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Author
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Topic: Dating from the Adams and Eves Threads
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robinrohan
Inactive Member
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Message 224 of 300 (273522)
12-28-2005 1:00 PM
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Reply to: Message 220 by Coragyps
12-28-2005 12:17 PM
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Re: Carbon Dating Fossils?
1221 posts here, and you still haven't realized that all radiodating methods "start the clock" only when the mineral (or living thing, for 14C) solidifies? Wow, Golfer! Why don't you pick "Osmium" for your next screen name? Or maybe "neutron star matter"? I just had a question. What is carbon dating used for? How far back can you date things using this method? I've never really understood it. --------------------------------------------------------------------------------
| This message is a reply to: | | | Message 220 by Coragyps, posted 12-28-2005 12:17 PM | | Coragyps has not replied |
| Replies to this message: | | | Message 227 by JonF, posted 12-28-2005 1:36 PM | | robinrohan has replied |
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robinrohan
Inactive Member
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Message 231 of 300 (273567)
12-28-2005 3:54 PM
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Reply to: Message 227 by JonF
12-28-2005 1:36 PM
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Re: Carbon Dating Fossils?
Right now we can get pretty solid dates back to 30,000-40,000 years, and we can obtain dates in the 50,000-60,000 year range which are less solid. It seems unlikely we will get much farther back than that unless somebody comes up with something really new and ingenious. Thanks, I think I picked up the principle. I suppose there's no doubt about those tree rings and so forth, right? Am I correct in thinking that for the really old stuff they use something called "radiometric" dating?
| This message is a reply to: | | | Message 227 by JonF, posted 12-28-2005 1:36 PM | | JonF has replied |
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robinrohan
Inactive Member
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Message 238 of 300 (273590)
12-28-2005 4:57 PM
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Reply to: Message 237 by JonF
12-28-2005 4:41 PM
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Re: Carbon Dating Fossils?
No evidence-based doubt whatsoever I was just wondering how they figured out about the tree rings in the first place. You would have to know how old the tree was beforehand. I suppose they grew one for a while and then looked at the rings?
| This message is a reply to: | | | Message 237 by JonF, posted 12-28-2005 4:41 PM | | JonF has not replied |
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robinrohan
Inactive Member
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Message 252 of 300 (273884)
12-29-2005 3:42 PM
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Reply to: Message 250 by Coragyps
12-29-2005 12:21 PM
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Re: Carbon Dating Fossils?
The rate would be some number on Day 1, due to the 0.117 grams of potassium-40 present (and measured by independent means) in the kilogram, and the rate would slowly decline, as less and less potassium atoms are there to be able to decay each passing day. So I guess the idea is to record a tiny amount of radioactive decay and then extrapolate that out for a half-life.
| This message is a reply to: | | | Message 250 by Coragyps, posted 12-29-2005 12:21 PM | | Coragyps has not replied |
| Replies to this message: | | | Message 253 by nwr, posted 12-29-2005 4:42 PM | | robinrohan has replied |
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robinrohan
Inactive Member
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Message 261 of 300 (274122)
12-30-2005 8:42 AM
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Reply to: Message 253 by nwr
12-29-2005 4:42 PM
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Re: Carbon Dating Fossils?
In fact, radioactive decay has been extensively observed and investigated, and has been should to alway be an exponential decay. That is, the rate of decay is proportional to the amount of the material present. Well, the idea is to find out when the clock began ticking, right? The clock is the radiation. So if you pick up a rock, it's already been emiting radiation a long time. How do you know when it started?
| This message is a reply to: | | | Message 253 by nwr, posted 12-29-2005 4:42 PM | | nwr has replied |
| Replies to this message: | | | Message 262 by nwr, posted 12-30-2005 8:51 AM | | robinrohan has replied | | | Message 264 by JonF, posted 12-30-2005 9:36 AM | | robinrohan has not replied |
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robinrohan
Inactive Member
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Message 263 of 300 (274124)
12-30-2005 8:59 AM
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Reply to: Message 262 by nwr
12-30-2005 8:51 AM
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Re: Carbon Dating Fossils?
The dating of rocks depends on radioactive decay that leaves byproducts behind in the rock. Then a measurement of the ratio of the undecayed atoms still in the rock and the amount of byproduct gives you how much decay there has been since the rock solidified. How do you identify these byproducts? Do we call the byproduct, in the case of Potassium 40, Argon?
Using that, together with the known decay rate and the equations of decay, you can compute the time of solidification. Yes, but I'm trying to figure out how they came up with the known decay rate in the first place. --------------------------------------------------------------------------------
| This message is a reply to: | | | Message 262 by nwr, posted 12-30-2005 8:51 AM | | nwr has replied |
| Replies to this message: | | | Message 265 by Coragyps, posted 12-30-2005 9:37 AM | | robinrohan has not replied | | | Message 266 by nwr, posted 12-30-2005 9:41 AM | | robinrohan has replied | | | Message 267 by JonF, posted 12-30-2005 9:44 AM | | robinrohan has not replied |
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robinrohan
Inactive Member
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Message 268 of 300 (274146)
12-30-2005 9:46 AM
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Reply to: Message 266 by nwr
12-30-2005 9:41 AM
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Re: Carbon Dating Fossils?
You determine byproducts by observing the decay in a lab. You can measure the decay rate in the lab I'm assuming these are two different types of operations. It would have to be. Otherwise, the argument is circular.
| This message is a reply to: | | | Message 266 by nwr, posted 12-30-2005 9:41 AM | | nwr has replied |
| Replies to this message: | | | Message 270 by nwr, posted 12-30-2005 10:02 AM | | robinrohan has replied |
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robinrohan
Inactive Member
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Message 271 of 300 (274157)
12-30-2005 10:07 AM
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Reply to: Message 270 by nwr
12-30-2005 10:02 AM
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Re: Carbon Dating Fossils?
ok, I think I got it.
| This message is a reply to: | | | Message 270 by nwr, posted 12-30-2005 10:02 AM | | nwr has replied |
| Replies to this message: | | | Message 284 by nwr, posted 12-31-2005 7:16 AM | | robinrohan has replied |
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robinrohan
Inactive Member
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Message 285 of 300 (274363)
12-31-2005 8:56 AM
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Reply to: Message 284 by nwr
12-31-2005 7:16 AM
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Re: Carbon Dating Fossils?
No, it doesn't have to be 100% potassium What I said was not quite what I meant (I was getting sleepy). What I meant was that when the clock starts ticking, there wasn't any Argon. Argon, I suppose, has to be a derivative of Potassium.
| This message is a reply to: | | | Message 284 by nwr, posted 12-31-2005 7:16 AM | | nwr has replied |
| Replies to this message: | | | Message 286 by nwr, posted 12-31-2005 9:07 AM | | robinrohan has not replied |
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