Black holes!

[SolarFlare]

Originally posted by Mick_2002
Deep Thoughts by ... SolarFlare...

(click)

[Andy Tacker]

Black Hole!
its not black really
hmm...
acc to s/w deptt of our cmpny, a BH is an app which came to existence after the Big Bang with the Folkz in Mgmnt. It consumes all the resources it can find and uultimately crashes down and leaves nothing ... absolute space...

horrible...

i started this thread to see how many are interested in Real BH, but seems nope, no one.
anyways, nice to hear the views tho'

[Simon666]

Black holes don't exist.

[hometown]

Originally posted by andy_tacker
Black Hole!
its not black really
hmm...
acc to s/w deptt of our cmpny, a BH is an app which came to existence after the Big Bang with the Folkz in Mgmnt. It consumes all the resources it can find and uultimately crashes down and leaves nothing ... absolute space...
horrible...
i started this thread to see how many are interested in Real BH, but seems nope, no one.
anyways, nice to hear the views tho'

Actually I like Blackholes in universe very much...It is a myth, unexplainable truth to me...As I have said in my first post I believe its existence...
It s nice to hear you also like it...I like to know about it too...

[sbrothy]

Here is a picture of a black hole:

Black Hole

[Simon666]

In the Yilmaz version of relativity theory, black holes can't exist. There is also this Hungarian guy I think who says they are impossible, only in the limit a very compact object can be like a black hole as described in the Schwarzschild solution.

[Dave McLelland]

Thus the Yilmaz theory predicts that relativistic effects should distort space in such a manner that the universe expands locally about every point in the universe, yet the size of the universe does not change.

My brain hurts now.

BTW isnt Cygnus X1 confirmed as a black hole.

[Simon666]

Originally posted by Dave McLelland
My brain hurts now. BTW isnt Cygnus X1 confirmed as a black hole.

It is only confirmed NOT to be a neutron star, with the current understanding of quantum mechanics. It is believed that if black holes exist (the majority of the scientific community believes this), Cygnus X1 is a black hole.

[Simon666]

Thus the Yilmaz theory predicts that relativistic effects should distort space in such a manner that the universe expands locally about every point in the universe, yet the size of the universe does not change.

I don't know how to interpret that either, but I have an idea: if everything expands, also the tools you use to measure distance, how do you know the distance has increased?

[voidspace]

I always wondered if there is an end to the universe... and what would it be like ..like a brick wall...etc

But I always end up beliving that there can be no end.

[Gabriel Fleseriu]

Originally posted by voidspace
I always wondered if there is an end to the universe... and what would it be like ..like a brick wall...etc

But I always end up beliving that there can be no end.

Maybe the universe is like a Pacman level: if you get out on the left, you come in on the right again

[CBasicNet]

Originally posted by voidspace
I always wondered if there is an end to the universe... and what would it be like ..like a brick wall...etc

But I always end up beliving that there can be no end.

Probably there is no end as I read that our universe is still expanding.

[Simon666]

Originally posted by Gabriel Fleseriu
Maybe the universe is like a Pacman level: if you get out on the left, you come in on the right again

Could be if the universe is curved in more dimensions, so far no such indication has been found. What you're saying is possible if the universe we know is the surface of a 4D sphere for example I guess.

[voidspace]

Originally posted by CBasicNet
Probably there is no end as I read that our universe is still expanding.

Yes...but it must be expanding into something


.................................................|
.................................................|
............... ....Universe end point-->|
.................................................|
.................................................|
.................................................|


But the other side would always exist and it is to have something like black holes or whatever ...but there would be something beyond it ..so it has no end.

[galathaea]

Well, for the question of the universe's boundaries, there are several options currently promoted. As Simon has pointed out, the universe may be topologically a 3-sphere (a sphere with a three dimensional surface), and this has been a prevalent belief ever since Friedman, Robertson, and Walker derived from general relativity this as a possible solution. Then, the universe could have a finite volume, but there would be no boundaries (like pac-man!). Einstein liked this solution alot, and work in the late 60's and early 70's showed such solutions to be fairly general. However, recent WMAP evidence tends to show that the curvature of our universe is very close to zero, which would imply an infinite universe. This is an alternative possibility, also one of the Friedman-Robertson-Walker solutions, though it might require very precise conditions of the universe for this to happen. Again, however, there is no boundary, and in fact, there is very little support in the science community that the universe would have a boundary since it is very difficult to get boundary conditions from general relativity that are consistent. However, it is likely that general relativity is only an approximation to some better theory, since it does not possess the proper mathematical structure to be compatible with quantum mechanics. For example, modern M-Theory predicts an 11 dimensional space-time with many of those dimensions coiled up so small as to have been undetected. Loop Quantum Gravity is another modern attempt at a consistent quantum theory of gravity, and though not yet well developed, another possibility (which overlaps both M-Theory and LQG) is non-commutative geometry. These are the only modern theories which can claim some sort of consistent quantisation of general relativity, and all of them show GR to be only an approximation. However, only recently have physicists been able to solve these theories for solutions of the global space-time geometry, and choosing the solutions that correspond to what we actually observe is very difficult.

Now, concerning black holes. They seem to be legitimate solutions to the evolution of dense cosmological structures, but their existence is still somewhat debated. However, since there are objects out there that behave exactly as black-hole predictions say they should (violent x-ray sources due to accretion discs, the "cosmic jet" events detected at galactic cores, the lack of luminescent objects where these events are occuring, mass estimates that fall within the black hole density range, etc.), alot of the debate seems centered more on just whether to call them black holes or not. Either way, there are certainly objects out there that behave a lot like black holes.

I am not sure, however, what to discuss about black holes. I am certainly interested in them. Maybe a topic list could help.

• The Schwarzschild and Kerr-Newman solutions to the Einstein equation.
• The "naked singularity" no-go theorems.
• (My favorite) The "no hair" theorem.
• Black hole thermodynamics (entropy, black-body radiation, etc.)
• The recent work in superstring theory on reformulating the language of black holes.
• The black-hole "disproof" of the Church-Turing thesis.
• Some of the more strange possibilities like the Kruskal extension and white holes.
• The black holes that Mick was alluding to...

Those are some options for discussion. I just don't know where to begin.