Planets collapsing into black holes?

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Discussion Overview

The discussion revolves around the hypothetical scenario of a planet with Earth-like mass and radius experiencing an extreme increase in the gravitational constant. Participants explore the implications of this change on the Schwarzschild radius and the conditions under which a planet might collapse into a black hole.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant proposes that if the gravitational constant were increased significantly, the Schwarzschild radius would also increase, potentially leading to immediate collapse of the planet.
  • Another participant confirms that altering the gravitational constant yields unphysical results, suggesting that the scenario is not realistic.
  • There is a question about the relationship between GM/c² and 2GM/c², with some participants noting that GM/c² represents a radius that is half the Schwarzschild radius.
  • One participant expresses uncertainty about the significance of the factor of 2 in the context of gravitational radius and Schwarzschild radius.
  • A later reply indicates that GM/c² is referred to as a gravitational radius, which is consistently half the size of the Schwarzschild radius.

Areas of Agreement / Disagreement

Participants generally agree that the scenario presented is unphysical due to the extreme values proposed. However, there is no consensus on the significance of the relationship between GM/c² and the Schwarzschild radius, as some express confusion and seek clarification.

Contextual Notes

The discussion includes assumptions about the nature of gravitational constants and their effects on physical properties, which are not grounded in realistic physics. The implications of changing fundamental constants remain unresolved.

Lamdbaenergy
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If you had a planet with the exact same mass and radius as the Earth, and adjusted the gravity constant to some value five-hundred million times larger, the schwarzschild radius should become considerably big, right? Instead of being about 8 millimeters, it would now be about 60 to 70 percent the radius of the body itself. So would this cause the planet to start collapsing immediately, and just how strong would the gravity have to be to cause the surface of the planet to start falling in on itself?
Also, what does GM/c2 mean compared to 2GM/c2?

I totally know that changing the gravity constant is impossible, let alone to that ridiculously high value.
 
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Yes, if you plug in a different and unphysical value for G, you get a different and unphysical value for R.

Lamdbaenergy said:
Also, what does GM/c2 mean compared to 2GM/c2?

It's half as big. (I think we're missing some context here)
 
Vanadium 50 said:
Yes, if you plug in a different and unphysical value for G, you get a different and unphysical value for R.
It's half as big. (I think we're missing some context here)

Why does the schwarzschild radius have to be twice as big as GM/c2? Is GM/c2 another special kind of radius that is always half the length of the schwarzschild radius? Thanks.
 
I don't think there is anything special about the 2.
 
Never mind the GM/c2 part. I found out that it is called a gravitational radius and it is half as large as the black hole.
 

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