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Author Topic:   Assumptions involved in scientific dating
Taq
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Posts: 10195
Joined: 03-06-2009
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Message 27 of 222 (791737)
09-20-2016 2:52 PM


Devil's Advocate
Since we are probably not going to hear from the creationists, I thought I would ask a question that has intrigued me, and also to take advantage of someone who has experience in the field.
How does one determine the extent or presence of exogenous 14C contamination in carbon dating? Do you test multiple samples from different environments in the same geologic layer? Do you avoid specific conditions, such as potential water contamination? Do you test material from the interior of a sample instead of the exterior? Are there controls to determine if contamination is an issue?
In my experience in other fields, sample selection is the bedrock of a solid methodology. Is this the case with 14C dating?
On a side note, does it drive you nuts when they call it "radiocarbon dating" when it is actually K/Ar dating or U/Pb dating? In my field, it drives me crazy when they people conflate bacteria and viruses, so I imagine you cringe when people confuse matters in your field of work.
Edited by Taq, : No reason given.

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Taq
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Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 29 of 222 (791770)
09-21-2016 11:47 AM
Reply to: Message 28 by Coyote
09-20-2016 4:35 PM


Re: Devil's Advocate
Coyote writes:
One way of determining how good your sample is is the C13 reading. Clean charcoal should have a reading somewhere close to —25 (don't worry about what the number means at this point). Good marine shell should be somewhere around 0 or 1.
This does pique my curiosity, so I have a few more questions if you have the time to answer them.
I suspect that this is due to both carbon source and fractionation during photosynthesis. Photosynthesis favors lighter isotopes, so I suspect that the 13C values you are giving are probably related to 13C/12C ratios. In terrestrial ecosystems, photosynthesizers fix carbon, and that carbon then filters down through each trophic level.
Is this not also the case with aquatic environments? I wouldn't be surprised if free 13C/12C ratios were different for aquatic environments, but do marine animals fix dissolve carbon dioxide instead of deriving it from photosynthesizers? Or is the dissolved CO2 in aquatic environments just that different?
Edited by Taq, : No reason given.

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Taq
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Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 44 of 222 (798919)
02-06-2017 2:24 PM
Reply to: Message 42 by ICANT
02-06-2017 1:32 PM


Re: Assumptions are not wild guesses
ICANT writes:
I stated the assumptions that I think are wild guesses.
None of those are assumptions involved in scientific dating.
The first assumption you have to make is that the universe is x years old, A constant rate of decay, an isolated system in which no parent or daughter element can be added or lost, and a known amount of the daughter element present initially.
1. We don't assume the universe is x years old. The age of the universe is a conclusion drawn from many lines of evidence, including the temperature of the cosmic microwave background. Also, radiometric dating does not involve the age of the universe.
2. We can observe that daughter element does not leave certain crystals, such as Pb in zircons. Also, we can use multiple independent parent/daughter isotope pairs on several different types of minerals from the same geologic strata. Loss of parent/daughter isotopes would not affect all rocks and all isotopes the same, so if loss were responsible for the ages then different systems would give different ages.
3. We can use the isochron dating methods to measure the amount of daughter element present when the rock solidified. That is definitely not an assumption.

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Taq
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Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


(1)
Message 71 of 222 (827318)
01-22-2018 4:05 PM
Reply to: Message 66 by DOCJ
01-21-2018 8:36 PM


Re: Questions
DOCJ writes:
I'm looking at the information and a few of the assumptions I'm seeing are how much daughter product was in the sample, how much parent was in the sample, that their model of gravitational physics is true, and I'm sure there are some inside the formula such as constant variables..
None of them are assumptions in the truest sense. They are more akin to the assumptions you use with any instrument and measuring technique. Let's use electronic scales as an example. When you are using electronic scales you assume that gravity is the same, the natural laws governing electricity (i.e. Ohm's Law) are the same, and you are also assuming that magical leprechauns are not producing false data. Radiometric dating is the same.
Constant decay rates: In order for decay rates to change you would need to change the fundamental forces of nature, specifically the strong and weak nuclear forces. Since we observe that these forces are the same throughout the universe, as demonstrated by astronomical observations, we can be very confident that these were the same in the past. There are also specific observations of past decay rates such as the decay of isotopes in Supernova 1987a 170,000 light years away (hence 170,000 years ago) where they were able to measure the decay rates of at least one isotope.
Presence of daughter isotope in newly formed rock: You can entirely avoid this problem by using isochron dating which can actually measure the concentration of daughter product in the newly formed rock. For non-isochron methods, this assumption has already been checked in rocks that are from known and historic volcanic eruptions. For example:
"Two extensive studies done more than 25 years ago involved analyzing the isotopic composition of argon in such flows to determine if the source of the argon was atmospheric, as must be assumed in K-Ar dating (Dalrymple 1969, 26 flows; Krummenacher 1970, 19 flows). Both studies detected, in a few of the flows, deviations from atmospheric isotopic composition, most often in the form of excess 40Ar. The majority of flows, however, had no detectable excess 40Ar and thus gave correct ages as expected. Of the handful of flows that did contain excess 40Ar, only a few did so in significant amounts. The 122 BCE flow from Mt Etna, for example, gave an erroneous age of 0.25 0.08 Ma. Note, however, that even an error of 0.25 Ma would be insignificant in a 20 Ma flow with equivalent potassium content. Austin (1996) has documented excess 40Ar in the 1986 dacite flow from Mount St Helens, but the amounts are insufficient to produce significant errors in all but the youngest rocks."
Radiometric Dating Does Work! | National Center for Science Education
At worst, there is enough atmospheric 40Ar in newly formed igneous rock to cause a difference of just 0.25 million years.
The real strength of radiometric dating is that there are several independent isotope systems that can be used to cross check each other. For example, you can use K/Ar, U/Pb, and Rb/Sr. If radiometric dating didn't work then there would be no reason to predict that these three completely independent isotope systems would produce the same dates, yet they do:
"There are several important things to note about these results. First, the Cretaceous and Tertiary periods were defined by geologists in the early 1800s. The boundary between these periods (the K-T boundary) is marked by an abrupt change in fossils found in sedimentary rocks worldwide. Its exact location in the stratigraphic column at any locality has nothing to do with radiometric dating it is located by careful study of the fossils and the rocks that contain them, and nothing more. Second, the radiometric age measurements, 187 of them, were made on 3 different minerals and on glass by 3 distinctly different dating methods (K-Ar and 40Ar/39Ar are technical variations that use the same parent-daughter decay scheme), each involving different elements with different half-lives. Furthermore, the dating was done in 6 different laboratories and the materials were collected from 5 different locations in the Western Hemisphere. And yet the results are the same within analytical error. If radiometric dating didn’t work then such beautifully consistent results would not be possible."
Radiometric Dating Does Work! | National Center for Science Education
Here is the table that the quote is describing:
Edited by Taq, : No reason given.

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Taq
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Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 73 of 222 (827320)
01-22-2018 4:19 PM
Reply to: Message 72 by JonF
01-22-2018 4:11 PM


Re: Questions
JonF writes:
IIRC the initial range of dates was significantly smaller.
The initial spread in the data was that large. It appears that the first samples contained a mixture of really old material that had eroded and mixed with the new material (lahars?). However, once this problem was identified they started getting a much smaller spread in dates.
"In a study to test the feasibility of dating samples from the tuff, the samples were contaminated with non-juvenile components which could not be separated out, giving ages over 200 million years. It was recommended that new samples be collected from which suitable individual crystals could be separated (Fitch and Miller 1970). These new samples were dated at 2.61 +/- 0.26 million years, based on the 40Ar/39Ar dating method (Fitch and Miller 1970). "
CD031: KBS Tuff dating
Edited by Taq, : No reason given.

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


(2)
Message 102 of 222 (827371)
01-23-2018 11:09 AM
Reply to: Message 75 by DOCJ
01-22-2018 10:29 PM


Re: Questions
DOCJ writes:
I'm just interested in the truth.
Is followed by . . .
FYI: I believe in the electrical model of the universe, birkeland currents, plasma physics, and accept gravitational physics as a weak force.
It would appear that the second quote contradicts the first quote. It seems you are more interested in unfounded conspiracy theories than the truth.

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 Message 75 by DOCJ, posted 01-22-2018 10:29 PM DOCJ has replied

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 104 of 222 (827373)
01-23-2018 11:13 AM
Reply to: Message 90 by DOCJ
01-23-2018 8:46 AM


Re: Questions
DOCJ writes:
My goal of providing a alternative valid narrative is providing truth AND in which not a single contrary valid argument FROM you regarding the points in the links has been posted.
You have not shown that anything from the links is valid, so there is nothing to disprove. Just posting links will not work.
You claimed that electrical currents will affect the dating of rocks. It is now time for you to present that evidence. If you fail to do so, then we can only assume that you are not seeking the truth but only trying to ignore evidence you don't like.

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 111 of 222 (827383)
01-23-2018 12:43 PM
Reply to: Message 99 by DOCJ
01-23-2018 10:47 AM


Re: Questions
DOCJ writes:
I disagree. Truth is the shedding of light, and I don't specifically mean in a theological sense. If person A is biased, and B, and they debate person C who is just spectating is seeing the bias. I'm merely attempting to point out that bias. I've said my point of view. I've also asked for your opinions. And soon I'll respond to Percy who has made a mess of things. I'm sure he is purposefully deceitful since it's clear he is conventional in his views, and would like to hate apparently vs being unbiased and debating as I have done.
A deceitful person would say that electrical currents change radioactive decay rates, and then have no intention of backing up this claim with scientific evidence.
A person not looking for truth would post a bunch of hour long videos, and have no intention of ever discussing them or have the familiarity with the science necessary to discuss them.
A person not looking for truth would adopt a post-modernist stance where all ideas are supposedly equal, even when there is 100 years of science demonstrating that one of the ideas is wrong.
Time will tell if you are not being deceitful and are actually looking for the truth.
Edited by Taq, : No reason given.

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 Message 99 by DOCJ, posted 01-23-2018 10:47 AM DOCJ has replied

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 113 of 222 (827385)
01-23-2018 12:56 PM
Reply to: Message 112 by DOCJ
01-23-2018 12:55 PM


Re: Questions
DOCJ writes:
Where is the contradiction?
You claim to be seeking truth, yet you link to pages full of lies.

This message is a reply to:
 Message 112 by DOCJ, posted 01-23-2018 12:55 PM DOCJ has replied

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 Message 117 by DOCJ, posted 01-23-2018 1:05 PM Taq has replied

  
Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


(1)
Message 118 of 222 (827390)
01-23-2018 1:06 PM
Reply to: Message 116 by DOCJ
01-23-2018 1:04 PM


Re: Questions
DOCJ writes:
Please point out where I was incorrect. If you can't see the difference it does shed some light on things.
Someone seeking truth would not shift the burden of proof when someone questions their claims.
You need to show that your claims are correct using evidence. If no such evidence is presented, then there is nothing that needs to be disproved.
"What can be asserted without evidence can also be dismissed without evidence."--Christopher Hitchens

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 120 of 222 (827392)
01-23-2018 1:08 PM
Reply to: Message 117 by DOCJ
01-23-2018 1:05 PM


Re: Questions
DOCJ writes:
Lies? Be more specific. Who lied about what?
You linked to a Thunderbolts page where they lied about the assumptions of the 14C dating method. They claimed that it is assumed that 14C production was the same in the past. This is a lie. The 14C dating method is calibrated to known historic fluctuations in 14C production as determined by objects of known age such as tree rings, lake varves, ice layers, and speleothems. And that's just the tip of the iceberg in that link.
Edited by Taq, : No reason given.

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 Message 117 by DOCJ, posted 01-23-2018 1:05 PM DOCJ has replied

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 121 of 222 (827393)
01-23-2018 1:09 PM
Reply to: Message 119 by DOCJ
01-23-2018 1:08 PM


Re: Questions
DOCJ writes:
Um I made a claim and provided a link to a source... Lol.
You need to present the information, not just give links.

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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 125 of 222 (827397)
01-23-2018 1:22 PM
Reply to: Message 123 by DOCJ
01-23-2018 1:18 PM


Re: Questions
DOCJ writes:
You need to research the source.
You need to research your source and present the information. It isn't up to us to do your research for you.

This message is a reply to:
 Message 123 by DOCJ, posted 01-23-2018 1:18 PM DOCJ has replied

Replies to this message:
 Message 135 by DOCJ, posted 01-23-2018 5:03 PM Taq has replied

  
Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


(1)
Message 127 of 222 (827400)
01-23-2018 2:32 PM
Reply to: Message 126 by DOCJ
01-23-2018 1:30 PM


Re: Questions
DOCJ writes:
Um my point was dating methods are disputed within the scientific community. Links provided... Lol..
Present evidence, lol.
Thunderbolts, youtube, and creationist websites are not the scientific community. Lol.

This message is a reply to:
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Replies to this message:
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Taq
Member
Posts: 10195
Joined: 03-06-2009
Member Rating: 3.2


Message 128 of 222 (827401)
01-23-2018 2:32 PM
Reply to: Message 123 by DOCJ
01-23-2018 1:18 PM


Re: Questions
double reply. please delete
Edited by Taq, : No reason given.

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