How does radiocarbon dating actually work?

[linux.poet]

What is the process to radiocarbon date a fossil(or rock layer)? What is the science that determines the “millions of years” numbers? What are the flaws with this process, if any?

Scientific answers only please. Go!

 

[Reluctant Theologian]

What is the process to radiocarbon date a fossil(or rock layer)? What is the science that determines the “millions of years” numbers? What are the flaws with this process, if any?

Scientific answers only please. Go!

In no way can I claim no be an expert on this. A wiki or ChatGPT question would be able to teach you some basics. Certain elements decay at a certain (assumed constant) rate. So slowly over time the amount of that element found (as a ratio) drops. When one knows the original (assumed) amount and one measures the (now) measurable present amount, one can calculate the amount of time that must have passed for that drop.

Radio dating can be used with many different elements, carbon (C) is only of the them. But typically carbon-dating cannot be used for really old stuff as it is only usable for things that are max 50-60 thousand years. So if one assumes certain fossils (or other objects) are younger than that, you can use carbon dating, for fossils are assumed to be older than that, carbon dating is unusable (but radio dating methods with other elements may still be usable - i.e. elements with a slower decay rate).

E.g. when the Shroud of Turin was carbon dated for the first time, results pointed to an origin of 13th-14th century. But then others pointed at possible contamination from a fire that may have skewed the results to a much younger era than accurate. Personally l think it's likely authentic ... so I think that it's highly likely it represents the actual face of Yeshua.

 

[dlamberth]

In no way can I claim no be an expert on this. A wiki or ChatGPT question would be able to teach you some basics. Certain elements decay at a certain (assumed constant) rate. So slowly over time the amount of that element found (as a ratio) drops. When one knows the original (assumed) amount and one measures the (now) measurable present amount, one can calculate the amount of time that must have passed for that drop.

Radio dating can be used with many different elements, carbon (C) is only of the them. But typically carbon-dating cannot be used for really old stuff as it is only usable for things that are only max 50-60 thousand years. So if one assumes certain fossils (or other objects) are younger than that, you can use carbon dating, of fossils are assumed to be older than that, carbon dating is unusable (but radio dating methods with other elements may still be usable - i.e. elements with a slower decay rate).

E.g. when the Shroud of Turin was carbon dated for the first time, results pointed at an original of 13th-14th century. But then others pointed at possible contamination from a fire that may have skewed the results to a much younger era than accurate. Personally l think it's likely authentic ... so I think that it's highly likely it represents the actual face of Yeshua.

Here's a short 16min video that I found interesting. I goes step by step through the U-Pb Zircon Geochronology process to date rocks. This process is used only to date rocks, mainly of the igneous and metamorphic kind. A very different process would be used to date something like the Shroud, but for myself, the video helped me understand the kinds of lab process that goes into dating things.

 

[Hans Blaster]

What is the process to radiocarbon date a fossil(or rock layer)? What is the science that determines the “millions of years” numbers? What are the flaws with this process, if any?

Scientific answers only please. Go!

Radiocarbon dating isn't used to date rock layers or mineralized fossils. It is only used on formerly living things that are still organic.

Radiocarbon dating doesn't return "millions of years" as it doesn't measure things that are that old.

 

[essentialsaltes]

In brief, radioactive isotopes have characteristic half-lives. If there are 1,000 atoms of a particular isotope in a sample, after one half life, there will be only 500. Different isotopes decay at different rates. Radiocarbon (C-14) has a half life in thousands of years. Others have half-lives in millions or billions of years (more suitable for dating the age of rocks or the earth).

If we know from the geology or the situation* that new radioactive isotopes can't enter or leave a sample, then this gives us a way to date the sample. The more general term is radiometric dating rather than carbon.

(* Say for plants, when they are alive, they continue to take in carbon from the air as carbon dioxide, and some of that carbon is radiocarbon. But when they die, they stop taking in new carbon so that 'starts the stopwatch' so to speak. Measuring the radiocarbon content now allows us to determine the age of that sample.)

If it's not too patronizing, someone asked to have it explained as to a child once upon a time. Childish though it is, it has some additional detail on the mother and daughter isotopes that adds a little detail to the above.

A Calculating Age

I agree that the entertainment factor of certain posters (myself included) is part of the reason why some people read this forum, however as we are here to discuss Creation and Evolution -- this thread will be for serious discussion. ( my question is below this amazing photograph ) Apparently...

www.christianforums.com

 

[essentialsaltes]

As for flaws, it's pretty robust and successful. The mathematics is relatively simple, the number of isotopes that decay is proportional to the total number of isotopes in the sample, since they're all identical, they all have the same odds of decaying. And the mathematics of that is much like compound interest, except that instead of adding interest, you're removing isotopes. For interest it's a growing exponential. For radioisotopes, it's a decaying exponential.

As far as we know, the rate of decay of a given isotope is fixed (unless we're talking about really extreme circumstances). This is something detractors point to as a potential source of error. What if it was different in the past? There are some lines of evidence that suggest this isn't possible, or would require an overwhelming coincidence.

So the main source of error or flaw is contamination of the sample, or using the wrong kind of sample entirely.

 

[Unqualified]

Everything contains a certain amount of Carbon 14 and it decays at a known rate or half life. So they measure the remaining carbon 14 and the carbon 12 ratio to see how old the specimen is. Carbon 14 is radioactive it decays at a known rate so they can measure how much is left, how much radioactive activity is left, and how long it’s been in existence.

But it’s flawed because of the flood. The upheaval was so great that it even changed the age of rocks Making them seem older. But then if it’s a young earth the thousands or millions of years it comes up with are wrong. God said He would do a short work on the earth. Dinosaurs were in existence in the history of the Bible before and after the flood.

 

[Hans Blaster]

Everything contains a certain amount of Carbon 14 and it decays at a known rate or half life.

Things that either photosynthesize or eat things that photosynthesize or eat things that eat things that photosynthesize (plants and most animals) have a certain fraction of their carbon as C-14. The half life is known.

So they measure the remaining carbon 14 and the carbon 12 ratio to see how old the specimen is. Carbon 14 is radioactive it decays at a known rate so they can measure how much is left, how much radioactive activity is left, and how long it’s been in existence.

For things that meet the qualifications given above (dead plants, animals, etc.)

But it’s flawed because of the flood. The upheaval was so great that it even changed the age of rocks Making them seem older. But then if it’s a young earth the thousands or millions of years it comes up with are wrong. God said He would do a short work on the earth. Dinosaurs were in existence in the history of the Bible before and after the flood.

Rocks are not carbon dated. Flooding does not change the isotopic ratios of rocks which are almost all set by some sort of volcanic activity. I had dinosaur for lunch on wednesday.

 

[dlamberth]

But it’s flawed because of the flood. The upheaval was so great that it even changed the age of rocks Making them seem older.

If said flood actually happened, especially with the upheaval so great that it changed the age of rocks , the evidence of said flood would be so in our face that there would be no question that the Biblical flood actually happened. But as we look around, that's not the case. I wonder sometimes about what happened to critical thinking.

But then if it’s a young earth the thousands or millions of years it comes up with are wrong. God said He would do a short work on the earth. Dinosaurs were in existence in the history of the Bible before and after the flood.

Are you making claim that dinosaurs died out less than 4000 years ago?

 

[sjastro]

Everything contains a certain amount of Carbon 14 and it decays at a known rate or half life. So they measure the remaining carbon 14 and the carbon 12 ratio to see how old the specimen is. Carbon 14 is radioactive it decays at a known rate so they can measure how much is left, how much radioactive activity is left, and how long it’s been in existence.

But it’s flawed because of the flood. The upheaval was so great that it even changed the age of rocks Making them seem older. But then if it’s a young earth the thousands or millions of years it comes up with are wrong. God said He would do a short work on the earth. Dinosaurs were in existence in the history of the Bible before and after the flood.

Well it didn't take long for this thread to be derailed.
In this thread the age of the Atlantic Ocean since the break up of Gondwana was determined using magnetic field striping and found to be around 180 million years old.
My Layer Challenge

In the thread I mentioned the date has been confirmed by radiometric dating of igneous rocks which are summarized in the following table.

Dating Method​	Dating range of Method​	Comments​
U-Pb​	Decay of Uranium 238 to Lead 206 1 million to 4.5 billion years​	Dating zircon in igneous rocks from continental shelves points to Atlantic Ocean formation 180 -200 million years ago.
Ar-Ar​	Decay of Argon 40 to Argon 39 10,000 - 4.5 billion years​	Dating of feldspar and hornblende formed by rapid cooling of igneous rocks sampled from the Central Atlantic Magmatic Province indicates Atlantic Ocean formed 200 million years ago.
K-Ar​	Decay of Potassium 40 to Argon 40 100,000 - 4.5 billion years​	Dating igneous rocks from continental shelves of South America and Africa points to Atlantic Ocean formation 180-200 million years ago.
Sm-Nd​	Decay of Samarium 147 to Neodymium 143 10 million to 4.5 billion years​	Dating igneous rocks from continental shelves of South America and Africa points to Atlantic Ocean formation 200 million years ago.
Rb-Sr​	Decay of Rubidium 47 to Strontium 47 10 million to 4.5 billion years​	Dating igneous rift related rocks from continental shelves of South America and Africa points to Atlantic Ocean formation 180-200 million years ago.

Including the magnetic striping age of the Atlantic Ocean there are seven independent tests pointing to its formation in the range of 180-200 million years ago which is a remarkable coincidence if they all happen to be wrong and of a similar magnitude.

 

[linux.poet]

In the thread I mentioned the date has been confirmed by radiometric dating of igneous rocks which are summarized in the following table.

Including the magnetic striping age of the Atlantic Ocean there are seven independent tests pointing to its formation in the range of 180-200 million years ago which is a remarkable coincidence if they all happen to be wrong and of a similar magnitude.

Wait a minute. A new form of dating has entered the chat here. What is the difference between radiocarbon dating, radiometric dating, and magnetic striping as a dating method?

 

[Warden_of_the_Storm]

Wait a minute. A new form of dating has entered the chat here. What is the difference between radiocarbon dating, radiometric dating, and magnetic striping as a dating method?

Radiocarbon dating uses the decay rate of carbon-14 as the measurement while radiometric dating is the broader area of dating that includes radiocarbon dating as a singular specific type, and magnetic striping is the measurement of magnetic anomalies which is caused by chemical and magnetic changes in the Earth's magnetic field.

 

[sjastro]

Wait a minute. A new form of dating has entered the chat here. What is the difference between radiocarbon dating, radiometric dating, and magnetic striping as a dating method?

The point being made is scientists don't rely on single dating methods as creationist sites would want you to believe.
In fact methods for dating the age of the Atlantic Ocean mentioned here is only a small subset of what is available.

 

[SelfSim]

What is the process to radiocarbon date a fossil(or rock layer)? What is the science that determines the “millions of years” numbers? What are the flaws with this process, if any?

Scientific answers only please. Go!

Here's a good, fairly simple YouTube, (about 4.5 mins), describing radiometric and carbon dating. It also describes, in simple terms, the geological features needed in the sample to ensure sound conclusions can be formed following measurements:
How Does Radiometric Dating Work?

A second more detailed YouTube is: Radiometric Dating, (about 9 mins), it focuses on Earth rocks, Organics and Meteorites and also describes the control conditions necessary for setting up valid conclusions in closed system tests.

 

[linux.poet]

The point being made is scientists don't rely on single dating methods as creationist sites would want you to believe.
In fact methods for dating the age of the Atlantic Ocean mentioned here is only a small subset of what is available.

I’m the only fool in this thread and I know nothing about scientific dating methods for rocks. I’m genuinely curious to find out why scientists think our rocks and fossils are millions of years old. So far what I have read is incredibly fascinating.

I haven’t read a creationist website in years. I couldn’t make heads or tails out of AiG when I tried to read it over a decade ago.

 

[sjastro]

I’m the only fool in this thread and I know nothing about scientific dating methods for rocks. I’m genuinely curious to find out why scientists think our rocks and fossils are millions of years old. So far what I have read is incredibly fascinating.

I haven’t read a creationist website in years. I couldn’t make heads or tails out of AiG when I tried to read it over a decade ago.

No one is suggesting you are a fool, having an inquisitive nature even if it maybe on the sceptical side is commendable, unlike the usual suspects here who use this forum to engage in libellous attacks on science because they find it a threat to their belief systems.

To add to what other posters have stated radiometric dating does not tell you when the rock was created (for lack of a better term) but some physical event which has reset the decay clock to zero.
For K-Ar decay the daughter or product atom Ar (argon) is a gas which is expelled from molten rock and when solidified the clock is reset.
For other decays mentioned such as U-Pb and Rb-Sr, clock resetting is somewhat more complicated and the role of stable or non-radiogenic atoms along with the parent and daughter atoms need to be considered as well.

When a rock is solidified it also undergoes crystallization and within a closed system of the mineral composition, if the ratio of the parent atoms/non-radiogenic atoms is plotted against the daughter atoms/non-radiogenic atoms you get a straight line relationship known as an isochron.
U-Pb and Rb-Sr are examples of isochrons where the non-radiogenic atoms are Pb 204 and Sr 86 respectively.
On remelting and recrystallization the ratios are changed and the clock is reset when a new isochron is formed or there is a significant deviation from the existing isochron.

Here is an example using Rb-Sr.

The gradient of the reset isochron is 0.719- 0.702 = 0.017.
The gradient of an isochron is given by the formula:

Gradient = exp(λt) -1

Where λ is the decay constant for Rb-Sr decay = 1.42×10⁻¹¹ per year.
Solving for t gives t = 1.2 billion years ago (1.2 Ga) when the isochron was reset.

 

[Job 33:6]

I’m the only fool in this thread and I know nothing about scientific dating methods for rocks. I’m genuinely curious to find out why scientists think our rocks and fossils are millions of years old. So far what I have read is incredibly fascinating.

I haven’t read a creationist website in years. I couldn’t make heads or tails out of AiG when I tried to read it over a decade ago.

Radiometric Dating Does Work! | National Center for Science Education

Radiometric dating of rocks and minerals using naturally occurring, long-lived radioactive isotopes is troublesome for young-earth creationists because the techniques have provided overwhelming evidence of the antiquity of the earth and life.

ncse.ngo

You should be aware that scientists use a variety of dating methods, and additionally ensure corroboration of those methods, to identify an objects age. For example, with the K-T boundary, several radiometric dating methods have been used. Argon Argon. Potassium Argon. Rubidium strontium. Uranium Lead. Among others, offer hyper specific results that have been replicated independently with samples collected worldwide by various independent teams around the world.

You should know that such results would be essentially impossible to gather, if the methods used were not accurate.

Genesis describes an ancient near east cosmology. It's something that Dr. John Walton describes as a 7-day temple inauguration hymnal. It's not something to be confused with the age of the earth.

 

[Job 33:6]

The thing about YECism is that, the church already had to deal with this same issue with Galileo and geocentrism. The Catholic Church just couldn't fathom the possibility that the Bible is not a science, nor a history textbook. They just couldn't accept the basic fact that what it speaks of is not scientific in nature. And they insisted that the Bible promoted something as absurd as geocentrism. After all, the Bible says that the earth may never be moved. That it rests on pillars and things of this nature.

Now, 300 years later, YECs talk about how silly geocentrism and flat earthism is, yet they just can't seem to figure out that the Bible also has nothing to do with geology. As though they just can't comprehend this basic concept. And everyone, the church and the scientific community, has to suffer from their inability to understand the Bible.

And many other Christians thankfully have figured this out. But there's just this persistent remnant that is going around giving everyone a headache.

 

[essentialsaltes]

I’m the only fool in this thread and I know nothing about scientific dating methods for rocks. I’m genuinely curious...

Agree with sjastro that no one sees you as a fool. The question in the OP was straightforward and garnered several straightforward responses that hopefully helped to satisfy that curiosity.

Sadly, the appearance of a sincere question on 'origins' is so rare in this forum that my ears perk up and I try to give a good response.

 

[Job 33:6]

I’m the only fool in this thread and I know nothing about scientific dating methods for rocks. I’m genuinely curious to find out why scientists think our rocks and fossils are millions of years old. So far what I have read is incredibly fascinating.

I haven’t read a creationist website in years. I couldn’t make heads or tails out of AiG when I tried to read it over a decade ago.

I agree with others that, unfortunately the broader topic of creation vs evolution and the age of the earth is unfortunately somewhat complicated. It requires a relatively strong foundation of technical or critical thinking, and it also requires quite a bit of time investment in regards to reading about things like, not only science and a variety of relatively complicated topics in science. But it also requires an unfortunately complicated review of ancient near east literature and history with respect to the Bible. This topic really takes two to tango. Its not just about the science, but its also about understanding the Bible. Which, in my opinion, the Bible is actually more complicated to understand than the science side of things.

But, a right understanding of Genesis, I would say begins with an understanding of ancient near east literature on creation narratives. You have to understand how ancient isrealites understood things like 3-tiered cosmology. And how they understood things like temple related themes throughout the old testament. Ancient Egypt also had creation stories that involved a primordial mound revealed by the gathering of the seas like in Genesis, and the concept of there being waters above the firmament and an underworld and things of this nature.