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aeacfm
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[*] posted on 24-2-2012 at 10:16
carbon dating



suppose good calibrated instruments , good prepared samples and every thing is ok !!!

How much is the radiocarbon dating reliable?????






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[*] posted on 24-2-2012 at 10:41


Please try and do some basic research yourself!

http://en.wikipedia.org/wiki/Carbon_dating
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24-2-2012 at 10:41
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[*] posted on 24-2-2012 at 10:56


i am sure sciencesquirrel knows about radiometric dating but was trying to trigger a discusion that i find myself very interesting...

i was recently reading about the 1978 STRUP (shroud of Turin Research Project) wich was carbon dated to the 13th century.
some scientist questioned the validity of the sample as many pieces on the shroud have been burned ,replaced and contaminated over the years..
even with the best sampling method, dating procedures and care , this remain a tricky business but i would say that carbon dating is pretty reliable at least for the last 55 000 years of history...

[Edited on 24-2-2012 by neptunium]




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[*] posted on 24-2-2012 at 12:15


He is quite welcome to come back and ask another question on this subject if he wishes to do so.
If he wants to ask a specific question or spark a debate he is very welcome to do so.
Thank you Neptunium, I hope we have an interesting debate on the validity of carbon dating.
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[*] posted on 24-2-2012 at 13:12


Quote: Originally posted by ScienceSquirrel  
He is quite welcome to come back and ask another question on this subject if he wishes to do so.
If he wants to ask a specific question or spark a debate he is very welcome to do so.
Thank you Neptunium, I hope we have an interesting debate on the validity of carbon dating.



thank you squirrel , i already read about carbon dating and all said it is so far reliable .... my friend told me the counter it is not reliable every time and because i don't haveANY experience about it so i asked if a practicing guy here could help !!!!
any way i will read more and i hope make a good debate
thanks again






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[*] posted on 24-2-2012 at 14:30


i used to work in the radiochemistry lab of a nuclear power plant (my best job ever!) and we had pure beta samples to analyse dayli, some of wich contained C14 but i dont know if the sample preparation for liquid scintillation is the same for C14 dating...

i dont think it should be much different though.. the dating calculation is pretty simple once we know the activity of C14 .

i cant help to think that the age of a sample is the one at wich the organism died so a piece of cloth made of fiber from a tree should yield the age at wich the tree was cut down ...
at wich point some years could go by before it is used to make the fabric. thus giving an age slightly off...i am sure one could think of many other examples..




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[*] posted on 24-2-2012 at 14:56


Not specific to the OP, but interesting to some of us:

Some amateurs have done carbon dating
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[*] posted on 26-2-2012 at 09:34


Oh, I know where this is heading...



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[*] posted on 3-2-2019 at 05:00


Ignoring possible sample selection and preparation issues, as the number of atoms n in a sample is likely large, the statistical estimation error is likely small compared to other issues as noted in the Wiki article (for example, the assumption that the proportion of radioactive CO2 in the atmosphere over time is constant). This is based on the Wiki reference above:

"More recently, accelerator mass spectrometry has become the method of choice; it counts all the 14C atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly."

And, the comment:

"The above calculations make several assumptions, such as that the level of 14C in the atmosphere has remained constant over time.[5] In fact, the level of 14C in the atmosphere has varied significantly"

owing to varying intensity over time of both galactic cosmic rays and more local solar radiation, as also noted by Wiki, and further in my opinion, the latter combined with oscillations in the effectiveness of the earth's protective magnetic field and possibly vulcanism introducing reflective atmospheric particles.

[Edited on 3-2-2019 by AJKOER]
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[*] posted on 3-2-2019 at 05:48


My highschool biology teacher believed the earth was 6000 years old and any type of radio dating was psuedo science because we don't know that the the half life of carbon or anything else at the time the sample was created is the same as it is now. She also believed that for the first 1000 years the earth could have orbited the sun multiple times every day, and that's why we have hundreds of thousands of years worth of ice core layers. Really weird stuff
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[*] posted on 3-2-2019 at 06:57


Quote: Originally posted by walruslover69  
My highschool biology teacher believed the earth was 6000 years old and any type of radio dating was psuedo science because we don't know that the the half life of carbon or anything else at the time the sample was created is the same as it is now. She also believed that for the first 1000 years the earth could have orbited the sun multiple times every day, and that's why we have hundreds of thousands of years worth of ice core layers. Really weird stuff


Your biology teacher should stick to simple biological concepts (and stop reading her bible in class).

She should talk to an earth science teacher who knows that rocks on earth are several BILLIONS of years old (see https://www.google.com/search?source=hp&ei=UwBXXJHLBqSq5... ).
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[*] posted on 2-11-2021 at 10:36


a little late to the party but relevant nonetheless

https://www.youtube.com/watch?v=qvi83-PTDN8




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[*] posted on 2-11-2021 at 13:49


Quote: Originally posted by AJKOER  
Ignoring possible sample selection and preparation issues, as the number of atoms n in a sample is likely large, the statistical estimation error is likely small compared to other issues as noted in the Wiki article (for example, the assumption that the proportion of radioactive CO2 in the atmosphere over time is constant). This is based on the Wiki reference above:

"More recently, accelerator mass spectrometry has become the method of choice; it counts all the 14C atoms in the sample and not just the few that happen to decay during the measurements; it can therefore be used with much smaller samples (as small as individual plant seeds), and gives results much more quickly."

And, the comment:

"The above calculations make several assumptions, such as that the level of 14C in the atmosphere has remained constant over time.[5] In fact, the level of 14C in the atmosphere has varied significantly"

owing to varying intensity over time of both galactic cosmic rays and more local solar radiation, as also noted by Wiki, and further in my opinion, the latter combined with oscillations in the effectiveness of the earth's protective magnetic field and possibly vulcanism introducing reflective atmospheric particles.

[Edited on 3-2-2019 by AJKOER]


There are 2 kinds of dates when it comes C14 dating.
One is called the Libby date. This is named after the inventor. This is based on the half-life of the C14 and it is assumed that the quantity of C14 in the atmosphere is even and a constant.

The other is the adjusted date. In this case, other factors are included.
1. The fact that the C14 production is not a constant over time. (Solar activity varies year to year)
2. The fact that the C14 production is not a constant over space. (The bombardment of the upper atmosphere varies by location).

In order to adjust, they can use samples who’s age is known. You can know the age of the sample, such as when a painting has been painted, when a cloths or shoe has been made. You can use dendrochronology.




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[*] posted on 2-11-2021 at 14:16


Nice video!
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[*] posted on 2-11-2021 at 14:20


Quote: Originally posted by walruslover69  
My highschool biology teacher believed the earth was 6000 years old and any type of radio dating was psuedo science because we don't know that the the half life of carbon or anything else at the time the sample was created is the same as it is now. She also believed that for the first 1000 years the earth could have orbited the sun multiple times every day, and that's why we have hundreds of thousands of years worth of ice core layers. Really weird stuff


What they mean to say is that the C14 half-life, 6000 y ago, was much shorter than now, so when you measure it now, it gives a very large age.
They are not able to give us a reason why it is different than now or why it was shorter and not longer.
If that were the case, it would apply to all radionuclides. This also might mean that the internal of the Earth might get too hot and melt the crust. (They can make some counter arguments to this since we don’t know how much U and Th are at the Earth’s core).

They also claim that the “god” fine tuned the universe. He fine tuned the mass of all sub atomic particles, he fine tuned the force of gravity, the electric force, the magnetic force, the nuclear force, the weak force and the hundreds of other fundamental constants.

They say that without fine tuning, life would not be possible.
So if things are fine tuned, why would the half-lives of any isotope be shorter than it is now? In order to change the half-lives, you may have to change a bunch of the universal constants.
This is called special pleading.

On top of that, experiments have shown that the half-lives of various radioisotopes can’t be changed. Using low pressure, using high pressures, using low or high temperatures, being surrounded by different atoms.
The only exception is in the case of decay via k-capture. In the case of beryllium compounds, I think it was written that the half-live can be extended by 12%. This is because the electron cloud of Be would be pulled more to the side of the anion so this reduces the probability of a k-capture event.
Also, Be is a lightweight atom. It only has 4 electrons and when it binds with a non-metal, it is left with 2 electrons, more or less.

^^^^^Notice that this elongates the half-life. There has been no cases of reduction.
They don’t use Be to measure the age of minerals and there are no radioisotopes of Be on Earth.





Source:
https://en.wikipedia.org/wiki/Special_pleading

Special pleading is an informal fallacy wherein one cites something as an exception to a general or universal principle, without justifying the special exception.[1][2][3][4][5] It is the application of a double standard.[6][7]

In the classic distinction among material fallacies, cognitive fallacies, and formal fallacies, special pleading most likely falls within the category of a cognitive fallacy, because it would seem to relate to "lip service", rationalization, and diversion (abandonment of discussion). Special pleading also often resembles the "appeal to" logical fallacies.[8][9]

In medieval philosophy, it was not presumed that wherever a distinction is claimed, a relevant basis for the distinction should exist and be substantiated. Special pleading subverts a presumption of existential import.






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