- #1
terrabyte
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what's the amount of gravity or exactly how many "Gees" a black hole must exert to be a black hole (strong enough gravity to contain any light it "emits")?
How Much Gravity Does a Black Hole Need to Contain Light?
- Context: Graduate
- Thread starter terrabyte
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Discussion Overview
The discussion revolves around the conditions necessary for an object to be classified as a black hole, specifically focusing on the gravitational strength required to contain light. Participants explore the implications of size and mass in relation to the formation of black holes, using hypothetical scenarios involving the mass of the Earth.
Discussion Character
- Exploratory
- Technical explanation
- Conceptual clarification
- Debate/contested
Main Points Raised
- One participant questions the amount of gravity needed for a black hole to contain light, seeking a quantifiable measure in "Gees."
- Another participant notes that calculating this requires a defined size for the black hole, suggesting a hypothetical scenario where the black hole is the size of the Earth.
- A participant states that to become a black hole, all mass must be within the Schwarzschild radius, providing the formula for this radius.
- There is a discussion about the nature of light in relation to black holes, with one participant expressing confusion about how a black hole could emit light if light cannot escape once it is within the black hole's influence.
- Further elaboration on the mass required for a black hole with the radius of the Earth is provided, with links to calculations.
- One participant humorously remarks on the impracticality of acquiring the mass of 700 million Earths to create such a black hole.
Areas of Agreement / Disagreement
Participants express various viewpoints regarding the conditions for black hole formation and the nature of light in relation to black holes. No consensus is reached, and multiple competing views remain present throughout the discussion.
Contextual Notes
The discussion includes assumptions about the size and mass of black holes and relies on specific definitions of the Schwarzschild radius. There are unresolved questions regarding the nature of light and its interaction with black holes.
- #2
terrabyte
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realizing that in order to do such a calculation we would need a "size" for the thing.
hmm that complicates matters
let's assume the "Black Hole" is the size of the earth. how many "Earth's" do we need to compress to the size of ONE Earth to create a black hole?
hmm that complicates matters
let's assume the "Black Hole" is the size of the earth. how many "Earth's" do we need to compress to the size of ONE Earth to create a black hole?
- #3
chroot
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To become a black hole, all the mass of an object must be within its Schwarzschild radius,
[tex]r_s = \frac{2 G M}{c^2}[/tex]
That is the only condition.
- Warren
[tex]r_s = \frac{2 G M}{c^2}[/tex]
That is the only condition.
- Warren
- #4
urtalkinstupid
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How can a black hole "emit" any light at all? If I'm not mistaken, light "falls" into a black hole. Once the light get's too close to the black hole, it is affected by the black hole's space-time curvature. The space-time curvature is so inclined that light falls in, but can not get back out. I dunno. 
- #5
chroot
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A black hole with the mass of the Earth would have a radius of...terrabyte said:
http://www.google.com/search?hl=en&ie=UTF-8&q=2+*+G+*+(mass+of+earth)+/+c^2&btnG=Google+Search
- Warren
- #6
chroot
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A black hole with the same radius of the Earth would have to have a mass of...
http://www.google.com/search?num=30...)+*+c^2+/+(2+*+G)+in+earth+masses&btnG=Search
- Warren
http://www.google.com/search?num=30...)+*+c^2+/+(2+*+G)+in+earth+masses&btnG=Search
- Warren
- #7
terrabyte
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sweet, thanks chroot that's exactly what i was looking for :D
now i just need to acquire 700 million more Earth's...
now i just need to acquire 700 million more Earth's...
- #8
HallsofIvy
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terrabyte said:
"If we had but world enough and time!"
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