# Can negative energy explain black holes?

I think black holes are peculiar and I want to know if there is a relation to negative energy. Does negative energy have positive mass and therefore can explain the nature of black holes? IS there any relation between negative energy and black holes or is negative energy just a way of saying that is takes energy?

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You do realize that we haven't study any black holes in an experimental way, and that they are known entirely from some limited observational evidence and the existence of a theoretical explanation, right? Is there a particular reason you think that they need a new explanation? Any particular reason you think that objects which are observed to curve space with very high positive energy density should be explained by negative energy? I'm tempted to close this as so speculative as to be off-topic until someone explains to me that I'm off base here. Using small words, please. – dmckee Mar 16 '13 at 18:29
I understand the comment and I thank you for letting me ask. I was thinking that negative energy coudl explain why black holes suck for positive energy. A negative energy will attract a positive energy won't it(?) – Programmer 400 Mar 16 '13 at 18:52
It looks like you want to "explain" black holes, as if their nature is a mystery. It isn't, their ability to absorb is very well explained by gravity. (On the other hand, phenomena happening inside the horizon are not). – Manishearth Mar 17 '13 at 16:03

In General Relativity energy density is the top left element, $T_{00}$, of the stress-energy tensor. It's mathematically possible to set this to a negative number, though you'd need some physical justification for doing so. Anyhow, if you put in a negative energy density you wouldn't get a black hole.
Negative energy corresponds to a negative mass, which is another concept that probably doesn't exist outside of theorists fevered dreams. Negative mass behaves very strangely. Two negative masses attract each other, but because $F = ma$ when mass is negative the acceleration and the force are in different directions. So two negative masses would accelerate away from each other even though they attract. When you have one negative mass and one positive mass the force is repulsive, so the ordinary matter is repelled and the negative matter is attracted giving you a perpetual motion device.
I don't understand the relationship with inflation. The exponential expansion happens there due to the equation of state parameter being close to -1, which is typically achieved by slow-roll. The energy density is still positive. It is just that the kinetic energy is much smaller and for a scalar field dominated universe, this leads to an exponential expansion. ($\rho + 3p$ is negative, not $\rho$). FRW and Schwarzschild are different solutions :) – contrariwise Mar 16 '13 at 22:17
Things aren't as simple with negative masses. I would imagine that violating the positive energy conditions would mean that an event horizon will not necessarily form. If $M \rightarrow -M$, $r=2M$ won't be the event horizon. A brief survey of the literature arxiv.org/abs/gr-qc/9705007 though shows that such solutions are, in principle, possible. – contrariwise Mar 18 '13 at 15:51