Register | Sign In


Understanding through Discussion


EvC Forum active members: 48 (9179 total)
2 online now:
Newest Member: Jorge Parker
Post Volume: Total: 918,231 Year: 5,488/9,624 Month: 513/323 Week: 10/143 Day: 0/10 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Carbon-14 Dating Debate Assistance Thread
RAZD
Member (Idle past 1520 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 15 of 38 (468717)
05-31-2008 9:13 PM
Reply to: Message 12 by SqU1r3
05-31-2008 3:21 PM


Re: "Creationist Lies"
Welcome to the fray, SqU1r3.
These are not "lies".
They are falsehoods, whether they are "lies" would be dependent on whether they were intentional falsehoods meant to delude the gullible, or just stupidity, ignorance, or insanity.
Though that said, I'm not yet fully acquainted with the entire Carbon dating field, I'm merely passing on Hovind's views.
So instead of reading information from a number of sources and cross-checking them for validity, you have just posted something you read, verbatum, and that you have no idea how true it is, or how trustworthy the author is. That said, how did you decide they are not "lies" eh? Did you ask the local used car salesman?
Here is an authority on radiometric dating methods: Radiometric Dating, A Christian Perspective, by Dr. Roger C. Wiens.
I also suggest you read the forum guidelines -- long cut and pastes with no comment on what you think they mean are frowned on. Here are some other tips:
type [qs]quotes are easy[/qs] and it becomes:
quotes are easy
or type [quote]quotes are easy[/quote] and it becomes:
quote:
quotes are easy
also check out (help) links on any formating questions when in the reply window.
Enjoy

we are limited in our ability to understand
by our ability to understand
RebelAAmericanOZen[Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 12 by SqU1r3, posted 05-31-2008 3:21 PM SqU1r3 has not replied

  
RAZD
Member (Idle past 1520 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 23 of 38 (492561)
01-01-2009 10:54 AM
Reply to: Message 20 by Peg
01-01-2009 8:30 AM


Overview of C-14 for Peg to aid her skepticism regarding reports of "unreliability"
Hey Peg, happy new year.
it looks like i am not alone in my skepticism of C14 dating
Nor are you alone in your ignorance of C-14 methodology. The popularity of an opinion has no relation to the validity of an opinion. This is known as the logical fallacy of popularity.
Popularity does not validate your skepticism nor challenge C14 dating. The question is if you are equally skeptical of the people telling you that C14 is "unreliable"?
... my question is why would you proclaim my ignorance when others here express similar sentiments??? Is it more acceptable coming from a fellow evolutionist or something?
What people think is irrelevant. What you want to look at is the science and how carbon 14 dating is done properly, what the assumptions are, how those assumptions are tested, and how the system is validated.
Message 11
you're right
i dont trust carbon dating...not one little bit
As this subject is not about the accuracy or 'inaccuracy' of carbon dating though, i wont be going into it... nor do i need to be an expert to be skeptical.
No, you don't need to be an expert to be skeptical, but real skepticism is equally skeptical of those that tell you it is unreliable. Otherwise you are claiming skepticism as a crutch for denial. What you want to use is open-minded skepticism.
You also do not need to be an expert to understand carbon-14 dating, you just need to be interested in the truth.
When you look at claims that C-14 is unreliable you see claims of false ages for certain samples. To be able to judge the validity of those statements you need to understand how carbon-14 works and where the C-14 comes from.
This is an excellent site that goes through the basics:
How Carbon-14 Dating Works | HowStuffWorks
and you don't need anything more than a high-school education to understand it.
quote:
How Carbon-14 is Made
Cosmic rays enter the earth's atmosphere in large numbers every day. For example, every person is hit by about half a million cosmic rays every hour. It is not uncommon for a cosmic ray to collide with an atom in the atmosphere, creating a secondary cosmic ray in the form of an energetic neutron, and for these energetic neutrons to collide with nitrogen atoms. When the neutron collides, a nitrogen-14 (seven protons, seven neutrons) atom turns into a carbon-14 atom (six protons, eight neutrons) and a hydrogen atom (one proton, zero neutrons). Carbon-14 is radioactive, with a half-life of about 5,700 years.
Note that this is atmospheric carbon. Note that the half-life is short, and that without replenishment of C-14 by cosmic radiation that the level of C-14 would quickly (~50kyr) fall to unmeasurable levels.
Carbon-14 dating only works when the source of C-14 is known well enough to assume initial levels, such as trees taking carbon from the atmosphere, thereby absorbing the C-14 mixed with other carbon (C-12 and C-13) atoms in the atmosphere.
quote:
Carbon-14 in Living Things
The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people eat plants and take in carbon-14 as well. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant. Maybe one in a trillion carbon atoms are carbon-14. The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate. At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage.
Living organisms have the same ratio of C-14 to C-12 as their source of carbon. When that source is the atmosphere, they have the same level as the atmosphere has while they are living.
quote:
Dating a Fossil
As soon as a living organism dies, it stops taking in new carbon. The ratio of carbon-12 to carbon-14 at the moment of death is the same as every other living thing, but the carbon-14 decays and is not replaced. The carbon-14 decays with its half-life of 5,700 years, while the amount of carbon-12 remains constant in the sample. By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely.
Thus by measuring the ratio of C-14 to C-12 in a sample and comparing it to the ratio of C-14 to C-12 today, the age of the sample can be estimated by the relative amount of decay of the C-14 atome.
Scientists also know common sources of error. See
Corrections to radiocarbon dates.
for the most common sources.
Note that one source of error is caused by taking samples from organic material that did not get carbon from the atmosphere, but from other sources. Marine samples are known to have different carbon sources from land samples for instance, and the atmospheric C-14 does not mix into water to the same ratio as in the air. This is known as a "reservoir effect" where the atmosphere and the ocean are "reservoirs" with different base ratios of C-14 to C-12. Once a reservoir C-14/C-12 ratio has been measured, the data can be corrected for this effect. Scientists publish this information here.
You see many creationist claims that C-14 is "unreliable" because marine organisms, or organisms that feed on marine life, have "too old" C-14 dates. The educated skeptic will understand that such claims are lies, as they misrepresent a sample from a marine source of carbon as being from an atmospheric source of carbon.
Also note another known source of error is that radioactivity can create C-14. This is why atmospheric C-14 spiked during above ground testing of bombs. This is also how C-14 is produced in the carbon rods used to control nuclear reactors, eventually reducing the effectiveness of the rods, so they are continually replaced.
You can also find creationist claims that C-14 is "unreliable" because oil, coal, diamonds have "too young" C-14 ages. What they don't tell you here is that (a) the levels found are at the threshold of detectability, and (b) the samples come from rocks with measurable radioactivity. The educated skeptic will understand that such claims misrepresent a sample from a radioactive source of carbon-14 as being from an atmospheric source of carbon-14.
Finally, note that another source of error is the variance of C-14 in the atmosphere due to varying cosmic ray levels and varying solar activity. Scientists have known this since the introduction of the method, and they have found ways to determine this error. This is a correlation curve of C-14 dates with actual dates known from counting tree rings:
Note that the real age is actually older than the calculated C-14 age, so the typical measurement error is for the objects to consistently date younger than they actually are.
This is a correlation curve of C-14 dates with actual dates known from counting lake varves:
Note that the tree ring data is shown as the green line at the beginning of this data, and that this data extends to the limits of practical C-14 dating. Note how this data continues the trend shown previously with real ages being older that the ones calculated by the C-14 method. Note that you can see an effect of change in C-14 atmospheric levels at ~30kyr ago.
Finally, this is a correlation curve of C-14 dates with actual dates known from a number of sources, some of them from marine samples that have been corrected for the marine resevoir effect:
Notice how the other correlations have the same pattern at ~30kyr as the lake varves.
Notice that there are variations about the mean for this curve, and that this is the amount of uncertainty that is involved with C-14 dating.
Having known degrees of variation about a mean does not make a method "unreliable" as all these different correlations reliably produced the same results. The degrees of variation mean that we have margins of error with this method, and this is one of the reasons you will see dates with max/min boundaries or mean+/-errors.
The error shown here is less than 10% on average. Certainly realiable enough to know that measurements of objects 30,000 years old are much older than 6000 years.
Enjoy.
Edited by RAZD, : clarity, added link to reservoir data

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 20 by Peg, posted 01-01-2009 8:30 AM Peg has not replied

Replies to this message:
 Message 24 by Coyote, posted 01-01-2009 11:45 AM RAZD has seen this message but not replied
 Message 25 by lyx2no, posted 01-01-2009 2:36 PM RAZD has replied

  
RAZD
Member (Idle past 1520 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 27 of 38 (492621)
01-01-2009 7:16 PM
Reply to: Message 25 by lyx2no
01-01-2009 2:36 PM


Re: A Short Aside - marine reservoirs
hey lyx2no,
However, you state this is atmospheric radio carbon. Would one use a different baseline for the ocean or a lake? To keep it short, just point me to a site; I can take it from there.
Corrections to radiocarbon dates.
quote:
One of the most commonly referenced reservoir effects concerns the ocean. The average difference between a radiocarbon date of a terrestrial sample such as a tree, and a shell from the marine environment is about 400 radiocarbon years (see Stuiver and Braziunas, 1993). This apparent age of oceanic water is caused both by the delay in exchange rates between atmospheric CO2 and ocean bicarbonate, and the dilution effect caused by the mixing of surface waters with upwelled deep waters which are very old (Mangerud 1972). A reservoir correction must therefore be made to any conventional shell dates to account for this difference. Reservoir corrections for the world oceans can be found at the Marine Reservoir Correction Database, a searchable database online at Queen's University, Belfast and the University of Washington. Human bone may be a problematic medium for dating in some instances due to human consumption of fish, whose C14 label will reflect the ocean reservoir. In such a case, it is very difficult to ascertain the precise reservoir difference and hence apply a correction to the measured radiocarbon age.
The same would hold true for the 1300 C-14 yr seal sample from McMurdo Sound used by creationists (google: McMurdo Sound Seal C-14)
Scientists publish this reservoir information here.
It's a pretty cool interactive site. You can click Antarctica near McMurdo sound (edge of map), for instance (where the YEC seal sample was taken), and find out that the "reservoir age" is about 1000 years, so any uncorrected sample taken today would calculate out at ~1000 years older than it is.
Enjoy

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 25 by lyx2no, posted 01-01-2009 2:36 PM lyx2no has replied

Replies to this message:
 Message 34 by lyx2no, posted 01-02-2009 9:56 AM RAZD has seen this message but not replied

  
RAZD
Member (Idle past 1520 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 38 of 38 (492794)
01-03-2009 12:08 AM
Reply to: Message 31 by Peg
01-02-2009 2:47 AM


Re: Bump for Peg to air her skepticism regarding carbon dating
Hello Peg,
It appears you didn't really read my Message 23 ...
here a few points of contention for C14 that i have found in print in various places
And curiously each one was addressed above. In fact from the information provided to you and lyx2no one could have predicted before the sample was tested that the seal from McMurdo Sound would test (uncorrected for the KNOWN marine reservoir effect) to be over 1000 years old.
Of course an honest skeptical person would want to know why a creationist would go to Antarctica to obtain a sample from a seal to subject to C-14 dating (it is not a cheap process), if they didn't know before hand that this is precisely what results they could expect. That they then pretend that they are using the method correctly (which they are NOT doing without the reservoir correction) means that they are intentionally misrepresenting the truth.
....so how do they account for all these possible variences in c14 in the atmosphere??? How can they honestly know how much to make allowance for???
By using the calibration curves given in Message 23, the ones developed from testing items of known actual age. By comparing calibration curves from hundreds of different places.
Curiously scientists don't just throw up there hands and give up when they have questions like this - they look for answers. Strangely C-14 is so well tested and improved method, that different laboratories with blind samples produce the same results.
The most recent calibration review was done in 2004, and it goes by the name of INTCAL04 (the previous, INTCAL98, was done in 1998):
http://www.radiocarbon.org/IntCal04_TOC.pdf
See: INTCAL04 TERRESTRIAL RADIOCARBON AGE CALIBRATION, 0-26 CAL KYR BP
http://www.radiocarbon.org/IntCal04.htm
from http://www.radiocarbon.org/ (Radiocarbon Journal on line archives) Volume 46 Number 3, where number 2 and 3 contain the proceedings of the conference.
Notice that they did not use the bristlecone pine data, as over a period of some 8000 years covered by the tree rings in three different dendrochronologies, the data was off by 37 years to the other two chronologies:
quote:
The replicate measurements have a mean offset of 37 6 14C yr (n = 21) from the Tucson measurements. Applying this shift to the Tucson data results in a close fit to the wiggles of the German oak, which would not occur if there were an error in the dendrochronology of either series. Because of this offset, the IntCal working group has decided not to include the BCP record in IntCal04.
(IntCal04 Terrestrial 14C Age Calibration, 0-26 cal kyr BP page 1033)
That's an error of 0.5% ...
In other words, the effects have been very closely studied and accounted for.
Here's a curve that I like: it also answers your question about volcanic effects:
Where:
age is the hoizontal axis,
sediment depth is the vertical axis
varve age is represented by a solid line
C-14 age is represented by the circles (the actual samples)
I want you to look at 4 things shown on this graph:
  1. at ~10kyr ago the slope of the varve line changes,
  2. the change in slope is matched by the C-14 age data (with the same offset you see in the calibration curves given previously)
  3. the ash from several volcano eruptions is included,
  4. the age of known volcanic eruptions (labelled) matches evidence from other sources.
From this graph you can see that the effect of the volcanoes is not significant to the ages of the samples measured.
Note that varve age is linear, every varve represents one year, while C-14 content is exponential, due to decay, and it is converted to age by an exponential formula, and yet the ages match regardless of the rate of sediment deposit for each of the different layers.
BTW, the samples tested were leaves, twigs and insects that fell into the lake, and thus their C-14 came from the atmosphere when they were living.
there is also the assumption that the level of carbon 14 in the atmosphere has always been the same as it is now. But we know that the carbon level has increased a lot since the explosion of neuclar bombs into the atmosphere and since the use of burning fossil fuels. So how do we really know what the levels were thousands of years ago?
Here's that calibration curve from the same data again:
That's how scientists know. Because they find out what the effects are.
Enjoy.
Edited by RAZD, : clarity
Edited by RAZD, : added
Edited by RAZD, : clarity again

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 31 by Peg, posted 01-02-2009 2:47 AM Peg has not replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024