Space Sciences Black holes: what are your thoughts?

[Blobbenstein]

It came as a revelation to me that there might not(isn't) be such a thing as an event horison(The ball like surface that surrounds a supposed singularity from which light can't escape)

I believe in the eternally collapsing object idea.

Here's a face page on it: https://www.facebook.com/EternallyCollapsingObject

Gravitational bodies self magnify; here is a diagram to show that process:

A is seen to be at C by observer B.
As the object collapses it becomes heavily time dilated and its collapse appears slowed(looks stopped) from the outside, and I believe heavily self magnified, so that it would look like the Schwarzschild radius black hole.

There probably is some sort of radiation for which Hawking Radiation is an analogy, so the BH won't last forever....I just don't believe that black holes create a situation where by light can't escape because of the space-time warpage...it taint natural.

Another page: http://www.newscientist.com/article/dn12089-do-black-holes-really-exist.html

I think there needs to be a paradigm shift away from the holes.
(bit of a quick OP)
Anyway thoughts.?

 

[Amy SF]

It's a convenient sci-fi device for getting quickly from point A to point B.

Otherwise I have no clue. Sorry.

 

[Blobbenstein]

I think event horizons BHs are a plot devise for science fact, to get from A to B without having to really deal with what really is happening.

 

[Blobbenstein]

here be a diagram I made with a simple program:

 

[Blobbenstein]

It would be nice to see a diagram showing the apparent shape, and size of a collapsing object, but using proper relativity equations.

But I think it would look similar.

 

[FortyTwo]

Hmm.

They're very often used when "wormhole" would be the correct term, so I can understand Amy's observation.

I wasn't aware that the event horizon was supposed to be a surface. What I grew up believing was that it simply represented the minimum distance from the collapsing center at which light could exist.

 

[Blobbenstein]

I think of it as a mathematical surface. In the mainstream view of BHs you are supposed to be able to fall through it, from the faller's point of view.

But at the same time, for the distant observer, things falling towards the event horizon become increasingly time dilated. The theory goes that nobody actually ever can see anything reach the event horizon, for the distant observer, and that's not because of the red shift of light.....if you could see any radiation(however red shifted) you would still not see anything cross the event horizon......as things approach the event horizon, they slow down to next to nothing..

I think the event horizon(whatever that shape it may appear to be) is a point centre for the collapsing matter, and that the thin layer of stuff just outside the event horizon, is the magnified version of the very small sphere of collapsing matter(see diagram in post 4). It is so magnified(I think) that it would look like an event horizon black hole...no apparent difference.

The thing is, if nothing ever crosses an even horizon, how is stuff supposed to get inside, to form the singularity and hence the event horizon? No singularity, no real event horizon, no black hole. Just a very small ball of eternally collapsing matter(except for it probably evaporates away in like 100billion years, or whatever)

 

[Blobbenstein]

From the falling matter's perspective, it would very quickly end up very crushed and evaporate away, billion's of years in the future....it would all be over in seconds, and you would be radiated away in the distant future, never having crossed any event horizon.

 

[FortyTwo]

I've always read that something can cross an event horizon, but it just can't be seen crossing it by an observer.

Unfortunately, despite all speculation, we'll probably never get to observe something being chucked into a black hole. Well, unless one of two things happens:

1.) CERN surprises us by destroying the Earth during their next test
2.) Dumb holes become actually useful and not something that sounds vaguely dirty

 

[Blobbenstein]

I've always read that something can cross an event horizon, but it just can't be seen crossing it by an observer.

they have to say that if they are going to continue to believe in the event horizon, singularity idea, but how is it scientific to say something happens, yet it cannot be witnessed(and not because of the constraints of the equipment)?
Science is based upon observation, so saying something crosses the event horizon but that cannot be witnessed doesn't seem like a scientific statement.

2.) Dumb holes become actually useful and not something that sounds vaguely dirty

from what I have read, the Russians call them 'Frozen stars':
http://blogs.discovermagazine.com/b...black-holes-even-the-name-sucks/#.UYXJokqb-kw

 

[FortyTwo]

they have to say that if they are going to continue to believe in the event horizon, singularity idea, but how is it scientific to say something happens, yet it cannot be witnessed(and not because of the constraints of the equipment)?
Science is based upon observation, so saying something crosses the event horizon but that cannot be witnessed doesn't seem like a scientific statement.

But isn't that basically the foundation of particle physics? We can't actually observe quarks. Their existence can be indirectly proven but we don't even have a definite grip on the atomic model yet.

from what I have read, the Russians call them 'Frozen stars':
http://blogs.discovermagazine.com/b...black-holes-even-the-name-sucks/#.UYXJokqb-kw

I didn't think about that! The ones I was talking about are sonic black holes.

 

[das_nut]

What do you mean by "event horizon", and how it may not exist?

As far as I know, an event horizon is basically where gravity around an object becomes so intense that information does not escape (to oversimplify things a bit).

Outside of fiction, it doesn't have any other special effects.

 

[Blobbenstein]

What do you mean by "event horizon", and how it may not exist?

As far as I know, an event horizon is basically where gravity around an object becomes so intense that information does not escape (to oversimplify things a bit).

Outside of fiction, it doesn't have any other special effects.

That's what I mean, I don't think there is any point in space, from which information cannot escape.

I believe that what looks like a black hole, is just a self-magnified piece of collapsing matter. That what may look like the event horizon is actually a single point in space, and to say anything goes through it, is like saying that you can go further north than the North Pole.

I don't think that in the mainstream models of black holes, the event horizon is a trivial boundary.

 

[Blobbenstein]

No More Black Holes?


............Physicist Lawrence Krauss and Case Western Reserve colleagues think they have found the answer to the paradox. In a paper accepted for publication in Physical Review D, they have constructed a lengthy mathematical formula that shows, in effect, black holes can't form at all. The key involves the relativistic effect of time, Krauss explains. As Einstein demonstrated in his Theory of General Relativity, a passenger inside a spaceship traveling toward a black hole would feel the ship accelerating, while an outside observer would see the ship slow down. When the ship reached the event horizon, it would appear to stop, staying there forever and never falling in toward oblivion. In effect, Krauss says, time effectively stops at that point, meaning time is infinite for black holes. If black holes radiate away their mass over time, as Hawking showed, then they should evaporate before they even form, Krauss says. It would be like pouring water into a glass that has no bottom. In essence, physicists have been arguing over a trick question for 40 years.
Asked why then the universe nevertheless seems to be full of black holes, Krauss replies, "How do you know they're black holes?" No one has actually seen a black hole, he says, and anything with a tremendous amount of gravity--such as the supermassive remnants of stars--could exert effects similar to those researchers have blamed on black holes. "All of our calculations suggest this is quite plausible," Krauss says.

http://news.sciencemag.org/sciencenow/2007/06/21-01.html

 

[Blobbenstein]

I think that in the middle of a collapsing star(a star that can no longer support its own weight), time dilation increases and becomes very strong, and as the star collapses its self magnification increases also. So as it collapses, it magnifies, which combined processes lead to a compromise of what looks like a black sphere*. This sphere is just a time dilated ball of collapsing matter.
The apparent black hole starts of small and grows within a collapsing star.


* really I don't think it would be a sphere, more like a squashed version of the diagram in post 4, more like a pancake for any observer.
A pancake that looks like things are falling towards an event horizon, but never reaching it, slowed down to a near stop.

 

[nog]

As an undergrad and grad student in Physics, I argued with several professors that it didn't seem reasonable to say black holes exist. Perhaps as an approximation. My main argument was that it would take an infinite i.e. (non-finite) amount of time for the black hole to form (with respect to a distant observer).

The main argument they made, was that if something happens in one frame of reference, then it must occur in all frames of reference. So in terms of looking at the collapsing star, it forms. In terms of looking at matter falling in, there is nothing special about the event horizon.

It still seems odd to say that something that will take an infinite amount of time to form can exist in a finite amount of time.

 

[nog]

Oh, and I think there is such a thing as an Event Horizon.

It was a terrible movie though.

 

[Mel]

This is a very interesting discussion. I don't really know enough to form my own opinions about this, but I might show this thread to my husband who has always been a Physics buff. It'll be interesting to hear what he has to say about it

 

[Blobbenstein]

Stephen Crothers believes that black holes aren't real.

http://www.sjcrothers.plasmaresources.com/

As an undergrad and grad student in Physics, I argued with several professors that it didn't seem reasonable to say black holes exist. Perhaps as an approximation. My main argument was that it would take an infinite i.e. (non-finite) amount of time for the black hole to form (with respect to a distant observer).

The main argument they made, was that if something happens in one frame of reference, then it must occur in all frames of reference. So in terms of looking at the collapsing star, it forms. In terms of looking at matter falling in, there is nothing special about the event horizon.

It is that sort of thinking that makes be doubt the scientific community sometimes.

If things never cross any event horizon, and there is an evaporative process that leads to BH to evaporate away in finite time, then the faller reference frame and the the observer frame would be connected. No need for anything to cross the event horizon...the faller frame would be heavily time dilated and presumable see the universe age by billions of years within seconds and then the compressed matter would evaporate. *puff* gone in seconds(from its own perspective) while the outside observer watched the BH evaporate away very slowly.

 

[nog]

It is that sort of thinking that makes be doubt the scientific community sometimes.

I think we should be careful with that though.

For example (as a side note, but related to the statement you bolded). Take an example in special relativity (I don't know how familiar you are with special relativity). You have a tunnel, a train, and a bomb. The train is longer than the tunnel with both are at rest relative to each other, and the bomb is at rest relative to the tunnel.

Now the tunnel has sensors so that if the train is entirely inside, the bomb will go off. If the train goes slowly through the tunnel, the bomb will not go off (from either reference frame; train or tunnel). However if the train moves through the tunnel at relativistic speeds, there will be a speed at which the train will fit completely inside the tunnel as viewed by the tunnel due to length contraction.

So the bomb would then go off.

However, when viewed in the reference frame at rest relative to the train, it's the tunnel that is moving. So at relativistic speeds the tunnel is length contracted. The train will never fit entirely inside the tunnel and the bomb should never go off.

Apparent paradox. But it's not and this very example is often used when studying special relativity. So in this case if the bomb goes off in one reference frame it must go off in all reference frames. It's a great example showing how events occurring at different points that in one frame might happen at the same time, don't happen at the same time in other frames.

If things never cross any event horizon, and there is an evaporative process that leads to BH to evaporate away in finite time, then the faller reference frame and the the observer frame would be connected. No need for anything to cross the event horizon...the faller frame would be heavily time dilated and presumable see the universe age by billions of years within seconds and then the compressed matter would evaporate. *puff* gone in seconds(from its own perspective) while the outside observer watched the BH evaporate away very slowly.

The only thing I think we need to be careful of, is stating which frame of reference we're talking about. Because for a frame of reference very close to the initially forming black hole you can calculate where the event horizon is and see things cross it (with nothing special happening). Assuming you're not destroyed by tidal forces, you can keep getting closer and still see the surface below you and things slowing down. It's just from an observer a great distance away (technically a non-finite distance) you'll see nothing ever crossing the event horizon.

At least based on my understanding.