Understanding through Discussion


Welcome! You are not logged in. [ Login ]
EvC Forum active members: 78 (8964 total)
38 online now:
Coragyps, DrJones*, Hyroglyphx, jar, JonF, PaulK (6 members, 32 visitors)
Newest Member: javier martinez
Post Volume: Total: 873,015 Year: 4,763/23,288 Month: 1,668/1,286 Week: 335/615 Day: 27/42 Hour: 2/4


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Assumptions involved in scientific dating
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 7 of 222 (789128)
08-11-2016 3:41 AM
Reply to: Message 1 by Coyote
08-10-2016 10:50 AM


coyote writes:

I would like to use radiocarbon dating as the main subject, as that's the one I'm most familiar with.

The primary assumption in radiocarbon dating that all organisms contained the same amount of C14 when they died. As atmospheric levels of C14 vary with cosmic radiation, and initial amounts of C14 can vary by a few percent, we need to calibrate our dates, and this is done quite successfully via tree-rings, varves and other annular data.

Another assumption is that the decay constant is and has been constant. There's no evidence to show that this is not correct.

And those seem to be all of the important assumptions!


Coyote, for calibrated dates (calibrated to tree rings, to give an actual calendar age), I would modify this a bit:

1. We "assume" that two similar organisms (e.g. two trees) living at the same time in the same region incorporate the same proportion of radiocarbon in their tissues.

2. We "assume" that the trees used for calibration grow one ring per year.

3. We "assume" that we can count tree rings.

4. We "assume" that the decay rate has been constant since the tree ring calibrations have been measured.


For calibrated dates, that's it. The main assumption is (3), that we can count tree rings. Assumptions 1 and 4 are almost "givens". Assumption 2 can be (and has been) verified.

For calibrated dates, we are essentially measuring the amount of radiocarbon in an unknown sample and comparing this to the amount of radiocarbon in the tree rings that were used for calibration. We find a match (accounting for the time difference between the calibration curve's measurement and the present--assumption 4), and count the rings (assumptions 2 and 3) to get the date.

It does not matter that the original atmospheric concentration of radiocarbon changed in the past; it did so the same for both the unknown sample and the calibration sample.

It would not even matter if the radiocarbon decay rate had changed in the past; it would have done so the same for both the unknown sample and the calibration sample.

If we are trying to date something other than wood, it might have preferentially incorporated more or less radiocarbon than our calibration samples. But we can detect this and make accurate corrections by doing a delta-13 measurement.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 1 by Coyote, posted 08-10-2016 10:50 AM Coyote has responded

Replies to this message:
 Message 8 by Coyote, posted 08-11-2016 9:23 AM kbertsche has not yet responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 12 of 222 (790898)
09-07-2016 4:00 PM
Reply to: Message 11 by Pressie
09-07-2016 8:25 AM


Re: Creationists have been very silent on assumptions
Back in the 1980s or so there were some YECs trained in geophysics, specifically in oil exploration. I think this was through the short-lived ICR graduate school. My friend Glenn Morton was one of the trainees; I've met at least two of his fellow trainees. The ones I met are all OEC or TE now.

I asked them how they could look for oil in a YEC context, and they said that the absolute dates are not very relevant. All that they need are relative dates and a knowledge of the underground morphology in which oil is found.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 11 by Pressie, posted 09-07-2016 8:25 AM Pressie has not yet responded

Replies to this message:
 Message 13 by Faith, posted 09-07-2016 5:05 PM kbertsche has responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 16 of 222 (790911)
09-07-2016 8:09 PM
Reply to: Message 13 by Faith
09-07-2016 5:05 PM


Re: Creationists have been very silent on assumptions

Pretty much what I've been saying. It's insisted that specific old age dates are needed but that makes no sense. All the OE dates do is point to the relevant rock, and it's the relevant rock that points to the oil.

ABE: Not the morphology, though, right? That would have to be discovered some other way in any case./abe

But if they see a way to find oil as a YEC, why become OEC?


Good question. If one's only interest is the pragmatic issue of finding oil, and not truth, one could continue as a YEC just fine. But the geologic data simply does not fit YEC.

Glenn Morton is a very inquisitive polymath with a nearly photographic memory. As he continued to look at the geologic data, he continued to see conflicts with the YEC paradigm. The geologic data gave evidence of long processes and much older ages than can fit in a YEC paradigm. You can read the details in his paper, "Why I Left Young-Earth Creationism".

But as Coyote pointed out, this thread is about scientific, radiometric dates. I believe Glenn pretty much accepted the YEC arguments against radiometric dates until he was already well on the road to leaving YEC.

Edited by kbertsche, : No reason given.

Edited by kbertsche, : No reason given.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 13 by Faith, posted 09-07-2016 5:05 PM Faith has responded

Replies to this message:
 Message 18 by Faith, posted 09-07-2016 11:16 PM kbertsche has responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 20 of 222 (790921)
09-07-2016 11:45 PM
Reply to: Message 18 by Faith
09-07-2016 11:16 PM


Re: Creationists have been very silent on assumptions
It remains interesting and important that there is no conflict between YEC assumptions and the practical work of finding oil, despite the familiar accusation that there is a conflict.

I don't think I've ever seen accusations that YECs cannot find oil. Do you really think this is a "familiar accusation"? (But I DO find it a bit surprising that absolute dates can be completely ignored while doing oil exploration, to be honest.)

But this thread is not about the pragmatic issue of finding oil; it is about the supposed "assumptions" used in radiometric dating. For radiocarbon, I claim that the major "assumptions" are that trees grow one ring per year, we can count tree rings, and we can measure the amounts of radiocarbon in tree rings and in unknown samples. The amount of radiocarbon originally in the atmosphere is irrelevant, and the radiocarbon decay rate is irrelevant.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 18 by Faith, posted 09-07-2016 11:16 PM Faith has responded

Replies to this message:
 Message 21 by Faith, posted 09-07-2016 11:56 PM kbertsche has responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


(3)
Message 23 of 222 (790930)
09-08-2016 6:11 AM
Reply to: Message 21 by Faith
09-07-2016 11:56 PM


Re: Creationists have been very silent on assumptions
think I probably misread your Message 12. You say what the YEC view is which I read as your agreeing with it. Apparently you don't.

I think you read my message 12 correctly. Though it is somewhat surprising to me, apparently oil exploration can be done without use of absolute (scientific, radiometric) dates. I agree that a YEC can find oil. But as Glenn found, to remain a YEC while doing oil exploration requires one to deny the huge amount of evidence for earth history that one starts to uncover while doing his job.

But again, this is a side issue to the thread topic. This is not a thread about finding oil, but about assumptions used in radiometric dating.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 21 by Faith, posted 09-07-2016 11:56 PM Faith has not yet responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


Message 33 of 222 (791809)
09-21-2016 9:09 PM
Reply to: Message 31 by Coyote
09-21-2016 4:43 PM


Re: Devil's Advocate
It's also interesting that there are two separate photosynthetic processes, with two different degrees of isotopic fractionation. Most plants follow the "normal" process, which I believe gives a delta-13 value of about -25. But corn follows a different process which I believe gives a lower value, maybe -12? (I'm pressed for time; maybe someone else can fill in the details on the names of the processes and the values?)

One interesting and useful result of this difference is that a delta-13 measurement can reveal whether or not various "natural fruit juices" or other foods have been spiked with corn sugar.


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 31 by Coyote, posted 09-21-2016 4:43 PM Coyote has responded

Replies to this message:
 Message 34 by Coyote, posted 09-25-2016 11:00 PM kbertsche has not yet responded

  
kbertsche
Member (Idle past 580 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007


(1)
Message 52 of 222 (799292)
02-08-2017 11:00 PM
Reply to: Message 42 by ICANT
02-06-2017 1:32 PM


Re: Assumptions are not wild guesses
I will address only radioCARBON dating here:
ICANT writes:


The first assumption you have to make is that the universe is x years old,


No, the age of the universe is irrelevant to radiocarbon dating. We don't need to assume anything about the age of the earth.

ICANT writes:


A constant rate of decay,


No, we don't need to assume a constant decay rate for radiocarbon dating. We only need to assume that, at all times, the decay rate in an unknown sample is the same as the decay rate in the tree rings that are used for radiocarbon calibration.

(Note: we have very good evidence, both experimental and theoretical, that the decay rate of radiocarbon IS constant. But even if it weren't, it would not invalidate calibrated radiocarbon dates.)

ICANT writes:


an isolated system in which no parent or daughter element can be added or lost,


It is important that no parent is added or lost (we call this "contamination"). But this is not an "assumption"; contamination can usually be detected by making multiple measurements of a sample, either from different physical locations or with different chemical pre-treatments.

ICANT writes:


and a known amount of the daughter element present initially.


No, for radiocarbon dating the daughter is ignored. Only the parent is measured.

Edited by kbertsche, : Corrected "NoNukes" to "ICANT"


"Science without religion is lame, religion without science is blind." – Albert Einstein

“I am very astonished that the scientific picture of the real world around me is very deficient. It gives us a lot of factual information, puts all of our experience in a magnificently consistent order, but it is ghastly silent about all and sundry that is really near to our heart, that really matters to us. It cannot tell us a word about red and blue, bitter and sweet, physical pain and physical delight; it knows nothing of beautiful and ugly, good or bad, God and eternity. Science sometimes pretends to answer questions in these domains, but the answers are very often so silly that we are not inclined to take them seriously.” – Erwin Schroedinger


This message is a reply to:
 Message 42 by ICANT, posted 02-06-2017 1:32 PM ICANT has not yet responded

Replies to this message:
 Message 53 by RAZD, posted 02-09-2017 7:39 AM kbertsche has not yet responded

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2018 by EvC Forum, All Rights Reserved

™ Version 4.0 Beta
Innovative software from Qwixotic © 2020