# Thread: Is the mass of Earth correct?

1. 卡文迪扭秤实验.jpg

The most important constant in Earth science is the mass of Earth. From this mass, scientists got the average density of Earth, which is about 5.5ton/m^3.

The average density of rocks near the top ground is about 3ton/m^3.

On the basis of these 2 densities, we got the current Earth model.

200 years ago, Mr Henry Cavendish got the mass of Earth in his experiment (Cavendish torsion balance experiment). The value he got is almost no different from current value.

We have to confess his experiment is too simple. Can we really believe he could actually get the mass of Earth with 4 lead balls and a torsion balance. If the mass of Earth is wrong, then a lot of theories in Earth science will collapse.

The mass of Earth is very important, we should make sure it's correct before we use it.

Please remember we still have no idea what the mass the The Himalays is.

Jin Guangnian

2.

3. Tom

The mass of the Earth is measured in many different ways. We can check one result against another.

So, yes. You can have great confidence in the reported mass of the Earth, within defined error limits.

4. Tom you have never been able to provide any evidence that the mass is wrong other then you dont like the experiment so in your opinion "it must be wrong". Its not wrong.

5. Tom, what mass did you get from your experiment? How much does it differ from the accepted value?

6. Originally Posted by tomjin2000
We have to confess his experiment is too simple.
Do we? Why?

Can we really believe he could actually get the mass of Earth with 4 lead balls and a torsion balance.
Why not? Can you explain precisely why this experiment would give the wrong result?

Can you describe in detail exactly what procedure you would prefer to use to measure the mass of the Earth?

7. Originally Posted by tomjin2000
卡文迪扭秤实验.jpg

The most important constant in Earth science is the mass of Earth. From this mass, scientists got the average density of Earth, which is about 5.5ton/m^3.

The average density of rocks near the top ground is about 3ton/m^3.

On the basis of these 2 densities, we got the current Earth model.

200 years ago, Mr Henry Cavendish got the mass of Earth in his experiment (Cavendish torsion balance experiment). The value he got is almost no different from current value.

We have to confess his experiment is too simple. Can we really believe he could actually get the mass of Earth with 4 lead balls and a torsion balance. If the mass of Earth is wrong, then a lot of theories in Earth science will collapse.

The mass of Earth is very important, we should make sure it's correct before we use it.

Please remember we still have no idea what the mass the The Himalays is.

Jin Guangnian
Actually, what Cavendish determined was the density of the earth.

8. That seems to be the case. What a marvellous experiment.

Cavendish experiment - Wikipedia, the free encyclopedia

9. Originally Posted by tomjin2000
The most important constant in Earth science is the mass of Earth.
You say that, but I don't recall using it recently.

Originally Posted by tomjin2000
From this mass, scientists got the average density of Earth, which is about 5.5ton/m^3.

The average density of rocks near the top ground is about 3ton/m^3.

On the basis of these 2 densities, we got the current Earth model.
Also, seismic data shouldn't be overlooked. It allows us to accurately infer the densities all the way down to the centre of the Earth.

[/img]http://www.preearth.net/density-versus-depth.gif[/img]

Originally Posted by tomjin2000
200 years ago, Mr Henry Cavendish got the mass of Earth in his experiment (Cavendish torsion balance experiment). The value he got is almost no different from current value.
Almost no different, but different nonetheless. Cavendish's result was accurate; more recent measurements are more precise.

Originally Posted by tomjin2000
We have to confess his experiment is too simple. Can we really believe he could actually get the mass of Earth with 4 lead balls and a torsion balance.
I can.

Originally Posted by tomjin2000
If the mass of Earth is wrong, then a lot of theories in Earth science will collapse.
Such as?

Originally Posted by tomjin2000
Please remember we still have no idea what the mass the The Himalays is.
We can quickly and easily work it out from the height above sea level, assuming isostatic equilibrium.

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