Gravity & Geothermal: Why is Earth's Core so Hot?

[gloo]

Why is the center of the Earth so hot so that we can use geothermal? Will the Earth deep down always be hot because of the pressure of all the mass on top all the way to the surface? In that sense, can we always draw on the geothermal heat?

 

[mgb_phys]

https://www.physicsforums.com/showthread.php?t=156760&highlight=earth+hot
Mostly due to the decay of radioactive materials when the Earth was young.
In theory geothermal is a non-renewable source of energy, but the amount of energy we could extract is tiny com pared to the age of the Earth.

 

[gloo]

isn't it possible that all the mass pushing down on the center of the earth, can cause some kind of atomic decay and create the heat that way? After all, the sun's mass collapsing in on it's center does the same and the heat is radiated into space?

 

[mgb_phys]

isn't it possible that all the mass pushing down on the center of the earth, can cause some kind of atomic decay and create the heat that way?

No

After all, the sun's mass collapsing in on it's center does the same and the heat is radiated into space?

That's a whole lot more pressure

Some of the energy generated in the Earth is form the pressure of the overlying rocks, but radioactive decay is now the main source. This is mostly alpha/beta decay from radioactive heavy elements - very different from the fusion reactions in the sun