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View Full Version : How much negative mass would it take to rip apart a planet?

tommac
2010-Apr-02, 10:15 PM
Assume that negative mass could exist.

From what I understand, please correct me if I am wrong anywhere here, a small amount of negative mass would fall in a gravitational field, lets say that of earth. However when it hit the surface, the surface of the earth would apply force upward away from the surface. However, since this is negative mass, the upward force would result in downward acceleration ( f= ma ) until it burrowed to the center of the earth ( hmmmm wouldn't it just burrow out the other side? ). If there was enough negative mass in the center of the earth, would the earth explode at one point as the repulsive force of the negative mass, would create pressure?

Totally dumb question ... but just wanted some help thinking it through.

swampyankee
2010-Apr-03, 02:12 AM
If I understand the concept of negative mass correctly, it would accelerate away from the Earth, so the only way it could fall to Earth would be for it to have a high (escape?) velocity towards the Earth.

tommac
2010-Apr-03, 06:46 AM
If I understand the concept of negative mass correctly, it would accelerate away from the Earth, so the only way it could fall to Earth would be for it to have a high (escape?) velocity towards the Earth.

no ... negative mass will fall towards a gravitational source, unless it is more negatively massed than the mass, in which case it will repel the mass.

mugaliens
2010-Apr-03, 06:59 AM
no ... negative mass will fall towards a gravitational source, unless it is more negatively massed than the mass, in which case it will repel the mass.

I'm afraid the gravity of the situation requires us to amass considerably more knowledge about this than any of us appear to possess, regardless of negative or positive connotations to the contrary, and despite what we may think we can repel by mere supposition.

PhillipJFry
2010-Apr-03, 07:05 AM
Assume that negative mass could exist.

How? I haven't got the slightest idea what that means. Could you describe what "Negative Mass" is?

tusenfem
2010-Apr-03, 07:15 AM
After all the "negative" threads we have had lately, I think this would fit better in OTB.

tommac
2010-Apr-03, 03:23 PM
After all the "negative" threads we have had lately, I think this would fit better in OTB.

OK ... I agree ... sorry. Just going through a negative energy/mass phase right now ( my BH phase is sooooooooo last week. )

tommac
2010-Apr-03, 03:24 PM
How? I haven't got the slightest idea what that means. Could you describe what "Negative Mass" is?

http://en.wikipedia.org/wiki/Exotic_matter#Negative_mass

Negative mass in general relativity
In general relativity, negative mass is generalized to refer to any region of space in which for some observers the mass density is measured to be negative. This can occur due to negative mass, or could be a region of space in which the stress component of the Einstein stress-energy tensor is larger in magnitude than the mass density. All of these are violations of one or another variant of the positive energy condition of Einstein's general theory of relativity; however, the positive energy condition is not a required condition for the mathematical consistency of the theory. (Various versions of the positive energy condition, weak energy condition, dominant energy condition, etc., are discussed in mathematical detail by Visser.)
Morris, Thorne and Yurtsever pointed out that the quantum mechanics of the Casimir effect can be used to produce a locally mass-negative region of space-time. In this article, and subsequent work by others, they showed that negative matter could be used to stabilize a wormhole. Cramer et al. argue that such wormholes might have been created in the early universe, stabilized by negative-mass loops of cosmic string. Stephen Hawking has proved that negative energy is a necessary condition for the creation of a closed timelike curve by manipulation of gravitational fields within a finite region of space; this proves, for example, that a finite Tipler cylinder cannot be used as a time machine.

TrAI
2010-Apr-03, 03:51 PM
Assume that negative mass could exist.

From what I understand, please correct me if I am wrong anywhere here, a small amount of negative mass would fall in a gravitational field, lets say that of earth. However when it hit the surface, the surface of the earth would apply force upward away from the surface. However, since this is negative mass, the upward force would result in downward acceleration ( f= ma ) until it burrowed to the center of the earth ( hmmmm wouldn't it just burrow out the other side? ). If there was enough negative mass in the center of the earth, would the earth explode at one point as the repulsive force of the negative mass, would create pressure?

Totally dumb question ... but just wanted some help thinking it through.

Hmmm... If the small negative mass hit the ground, I suspect it would absorb the positive mass in that area, until the -mass was completely nullified.