JEROME - Black holes do not exist

In a sense, the term "Black Hole" is a made up item. Before "black holes" they were called other names. But they were all theoretical objects. Made up due to theory.

As opposed to something that was discovered, then given a name.

The invisible objects that stars rotate around might be what we think of when we say "black holes", but so far it isn't like we have photographic evidence that there are black holes.

They could be neutron stars, or something we don't know about yet. Same for the massive objects causing all those huge jets of matter and energy to go shooting across the Universe, at almost the speed of light.

We call them "black holes", but from a super skeptical point of view, they are what they are. Black Holes is what we made up to call them.

Just like we make up names for all kinds of invisible objects. Sometimes we make up names before we even have evidence that something exist, then later find that there is something, just like was predicted.

But it is true, that Jerome did not say "Black Holes do not exist", which makes the topic title misleading. Of course some people will say this is all semantics, or nitpicking, or something. People say all kinds of things.

So what? What I don't get is why a few people get so emotional and insulting over the matter. It isn't like Jerome ran over your cat.

As the thread just keeps getting longer and longer, it is educational. If you want to really get some skeptics riled up, and have a really long thread, just say something like, "Neutrinos don't exist", or "There are electric currents in outer space".

For some reason that gets way more attention than trying to discuss sound science in a logical and rational way.
 
robinson said:
...snip...The invisible objects that stars rotate around might be what we think of when we say "black holes", but so far it isn't like we have photographic evidence that there are black holes.

They could be neutron stars, or something we don't know about yet. Same for the massive objects causing all those huge jets of matter and energy to go shooting across the Universe, at almost the speed of light.
...snip...
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We do have photographic evidence that there are black holes. The UCLA Galactic Center Group has been photographing the center of our galaxy for many years (since at least 1995). They noted that all of the stars close to the center has high proper motions. There are 7 stars that move enough so that their orbits can be determined. They are orbiting around a common object. The mass of that object is 3.7 million solar masses. The maximum radius of the object is 45 AU. The object does no appear in visible light. However astronomy is not limited to visible light and x-ray "photographs" show an x-ray emitting object in the same place. To summarize, we have photographic evidence of an object that has
  • a mass of 3.7 million solar masses.
  • a maximum size of 45 AU.
  • no visible light emission.
  • x-rays being emitted from close by.
This is basically the definition of a black hole.

As for neutron stars - it was way too massive for that.
 
Well then, that is the sort of observation and calculation that leads to thinking there is a black hole there. Isn't it?

Unless gravity is somehow different there, (unlikely), or our observations are wrong, (possible), or the calculations are wrong, (very unlikely), that object fits our theory of a black hole.
 
A dead star with a weight of less then 1.4 solar masses will be a white-dwarf star (and as it cools it becomes a black-dwarf star) about the size of the earth, anything above that in weight is too much for the electron force to stop and will collapse into a neutron star with is about 10 to 20 miles in size, anything above about 3 to 3.2 solar masses is to much for the nuclear force to stop and it will then collapse into a black-hole.

Paul

:) :) :)
 
Black holes are a tricky question. I think that much of what you read about them is all hype, and few predictions about them or how they work have turned out correct.

I think that nearly all BH candidates can be explained by dense plasma objects instead, whether neutron stars, magnetars, white dwarfs, or anything similar. Especially the supermassiveblackholes that are thought to exist at the centre of galaxies. They were once belived to be required for energy reasons. But nuclear burning (H to Fe) is almost as efficient a lamp as black hole accretion, yielding the guaranteed <1% of the rest energy, and is suggested the fact that quasar BLR spectra show ~> 1000-fold metal enrichment compared with solar abundances, and there are problems with the missing mass, the strengths of their winds, their hard spectra peaking at about TeV energies (the heat radiation of a swallowing black hole is thought to culminate near KeV), and a few more things more easily explained by a neutron star, or other similar dense objects including a dense accretion disk.

I take a similar view to (the late) Victor Ambartsuman, Hoyle, and also the opinion of Wolfgang Kundt, who bears many scars from going against the grain on the idea of black holes.


http://www.astro.uni-bonn.de/~wkundt/
Black Holes

Black Holes (BHs) describe the ultimate state of sufficiently compressed matter of arbitrary mass: mini ( 1015g), midi, and maxi ( 1034g). The literature talks of more than 102 of identified (maxi) BHs, both of stellar mass (101 ± 0.5 Msun, in X-ray binaries), and of galactic mass (supermassive, 107.5 ± 2 Msun, in the nuclei of galaxies). Yet there are hurdles to BH formation, such as centrifugal, radiative, and nuclear detonative - hence BHs are likely very rare - and what has been proposed is too variable and has too strong winds, and too hard a spectrum for an accreting BH. It conforms much better with a dense accretion disk, either around a neutron star, or the central part of a galactic disk.[....]
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What I find more fascinating is the reaction Kundt gets from other scientists for having an opinion different to theirs. Disgraceful comes to mind.

http://arxiv.org/abs/astro-ph/9810059
The Gold Effect: Odyssey of Scientific Research

Seventy-nine physical problems are listed and explained with whose proposed solutions I do not agree. Such disagreements -- even though some of them may simply reflect our preliminary insight into the laws of nature -- have occasionally caused deplorable damage to personal relationships.
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And this list was later explored in the recent popular book; Against the Tide: A Critical Review by Scientists of How Physics and Astronomy Get Done, which also comes to the conclusion that this sort of attitude towards different than normal ideas is the main obsticle faced by cosmology and astronomy. I cant see how any progress can be made if new theories are dismissed before even being developed fully for simply being inconsistant with the current scientific trend.

I guess i'm just more open minded than most other astronomers. Not necissarily a good thing though, half the time you dont know what your letting in :)
 
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Reality Check said:
To summarize, we have photographic evidence of an object that has
  • a mass of 3.7 million solar masses.
  • a maximum size of 45 AU.
  • no visible light emission.
  • x-rays being emitted from close by.
This is basically the definition of a black hole.

As for neutron stars - it was way too massive for that.
Click to expand...

Excellent Reality Check (pun intended :))

Here's another related link: http://www.mpe.mpg.de/ir/GC/res_s2orbit.php?lang=en
 
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Zeuzzz: An invisible body of plasma with a mass of 3.7 million solar masses in a radius of 45 AU?
You do the math and tell us a few small things
  • How do electromagnetic forces prevent the plasma from forming a neutron star?
  • How do the nuclear forces prevent this neutron star from collapsing into a black hole?
  • Just what are the parameters of this "plasma" - Debye screening length, electron plasma frequency, degree of ionization, etc.?
 
If you keep thinking of a spherical mass of 3.7 million sols there is no way to avoid the collapse into a black hole. But if this is a spinning disk with a radius of 45 AU and a mean density equivalent to the earth, it would be less that 10,000 km thick. Gravity on this "world" would be normal to the surface and only a few G's.
 
Reality Check said:
Zeuzzz: An invisible body of plasma with a mass of 3.7 million solar masses in a radius of 45 AU?
You do the math and tell us a few small things
  • How do electromagnetic forces prevent the plasma from forming a neutron star?
  • How do the nuclear forces prevent this neutron star from collapsing into a black hole?
  • Just what are the parameters of this "plasma" - Debye screening length, electron plasma frequency, degree of ionization, etc.?
Click to expand...
RC,

Your questions/statements contain a key assumption concerning consistency (and another on 'math'); I think Zeuzzz' posting record is crystal clear ... consistency is entirely optional ... (and math too perhaps).
 
DeiRenDopa said:
RC,

Your questions/statements contain a key assumption concerning consistency (and another on 'math'); I think Zeuzzz' posting record is crystal clear ... consistency is entirely optional ... (and math too perhaps).
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Without consistency, you have no science.

Paul

:) :) :)
 
JEROME DA GNOME said:
Wrong.

Do you find it is much easier to presume an avatar as this allows one not to have to think?
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I wasn't looking at your avatar, I was looking at your posts. However, if you claim not to believe in Sky Daddy, I will be suprised, but I will take you at your word.
 
Dan O. said:
If you keep thinking of a spherical mass of 3.7 million sols there is no way to avoid the collapse into a black hole. But if this is a spinning disk with a radius of 45 AU and a mean density equivalent to the earth, it would be less that 10,000 km thick. Gravity on this "world" would be normal to the surface and only a few G's.
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That is an interesting concept. Is that from a paper? Did you come up with that?
 
robinson said:
Well then, that is the sort of observation and calculation that leads to thinking there is a black hole there. Isn't it?

Unless gravity is somehow different there, (unlikely), or our observations are wrong, (possible), or the calculations are wrong, (very unlikely), that object fits our theory of a black hole.
Click to expand...
That's the kind of thing that we've spent over 800 posts trying to get Jerome to accept, and he continues to fail. I don't know why.
 
Dan O. said:
If you keep thinking of a spherical mass of 3.7 million sols there is no way to avoid the collapse into a black hole. But if this is a spinning disk with a radius of 45 AU and a mean density equivalent to the earth, it would be less that 10,000 km thick. Gravity on this "world" would be normal to the surface and only a few G's.
Click to expand...

Pure speculation here, but, how fast would this thing have to be spinning? Why would expect in to be stable? It seems like tidal effects and coriolis forces would inevitably cause anything above or below the plane to (even 5,000 km) to collapse in. Ie the stable configuration would approach a sphere. Also where would the system get all this angular momentum?

While perhaps possible, it seems very improbable.

ETA: Also, the thing would have to be closer to an angular cross section of a sphere, not a true disc or cylinder. This is because centripital acceleration would not oppose any matter perpendicular to the plane.
 
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I read about the concept years ago in conjunction with Ring World and Dyson spheres. In the ideal case of no thickness the centrifugal force due to rotation can exactly balance the gravity due to the mass closer to the hub (assuming I did the math right so many years ago). The rotation rate would be the same as a planet 45 AU from a 3.7 million solar mass sun which I work out as a little under 5 hours.

ETA: The outer rim would be traveling at .17c

see also: Alderson diskWP
 
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Dan O. said:
I read about the concept years ago in conjunction with Ring World and Dyson spheres. In the ideal case of no thickness the centrifugal force due to rotation can exactly balance the gravity due to the mass closer to the hub (assuming I did the math right so many years ago). The rotation rate would be the same as a planet 45 AU from a 3.7 million solar mass sun which I work out as a little under 5 hours.

ETA: The outer rim would be traveling at .17c

see also: Alderson diskWP
Click to expand...

149598000*45*2*pi =4.2297838 × 1010 km

4.2 * 1010 / (5*60*60) = 2 349 879.89 km/s = 2.3 * 109 m/s

2.3 * 109 / 299792458 = 7.8 c

I get 7.8 c

Another check on this is to note that light can go 1 AU in 8 minutes.
That means that is can go 5*60/8 = 37.5 AU in 5 hours

45*2*pi / 37.5 = 7.5 c

Also the article on the Alderson disk mentions that it would require unphysical material strengths. Would this be a solid disk? I would think that segments at different radii would tend to rotate at different angular velocities. Or is there some particular characteristic of this solution that prevents that?
 
I'll need to recheck the formulas for the rotating disk. Right now I am coming up with needing a wedge shape in order to have a uniform orbital period at any radius.
 
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