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Author Topic: Is a black hole infinitely dense?  (Read 21122 times)

Offline Bill S

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Is a black hole infinitely dense?
« Reply #25 on: 25/11/2010 23:13:36 »
Quote from: ArkAngel
And what about something eternal, does it have to be infinite?

Before I try to answer that one, let me ask you one more question, just to make sure we are on the same page.
What is the difference between infinite and eternal?
 

Offline CPT ArkAngel

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Is a black hole infinitely dense?
« Reply #26 on: 25/11/2010 23:26:59 »
Infinite in space and eternal (infinite) in time.
 

Offline acsinuk

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Is a black hole infinitely dense?
« Reply #27 on: 26/11/2010 15:53:48 »
We are all playing with words because we just do not know.  But things in this universe are logical and black holes with huge negative masses are certainly not logical; and neither are worm holes to other universes.
There is an alternative electric option. What if super massive black holes are at the centre of every galaxy like a giant magnetic hub around which all the stars rotate in a set order.  The magnetic field not only spins the stars into position [ which gravity cant] but can accept feedback to avoid collisions.  If collisions  occur then the tiny galaxy may turn into a vibrating quasar or a magnetar. What do you think?
CliveS
 
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #28 on: 26/11/2010 18:31:18 »
There is a lot of playing with words, it can be fun, but is usually not very productive.  However, there are also lots of lines of discussion that are less productive than they could be, simply because different people ascribe different shades of meaning to particular words.  Infinity is a concept that suffers greatly in this regard.  For example; it is important to establish if we are talking about mathematical infinities or a physical infinity.  It is also crucial to distinguish between infinite and boundless.  That's before getting into some of the finer points.  Take, for example, ArkAngel's response to my question:
Quote
Infinite in space and eternal (infinite) in time
Infinity is not infinite space, nor is eternity infinite time.  We have to think of them in that way because we are unable to even imagine the possible dimensions of infinity.  While there is nothing wrong with ArkAngle's answer in terms of our 4D thinking, it is important to remember that it is a sort of "model", perhaps the nearest we can come to understanding the real thing.  Just think about a spider walking through "Flatland".  ;)
You raise an interesting point, Clive, but it will take me a little while to get my brain around it.   :-\
 

Offline 5nutjob

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Is a black hole infinitely dense?
« Reply #29 on: 26/11/2010 18:44:13 »
Singularities are not necessarily 0-dimensional points; for instance they may well be circles, spheres & hyperspheres; so energy 'density' never becomes infinite.  [:I]
 

Offline tbarron

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Is a black hole infinitely dense?
« Reply #30 on: 26/11/2010 18:51:33 »
Infinity is not infinite space, nor is eternity infinite time.  We have to think of them in that way because we are unable to even imagine the possible dimensions of infinity.  While there is nothing wrong with ArkAngle's answer in terms of our 4D thinking, it is important to remember that it is a sort of "model", perhaps the nearest we can come to understanding the real thing.

How can we even know there's a "real thing" to be modelled? Just because we can imagine invisible pink unicorns doesn't mean they exist. Similarly, just because we can grok the concept of infinity doesn't necessarily mean anything actually is infinite.
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #31 on: 26/11/2010 19:52:49 »
Quote from: tbarron
just because we can grok the concept of infinity doesn't necessarily mean anything actually is infinite

Perhaps you should start by asking yourself if there can ever have been a time when there was nothing. It's surprising where you can go from there.  [8D]

« Last Edit: 26/11/2010 19:57:19 by Bill S »
 

Offline peppercorn

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Is a black hole infinitely dense?
« Reply #32 on: 26/11/2010 19:55:22 »
Similarly, just because we can grok the concept of infinity doesn't necessarily mean anything actually is infinite.

A Series can be! ;) (tongue firmly in cheek!)
No one can say for sure that anything physical has infinite dimension (gravity, distance, etc).


Re: singularities -
Wikipedia - that bastion of all knowledge ;) says of singularities:
"A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system. These quantities are the scalar invariant curvatures of spacetime, some of which are a measure of the density of matter."
It also says there are theories that specify that singularities can not exist. mmmm ???
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #33 on: 26/11/2010 20:18:10 »
Quote
A Series can be!  (tongue firmly in cheek!)

Very sensible; you knew that would set me off if you said it seriously, didn't you? :-X

Quote
"A gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system. These quantities are the scalar invariant curvatures of spacetime, some of which are a measure of the density of matter."

OK. You quoted it, you translate it so the plebs can understand it. :P
 

Offline CPT ArkAngel

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Is a black hole infinitely dense?
« Reply #34 on: 27/11/2010 05:10:38 »
Is it possible that the universe has appeared from nothing? If not, the universe is eternal (even if maybe discrete in some way). But it doesn't mean it is necessarily infinite in the other dimensions.

It is open to a more casual and funny discussion i hope...

By experiences, Physics tend to say any singularity is very improbable, to say the least...
« Last Edit: 27/11/2010 06:38:04 by CPT ArkAngel »
 

Offline joshrego

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Is a black hole infinitely dense?
« Reply #35 on: 27/11/2010 07:11:50 »
I just feel that we all can ever imagine to do with black holes theorize.In fact a black whole is a tunnel between universes.  Black hole attracts matter that does not collapse into a point, as predicted, but a black one out the other end of the "white hole" say, the theory goes.
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #36 on: 27/11/2010 15:03:02 »
Quote from: ArkAngel
Is it possible that the universe has appeared from nothing?

If there had ever been a time when there was nothing, there would be nothing now. Manifestly, there is something now, so something must be eternal.

Quote
But it doesn't mean it is necessarily infinite in the other dimensions.

I've been trying to get my head round this for some time.  Does "eternal" automatically imply "infinite"?  I feel it should, but have yet to formulate the necessary argument to my own satisfaction. 

Welcome, joshrego.  Hope to see lots of posts from you. Don't take all of us too seriously, though.

Quote from: joshrego
In fact a black whole is a tunnel between universes.

Is this an assumption, or do you have evidence that would make William of Ockham turn in his grave?
 

Offline tbarron

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Is a black hole infinitely dense?
« Reply #37 on: 28/11/2010 00:13:03 »
Perhaps you should start by asking yourself if there can ever have been a time when there was nothing. It's surprising where you can go from there.  [8D]

A similar question would be whether there could be a place where there was no time.

In both cases, the answer depends on my assumptions. If I assume that nothing cannot become something, I answer "No, there could not be a time when there was nothing." If I assume that nothing can become something, I answer, "Yes, there could have been nothing at one point in time, and then something at a later point." I'm not even sure what it would mean to have a place without time. How long would it last? :)

However, when I think of space-time as a four dimensional structure, I can imagine bounds in both time directions.

Of course, I also have to ask whether what I can imagine has anything to do with what is.
 

Offline tbarron

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Is a black hole infinitely dense?
« Reply #38 on: 28/11/2010 00:19:25 »
I've been trying to get my head round this for some time.  Does "eternal" automatically imply "infinite"?  I feel it should, but have yet to formulate the necessary argument to my own satisfaction.

I think "eternal" just means "outside time", not "infinite in duration". Something eternal is something that doesn't have extension in the temporal direction. Its value is the same at all points on the time axis. I don't think we'd have any way of observing such an object since our experience is so aligned to the temporal dimension.

Wiktionary offers the following definition for "eternal": "(philosophy) existing outside time; as opposed to sempiternal, existing within time but everlastingly"
« Last Edit: 28/11/2010 00:22:27 by tbarron »
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #39 on: 29/11/2010 18:58:16 »
Quote from: tbarron
Something eternal is something that doesn't have extension in the temporal direction. Its value is the same at all points on the time axis.

This captures a major factor in the problem. If it "doesn't have extension in the temporal direction", how can it be present "at all points on the time axis"?

 

Offline tbarron

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Is a black hole infinitely dense?
« Reply #40 on: 29/11/2010 23:48:07 »
Quote from: tbarron
Something eternal is something that doesn't have extension in the temporal direction. Its value is the same at all points on the time axis.

This captures a major factor in the problem. If it "doesn't have extension in the temporal direction", how can it be present "at all points on the time axis"?

1) Its value might be zero at all points on the time axis.

2) Its value might be some fixed non-zero value. If it doesn't change with time, how would we notice its presence?
« Last Edit: 29/11/2010 23:50:22 by tbarron »
 

Offline imatfaal

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Is a black hole infinitely dense?
« Reply #41 on: 30/11/2010 10:39:26 »
We noticed gravity and understood it well - at a point in our history when gravitational attraction was observable as a fixed (in place and in time)  non-zero quantity
 

Offline Foolosophy

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Is a black hole infinitely dense?
« Reply #42 on: 30/11/2010 13:01:18 »
a black hole is mathematically defined as a singularity

what does this say about a black holes density - or any other property for that matter???
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #43 on: 30/11/2010 15:54:22 »
Quote from: tbarron
Its value might be zero at all points on the time axis.

I suspect you are still thinking in terms of mathematical infinities.  Eternity can neither have, nor be placed on, a time axis.  It is not time.

Quote from: imatfaal
We noticed gravity and understood it well - at a point in our history when gravitational attraction was observable as a fixed (in place and in time)  non-zero quantity

Are you saying that gravity is eternal?
 

Offline rwjefferson

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Is a black hole infinitely dense?
« Reply #44 on: 30/11/2010 21:59:55 »
Is black hole mass infinitely dense?
Is this proved or dogma?

peace
rwjefferson

force is inertial differential


  It isn't proven as such. Penrose and Hawking singularities dictate that a black hole has a singular region which is infinitely dense.
We are all playing with words because we just do not know. 
I don't think anyone can definitively answer this question since our theories don't cover it... 
  In other words, your own personal theories are new or disproved.

Bonus Questions
According to the dictates of Penrose and Hawking; how much dirt is in a hole 1x1x1x1? 
What is the relative density at the eye of a drain? 
Is black hole mass closer to infinitely less than dense?

Fellow Geezers
Force as inertial differential is not a new theory.
Force as inertial differential is not a disproved theory.

Force as inertial differential is the law of physics.

peace
ron
 

Offline Bill S

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Is a black hole infinitely dense?
« Reply #45 on: 01/12/2010 21:25:42 »
You are not getting away as easily as that.  :P
Quote from: tbarron
Its value might be zero at all points on the time axis.

What does this mean? 
If it has zero value, is it really there? 
How can eternity be accommodated at any point on a time line?
 

Offline Geezer

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Is a black hole infinitely dense?
« Reply #46 on: 02/12/2010 07:31:34 »

Fellow Geezers
Force as......


Oi! I'll have you know there is only one Geezer on this forum.
 

Offline Foolosophy

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Is a black hole infinitely dense?
« Reply #47 on: 02/12/2010 12:38:41 »
....a black hole is really just a very dense de-fusionised star

A singularity is a mathematical construct

never the twain shall meeteth
 

Offline yor_on

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Is a black hole infinitely dense?
« Reply #48 on: 03/12/2010 21:44:11 »
Infinity exists, matter accelerated to light-speed has to be an 'infinite slope', as matter otherwise would break the light barrier at some point if accelerated enough. And the predecessor to a black hole is a finite object becoming a singularity. It's like 'distance' though, plasticity incorporated, but I'm sure it exist, even if we never will 'see it' practically.
 

Offline CPT ArkAngel

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Is a black hole infinitely dense?
« Reply #49 on: 04/12/2010 01:17:59 »
Any particle has a maximum acceleration point. Beyond that acceleration, the particle will break and changed into photons going at the speed of light...
 

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Is a black hole infinitely dense?
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