Something new under the sun

[sol invictus]

Here's a well-written little anecdote our local crackpots might benefit from reading:

http://www.edge.org/q2008/q08_9.html#carroll

 

[iantresman]

If you believe that, you don't believe in general relativity. The inevitability of the formation of black holes when the total energy within a region reaches a certain cutoff (and it doesn't matter what form the energy takes - adding magnetic fields makes it worse) can be proven rigorously.

Do you believe in GR?

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I don't believe that Carlqvist and Alfvén's model of plasma cloud collapse has anything to do with black holes, and certainly has no relationship to whether I believe in general relativity or not.

It does look like their paper is based on known laboratory physics of plasmas, and they have made their case quite rigorously.

 

[sol invictus]

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I don't believe that Carlqvist and Alfvén's model of plasma cloud collapse has anything to do with black holes, and certainly has no relationship to whether I believe in general relativity or not.

You claimed magnetic fields can stop gravitational collapse. According to GR that is simply false (and no laboratory experiment on earth has any direct bearing on this) if the region is either sufficiently large (at fixed density) or sufficiently dense (at fixed size). Such regions always collapse to form BHs, period. That's a good example of where you can get utterly wrong answers by naively extrapolating the results of meter-sized experiments to astrophysical scales.

The regions at the centers of galaxies are known from observations and simulations to be incredibly dense. I don't know for certain whether they are proven to exceed the bounds I just mentioned (and therefore must be black holes in GR is correct), but they at least come close.

 

[MattusMaximus]

I've not said black holes are necessarily a fiction (although has anyone actually seen one?) ... just their ubiquitous use to explain away every little unexplainable observation Big Bang encounters. Especially when other physics is already available that would seem to explain those observations. Plus the fact that they now seem to number as many as stars in the heaven.

Again, you purposefully confuse "observable" with "visible". Black holes are detected indirectly by their gravitational effects on other objects, accretion disks (which we've imaged), emissions from the accretion disks, and polar jets.

Using your line of thinking, I suppose that you will maintain that ultra-violet & infra-red radiation as well as the wind are all not "observable" because they aren't visible.

Actually, general relativity did not "predict" dark energy. Lambda was actually added to the equation by Einstein in order to make the universe static. And for no other reason.

I concede this point concerning Einstein - that term was inserted by Einstein as a "correction." However, it should be noted that another physicist, Alexander Friedman, did use GR to predict such a cosmological constant (what we now call "dark energy") in 1922...

http://en.wikipedia.org/wiki/Alexander_Alexandrovich_Friedman

"He discovered the expanding-universe solution to general relativity field equations in 1922, which was corroborated by Edwin Hubble's observations in 1929.(Ferguson, 1991: 67). Friedman's 1924 papers, including "Über die Möglichkeit einer Welt mit konstanter negativer Krümmung des Raumes" (On the possibility of a world with constant negative curvature of space) published by the German physics journal Zeitschrift für Physik (Vol. 21, pp. 326-332), demonstrated that he had command of all three Friedman models describing positive, zero and negative curvature respectively, a decade before Robertson and Walker published their analysis.

This dynamical cosmological model of general relativity would come to form the standard for the Big Bang and steady state theories. Friedman's work supports both theories equally, so it was not until the detection of the cosmic microwave background radiation that the steady state theory was abandoned in favor of the current favorite Big Bang paradigm."

There is more to general relativity than just Einstein, pal...

And far as it "predicting" black holes is concerned, Einstein actually said that a theory that incorporates the existance of singularities should be avoided.

And Einstein was wrong. He was wrong about a lot of stuff, like his opposition to a fully developed quantum theory.

One month after the black hole concept was first introduced in 1939 by Oppenheimer and a graduate student, Einstein wrote a paper ("On a stationary system with spherical symmetry consisting of many gravitating masses", Annals of Mathematics, Oct. 1939, vol 40, No 4, pp 922-936) wherein he stated (calling black holes "Schwartzschild singularities") that "The essential result of this investigation is a clear understanding as to why the ‘Schwartzschild singularities’ do not exist in physical reality."

The concept of infinite gravitational collapse (what we now call "black holes") into a singularity was first proposed in 1915 by Karl Schwartzchild, you moron. Where do you think the term "Schwartzchild singularities" came from?

Here's a link if you don't believe me:
http://en.wikipedia.org/wiki/Schwarzschild_metric

"The Schwarzschild solution is named in honour of its discoverer Karl Schwarzschild, who found the solution in 1915, only about a month after the publication of Einstein's theory of general relativity. It was the first exact solution of the Einstein field equations other than the trivial flat space solution. Schwarzschild had little time to think about his solution. He died shortly after his paper was published, as a result of a disease he contracted while serving in the German army during World War I."

See?! Einstein's equations did predict the existence of black holes, though they weren't called "black holes" until later. Duh...

And here is what Einstein wrote in 1945 (Albert Einstein, The Meaning of Relativity) regarding the big-bang singularity: "Theoretical doubts [concerning the creation of the universe] are based on the fact that [at the] beginning of the expansion, the metric becomes singular and the density becomes infinite. . . In reality, space will probably be of a uniform character, and the present [relativity] theory will be valid only as a limiting case. . . One may not therefore assume the validity of the equations for very high density of field and of matter, and one may not conclude that the 'beginning of the expansion' must mean a singularity in the mathematical sense. All we have to realize is that the equations may not be continued over such regions."

And Einstein was wrong. His theory was right, but he just didn't want to accept its conclusions concerning an expanding spacetime. The fact that you keep harping on the incorrect conclusions drawn by Einstein again show how you keep missing the point and attempting to present information out of context.

Typical woo behavior...

So it's probably inaccurate to claim GR predicted black holes or BBC.

You're an idiot. Learn some history in addition to physics.

No, you need only adopt either Narlikar's QSSC or SCC cosmology. Both still adhere to GR but both do not require a BB or ubiquitous BHs.

More Big Gnomes?

 

[MattusMaximus]

Here's a well-written little anecdote our local crackpots might benefit from reading:

http://www.edge.org/q2008/q08_9.html#carroll

Hilarious! LOL

 

[Cuddles]

One month after the black hole concept was first introduced in 1939 by Oppenheimer and a graduate student, Einstein wrote a paper ("On a stationary system with spherical symmetry consisting of many gravitating masses", Annals of Mathematics, Oct. 1939, vol 40, No 4, pp 922-936) wherein he stated (calling black holes "Schwartzschild singularities") that "The essential result of this investigation is a clear understanding as to why the ‘Schwartzschild singularities’ do not exist in physical reality."

As MattusMaximus has already pointed out, black holes were predicted well before you seem to think they were. However, I should also point out that this quote is technically correct. Schwartzschild singularities do not exist in physical reality. The reason for this is very simple - conservation of angular momentum. A Schwartzschild black hole does not rotate. Since it is essentially impossible to have any collection of matter with zero angular momentum, and even if such a thing happened, the first interaction with anything else would spoil it. Schwartzschild black holes are theoretically possible under general relativity, but can't actually happen in the real world.

However, this says absolutely nothing about black holes in general. Schwartzschild ones were the first found, being by far the simplest ones to find, but there are many other types of black hole predicted by general relativity. Some of them also have problems that mean they are unlikely, or impossible, in the real world. Many of them don't.

People who deny black holes are faced with a similar problem to that of creationists. Creationists love to claim that evolution doesn't happen, the problem is that evolution is an inevitable conequence of certain conditions. If you have imperfect self-replicators and competition for limited resources, there is no logical way to avoid evolution happening. The same is true of black holes. They are simply an inevitable consequence of relativity. In fact, they are an inevitable consequence of a finite speed of light. The problem isn't on our side, it's that the deniers have to come up with some logical explanation of how it can be possible for them not to exist.

 

[sol invictus]

As MattusMaximus has already pointed out, black holes were predicted well before you seem to think they were. However, I should also point out that this quote is technically correct. Schwartzschild singularities do not exist in physical reality. The reason for this is very simple - conservation of angular momentum. A Schwartzschild black hole does not rotate. Since it is essentially impossible to have any collection of matter with zero angular momentum, and even if such a thing happened, the first interaction with anything else would spoil it. Schwartzschild black holes are theoretically possible under general relativity, but can't actually happen in the real world.

Well... I haven't read that paper, but I don't think that's the kind of "do not exist" Einstein had in mind. Rotating black holes are smoothly connected to Schwarzschild in the sense that when you take the angular momentum small, the solution reduces to Schwarzschild. That's clear outside the hole, but it's true even inside if you take any perturbation away from exact rotational symmetry (because the inner Cauchy horizon is unstable to forming a spacelike singularity). And anyway, rotating holes have singularities too.

The real solution to the problem of singularities is cosmic censorship - black hole singularities (it seems) are always cloaked by event horizons. As long as you're not unfortunate enough to fall into one, physics remains perfectly under control and you can predict the results of any experiment you could do with very good accuracy.

 

[Dancing David]

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I think you're not far wrong. The magnetic field in a plasma cloud may stop gravitational collapse. This was investigated by Per Carlqvist in 1988, resulting in the eponymous Carlqvist Relation, peer reviewed in (ref, full text). As Carlqvist and Hannes Alfvén mention in another paper, the magnetic field may either counteract, or aid the contraction of cloud resulting in a pinch.

Sorry Ian, but how does that allow the plasmoid to overcome gravity and where does the energy come from to maintain against gravity.

The issue is that the mass of the plasmoid will still cause it to contract, and at some point it has to get more energy to sustain against the pull of gravity.

I did not see where the Carlqvist relation provides for the repulsive force and it still will require energy to maintain against gravitational collapse.

It is shown that magnetic fields, which have generally been regarded as obstructing the condensation of interstellar clouds, will promote the contraction of such clouds under certain conditions and may even constitute the main mechanism for contraction.

is what the abstract for the linked paper says.

 

[Dancing David]

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I don't believe that Carlqvist and Alfvén's model of plasma cloud collapse has anything to do with black holes, and certainly has no relationship to whether I believe in general relativity or not.

It does look like their paper is based on known laboratory physics of plasmas, and they have made their case quite rigorously.

Uh, the abstract talks about magnetic fields causing a collapse, not maintaining a plasmoid against gravitational collapse.

You can't escape the black hole, light has been demonstrated to be bent by gravity, if you bend it enough you have a black hole.

 

[iantresman]

You claimed magnetic fields can stop gravitational collapse.

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I don't think I did. I noted that Carlqvist's and Alfvén's paper said that magnetic fields may counteract gravitation collapse of a plasma cloud. I refer you to:

II.4. Do Magnetic Fields Aid or Counteract a Compression? (p.498) in "Interstellar clouds and the formation of stars" Astrophysics and Space Science, vol. 55, no. 2, May 1978, p. 487-509.​

Now, it may be that while magnetic fields counteract gravitational collapse, they may not be able to prevent it; once grain sizes increase, gravity certainly plays the dominant role. But magnetic plasmas whose particle size is less than grains, electromagnetic forces dominate. Period. (See Gravitoelectrodynamics)

 

[sol invictus]

Sorry Ian, but how does that allow the plasmoid to overcome gravity and where does the energy come from to maintain against gravity.

The issue is that the mass of the plasmoid will still cause it to contract, and at some point it has to get more energy to sustain against the pull of gravity.

Actually it's not like that. Gravity acts on all forms of energy. There is no way to add energy to prevent gravitational collapse - once you are close to the bound, adding energy (of any form) makes the problem worse, not better.

Now, it may be that while magnetic fields counteract gravitational collapse, they may not be able to prevent it; once grain sizes increase, gravity certainly plays the dominant role. But magnetic plasmas whose particle size is less than grains, electromagnetic forces dominate. Period. (See Gravitoelectrodynamics)

OK, that is a concrete claim for once. It's also totally wrong (as usual with plasma cosmology) - and it's wrong at a level that anybody who has studied even a little general relativity will recognize immediately.

It violates singularity theorems which have been proven rigorously (by Stephen Hawking and others).

The conditions for gravitational collapse have nothing to do with particle or "grain" sizes, or any other local characteristic of the fluid or matter in question. They are extremely simple, and depend only on the total mass in some region and the size of that region. Such conditions are non-local and simply cannot be expressed in terms of some characteristics of the particles making up the plasma (or whatever).

 

[MattusMaximus]

Uh, the abstract talks about magnetic fields causing a collapse, not maintaining a plasmoid against gravitational collapse.

You can't escape the black hole, light has been demonstrated to be bent by gravity, if you bend it enough you have a black hole.

And light is an electromagnetic wave, which means that magnetic effects are already competing against gravity near a black hole...

... and they lose. Gravity wins.

 

[iantresman]

Actually it's not like that. Gravity acts on all forms of energy. There is no way to add energy to prevent gravitational collapse - once you are close to the bound, adding energy (of any form) makes the problem worse, not better.

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I stand corrected. It just occurred to me that you are referring to "Gravitational Collapse" of a massive body, whereas I was discussing the collapse, gravitationally, of a plasma cloud (a non-massive body).

 

[sol invictus]

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I stand corrected. It just occurred to me that you are referring to "Gravitational Collapse" of a massive body, whereas I was discussing the collapse, gravitationally, of a plasma cloud (a non-massive body).

I am talking about plasma clouds. I'm also talking about the collapse of massive bodies, giant tubes of toothpaste, regions full of visible light, and absolutely everything else in the universe.

Again, this argument is completely independent of the details of the stuff inside. When I said it depends on the total mass, I meant the energy equivalent - so if there is some mass and some energy, the condition for collapse depends on the total of the two.

 

[Dancing David]

Actually it's not like that. Gravity acts on all forms of energy. There is no way to add energy to prevent gravitational collapse - once you are close to the bound, adding energy (of any form) makes the problem worse, not better.



.

Cool, I just figured that there was an idea that somehow the magnetism was holding the plasma in expansion against gravitational attraction. So i assumed that energy would would get used and have to be replaced to have a plasmoid that does not contract.

 

[Zeuzzz]

Originally Posted by iantresman
Now, it may be that while magnetic fields counteract gravitational collapse, they may not be able to prevent it; once grain sizes increase, gravity certainly plays the dominant role. But magnetic plasmas whose particle size is less than grains, electromagnetic forces dominate. Period.

OK, that is a concrete claim for once. It's also totally wrong (as usual with plasma cosmology) - and it's wrong at a level that anybody who has studied even a little general relativity will recognize immediately.

Well i have studied it (although briefly), and I see nothing wrong with that statement. This the whole probem with gravity, it barely has any effect at a particle level at all, only on large scales, and so is very hard to test. Gravity at atom/molecule level is negligable, and only comes into play significantly when you get above dust size, so I see nothing wrong with the statement that small particles are more effected by EM forces.

Millikan made an oil drop hover by applying an electric field to it in his original experiment, making the electric force surpass the force of gravity on something as large as a oil drop. When it comes to dust size and below (until you reach the weak and strong force), EM forces really do reign supreme.

Improvements in our knowledge of the absolute value of the Newtonian gravitational constant, G, have come very slowly over the years. Most other constants of nature are known (and some even predictable) to parts per billion, or parts per million at worst. However, G stands mysteriously alone, its history being that of a quantity which is extremely difficult to measure and which remains virtually isolated from the theoretical structure of the rest of physics. Several attempts aimed at changing this situation are now underway, but the most recent experimental results have once again produced conflicting values of G and, in spite of some progress and much interest, there remains to date no universally accepted way of predicting its absolute value.

It violates singularity theorems which have been proven rigorously (by Stephen Hawking and others).

How does the fact that EM forces far dominate gravity at small scales violate singularity theorem?

The conditions for gravitational collapse have nothing to do with particle or "grain" sizes, or any other local characteristic of the fluid or matter in question. They are extremely simple, and depend only on the total mass in some region and the size of that region.

Yes, those gravitational collapse equations are very simple, and dont take into account many variables. I totally agree.



I have a question that has been bugging me for a while, maybe you could answer it Sol, or anyone else.

Take a large, Isolated, nebula that is collapsing in on itself, and contains an overall charge of any value spread out across its length (lets say 20 C overall). Since it is isolated, there is no surrounding conducting medium to discharge the cloud.

Now the only thing I can see resulting from this situation is a star with a charge on it. If the gravitational force is compressing the plasma to a certain size, as this happens the repulsive force of the similar charges inside the plasma will increase with time, until the compressive force of gravity equals the repulsive force of the ions, leading to a state of equilibrium where the collapsing force equals the repulsive force. I think this may be why some people think that gravity itself plays a part in 'charging' stars. Would this work? i can't think of a reason why this would not happen, given the original conditions.

 

[MattusMaximus]

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I stand corrected. It just occurred to me that you are referring to "Gravitational Collapse" of a massive body, whereas I was discussing the collapse, gravitationally, of a plasma cloud (a non-massive body).

You're kidding me, right? As Sol just pointed out, this makes no sense whatsoever...

Plasmas are basically composed of electrons and ions, which are made of protons & neutrons, all of which have mass -- so plasma clouds have mass!

But beside that point, iantresman is again ignoring the effects of relativity theory (which you EU-PU woos accept, I think) because even if the plasma was non-massive (pure energy) it would still be affected by gravity due to...

E = mc²
This is precisely the reason why light (photons) is affected by gravity. Photons are massless, yet they have a mass equivalence by that equation, so the path of a photon is bent by a gravitational field.

Yet another example of butchering well-known physics to make their crack-pipe "theories" have some semblance of reality. If these EU-PU woos keep flapping their arms like this, eventually they're going to achieve liftoff

 

[sol invictus]

Well i have studied it (although briefly), and I see nothing wrong with that statement.

Then you didn't understand it - which we already knew.

This the whole probem with gravity, it barely has any effect at a particle level at all, only on large scales, and so is very hard to test. Gravity at atom/molecule level is negligable, and only comes into play significantly when you get above dust size, so I see nothing wrong with the statement that small particles are more effected by EM forces.

It's completely false, that's what's wrong with it.

Look - your argument is like saying, I don't know - the existence of nuclear bombs is not very important for the growth of trees. That's a true statement... unless there's a nuclear war and all the trees die during the resultant nuclear winter.

It is true that gravity is a much weaker force than EM when it's acting only on two charged particles. But the fundamental fact about physics that you guys seem not to be able to comprehend is that it's a much, much stronger force than EM when it's acting on lots of particles. That's true even if the particles all had the same charge, if there are enough of them.

Millikan made an oil drop hover by applying an electric field to it in his original experiment, making the electric force surpass the force of gravity on something as large as a oil drop. When it comes to dust size and below (until you reach the weak and strong force), EM forces really do reign supreme.

Had Millikan tried to do an experiment with an oil drop the size of the galaxy, the answer would have been rather different. Or to make a better analogy, if you had a trillion Millikan oil drop experiments distributed in some region, their mutual gravitational attraction would cause them to form a black hole and get crunched at the singularity, thus rather strongly affecting the results of each.

How does the fact that EM forces far dominate gravity at small scales violate singularity theorem?

The claim was that we can ignore gravitational forces. That is false and violates the theorem if the cloud of plasma is large enough, regardless of what precisely it's composed of.

Yes, those gravitational collapse equations are very simple, and dont take into account many variables. I totally agree.

They take into account all the relevant quantities. In this case, simple=general.

I have a question that has been bugging me for a while, maybe you could answer it Sol, or anyone else.

Take a large, Isolated, nebula that is collapsing in on itself, and contains an overall charge of any value spread out across its length (lets say 20 C overall). Since it is isolated, there is no surrounding conducting medium to discharge the cloud.

Now the only thing I can see resulting from this situation is a star with a charge on it.

The result could be a cloud of gas, or it could be a star, or it could be a black hole, all depending on various numbers (such as the size and density of the cloud, the temperature of the particles inside, and angular momentum, etc.). The charge might fly out away from the rest of the cloud (if it's attached to a small number of particles), or it might remain bound. There are many possibilities.

 

[MattusMaximus]

Now the only thing I can see resulting from this situation is a star with a charge on it. If the gravitational force is compressing the plasma to a certain size, as this happens the repulsive force of the similar charges inside the plasma will increase with time, until the compressive force of gravity equals the repulsive force of the ions, leading to a state of equilibrium where the collapsing force equals the repulsive force. I think this may be why some people think that gravity itself plays a part in 'charging' stars. Would this work? i can't think of a reason why this would not happen, given the original conditions.

Even if it did happen, I don't see how this gives any validity to the Electric Universe claims because these effects would not be significant on interstellar and larger scales.

This is by the admission of the people who wrote the paper that Zeuzzz continually references on this point... they conclude that such electrostatic effects would be weaker than gravity by a factor of 10³⁶. That's right, the people who wrote the paper on electrostatically-charged stars say that on large scales, gravity wins!

Yet Zeuzzz keeps coming back again and again to the same old argument, taking that paper out of context, and this time trying from a different direction. The last time is outlined here in post #188 of this thread.

Zeuzzz and the other EU-PU woos - no matter how many times you make a bad argument, it is still a bad argument. Repeating it again and again just makes you look like a fool, a liar, or both.

 

[Ziggurat]

How does the fact that EM forces far dominate gravity at small scales violate singularity theorem?

Gravity, unlike E&M, is nonlinear. So let's suppose we take some cloud with some mass density and some charge density, such that the gravitational attraction balances the electric repulsion. Now, if gravity were linear, then we could take this same ratio and apply it to a more dense (both charge and mass) system, or a larger system of the same density, and find the same result. But it's not. It's nonlinear, which means that you can generate infinite forces with finite mass (which is what the event horizon of a black hole is). You cannot do that with electromagnetism. So what happens is that past a certain mass, it no longer matters how strong you try to make the electromagnetic forces: gravity has already won, collapse is inevitable. and it will only accelerate (due to the nonlinearity) as that collapse proceeds.