Guess how long the first Sultan of Jogjakarta died? The answer is simple. Let’s subtract today’s date to the date of the sultan’s death. But, what if we were asked, how long has it been since the first Egyptian Pharaoh died? Or, how long has his beloved cat been dead? This kind of question, it seems, can always be answered by researchers of ancient objects. Evidently, every historic relic that we see in the museum is always a description of its age. But like this question, have you ever wondered, how to know the age of ancient objects, such as mummies, inscriptions, or other ancient objects?
In fact, they had obviously not been born in those days. Are they just guessing? Or else, do these researchers secretly have a time machine?
The Dating Techniques
As it turns out, the age measurement of ancient objects can be done scientifically without the need for time-travel, namely with dating techniques. No. Not that “dating”, but the other one. The ancient object dating technique itself is divided into two, namely Relative Dating and Absolute Dating.
With Relative Dating, researchers can compare various historical periods, for example from the principle of differences in soil layers. Using the help of Geology, we can estimate the age of an ancient object based on its location in a layer of soil.
By marrying Archaeology and Chemistry, the second type of dating was born, namely Absolute Dating. With this one dating technique, we can find out the age of ancient objects more specifically.
Absolute dating has many types, but the most popular is Carbon Dating aka Radiocarbon. How does this work? Alright. Prepare yourselves. Fasten your seat belts! It’s time we learned something very challenging, Chemistry!
Meet The Siblings
Alright. First, everything in this universe is made up of very, very small matter, called atoms. There is one type of atom that all living things must have, the carbon atom. The carbon atoms themselves are made up of siblings called isotopes. To learn Carbon Dating, we will meet siblings named Carbon-12 and Carbon-14.
Carbon-12 is the most common carbon isotope we find in nature. While his brother, Carbon-14, created every day when cosmic rays broke into the Earth’s atmosphere, then hit the most atomic element in the air, namely Nitrogen.
Every day, these siblings are absorbed by plants through the process of photosynthesis. This plant is what other living things eat, including us. Well, when we die, a unique thing happens! The amount of Carbon-14 in our body will begin to decrease, while the amount of Carbon-12 remains unchanged.
That’s because Carbon-14 is unstable. In order to stabilize, Carbon-14 must decompose back into its original atoms.
So, how does this Carbon 14 decay?
In fact, all the radioactive atoms in the world have a “half-life”, which is the time it takes for an atom to burst in half. Well, the half-life of Carbon-14 is 5730 years. So, in 5730 years, the total amount of carbon-14 in a specimen will be reduced by half. And it will decrease by half in the next 5730 years.
Well, to measure the number of carbon siblings in a specimen, the researchers used an advanced device called the Mass Spectrometer. By comparing the ratio of both carbon in the specimen and in nature, add the half-life in very complicated and dizzying calculations… Tada!
We can tell the age of a specimen from thousands of years ago. To be more precise, researchers will also match their calculations with various natural time pointers.
Unfortunately, Carbon Dating can only be used on specimens of living things that died less than 50,000 years ago. So, what’s the fate of a dinosaur fossil that’s over 50 thousand years old?
No favoritism. They’re just going to use another atom with a longer half-life, like potassium-argon with a half-life of 1.26 billion years.
Hm… the ancient age counting technique is really difficult. But if we can master the way of how to know the age of ancient objects, we can calculate the time of death of Pharaoh’s beloved cat, even other ancient cats. Wow! Thank you.
