Is there a limit to singularity small-ness?

[Obnoxious]

Or is Planck length as small as they get.

[ssarda]

Due to advancement of technology Singularty will be an obvious thing to happen

[Ollie]

Wrong kind of singularity ssarda. Obnoxious: aren't they just infinitley small? Which would then be measured as Planck length because that's the smallest measurable.

 

Ollie

[Martin]

Wrong kind of singularity ssarda. Obnoxious: aren't they just infinitley small? Which would then be measured as Planck length because that's the smallest measurable.

 

Ollie

 

I think it is a good question and I like your reply, which makes a lot of sense.

 

Interestingly enough the question isnt settled. Something came out this year about it. I will see if I can get the link.

 

the point is that most of what we hear about geometry of BH and singularities is based on the CLASSICAL pre-quantum model (Einstein Gen Rel)

 

what Hawking and Bekenstein and others added, about the radiation and temperature and evaporation etc. did not change the GEOMETRY of the model, so it's called a "semiclassical" analysis. It adds some bells and whistles but it doesnt fundamentally change things.

 

But now there are beginning to be QUANTUM geometry models of BH and other kinds of singularities, coming from Loop quantum gravity mostly, which have a FINITE density. the singularity does not go down to zero size, because of quantum effects, the curvature does not go up to infinity.\

In the quantum gravity model you dont get a perfect classical (ideal point) singularity with zero diameter and infinite density.

 

there are quite a few papers about this now

its an active research area

I will get a link or two, but all I know is technical articles---it may be too recent to have gotten into wide audience media

[Martin]

Here is a list of papers, some are about this

 

http://arxiv.org/find/grp_physics/1/au:+bojowald/0/1/0/all/0/1

 

 

for example check out the one about "nonsingular BH"

and the one about a "BH mass threshhold"

 

the mass threshhold result is interesting, it says that you cant have BH forming of arbitrarily small mass,

you have to have enough mass or you cant get it to collapse.

 

the classical model didnt have this threshhold, you could take as small a mass as you pleased and as long as you compressed it to a high enough density then it would collapse to a singularity. Bojowald paper this year says no, that cant happen.

[hamish]

Have any of you thought about the possibility of singularities in black holes and whether these are the same kind that was ment to be at the beginning of the universe.

[diddly-squat]

A singularity is a mathematical artefact and thus has no real 'physical' form.

 

It is simply a place where our models cease to work. A good example is that of an even horizon (which is by definition a 'singularity').

[[Tycho?]]

Have any of you thought about the possibility of singularities in black holes and whether these are the same kind that was ment to be at the beginning of the universe.

 

This was thought of a long time ago, largely work done by Hawking and whats his face.... Roger Penrose.

 

Now correct me if I'm wrong here, but I believe the reasoning went like this: matter falls into a black hole, where it is compressed so much that it becomes a singularity. Since the big bang is matter moving outwards, this can be thought of as a black hole in reverse, with the matter going out instead of in. As one moves back in time, the matter of the universe will have been closer together. At only a short time after the big bang all the matter in the universe would be at a super tiny size, and the further back you go the denser the matter becomes. Once one goes to time zero one reaches a point where the density is infinite.

 

I believe this is where the big bang was first proposed to have started as a singularity.

 

(if the singularity acutally exists is open to question, its simply what GR predicts)