful information that is of value in elucidating thermal histories.
Rationalization pours from the TO article you mentioned:
"There are many situations where radiometric dating is not possible, or where a dating attempt will be fraught with difficulty. This is the inevitable nature of rocks that have experienced millions of years of history: not all of them will preserve their age of origin intact, not every rock will have appropriate chemistry and mineralogy, no sample is perfect, and there is no dating method that can effectively date rocks of any age or rock type. For example, methods with very slow decay rates will be poor for extremely young rocks, and rocks that are low in potassium (K) will be inappropriate for K/Ar dating. The real question is what happens when conditions are ideal, versus when they are marginal, because ideal samples should give the most reliable dates. If there are good reasons to expect problems with a sample, it is hardly surprising if there are! Andrew MacRae "Radiometric Dating and the Geological Time Scale Circular Reasoning or Reliable Tools?" Copyright © 1997-1998, http://www.talkorigins.org/faqs/dating.html
But I am talking about the basic assumption of measurement, you measure with an appropriate tool to fit the job to be measured. For instance you don't use the width of you thumb to measure the circumference of the earth. The earth is too big to be measrued accurately because of the size of the thumb in comparison to the earth and the margin of error in measuring by a thumb. You don't measure the size of an atom with a meter stick. The stick is many orders of magnatude too big. You don't measure the vast distances of the universe according to your height. You invent a much vaster unit called the light-year. In all these cases, to make a reasonable measurement you make an assumption of the size of the object to be measured and then used a measuring device to fit that assumption.
The same applies to radiometric dating. You must first assume that a rock is old enough to be measured by whatever means of measurement you expect will get the correct results. Then you do your measurments. Then you compute the resulting age. BUT, that age does not and connot prove that the rock old, nor that it is even that age, BECAUSE it is FIRST ASSUMED that the rock is old enough to be measured as that old! One of the first rules of logic is that you cannot prove what you have assumed.
> Allen:
> > It all comes down to which is true. The Bible is. All others are not.
>
> and why is that? because you believe so? or do you have some evidence? There
> is an identical amount of evidence for Spider Woman and the Cosmic Egg.
>
The following comes from one of my web pages:
>
AN UNFORGETTABLE CHALLENGE!
Atheists! Agnostics!
New Agers! Occultists! Satanists! Hindus!
Buddhists! Shinto!
The God of the Bible Demands!
a.. "Who was it that made this happen?
Who has determined the course of history?
I, the LORD, was there at the beginning, and
I, the LORD God, will be there at the end." Isaiah 41:4
b.. The LORD, the king of Israel, has this to say:
"...Come here and predict what will happen,
so that we will know it when it takes place.
Explain to the court the events of the past,
and tell us what they mean.
Tell us what the future holds --
then we will know that you are gods!
Do something good or bring some disaster;
fill us with fear and awe!" Isaiah 41:21-23
c.. "I alone am the LORD your God. ...
The things I predicted have now come true.
Now I will tell you of new things even before they begin to happen." Isaiah 42:8, 9
d.. God says, "Summon my people to court.
They have eyes, but they are blind;
they have ears, but they are deaf!
Summon the nations to come to the trial.
Which of their gods can predict the future?
Which of them foretold what is happening now?
Let these gods bring in their witnesses
to prove that they are right,
to testify to the truth of their words." Isaiah 43:8, 9
e.. The LORD, who rules and protects Israel,
the LORD Almighty, has this to say:
"I am the first, the last , the only God;
there is no other god but me.
Could anyone else have done what I did?
Who could have predicted all that would happen
from the very beginning to the end of time?
Do not be afraid, my people!
You know that from ancient times until now I have predicted all that would happen, and you are my witnesses.
Is there any other god?
Is there some powerful god I never heard of?"
Isaiah 44:6-8
f.. "Come and present your case in court;
let the defendants consult one another.
Who predicted long ago what would happen?
Was it not I, the LORD,
the God who saves his people?
There is no other god!" Isaiah 45:21
g.. "Remember what happened long ago;
acknowledge that I alone am God
and that there is no one else like me.
From the beginning I predicted the outcome;
long ago I foretold what would happen.
I said that my plans would never fail,
that I would do everything I intended to do."
Isaiah 46:9, 10
DO YOU GET THE PICTURE!
Fulfillment of the prophecies of Daniel and Revelation prove God exists!
Come see for yourself that most of these prophecies have been fulfilled and with uncanny accuracy. Some are yet to be fulfilled and you can know what is what. The prophecies are made plain and there can be no doubt that God made it so.
Start with Daniel (http://www.tagnet.org/anotherviewpoint/Daniel) and then move on to Revelation (http://www.tagnet.org/anotherviewpoint/Revelation) because what one learns while studying the prophecies of Daniel make understanding Revelation much easier and more accurate. Daniel is the key to Revelation.
It was the study of the fulfillment of the prophecies of Daniel and Revelation that convinced me that the God of the Bible was real.
Allen Roy
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