Do Naked Singularities Break the Rules of Physics?

I'm a little skeptical about the simulations that show how naked singularities can exist. We know that General Relativity breaks down when the density of matter/energy becomes extreme. We also know that Quantum Gravity is far from a solved case for such states - we do not have a consistent quantum theory that includes gravity yet. Simulations that include both are pretty interesting, but the results are obviously somewhat speculative.

I find it a little hard to fathom how an extreme density could exist without the gravitational pull getting so strong that nothing can escape - i.e., forming an event horizon. However, if Quantum Gravity ever reaches a mature state, it may perhaps show us how...

Jorrie

What struck me about this article is that the author referred to the event horizon as a thing, rather than its simply being a boundary which, at its most fundamental, is simply a place beyond which the escape velocity exceeds the speed of light.

If one has an infinite density (else it would not be a singularity, would it?), how then can one not have an escape velocity greater than c somewhere in the immediate vicinity?

One thing that has puzzled me, Jorrie, is that singularities are usually ascribed dimensions infinitely small. To my understanding, infinitely small means infinitely smaller than anything having any dimensions at all, including (and especially) anything smaller the dimensions of a Planck Length. What happens at this scale to things as they approach "infinitely small?" Wouldn't they tend to flicker in and out of existence?

For my part I don't believe singularities ever reach infinitesimal size and I don't believe this for the same reason I don't believe that the electric field around an electron (which has no size as far as we know) reaches infinite density. Nature abhors infinities, it would seem, and so I'm sure something else -- a froth of virtual particles, if you will - forms around such objects as they approach this final stage in their demise and smears the distribution of mass such that infinite density is never reached.

Hi e, on the definition of a singularity: I think something with finite size and infinite density would also be described as a singularity (mathematically), but I'm with you that such a state probably doesn't exist.

As far as I can gather from the article, there may be some transient, distributed 'naked' singularities during the formation of the hole. I do not believe a photon (or graviton) can leave such a place for anyone to observe, but quantum uncertainty may cause particles to tunnel from there and become observable outside of the inevitable event horizon. Whether that enables "observing a singularity", I doubt...

-J

Jorrie, I found the article (Naked Singularities) interesting, but I find your comment re tunneling from a black hole, or its singularity, and out through the event horizon, very difficult to comprehend. I usually think of tunneling on the atomic level, not across the vast distances from the black hole to the edge of the event horizon, especially in mega-mass black holes. Possibly another facet of Hawking's "evaporation" theory. I still don't understand why we have neutron stars and then jump all the way down to black holes. Shouldn't there be a transition state where we would have quark-stars? Where the neutrons themselves are crushed, like squeezing an orange to get the juice? Think of the density of the "matter" of such a quark star! Are quarks the final limit for building blocks size and mass? We've gone from molecules to atoms to atomic particles to quarks.... What's next? Pure energy?

Hi Cardio07, as I have it, the singularities that the article talks about are tiny masses, forming from density fluctuations all over a region inside the collapsing star. They are Planck scale things, where the probability of tunneling is non-zero. Is I understand it, radiation could leak from those micro black holes and escape from the star before the final event horizon forms. Hence, for some short time it is theoretically possible to "view" those multitude of "naked singularities".

They would probably all be drawn into the central singularity quite quickly and the final event horizon will prevent them from radiating from the inside. Hawking radiation comes from the outside of the event horizon - one of a virtual particle pair escaping while the other one falls in.

-J

"Wouldn't they tend to flicker in and out of existence?"

Wouldn't they just?!? If we can take the Planck length as the shortest physical dimension, and we then cram the mass of perhaps a galaxy worth of suns into that space, something's got to give somewhere. 10 pounds worth into a 5 pound sack comes immediately to mind...

I must agree with the wise and knowledgeable Jorrie. A singularity simply cannot be "naked". An event horizon must be present.

But even accepting for a moment that a naked singularity could exist, I feel that it still can not be observed. That is, even if the event horizon as we define it now was non-existent, some other as yet unrecognized property of the universe would intervene to prevent us from observing an infinite density and what (if any) actions take place there.

Then again, I predicted there would always be wooly mammoths and that people would never pay to slide down snowy mountians on two planks of wood. So perhaps I am not the best to guess!

I heard about black holes quite a few years ago, and singularities more recently, and now they're naked? The French must really be upset!

"Researchers have found a wide variety of stellar collapse scenarios in which an event horizon does not in fact form, so that the singularity remains exposed to our view. Physicists call it a naked singularity."

I would suspect this research was mathematical, and not astronomical. Current math is incomplete (wrong), as others have said, so I'm not going to lose any sleep over their conclusions. It is a curiosity whether gravity or matter would cease to exist if the size went below the Planck value.

S