How Would a Hollow Earth Structure Impact Gravity?

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  • Thread starter Thread starter Tris Fray Potter
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Discussion Overview

The discussion revolves around the hypothetical scenario of hollowing out the Earth, leaving only the crust as the mass, and its implications for gravity experienced outside the structure. Participants explore theoretical aspects of gravity in this altered configuration, considering both the physical principles and the consequences of such a change.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions how hollowing out the Earth would affect outside gravity, specifically if the crust were the only mass remaining.
  • Another participant suggests that if the Earth were hollowed out, one would be significantly lighter, estimating a reduction to about 99% lighter.
  • A third participant explains that if the Earth were turned into a thin uniform spherical shell, the gravitational force experienced outside would still follow the inverse square law, treating the mass as concentrated at the center, but the force of attraction would be smaller due to the reduced mass of the shell.
  • This participant also notes that compressing all of Earth's mass into a thin uniform shell would not result in much difference in gravitational effects, although living conditions would be drastically altered.

Areas of Agreement / Disagreement

Participants express differing views on the extent of the impact on gravity, with some suggesting a significant reduction in weight while others focus on the theoretical implications of gravitational forces in a hollow Earth scenario. The discussion remains unresolved regarding the exact effects and implications.

Contextual Notes

There are assumptions regarding the uniformity of the shell and the nature of gravitational forces that are not fully explored, as well as the practical implications of such a scenario that remain unaddressed.

Tris Fray Potter
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This is a question that has been bothering me, but I can't find an answer anywhere:
If I were to hollow out Earth so that the crust was the only mass, and Earth was to keep it's shape, how would this affect the outside gravity?
 
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You'd be a lot lighter. Like 99% lighter.
 
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Tris Fray Potter said:
This is a question that has been bothering me, but I can't find an answer anywhere:
If I were to hollow out Earth so that the crust was the only mass, and Earth was to keep it's shape, how would this affect the outside gravity?

If you turned Earth into a thin uniform spherical shell,
$$\vec {F}=-G\frac {M_sm_p} {r^2}\hat {r} $$
Still holds assuming your r is greater than the radius of the shell. You would still treat the shell as though all the mass is concentrated in the center. So what changes is the mass of the shell, and as a result your force of attraction becomes much smaller assuming the only difference is you've simply gutted the Earth.

If you were to take all of Earth's mass and compress it into a thin uniform shell, so that the masses remain equal, you wouldn't see much of a difference from this stand point. Although, you probably wouldn't want to live there anymore.
 
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Thank-you!
 

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