question on science, as its taught

So I'm fairly competent with science, as its taught in school,books, tv ect.
And the one big rule on energy is, it cannot be created from nothing, aka imput minus losses = output.

Like how gas burns in the combustion chamber of your car, turning the crankshaft,transmission,axles, and finally wheels to get it moving with kinetic energy, its basicly the same energy, just in a different form.

But my question is this. Science does not classify gravity as a form of energy, it sees it as some imaginary particle from another dimension or something silly, but anyways. If energy cannot be just "created" then how is all that heat in the center of our earth there? You would think after 4.6 billion years, it would of finally cooled down and solidified but obviously that's not the case.

The heat is coming from all the weight of the crust and mantle above it, pressing down with countless tons of pressure, squeezing the atoms close together. How is this energy not "coming from nothing"?

Not saying who is right or wrong here, just this has been bothering me for a while.

Fair enough, the world is just like a big ice cube, except the other way round. You know how little ice cubes melt quickly, but big ones more slowly, it does go weight for weight and has to do with ratios between surface area and big volumes. Venus is crackling hot and has gone all wrong for it, but our planet is weighty, and can keep burning off heat for ages. And the sun is getting hotter!!! Barbeque round yours or mine?

Originally posted by Snift
So I'm fairly competent with science, as its taught in school,books, tv ect.
And the one big rule on energy is, it cannot be created from nothing, aka imput minus losses = output.

Like how gas burns in the combustion chamber of your car, turning the crankshaft,transmission,axles, and finally wheels to get it moving with kinetic energy, its basicly the same energy, just in a different form.

But my question is this. Science does not classify gravity as a form of energy, it sees it as some imaginary particle from another dimension or something silly, but anyways. If energy cannot be just "created" then how is all that heat in the center of our earth there? You would think after 4.6 billion years, it would of finally cooled down and solidified but obviously that's not the case.

The heat is coming from all the weight of the crust and mantle above it, pressing down with countless tons of pressure, squeezing the atoms close together. How is this energy not "coming from nothing"?

Not saying who is right or wrong here, just this has been bothering me for a while.

Pretty much, you're wrong.

Compressing things heats them up, but decompressing things cools them down. The heat of the center of the earth isn't mostly from pressure, though, it's still mostly left over from when the earth was formed.

1. The earth is very big. VERY big. It's a sphere of rock and iron and such 3600 miles in radius. Find a reasonable specific heat capacity and tell me how much energy is in that. Figure out how much heat the ground puts out, use that and the surface area of the earth to find out how much energy the earth loses, and then calculate how long it would take to cool off. I think you'll find it's quite a while.

Remember: too cool off, the earth has to transfer the heat from inside the mantle and core to space. You'll notice that the ground isn't very hot; in some parts of the world it is permanently frozen. That doesn't lead me to believe that the earth is losing heat very fast.

also a few miles of rock makes a pretty good insulator. So does an atmosphere. I think you vastly underestimate how long it takes for something the size of the earth to change temperature.

2. There's also a lot of radioactive heavy elements that would sink to the bottom of the mantle and core when molten, most notably uranium and thorium. Their decay probably helps keep things hot.