Why is the Center of the Earth so Hot?

[bkelly]

does "gravitational heating" mean pressure? Because pressure is a major cause of heat.

Pressure is not a cause of heat. When a gas is compressed, the total heat energy contained in the gas is squeezed down to a smaller volume. This heat goes up because the volume is smaller. The total energy is about the same as compressing it does add energy, but mostly is the smaller volume.

Put a chunk of iron in a vice and squeeze it as hard ad you can. Apply all the pressue you you can, it will not get hotter. (Not any hotter than you and I can mearusre with our figer tips.)

 

[D H]

Pressure is not a cause of heat. When a gas is compressed, the total heat energy contained in the gas is squeezed down to a smaller volume. This heat goes up because the volume is smaller.

You have a mistaken concept of heat. Objects do not contain heat. You also have misconception regarding pressure and temperature. Compressing a gas adiabatically (no heat flow) *does* cause the gas to get hotter. Diesel engines would not work if compressive heating did not exist.

 

[Xnn]

Objects above absolute zero, do contain internal heat energy.

Anyhow, up to 90% of the Earth core heat is from radioactive decay.
About 5 to 10% is from friction caused by gravity.
About 5 to 10% is residual left over from the original formation of earth.
A small amount is latent heat released when molten materials turn into solids.

As I understand it, tidal push and pulls are part of the 5 to 10% gravity friction portion.

Here is a link to an article on the subject: http://www.physorg.com/news62952904.html

 

[Bill Illis]

The core of Jupiter is 24,000K (4 times that of the surface of the Sun).

Compression from gravity creates the heat.

You can also think of it in terms of stars. Stars need to reach about 10 million K in their cores (mainly caused by gravitational compression) before they can start to initiate fusion. The earliest stars had no radioactive elements. [Note there is some fission heat produced by hydrogen and helium isotope burning before fusion starts, but the process is inevitable without this].

 

[D H]

Objects above absolute zero, do contain internal heat energy.

Objects above absolute zero contain internal energy. Calling this internal energy "internal heat energy" is a misnomer. This phraseology recalls the long-falsified phlogiston and caloric theories of heat. Objects do not contain "heat".

Heat transfer is a process variable rather than a state variable. Internal energy is a state variable. How that internal energy changes due to heat transfer and work depends on path taken through state space. That the change in energy is path dependent is why it is invalid to say that objects contain heat.

 

[Xnn]

DH;

There is more than 1 type of internal energy: Chemical, Nuclear, Latent and Thermal.
Most people understand thermal energy to be heat energy.
So, it's best to specify which type is being discussed to avoid confusion.
Anyhow, this is somewhat OT to the original posting topic.


Up to 90% of the heat in the core of the Earth is from radioactive decay.
Between 5 to 10% is from friction caused by gravity.
Between 5 to 10% is residual left over from the original formation of earth.
And a small amount is latent heat released when molten materials turn into solids.

Another reason why the center of the Earth is so hot, is that it takes a long time to conduct heat thru the crust simply because it is so thick.

 

[Bored Wombat]

Objects above absolute zero contain internal energy. Calling this internal energy "internal heat energy" is a misnomer. This phraseology recalls the long-falsified phlogiston and caloric theories of heat. Objects do not contain "heat".

I don't think of heat as phlogiston nor caloric. But I do think of objects containing heat, which is an energy, and a function of temperature for a given substance of a given density and phase.

What is wrong with this thinking?

 

[oliason]

One of you fellows got the answer correct. Friction. It is well known that the Earth's axis has a wobble which shifts the entire mass of the Earth each day. In effect the wobble causes a shaking of the Earth's mass which keeps the crust flexing resulting in Earth quakes and volcanoes and the generation of heat. Ok?

One can speculate on changing of the poles, ancient shifting of Mars and Venus, pressure of all that weight, and one will grow old speculating, die and pass such speculation on the the next generation who will grow old and .....

 

[Xezlec]

One of you fellows got the answer correct. Friction. It is well known that the Earth's axis has a wobble which shifts the entire mass of the Earth each day. In effect the wobble causes a shaking of the Earth's mass which keeps the crust flexing resulting in Earth quakes and volcanoes and the generation of heat. Ok?

Nope. Not OK until you back up your claim, as someone already asked you to do when you posted the same thing earlier in this thread. Without evidence, you seem to be merely guessing. Gravitational heating sounds more plausible to me.

 

[JaredJames]

One of you fellows got the answer correct. Friction. It is well known that the Earth's axis has a wobble which shifts the entire mass of the Earth each day. In effect the wobble causes a shaking of the Earth's mass which keeps the crust flexing resulting in Earth quakes and volcanoes and the generation of heat. Ok?

One can speculate on changing of the poles, ancient shifting of Mars and Venus, pressure of all that weight, and one will grow old speculating, die and pass such speculation on the the next generation who will grow old and .....

You've made 2 posts in 2 years, both identical and neither with evidence to back up your claims.

 

[a2d4r6o8]

If we go with the theory that the Earth is cooling, then why couldn't the book Journey to the Centre of the Earth be real? Most people will say it's impossible, but since the discovery of other galaxies, who is to say that anything is impossible?

 

[Drakkith]

If we go with the theory that the Earth is cooling, then why couldn't the book Journey to the Centre of the Earth be real? Most people will say it's impossible, but since the discovery of other galaxies, who is to say that anything is impossible?

Getting to the center of the Earth is not theoretically impossible, it is simply impossible to do given todays technology. The vast majority of the details in the book are simply fiction for a good story and have no relevance to real life.

 

[a2d4r6o8]

Thank you, but then again, with todays technology shouldn't it be easier to get to the centre of the earth. If we could we could actually have proof of why the centre of the Earth is so hot and who's to say there isn't a granite shaft that may block out the central heating of the world, making it possible to enter the centre of the earth?

 

[Drakkith]

Thank you, but then again, with todays technology shouldn't it be easier to get to the centre of the earth. If we could we could actually have proof of why the centre of the Earth is so hot and who's to say there isn't a granite shaft that may block out the central heating of the world, making it possible to enter the centre of the earth?

Granite is formed from magma, which is molten rock. The shaft would melt long before it got close to the center of the Earth. Not only that, there is immense pressure building up as you get further underground, so the shaft would never be able to hold up.

 

[Evo]

Thank you, but then again, with todays technology shouldn't it be easier to get to the centre of the earth. If we could we could actually have proof of why the centre of the Earth is so hot and who's to say there isn't a granite shaft that may block out the central heating of the world, making it possible to enter the centre of the earth?

This is absolute nonsense.