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Carbon Dating

|< < Prev #3205 (February 9, 2026)

Title text: This dating is corroborated by the presence of stone tools at the site, rather than earlier and less effective helium ones.

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Explanation

Carbon dating is a method for determining the age of an object containing organic material by using the properties of radiocarbon, a radioactive isotope of carbon. This method is commonly used by archaeologists and is invaluable in terms of predicting the time a piece of organic matter (such as a fossil) came from. It uses the fact that carbon consumed by living organisms contains a ratio between the carbon isotopes ¹²C, ¹³C, and ¹⁴C. ¹⁴C is generated in the atmosphere by interactions between nitrogen and cosmic rays, and it is radioactive, with a half-life of approximately 5,730 years, decaying over time. Its relative concentration in the environment is relatively stable — a balance between its creation and decay, depending on the rate of bombardment by cosmic rays. Its intake by organisms (by photosynthesis, in the case of plants, or by consumption in the case of non-plants) is also relatively stable, until the organism dies and stops taking in carbon compounds. From that point on, its relative concentration in the dead organism decreases by radioactive decay. By measuring how much ¹⁴C is left in the remains of an organism, archaeologists can determine how long ago that organism consumed carbon, and thus how long ago it lived. This method is useful only so long as the remaining concentration of ¹⁴C can be measured accurately, approximately 9 to 10 half-lives, or 50,000 to 60,000 years. Other forms of radiometric dating, based on other elements and isotopes, are used for other purposes. Even the ratios between abundances of stable isotopes can vary, providing historical information about things such as temperatures and atmospheric mixing, via isotope geochemistry.

Here, however, Ponytail, in the role of a cosmologist, takes a rather different perspective on using carbon for dating. She is interested only in the mere presence of carbon, which tells her that the skeleton being studied was formed after the first carbon in the universe was created in the first round of stars fusing elements, 13.6 billion years ago. This is not useful information for differentiating artifacts originating on Earth, which is itself less than 5 billion years old, since it would apply to all of them.

The title text looks like the kind of statement that would provide corroborative dating evidence for an archaeological site. The type and composition of tools can help to place a site, relative to others, on a developmental timeline. Here, however, they claim that the presence of stone tools dates the site as later than a non-existent age of helium tools. Tools made out of stone, usually dating from the Stone Age, are often solid and durable, making them great choices for heavy duty tasks, and well-preserved in the archaeological record. Helium is a gas and is difficult to shape into a solid mass for use as a tool.^{[citation needed]} It would also be near impossible to identify such tools if they had existed, since they would tend to disperse easily. Helium was produced in great quantities after the Big Bang, accounting for about ~25% of the mass of atoms produced by the early universe, so would have been available before stone was, but there were no people around at the time to fashion tools from it.

The themes of the comic are similar to 2723, which imagines a periodic table published just after the Big Bang, when most elements did not yet exist.

Transcript

[Ponytail, standing, is pointing at a blackboard containing a drawing of a skull and some bones/bone fragments, as well as a graph and some lines of text. She is speaking to Cueball and Megan, who are standing beside her.]

Ponytail: The high carbon content of the skeleton indicates that the individual lived less than 13.6 billion years ago, after the first round of stellar nucleosynthesis.

[Caption below the panel:]

Cosmologist carbon dating

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