From unmasking art forgery to uncovering the secrets of the Notre-Dame cathedral, an imposing machine outside Paris can turn back the clock to reveal the truth.
It uses a technique called carbon dating, which has “revolutionized archaeology,” winning its discoverer a Nobel Prize in 1960, French scientist Lucile Beck said.
Beck spoke in front of the huge particle accelerator, which takes up an entire room in the carbon dating lab of France’s Atomic Energy Commission in Saclay, outside the capital.
Photo: AFP
Beck described the “surprise and disbelief” among prehistorians in the 1990s when the machine revealed that cave art in the Chauvet Cave in France’s southeast was 36,000 years old.
The laboratory uses carbon dating, also called carbon-14, to figure out the timeline of more than 3,000 samples a year.
HOW DOES IT WORK?
First, each sample is examined for any trace of contamination.
“Typically, they are fibers from a jumper” of the archaeologist who first handled the object, Beck said.
The sample is then cleaned in an acid bath and heated to 800 degrees Celsius to recover its carbon dioxide. This gas is then reduced to graphite and inserted into tiny capsules.
Next, these capsules are put into the particle accelerator, which separates their carbon isotopes.
Isotopes are variants of the same chemical element which have different numbers of neutrons.
Some isotopes are stable, such as carbon-12. Others — such as carbon-14 — are radioactive and decay over time.
Carbon-14 is constantly being created in Earth’s upper atmosphere as cosmic rays and solar radiation bombard the chemical nitrogen.
In the atmosphere, this creates carbon dioxide, which is absorbed by plants during photosynthesis.
Then animals such as ourselves get in on the act by eating those plants.
So all living organisms contain carbon-14, and when they die, it starts decaying. Only half of it remains after 5,730 years.
After 50,000 years, nothing is left — making this the limit on how far back carbon dating can probe.
By comparing the number of carbon-12 and carbon-14 particles separated by the particle accelerator, scientists can get an estimate of how old something is.
Cosmic radiation is not constant, nor is the intensity of the magnetic field around Earth protecting us from it, Beck said.
That means scientists have to make estimations based on calculations using samples whose ages are definitively known.
This all makes it possible to spot a forged painting, for example, by demonstrating that the linen used in the canvas was harvested well after when the purported painter died.
The technique can also establish the changes in our planet’s climate over the millennia by analyzing the skeletons of plankton found at the bottom of the ocean.
NOTRE-DAME REVEALED
Carbon dating can be used on bones, wood and more, but the French lab has developed new methods allowing them to date materials that do not directly derive from living organisms.
For example, they can date the carbon that was trapped in iron from when its ore was first heated by charcoal.
After Paris’s famous Notre-Dame cathedral almost burned to the ground in 2019, this method revealed that its big iron staples dated back to when it was first built — and not to a later restoration, as had been thought.
The technique can also analyze the pigment lead white, which has been painted on buildings and used in artworks across the world since the fourth century BC.
To make this pigment, “lead was corroded with vinegar and horse poo, which produces carbon dioxide through fermentation,” Beck explained.
She said she always tells archaeologists: “don’t clean traces of corrosion, they also tell about the past!”
Another trick made it possible to date the tombs of a medieval abbey in which only small lead bottles had been found.
As the bodies in the tombs decomposed, they released carbon dioxide, corroding the bottles and giving scientists the clue they needed.
“This corrosion was ultimately the only remaining evidence of the spirit of the monks,” Beck mused.
One of the biggest sore spots in Taiwan’s historical friendship with the US came in 1979 when US president Jimmy Carter broke off formal diplomatic relations with Taiwan’s Republic of China (ROC) government so that the US could establish relations with the People’s Republic of China (PRC). Taiwan’s derecognition came purely at China’s insistence, and the US took the deal. Retired American diplomat John Tkacik, who for almost decade surrounding that schism, from 1974 to 1982, worked in embassies in Taipei and Beijing and at the Taiwan Desk in Washington DC, recently argued in the Taipei Times that “President Carter’s derecognition
This year will go down in the history books. Taiwan faces enormous turmoil and uncertainty in the coming months. Which political parties are in a good position to handle big changes? All of the main parties are beset with challenges. Taking stock, this column examined the Taiwan People’s Party (TPP) (“Huang Kuo-chang’s choking the life out of the TPP,” May 28, page 12), the Democratic Progressive Party (DPP) (“Challenges amid choppy waters for the DPP,” June 14, page 12) and the Chinese Nationalist Party (KMT) (“KMT struggles to seize opportunities as ‘interesting times’ loom,” June 20, page 11). Times like these can
June 23 to June 29 After capturing the walled city of Hsinchu on June 22, 1895, the Japanese hoped to quickly push south and seize control of Taiwan’s entire west coast — but their advance was stalled for more than a month. Not only did local Hakka fighters continue to cause them headaches, resistance forces even attempted to retake the city three times. “We had planned to occupy Anping (Tainan) and Takao (Kaohsiung) as soon as possible, but ever since we took Hsinchu, nearby bandits proclaiming to be ‘righteous people’ (義民) have been destroying train tracks and electrical cables, and gathering in villages
Dr. Y. Tony Yang, Associate Dean of Health Policy and Population Science at George Washington University, argued last week in a piece for the Taipei Times about former president Ma Ying-jeou (馬英九) leading a student delegation to the People’s Republic of China (PRC) that, “The real question is not whether Ma’s visit helps or hurts Taiwan — it is why Taiwan lacks a sophisticated, multi-track approach to one of the most complex geopolitical relationships in the world” (“Ma’s Visit, DPP’s Blind Spot,” June 18, page 8). Yang contends that the Democratic Progressive Party (DPP) has a blind spot: “By treating any
RSS