[VIEWPOINT]Atomic history

The Gyeryongsan Natural History Museum was established by late Rhee Ki-suk, an opthalmologist in Daejeon, who donated all his personal assets for the project. Out of his wish that a Korean scientist should win a Nobel Prize in science some day, he planned to establish the museum a long time ago and invested a great deal of time and money in collecting relics of the past, including the excavation of the fossil remains of a dinosaur in the United States.
As a result of Mr. Rhee’s tenacious efforts, that fossil, one of the most complete specimens of its type, was unearthed and put on display permanently at the museum.
It is known there as Gyeryong-i, a nickname for a dinosaur generically and this one in particular.
In addition to those remains, over 200,000 other relics are displayed in the museum.
They include rare ones like the 600-year-old mummy of a Joseon Dynasty general, fossilized remains of a cave lion which is said to be one of only four found in the world to sar, a fossilized mammoth ivory tusk which weighs 85 kilograms (187 pounds) and a meteorite weighing over 150 kilograms.
Whenever I look at the relics there, they remind me of one of the uses of atomic energy that made Mr. Rhee’s effort and dedication meaningful.
If it were not for atomic energy, the relics there might have been foundering in a sea of musty warehouses without finding their places, because it might have not been possible to determine how old they were.
The value of a relic is decided only when we know the date when it was made or born.
The most universal and widely used method of assessing the date of a relic uses radioactive isotopes, and making and using radioactive isotopes is an important field in atomic energy research.
Among the dating methods with the use of isotope, the one that use radioactive carbon (carbon14) is the most representative.
Radiocarbon has the characteristic that half of the atoms in a sample have decayed after 5,568 years, and a half of the remainder decays after another 5,568 years. The half-life is name given to that phenomenon.
All living things, both animal and vegetable, get carbon through photosynthesis or their food chain. There are three naturally occurring isotopes of carbon, with atomic weights 12 and 13 (both stable) and 14, an unstable, or radioactive isotope.
When animal or plants die, the “carbon-14 clock” starts to tick, because no additional carbon is being ingested.
The amount of the stable isotopes will not change, but the amount of carbon 14 will begin to drop as the atoms decay.
So if we compare the ratio of carbon 12 to carbon 14, we can determine how long it has been since the animal or plant died.
The most well known radiocarbon dating test may be that of the Shroud of Turin.
It is a religious relic that has stirred the Christian world because it was believed to be Jesus’s burial shroud. But the carbon dating proved that the shroud was fraudulent, made in the Middle Ages. The test revealed that the linen of the robe was made of flax harvested in about 1325.
It was a radioactive isotope, a manifestation of atomic energy, that linked this encounter of religion with science.
As the half-life of carbon 14 is 5,568 years, the accuracy of the age test diminishes rapidly if it is used to date relics over 50,000 years old. Also, the radiocarbon aging method cannot be used to determine the age of mineral things.
In order to determine the age of relics older than 50,000 years or of non-living objects, isotopes that have much longer half-life, such as those of potassium and argon, are used.
To determine the age of the earth, billions of years old, scientists used uranium 238. The half-life of uranium 238 is 4.46 billion years, and the age of the earth as assessed by that test is around 4.5 billion years.
Now that we are in a new year, we all get a year older; Koreans date their age beginning on Jan. 1.
When we were young, we wanted to get older and become adults, but if we are already in our later years, we no longer welcome getting older.
Some tens of thousands or hundreds of thousands of years from now, we all will no longer exist in this world.
But to be remembered by people only a few years or decades from now, we must work hard. I recommend a visit to Gyeryongsan Natural History Museum and take a moment to reflect on yourself.

*The writer is the president of the Korea Atomic Energy Research Institute. Translation by the JoongAng Daily staff.

by Park Chang-kue