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Old 10-03-2006, 04:06 PM
Ronaldo Ronaldo is offline
Join Date: Oct 2006
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Random Astrophysics Question

I have had a couple of classes in physics in college but I recently saw a program on the Science Channel that brings a question to mind. It stated that if the Earth passed into a Black Hole, due to the enormous forces, it would be compacted to the size of a pea. While this is occurring, is it possible that some of the Earth's mass be lost during this change? I'm thinking in terms of action/ it prudent to think in these terms in this case?
Old 10-03-2006, 06:21 PM
Exapno Mapcase Exapno Mapcase is offline
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Location: NY but not NYC
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If the earth passed into a black hole, it would be torn into shreds by the differing gravitational forces across its diameter.

However, none of the mass would be lost. This is true even if by some magic you coudl hold it together during the process.
Old 10-03-2006, 07:41 PM
Anne Neville Anne Neville is offline
Join Date: Jul 2004
Location: Pittsburgh
Posts: 12,064
What you may be thinking of is the size of a black hole that would result if the Earth were somehow compressed enough to form a black hole. The size of the black hole you could make from an object is dependent on its mass, and is called the Schwarzschild radius If you do the math, the Earth's Schwarzschild radius comes out to about 9 millimeters, which is about the size of a pea.

Black holes tend to form through massive stars going supernova, from the formation of really huge stars in the centers of galaxies, or possibly in the early universe shortly after the Big Bang. None of those methods of making a black hole could apply to making the Earth into a black hole. Since we don't know of any way to make the Earth into a black hole, we can't really say whether or not any of its mass would be lost in the process. The one method of black hole formation that I'm at all familiar with (IANA black hole physicist), a massive star going supernova, does result in the ejection of most of the star's mass prior to the formation of the black hole, so it's certainly possible that, if we somehow found a way to make the Earth into a black hole, part of its mass would be lost.


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