THE EARTH'S AGE AND FOSSILS

Historical bases

First calculations by physicists, geologists and biologists

Buffon, a French naturalist, calculated that the age of the earth was at least 180,000 years old, a small figure that in his time was far from the biblical calculations of the time. Glasgow physicist William Thomson estimated that the age of the earth estimated between 24 and 400 million years. He supposed that the Earth would have formed like a ball of molten rock, and he calculated the time it took for the cooling process to reach the current temperatures.

The German physicist Hermann von Helmholtz and in 1892 the Canadian astronomer Simon Newcomb presented their own calculations of 22 and 18 million years.

Radiometric dating

Radiometric dating is a technical procedure used to determine the absolute age of rocks, minerals and organic remains. By using an isotope, the half-life of the sample to be studied is known and its age is calculated; depending on the type of sample, a different type of isotope will be used.

Carbon 14 is used in the organic remains and uranium in geological remains.

John Perry used a convective mantle model and a thin crust, estimating that the age of the Earth was between 2000 and 3000 million years.

Radioactivity

In 1896, the French chemist A. Henri Becquerel discovered radioactivity. And in 1898, two other French scientists, Marie and Pierre Curie, discovered the radioactive elements polonium and radio. In 1903 Pierre Curie and his colleague Albert Laborde announced that the radio produced enough heat to produce the melt of the equivalent of its own mass in the form of ice in one hour. With radioactivity the assumptions of the previous Earth Age were useless and therefore new investigations were necessary to clear the mystery of the Age of our planet. With radioactivity many geologists began to calculate the age of the rocks located in the various terrestrial strata.

Let's use meteorites

In 1956 C.C. Patterson calculated that the age of the Earth was 4555 million years old using radiometric dating in meteorites being the most accurate datation of the Earth's age.

Current knowledge

THE AGE OF THE EARTH, HOW OLD IS OUR PLANET?

4,600 million years, almost as much as my grandfather For a long time, the age of our blue planet has been unknown to all of humanity. Nowadays, practically all of us already know the answer, but do we know how this data is obtained?

On our planet there are some radioactive isotopes in nature that act like a stove generating energy with a "radioactive decay", and you wonder what all this has to do with the age of my planet?

Radioactive isotopes can be used as clocks, this is because they are unstable elements, but by their transformation or decay where they release energy, you can measure some time intervals and thus find out the age.

To clarify things a little more; a radioactive isotope is carbon 14, it is used for example to know when a living being has died, therefore it is used in the study of mummies, remains of animals, etc.

This technique is possible since this isotope is found in the atmosphere naturally and is absorbed by plants through photosynthesis; The living beings when we eat plants absorb part of these isotopes. The quantity remains proportional to the one that is in the atmosphere and while the living being continues in life this quantity is renewed, when dying the amount of carbon stops renewing and begins to decay little by little becoming 14N at a certain rate. The drawback of this method is that once the carbon has become totally 14N (nitrogen) cannot be measured and therefore this method is not very effective to study the age of things geologically speaking. To calculate the age of even older things, other types of isotopes are used that have a lower decay, such as Rubidium (87Rb), Uranium (235U, 238U), Potassium (40K) ...

Returning to the age of the Earth, we already know that for its calculation it is necessary to use isotopes such as Uranium to be able to measure ages that are as old as possible, but, what is as old as Earth? Meteorites, if we were to search for rocks on the Earth's surface we would not find any as old as Earth; therefore we must look for rocks that have not been affected by terrestrial processes, that is, meteorites.

Looking at the isotopes of the meteorites we deduce that the Earth and other celestial bodies of the solar system are approximately 4.6 billion years old, is not that amazing?