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I believe that carbon 14 is measured, then based on how much has decayed, the age is measured because we know the rate at which C-14 is measured. And C-12 is used as some sort of control, since the ratio is always the same.dlamberth said:In your mind, how do you think the process goes when a paleontologist dates an old fossil bone or plant?
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shinbits said:I believe that carbon 14 is measured, then based on how much has decayed, the age is measured because we know the rate at which C-14 is measured. And C-12 is used as some sort of control, since the ratio is always the same.
Right?
details from:The cosmogenic dating clocks work somewhat differently than the others. Carbon-14 in particular is used to date material such as bones, wood, cloth, paper, and other dead tissue from either plants or animals. To a rough approximation, the ratio of carbon-14 to the stable isotopes, carbon-12 and carbon-13, is relatively constant in the atmosphere and living organisms, and has been well calibrated. Once a living thing dies, it no longer takes in carbon from food or air, and the amount of carbon-14 starts to drop with time. How far the carbon-14/carbon-12 ratio has dropped indicates how old the sample is. Since the half-life of carbon-14 is less than 6,000 years, it can only be used for dating material less than about 45,000 years old. Dinosaur bones do not have carbon-14 (unless contaminated), as the dinosaurs became extinct over 60 million years ago. But some other animals that are now extinct, such as North American mammoths, can be dated by carbon-14. Also, some materials from prehistoric times, as well as Biblical events, can be dated by carbon-14.
The carbon-14 dates have been carefully cross-checked with non-radiometric age indicators. For example growth rings in trees, if counted carefully, are a reliable way to determine the age of a tree. Each growth ring only collects carbon from the air and nutrients during the year it is made. To calibrate carbon-14, one can analyze carbon from the center several rings of a tree, and then count the rings inward from the living portion to determine the actual age. This has been done for the "Methuselah of trees", the bristlecone pine trees, which grow very slowly and live up to 6,000 years. Scientists have extended this calibration even further. These trees grow in a very dry region near the California-Nevada border. Dead trees in this dry climate take many thousands of years to decay. Growth ring patterns based on wet and dry years can be correlated between living and long dead trees, extending the continuous ring count back to 11,800 years ago. "Floating" records, which are not tied to the present time, exist farther back than this, but their ages are not known with absolute certainty. An effort is presently underway to bridge the gaps so as to have a reliable, continuous record significantly farther back in time. The study of tree rings and the ages they give is called "dendrochronology".
How so?shinbits said:This is now just a "nuh-uh" statement.
Not much I can do about that.shinbits said:How?
Right. I forget you're just fifteen.
and when I pressed for examples of scientists using this method, you changed your sentence.shinbits said:the problem I'm adressing is when people claim to have used this method for fossils.
the need for a steadily increasing scale is a point that is being argued as such.Nooj said:How so?
don't do anything, enjoy it while it lasts.Not much I can do about that.
I never hinted or implied that scientists did this. From reading posts on this board, that was the impression I got of what the concensus was.Come now shinbits, the evidence is in the quotes. You stated that:
and when I pressed for examples of scientists using this method, you changed your sentence.
I didn't. I wouldn't have even brought it up if I did.Minor quibbles, but it suggests you originally didn't know that radiometric dating is not used for fossils.
Okay. I do know that C-12 remains constant in a sample while C-14 decays. That's why I ascribed "control" to it.rmwilliamsll said:in a nutshell, it is the comparison of two ratios.
C14/C12 now present in the sample
vs
C14/C12 then, the last time the living creature metabolized Carbon thus had the "normal" living ratio
what you got wrong is misunderstanding C12 ratios versus controls.
C12 is an integral part of the process, not a control element/factor/standard.
Okay, but people never claimed to have used this method for fossils. That's all I wanted to say.I never hinted or implied that scientists did this. From reading posts on this board, that was the impression I got of what the concensus was.
shinbits, the loss of isotopes in an open system like a rock is negligible to the overall ratio of daughter/parent isotopes and therefore, the dating of the rock.the need for a steadily increasing scale is a point that is being argued as such.
shinbits said:Okay. I do know that C-12 remains constant in a sample while C-14 decays. That's why I ascribed "control" to it.
The issue of sunlight being measured on an ascending scale though, is one that isn't factored. This is the problem with C-14.
I've repeated this many times already. It's not just the sun's strength, but that the sun's strenth increases each year that you go back in time, due to the fact that it loses mass over time. As a result, the amount of light recieved by earth from the sun increases.rmwilliamsll said:cosmic rays, ie the C14 process in C14/C12 ratio does taking sun's strength into account. that is what the calibration curve is showing.
shinbits said:I've repeated this many times already. It's not just the sun's strength, but that the sun's strenth increases each year that you go back in time, due to the fact that it loses mass over time. As a result, the amount of light recieved by earth from the sun increases.
As I've mentioned before, you can't use a constant rate to factor in the sun's light output; you MUST use a rate that is on a rising curve for each year you go back in time.
Do you understand what I'm saying?
from: http://www.c14dating.com/int.htmlThe radiocarbon method is based on the rate of decay of the radioactive or unstable carbon isotope 14 (14C), which is formed in the upper atmosphere through the effect of cosmic ray neutrons upon nitrogen 14. The reaction is:
14N + n => 14C + p
(Where n is a neutron and p is a proton).
shinbits said:http://www.regulusastro.com/regulus/papers/stars/
"The more massive the star, the more light output it generates, and the more hydrogen burning there must be to counteract the gravitational potential for collapse."
The sun has loss trillions of tons of mass over thousands of years. That means that at one point, the sun's light output was more then what is now.
never claimed it did.
I'm not at all down playing the role of hydrogen conversion. But you seem to be down playing the role that the sun's mass has on it's luminosity. Ignoring that is part of what makes C-14 dating unreliable.
But ignoring the sun's mass and it's increasing energy output as we go back in time is not something you can just gloss over. This directly affects the amount of light coming into the earth.
shinbits said:http://www.regulusastro.com/regulus/papers/stars/
"The more massive the star, the more light output it generates, and the more hydrogen burning there must be to counteract the gravitational potential for collapse."
The sun has loss trillions of tons of mass over thousands of years. That means that at one point, the sun's light output was more then what is now.
I'm not at all down playing the role of hydrogen conversion. But you seem to be down playing the role that the sun's mass has on it's luminosity. Ignoring that is part of what makes C-14 dating unreliable.
But ignoring the sun's mass and it's increasing energy output as we go back in time is not something you can just gloss over. This directly affects the amount of light coming into the earth.
shinbits said:I've repeated this many times already. It's not just the sun's strength, but that the sun's strenth increases each year that you go back in time, due to the fact that it loses mass over time. As a result, the amount of light recieved by earth from the sun increases.
OdwinOddball said:Shin, as Kerr and others have tried to explain to you, this statement is absolutely backwards.
Here is why.
The statement that a more massive star produces more energy is correct for the birth of stars. When stars are born, they consist almost entirely of Hydrogen. In this, stars are essentially all the same, and thus the more massive a star is, the more energy it puts out.
However, this does not stay correct over time. Yes, the star is losing mass, and thus it does produce less and less energy from its hydrogen reactions. However, it is not losing all the mass of the hydrogen involved in fusion.
Fusion is what powers the sun. 2 hydrogen atoms under immense pressure and heat fuse into a single Helium atom , 2 alpha particles, and electro magnetic radiation. This energy is then felt here on earth in the form of heat, visible light, and the solar wind.
Over time, the amount of hydrogen decreases, and the amount of Helium increases. Thus the molecular weights of the atoms in the sun increase over time. This actually increases the speed of the reactions over time, and thus increases the energy output.
Eventually the Sun's core will increase in temperature, and the energy output will get so high, that gravity is no longer strong enough to hold it all together. The sun will expand dramatically untill a point of equilibrium is met. The sun will now be a red giant, and will be burning Helium instead of hydrogen.
This cycle will continue, with the sun burning progressively heavier elements, helium-beryilum-carbon, till the energy output and gravity are no longer in balance, and the sun collapes into a white dwarf.
So yes Shin, in one respect you are correct. A more massive star does emit more energy than a less massive star. However, trying to aply this to the entire life of a star is a fallacious method. It is much like trying to apply Newtonian Mechanics to sub-atomic particles, it just doesn't apply at these levels.
Shin, you know the surface level information on most of these subjects. However, instead of following through with your studies to get to the deeper, more advanced understanding, you are taking these simple beginings and trying to solve problems for which they are inadequete.
You are trying to establish yourself as an authority on these subejcts, when every post you make demsontrates the glaring holes in your understanding. Instead of coming off as educated, you are coming off as ignorant and bull headed. Please, as I have asked you numerous times, take some time to actually learn the full complexities of a subject before you try to debate it. Stop voluntarily looking foolish, take some responsibility for your education, and learn.
KerrMetric said:Mostly correct. The red giant thing is in error. It is not helium burning it is the core being helium (and isothermal and degenerate in a low mass star - higher mass stars are somewhat different) and the hydrogen burning being in a shell around the core that the red giant stage begins.
Core helium burning occurs in a flash at the tip of the giant branch and then settles down to steady core helium burning on the horizontal branch after ejecting a lot of mass. Then when this runs out you have shell helium and hydrogen burning as the star moves up the asymptotic giant branch (AGB).
Loudmouth said:How can anyone claim that anyone is assuming constant C14 production when scientists publish papers on the historic variation of atmospheric C14? From here:
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