How do scientists calculate how old the earth is?

1 Name: Anonymous : 2015-12-23 22:47

I mean it seems sometimes like people are just pulling numbers out of thin air. Billions of years? What proof that there's billions of years? How do you measure the age of a solar system or planet? I sometimes wonder if scientists are actually accurate with their numbers or are just making educated guesses.

2 Name: Anonymous : 2015-12-23 22:51

Do you know what a half-life is? Or a radioactive isotope? Or a ratio?

3 Name: Anonymous : 2015-12-23 22:55

I forget the science behind it.

Something about chemical processes that happen to the rocks and trees and stuff.

Very specific chemical processes that follow very specific time restraints.

Scientists and geologists can look at certain rocks and know exactly how old it is.

Or something like that.

And yeah. We're talking billions of years.

I know some people religious folk don't like science, but that doesn't make it any less true.

4 Name: Anonymous : 2015-12-23 22:57

I wasn't doubting science, I was just confused how scientists from today can be accurate to measure the timeframe of things billions of years old.

5 Name: Anonymous : 2015-12-23 23:01

You should google it. I'm sure there are several reputable scientific and geological websites out there that can shed some light on it.

I don't remember a lot of it myself, but I do remember there being very logical explanations.

It's all about certain laws of chemistry and physics that allow modern scientists to look at something a certain way and determine (within thousands of years) how old something is.

They might be a few thousand years off, but they've already determined that the earth is billions of years old.

Or maybe millions....and it was the galaxy that's billions of years. I forget.

Either way, it's most certainly older than 10,000 years like some crazy Christians want to believe. Hell, there are fucking cave paintings that are over 60,000 years old, and they can determine that by the substances on the wall and the size of stalactites, etc.

6 Name: Anonymous : 2015-12-23 23:06

Lots of different ways. Radiometrics is the biggest. On the off chance that you're actually interested, which I doubt, here's a good basic overview that has links to more information.

https://en.wikipedia.org/wiki/Age_of_the_Earth