fando

Hmm.. I should've noticed this sooner, but the singularity will not have infinite mass. A point in spacetime can definitely have infinite density, but it doesn't imply infinite mass. This is simple math: the limit of a ratio as the denominator approaches 0 is infinity, however that doesn't imply that the numerator is also infinite.

In the case of our singularity, the density D = M/V approaches infinity when V approaches 0, but the value of M remains the same. This of course assumes that we can compactify "mass" into zero volume. There are grave consequences to such a situation, and this should be the real argument against singularities existing. However, until we can come up with a theory that avoids this, we can't just reject the possibility that this can happen in our universe.

The reason why I was astounded is because I felt people were jumping to conclusions.

Bill,

Apologies if my last post seemed antagonistic. I forgot to add smileys.

Answerer

Well, I prefer to understand some other simpler concepts of physics first before comprehending the 'singularity' concept which is far beyond the scope that I can cover now.

Ted Hoffman

Fando, excellent post.
You've got me thinking. Its easy to make the mistake of associating infinite density with infinite mass.

Ted Hoffman

I have this model - I am a layman (totally) that can simplify those complex mind-breaking models presented by physicists:

1. At the center of a black hole (the singularity?) initially a hot body emitting thermal radiation - I an element with very high Melting Point. (whatever element(s) they are or it is (could be matter or antimatter), its heavy(high density). Classically, no radiation can escape from a black hole, but if we quantise the matter fields, we find there is steady flux of radiation coming out of the black hole! This outgoing radiation decreases the mass of the black holes, so eventually the black hole will disappear. The temperature goes up as the black hole gets smaller (unlike most things, which cool off as they lose energy), so the black hole will disappear abruptly, in a final flash of radiation.

2. This body is then surrounded by a vaccum - or a super-vaccum (which makes up the schwarzchild radius - some have called this region the event horizon)

3. The vaccum gets "poorer" as you move away from the center of the black hole.

My reasons :

for 1.: I think an element that can survive a supernova explosion (millions of kelvins) will make up the core of the black hole (by collapsing onto itself after the explosion since only gravitational forces exist).
for 2: I believe the schwarzchild radius of the blackhole is created after the explosion. The elements that survive it are attracted to each other to form a dense body. Anything else (air light etc) that enters the radius is pulled at the speed of light to the core of the hole. This creates a vaccum around the body.
for 3. Well, gravitational strength between bodies is inversely proportional to the distance between the two bodies.

To answer Hans question(he seems to know so much already!).
I believe if interstellar matter entered the event horizon of the black hole, it would rush towards the singularity at the speed of light. As it gains kinetic energy, it heats up, is squeezed by tidal forces while at the same time the heating ionizes the atoms, and when they reach a few million Kelvin, they emit X-rays which are sent off into space before the matter (or the part of it thet still exists) crosses the Schwarzschild radius and crashes into the singularity.

So what we observe (outside the event horizon) are X ray emissions as the matter (somewhat) gets accreted to the singularity.

Phew - *wears helmet and protective gear wipes sweat from forehead using the back of his right - sorry, left hand - Takes a deep breath*
Now all ye scientists can tear down my model. Be Gentle though - It's just a laymans version.

[ April 22, 2002: Message edited by: IntenSity ]</p>

Joe Nobody

One if not the best book on Black Holes ever written is Kip S. Thorn's Black Holes and Time Warps. It was published in 94 so it might be a bit outdated now on some things but it is very informative still.

I believe Thorn touches this a little in the book. On page 477:

I guess the topology of space is said to be probabilistic instead of definite. I think all the problems with the infinities come from the GR understanding of it but the small size means GR is not enough by itself. We need to incorporate QM as well. Back then they were working on incorporating quantum gravity and having it take over. Anyways, the book is good. There is a whole chapter called "Inside Black Holes" but some of the material is going to be a little outdated but as an introduction to black holes its still an invaluable resource.

In a more recent book from 1999 on Superstring Theory, we can get an update from Briane Greene:

We find out that the qestion of the center of a black hole is an area of intense research in superstring theory right now. But so far the black hole singularity has eluded the reach of string theorists.

The Elegant Universe, p 344.

I highly reccomend the Elegant Universe by Greene. It was a very good read but some of string stuff can get complex. A lot of esoteric terms will be thrown around. The explanations of GR and QM were probably the best I've ever seen in a book like this.

Joe Nobody

Joe Nobody

Have any of you ever heard of a naked singularities? All I heard was from the Thorn book I referenced above. I am wondering if anyone has any new info on whether they are possible or not?

Joe Nobody

Freethinking Ferret

Not: law of cosmic censorship.

Joe Nobody

"The whole incredible big bang story with its climactic human ending is merely the result of physical and chemical processes that are completely random, accidental, and meaningless. We may think we're pretty good and important, but there is absolutely nothing in the blind, meaningless events to suggest the slightest purpose, value, or significance in our existence. If we should be so foolish as to annihilate ourselves in an atomic holocaust or through the strangling pollution of the earth, it will make not the least difference in the scheme of things. The planets, stars, and galaxies will continue on their cosmic schedules, completely oblivious to our passing. So much for human significance."
Jones, Physics for the Rest of Us

Cosmic who?

Ted Hoffman

Nobody
How is this relevant? How do you know it was accidental? How was it supposed to be?
Meaningless to who?

Joe Nobody

It was in response to the cosmic censorship post. Basically saying, the Cosmos doesn't care Jones stated in the book he was going to be exaggerating for effect in the chapter that falls in.

Joe Nobody