How do we determine the age of the Earth?
The age of rocks is determined by radiometric dating, which looks at the proportion of two different isotopes in a sample. Radioactive isotopes break down in a predictable amount of time, enabling geologists to determine the age of a sample using equipment like this thermal ionization mass spectrometer.
How do we know how old everything is?
Scientists use a technique known as radiometric dating. The nuclear age taught us how to blow up stuff real good, but it also helped understand how elements transform from one element to another through radioactive decay.
How did geologists find out that the Earth is 4.6 billion years old?
The process of figuring out a rocks age often falls to the scientific techniques of radiometric dating, the most famous of which is radiocarbon dating. Based on the very old zircon rock from Australia we know that the Earth is at least 4.374 billion years old.
How long will humans survive on earth?
Humanity has a 95% probability of being extinct in 7,800,000 years, according to J. Richard Gotts formulation of the controversial Doomsday argument, which argues that we have probably already lived through half the duration of human history.