Carbon analysis: The process that illuminates ancient life's presence in the current era
Tucked away in the outskirts of Paris, a colossal machine, the size of a room, sniffs out secrets. From exposing art forgery to uncovering the hidden past of the Notre-Dame cathedral, this beast has been turning back the hands of time to spill the truth. The technique it uses is called carbon dating, a game-changer in archaeology, earning its pioneer a Nobel Prize in 1960.
Lucile Beck, a French scientist, beamed with pride as she stood before the massive accelerator, nestled in the carbon dating lab of France's Atomic Energy Commission in Saclay. Beck reminisced about the awe-stricken prehistorians in the 1990s, when the machine confirmed that the cave art in France's southeast, the Chauvet Cave, was around 36,000 years old. This lab handles around 3,000 samples a year, all using the carbon dating technique.
So, how does carbon dating work?
First, each sample is scrutinized to weed out any residual contamination. As Beck shared, "Typically, they are fibers from a jumper" of the archaeologist who first handled the object.
After cleaning the sample in an acid bath and heating it to a scorching 800 degrees Celsius, the carbon dioxide is regained and reduced to graphite, neatly tucked into tiny capsules. These capsules are then jolted in a particle accelerator, splitting the carbon isotopes.
Carbon isotopes are identical chemical elements with varying neutron counts. Some isotopes are solid as a rock (like carbon-12), while others, such as carbon-14, are radioactive and degrade over time. Carbon-14 is constantly brewed in the Earth's upper atmosphere by cosmic rays and solar radiation bombarding nitrogen. This chemical cocktail produces carbon dioxide, which plants absorb during photosynthesis, further circulated as animals consume those plants. Consequently, all living organisms boast carbon-14, which ceases to replenish once they kick the bucket, starting its decay.
After 5,730 years, just half of the carbon-14 remains; vanishing completely after 50,000 years. By comparing the number of carbon-12 and carbon-14 particles flung by the particle accelerator, scientists can pinpoint an object's age.
The key here is that cosmic radiation isn't constant, and neither is the protection provided by the Earth's magnetic field. Thus, scientists must make approximations based on calculations using samples of known age.
Take for instance, a forged painting. By demonstrating that the linen used in the canvas originated from a time when the artist was long gone, one can reveal the art as a falsity. Similarly, the technique can trace changes in the Earth's climate over the centuries by studying the remains of plankton at the ocean floor's depth.
Notre-Dame Revealed
While carbon dating works wonders on bones, wood, and the likes, the French lab has cooked up new methods for dating materials not traceable to living organisms. For example, they can pinpoint the age of the iron staples that held together Notre-Dame, proving they were originally from when the cathedral was first built – not from a later restoration as initially believed.
The lab can also date lead white, a pigment that has been prevalent in art and buildings since the fourth century BC. Lead was corroded using vinegar and horse poop to produce carbon dioxide via fermentation – a useful clue for archaeologists.
Even more intriguingly, the lab devised a method to date the tombs of a medieval abbey, where only small lead bottles were found. The decomposition of the bodies released carbon dioxide, corroding the bottles and providing scientists with a valuable clue. As Beck put it, "This corrosion was ultimately the only remaining evidence of the spirit of the monks."
- The carbon dating technique, used by the French lab in Saclay, can provide insights not only into the age of bones and wood but also medical-conditions, such as unraveling the age of iron staples that held together Notre-Dame, proving they were originally from when the cathedral was first built.
- Being a game-changer in archaeology, carbon dating can also be utilized to investigate general-news related to the advancement of technology. For instance, the lab discovered a unique method to date lead white, a pigment used in art and buildings since the fourth century BC, which requires vinegar and horse poop fermentation to produce carbon dioxide, aiding archaeologists in their research.
