quote:KalvinB:
I have X isotopes left of a substance that started with X0 isotopes with a half life of Y years that has been sitting for Z years

One equation. Two unknowns. You either have to know the original amount or the time that it spent decaying. All that's given is X and Y.

Ah, I see the confusion. You see, X0 is actually not unknown. The carbon-14 isotopes are present in the air at a relatively constant concentration and are absorbed by plants and plant-eating animals. Since we have estimated, using a variety of techniques, the carbon-14 concentration in the atmosphere over the last 50000 years, we can estimate when a creature died (i.e. stopped absorbing carbon).

Also technically the number of C14 atoms isn't important; the C14:C12 ratio is. So it doesn't matter how much carbon the animal/plant absorbed.

If you wish, you can Google and find the calibration techniques they use to verify carbon-dating and the presence of C-14 in the atmosphere.

The only decent counterargument you could bring up here is how the concentration of C-14 in the atmosphere remains constant. Since it decays, obviously new C-14 is being created, so why can't it be created in the bones of corpses? Well, here is a good explanation:

quote:Radioactive carbon, produced when nitrogen 14 is bombarded by cosmic rays in the atmosphere, drifts down to earth and is absorbed from the air by plants. Animals eat the plants and take C14 into their bodies. Humans in turn take carbon 14 into their bodies by eating both plants and animals. When a living organism dies, it stops absorbing C14 and the C14 that is already in the object begins to disintegrate. Scientists can use this fact to measure how much C14 has disintegrated and how much is left in the object. Carbon 14 decays at a slow but steady rate and reverts to nitrogen 14. The rate at which Carbon decays (Half-life) is known: C14 has a half-life of 5730 years. Basically this means that half of the original amount of C14 in organic matter will have disintegrated 5730 years after the organisms death; half of the remaining C14 will have disintegrated after another 5730 years and so forth. After about 50,000 years, the amount of C14 remaining will be so small that the fossil can't be dated reliably.

A buried fossil/pot/whatever wouldn't be exposed to this radiation. Also when I said the C-14 concentration was "relatively constant" it's because they've discovered the sun's energy output hasn't remained constant. But it didn't change very much in 50000 years.

~CGameProgrammer( );



[edited by - CGameProgrammer on May 1, 2003 8:19:09 AM]

quote:Original post by Senses777
OK, when did I say that because one experiment failed everything was proven or dis-proven?

I agree with MDI here. You sounded as if you were trying to discredit the technique because your class didn't manage to pull it off.

quote:Anyway, you guys seem to be missing KB's point. Here's a possible situation; a long time ago, a rock formed. You say you can tell how old it is by comparing the parent element with its daughter element (which is what the parent element decays into). Let's use potassium-argon, for fun. Now, you can guarentee to me that there was no argon in that rock when it formed?

this gave an explanation. I'm pretty sure we're not going to uncover a conspiracy theory among the scientists in this thread.

I don't understand how you can be so skeptical about this kind of stuff and yet not skeptical whatsoever about your "conclusive" evidence for Jesus rising from the dead.

[edited by - NotAnAnonymousPoster on May 1, 2003 8:17:35 AM]

Seeing as people seem to have an aversion to reading the links that are posted:

quote:
Lead comes in two forms -- one with 206 protons and neutrons, one with 204.

Uranium exculsively decays to the form with 206 protons and neutrons.

The ratio of 206 to 204 in naturally occurring lead is a constant.

Measure the amount of 204 in the sample under study and that will tell you how much of the 206 was there originally. The excess 206 will have been produced by the decay of Uranium.

Ohh look, exactly what I said.

quote:Original post by 23yrold3yrold
Let''s use potassium-argon, for fun. Now, you can guarentee to me that there was no argon in that rock when it formed? Because if it was, it''ll blow your dating to hell and there''s not a thing you can do about it. You laugh about my example of that rocked formed 2 decades ago being dated to 35,000 years old, but that''s how errors like that appear. How do you handle that? I''ve never seen a method of dealing with that; enlighten me.

I wasn''t going to get into this either, but: With the Uranium->Lead decay paths, you use the proportions of other isotopes of lead (e.g Lead 204, which is NOT a decay product) to make an estimate of the original amount of lead in the rock.

Another link on the subject

Also, I never really understood the creationist objection to an old earth, it''s not like the bible specifically states the earth is only 6000 years old - that figure came from a bunch of catholic scholars who thought they could figure it out.

So if you believe in a 6000 year old earth, you''re believing in catholicism

quote:So if you believe in a 6000 year old earth, you''re believing in catholicism

Well that theory isn''t based on nothing. God was supposed to have created man within the first week the Earth existed, so you look for the oldest human remains and conclude that''s when the Earth was formed.

Of course you''d need carbon dating to determine that and yet this seems to be contested. Also you''d have to only go with skeletons exactly matching present-day humans and ignore extremely similar older skeletons.

~CGameProgrammer( );

I tried to explain this to one christian and got shot down (because, god forbid anything in the bible might not be litral).

Anyway, science has shown that the earth is almost certianly very old and much older than man.

Therefore it is not unreasonable that the whole "one week" think may have been symbolic? Perhaps instead of one day, these things took many thousands of years each to happen.

After all, back then was there even a unit known as "one week"? A week is based off earth days, well, how long was an earth day back then?


This one might really start the flames, but is it at all possible that it can be acceped that perhaps that section of the bible is not an exact history, the exact word of god (or even the word of god at all!) but something interpreted/created by the wise people of the time and simplified for the common man to understand? The guy I was dicussing this theory with would not even accept it as a possibility.

Just my two cents.

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Edited last nights posts and removed insults. Sorry and...man..i must have been in a BAD mood


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"OMG! I have it! Some people have red hair, therefore by your logic all people have red hair?"

You''re the only one that ever claimed all elements decay at the same rate. I certainly never did.

Ben

quote: Also, I never really understood the creationist objection to an old earth, it''s not like the bible specifically states the earth is only 6000 years old - that figure came from a bunch of catholic scholars who thought they could figure it out.

So if you believe in a 6000 year old earth, you''re believing in catholicism

If you add the ages of the people in the Bible up, you come to roughly 6000 years. It’s been done many times.