How old is the earth according to carbon dating Freesexchat cam4
Astronomers use the distance to galaxies and the speed of light to calculate that the light has been traveling for billions of years.
The expansion of the universe gives an age for the universe as a whole: 13.7 billion years old.
Some isotopes have short half-lives of minutes or years, but Potassium-40 has a half-life of 1.3 billion years.
Radiometric dating requires that one understand the initial ratio of the two elements in a given sample by some means.
In this case, Argon-40 is a gas that easily bubbles out and escapes when it is produced in molten rock.
Once the rock hardens, however, all the Argon-40 is trapped in the sample, giving us an accurate record of how much Potassium-40 has decayed since that time.
As time passes, a rock will have more and more Argon-40 and less and less Potassium-40.
So, if we find a rock with equal parts Potassium-40 and Argon-40, we know that half the Potassium-40 has decayed into Argon-40, and that the rock hardened 1.3 billion years ago.
It’s hard to find rocks on the surface of the Earth that have not been altered over time.
An element in the periodic table can come in different flavors called isotopes.
Some isotopes are unstable, and over time these isotopes “decay” into isotopes of other elements.