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August 11th, 2011, 08:27 AM
is there a single proof of a singularity in nature?
Gravitational singularities (i.e. black holes) are predicted to exist by general relativity- if you compress a body of given mass down to a sphere of radius which is smaller than the objects' Schwarzschild Radius
then the escape velocity of such a body would exceed the speed of light; such an object is not necessarily a singularity- but black holes have this property, and our best theories predict there to be some form of gravitational singularity at the centre of a black hole. The very nature of a black hole means that we may never actually observe such a singularity due to not being able to see past the event horizon- light cannot escape past the horizon.
I think a lot of people suspect that singularities show a deficiency in the current theories, but since they work so well everywhere else, we can't simply throw them out.
The main shortcoming is that to get to the singularity you have to ignore quantum theory. Physics won't let you. Current theory does not know what is really going on inside a black hole.
I'm of the opinion that singularities don't exist as the concept seems absurd to me. In your example of black holes, I would suggest an alternative theory to discredit the singularity. Perhaps blackholes lead to another dimension, another universe or matter converts back into energy. I'm not suggesting for a second that I know the answer. I just don't believe the answer is a singularity.Originally Posted by x(x-y)
Gravitational singularities (i.e. black holes) are predicted to exist by general relativity- if you compress a body of given mass down to a sphere of radius which is smaller than the objects' Schwarzschild Radius
then the escape velocity of such a body would exceed the speed of light; such an object is not necessarily a singularity- but black holes have this property, and our best theories predict there to be some form of gravitational singularity at the centre of a black hole. The very nature of a black hole means that we may never actually observe such a singularity due to not being able to see past the event horizon- light cannot escape past the horizon.
Edit: sorry, didn't grammar check this very well.
Don't count on your intuition. Human intuition is based on a certain, fairly narrow range of experiences and general fails outside of that. That said, there are better reasons to suspect that a true singularity doesn't really exist. (Random guessing as to what does exist at the center of a black hole isn't particularly productive though.)
Seeing as gravitational singularities are predicted by GR, and GR has remained standing against all of our experiments so far, there is a reason to accept the existence of singularities- that is not to say that they certainly exist, however.
I was wondering, though, if anybody could tell me- are singularities a problem of renormalisation in physics? I would've thought they are, so are physicists trying to rid singularities from theories (renormalising the infinities produced by the equations).
By single proof of a singularity, are you expecting someone to say 'yeah, I've got one in my backyard' ?
The contents of an event horizon are by definition, unveryfiable, since no information can leave the horizon.
And since the universe will not allow a naked singularity, all we have are various mathematical models.
You mock my question as if it were an ignorant question to ask. You could place this same hinted stupidity onto most any question asked about anything. I simply did not know of any singularities that existed in nature apart from perhaps black holes and thus I asked the question.
I was aware of this trait of black holes and perhaps I should have excluded black holes from my question as I was wondering about any singularities other than black holes.
What do you mean by "naked singularity"?
On a semi unrelated note, I read recently on a post that there is a big difference between escape velocity (projectile) and simply elevating yourself away from an object. The immediate question that springs to mind would be "can something 'elevate' itself out of a blackhole?", but I already know the answer to be no because nothing escapes a black hole fullstop. So my question then is "why would this 'elevation' not work"?
Edit: incase I haven't been clear. I compare escape velocity (shooting a gun at the sky) versus elevating an object (not the technical word used but I cant recall the technical word and I would compare this to climbing a ladder all the way out of the atmosphere)
This is a singularity which is not "shielded" by some sort of event horizon- i.e. a naked singularity could be seen by an outside observer, which is impossible as far as we know due to the existence of event horizons; boundaries at which past this point, the speed required to leave the horizon exceeds c.
The very same reason as above, the velocity required to leave the event horizon exceeds c- and nothing, as far as our current theories tell us, (except for the "expansion of space" itself) can exceed light speed.
You are in good company, as a lot of physicists tend to agree on the uncertainty that an actual singularity exists at the centre of a black hole.
I cannot really comment on the speculation that black holes lead to another dimension, but there is the theoretical possibility of a wormhole at the centre a "rotating" black hole.
Journey into and through a Reissner-Nordström black hole
I didn't intend to 'mock' your question and I'm sorry if I came across that way.
You ask for an example of a singularity that you may be familiar with, and I should have said that no-one is familiar with any type of singularity as none has ever been observed. A singularity is the collapse of any size object to dimensionless point size, ie anything, no matter how small, will become a black hole, and the universe will shield it with an event horizon.
As for the difference between shooting a bullet in the air and actually having the bullet escape the gravitational field, the bullet is actually following an orbit while escape velocity breaks the orbit and is free. All captive stable orbits around a singularity are outside the event horizon, any that pass into the horizon have only the singularity in their future.
My original question has been misinterpreted. When I asked about singularitys, everyone jumped strait to blackholes as if that were the only definition of a singularity.
Other singularitys:
There are plenty of graphs that have singularitys. I would list one if I was a little more competent in maths.
Some people suggest at a technology singularity (not saying I believe this but it stands as an example).
It is proposed that the expansion of space might accelerate into a singularity.
The amount of energy required to accelerate matter to higher and higher speeds (approaching light speed).
I realize these are not the greatest examples but it stands to clarify my question. Is there any observable singularity (not just theoretical but practically shown) that nature or man has created.
Edit: Apon reading over my post I realize it could appear condescending or insulting, this is not the intent, I only mean to clarify my question.
A singularity is, by definition, a deficiency in a theory. It is a place where the mathematics of a theory fail to produce a physically meaningful description. The most famous of these seem to be the gravitational singularities where there is infinite density, thus the popular misuse of the term.
You are confusing infinities with singularities in your examples- they are, actually, not the same; singularities are infinitesimally small points in space-time, infinity itself is a concept of the set of real numbers "never ending"- it's interesting to note that infinity is not included in the set of real number.
Graphs such as the tan x graph or exponential graphs have an increasing (or decreasing) range without bound- i.e. they are asymptotic, for example ifthen
as x approaches 90° (
).
"... singularities are infinitesimally small points in space-time ..." Are you sure about this? does a singularity HAVE to be a point of matter? I get what you are saying about infinitys and I suspected that as I was typing some of my examples, but what about the technology singularity? "technology singularity" Aren't even my own words so I wouldv'e assumed the terminology is correct.
First define a "singularity". Some define it as any number divided by zero. In mathematics, anything is possible. In the real world, what is "zero"? It is the absence of something. So what is something divided by the absence of something? Doesn't make much sense, does it?
In the complex plane of the Laplace transform, we can utilize singularities such as poles and zeroes to good advants. However, they never exist in reality, since you have to integrate over infinite time to reach infinity.
Those who talk about singularities in the universe, such as "black holes" can never prove that they exist. They are only abstract theories. Very convenient to discuss something that cannot be measured. That is the good and bad about cosmology.
As Professor Max Planck put it, infinity is simply a "very large number". That works for me.
You give in too easily, "somefoolishfool'.
No, he's correct. Singularities are the result of divergent equations. Commonly, this may be referred to as a division by zero problem.
If we are discussing singularities as 'predicted' by GR, and I say predicted tongue-in-cheek because GR breaks down at the singular point, then we need to consider the GR field equations. By definition they need be smoothly varying in space/time such that the derivative is smooth and continuous. Any point where there is a discontinuity or an abrupt change such as due to the infinite curvature at the singular point, indicates a breakdown of GR.
If we are considering any other definition of singularity, then I don't know.
My somewhat educated opinion is that a singularity is a mathematical phenomenon only, and does not exist in nature. There is no known example of any singularity being observed. How could it be observed? Even in mathematics we do not deal with infinity. At the point where something would go to infinity, we say it is undefined.
A better, more cmplete description of singular points and their effect on GR is given by a former member ( who gave a bit of needed sanity to this forum as he was a Doctor ), and states...
"A region of spacetime is said to be singular if timelike geodesics cannot be extended in the forward or backward direction. In the case of the big bang singularity it is the backward direction that fails. In te case of black holes it the forward direction that fails."
In other words GR allows for singular points but cannot deal with them as they fall outside boundary conditions.
So he's kind of saying that it's ok for something to be impossible as long as we can't observe it in the act of being impossible :P.
I found that quite hard to understand to be honest but I think I got the gst of it.
Not quite, nothing is stated about possibility or impossibility.
As an example Newton's laws of motion do not allow of disallow faster than light travel, but clearly relativistic speeds fall outside the boundary conditions, and are only valid for slow non-relativistic speeds.
It is the same for singularities in GR. The theory cannot deal with them. What is needed is a quantum field description of gravity.
A bit off topic, but quantum mechanics seems to allow some "impossible" things as long as the universe doesn't have time to catch on. Though as MigL mentioned, this is really more a failing of our current notion of impossible.
That said, the singularity in the center of a black hole may be something completely different and we just don't have the theories to describe it at the moment.
There is no real proof of "black holes". Einstein predicted them on the premise that so much matter would be accumulated that no object could escape it. The only evidence is from radiation from deep space. But black holes were not expected to radiate anything.
Same thing for backward time. These are all theories not fully supported by evidence. Some of you are just quoting theory and neglecting to cite any substantial evidence. Singular points simply do not exist in nature as supported by any substantial evidence. Again, for a singular point to exist in the complex plane, it is necessary to integrate for all time. We simply cannot do that since we do not have access to all time.
While I may agree with you regarding singularities being not possible, I believe there has already been ample indirect proof of black holes in galactic centres and as polar X-ray emitters. Do a google search.
What method do YOU propose for stopping the gravitational collapse of non-radiative masses greater than 3-4 solar mass from collapsing to a black hole ??
How do you know for sure that any non-radiative mass will collapse to a black hole? The theory depends on the assumptions and the reality of measurements. When we look out into outer space to see radiating waves, how do we know for sure what we are seeing? If nothing, including light waves, can escape from a black hole, then I would expect that a black hole would indeed appear black at any wavelength and that no type of radiation could go through it. Has any such event ever been captured? Seems to me that the theory had to be modified since it didn't comply with the original definition. Feel free to educate me on this. I am interested in your answers.
What we see comes from outside the event horizon.
Well we know that giant stars eventually go supernova. This happens because the fusible material, hydrogen becomes depleted in the core , and successive rings of Hydrogen, heliun, lithium, carbon , oxygen, etc fuse to provide the radiation pressure to counter the force of gravity. When the core is composed of iron no further fusion can occurr and gravity takes over producing first a supernova and then gravitational collapse. Look this stuff up.
We have seen the results of smallish giants ( up to about 2x sun's mass) going nova. They result in white dwarf which are composed of 'degenerate matter', ie the electron degeneracy force, also known as Chandrashekar limit and due to the pauli exclusion principle. Look this stuff up.
Medium size giants ( 2 to 5 sol masses ) also go supernova and while they blow off some mass in the explosion, they become neutron stars ( or pulsars ) which are composed of degenerate neutrons after the free electrons have ben forced into the nucleii by the unrelenting force of gravity. Incidentally this also happens to white dwarfs which continue to accrete mass from nearby stars or dust/gas clouds, and result in what has been observed numerous times and provided the yardstick by which we measure universal distances, type Ia supernovas. Look this stuff up.
For any giant stars over this size even neutron degeneracy isn't enough to stop gravity, and according to GR when a certain size of compaction is reached, the universe set up a screen to keep us from observing further events. This is called the Swartzchild radius and the event horizon. and we will never know what goes on inside since no information can ever leave. Look this stuff up.
So like I said, what method do you propose for stopping the gravitational collapse of massive, no longer radiating stars?
Maybe he is making the common mistake of equating singularities with black holes? Whether singularities exist or not, it doesn't really affect the basic concept of what constitutes a black hole. In simple terms, once the escape velocity exceeds C, you have a black hole.
By the way, AFAIK, observations have been made of stars orbiting invisible objects massive enough to be a black hole, or some similar situation. The thing is that even if we cannot see a black hole (if not for energised accretion material), then we can certainly observe their gravitational effects. Another way is to observe a lensing effect when a light source is behind the black hole in our line of sight and the black hole's gravity bends the light, though I don't think this has been observed yet.
if ur q's is based on the criteria of living things then my ans is no.....
Everything that you quote is all based on assumptions and theories. There is no thorough proof of what is happening in outer space. Einstein's theory, in fact, implies that what you see is not exactly what you see.
No.
White dwarfs have been observed as have neutron stars or pulsars. Black holes cannot be directly observed but they have been indirectly identified.
The quantum mechanics of fusion are well understood as is GR and both make accurate predictions to 9 to 12 decimal places.
The only thing we are unsure of is what happens behind the curtain of an event horizon. Everything else is based on mathematics and observations.
What is your denial based on ??
What are your theories based on ???
The fact that it doesn't 'seem right' to YOU ????
Isn't the idea of the "big bang" the only singularity that exists, the only common denominator?
A] Mass and matter are identified for gravitation.
B] All mass is thought of as concentrated in a massmiddlepoint or line.
With these premisses what else to expect then
C] blackholes ie singularities.
C is the consequence of A and B. Suppose A and B are premisses (not sure if the word applies here) from which blackholes are created for any objekt by a sudden premisse-jump B] concentrating all matter and or mass to this imaginary massmiddlepoint.
Even a simple bar of some material is made to a blackhole by a system that has these premisses a and b.
But this could never come out of this system according to the same premisses.
If one keeps A and B for thruths because they are thruths in a certain system and the system is also kept for truth...Then the system can make anything real fysics. It,s real fysics. But fysics is not thát real.
Mass in a black hole is concentrated in a single point or line? That is not possible since electrons and proton would have to unite and compress. If they were to compress, then there would be no gravity. This is simply a wild assumption.
A] Mass and matter are identified for gravitation.
B] All mass is thought of as concentrated in a massmiddlepoint or line.
With these premisses what else to expect then
C] blackholes ie singularities.
C is the consequence of A and B. Suppose A and B are premisses (not sure if the word applies here) from which blackholes are created for any objekt by a sudden premisse-jump B] concentrating all matter and or mass to this imaginary massmiddlepoint.
Even a simple bar of some material is made to a blackhole by a system that has these premisses a and b.
But this could never come out of this system according to the same premisses.
If one keeps A and B for thruths because they are thruths in a certain system and the system is also kept for truth...Then the system can make anything real fysics. It,s real fysics. But fysics is not thát real.
Again, what you view from outer space cannot be thoroughly tested and is based on assumptions without full proof.
As to whether the mass actually concentrates to a single point is unknown at this point of time, but even if it doesn't this does not preclude the existence of black holes. Al that is needed for a black hole is for the mass to be contained inside the event horizon. For a typical stellar black hole, this works out to be a volume ~30 km in radius, for the black hole at the center of the galaxy it is a sphere ~22,000,000 km in radius in which a mass of ~40,000 solar masses is enclosed. The last would only require an over-all density close to that which exists at the center of the Sun.[/quote]
That is not possible since electrons and proton would have to unite and compress.
[/quote]Which they do in neutron stars. The electrons and protons are forced together to form a single mass of neutrons. At that density, any neutron star larger than ~21 km in radius will be a black holeAnd that is simply wild speculation on your part. you are awfully quick to accuse others of that which you practice yourself.If they were to compress, then there would be no gravity. This is simply a wild assumption.
That being said, I'm going to put my moderator hat on:
This is the physics sub-forum, where we discuss established physics, if you wish to discuss your own personal ideas, the forum for that is the New Ideas and Hypotheses sub-forum.
I'm afraid I don't fully "Ghrasp" what you are trying to say here with B and after C.
A] Mass and matter are identified for gravitation.
B] All mass is thought of as concentrated in a massmiddlepoint or line.
With these premisses what else to expect then
C] blackholes ie singularities.
C is the consequence of A and B. Suppose A and B are premisses (not sure if the word applies here) from which blackholes are created for any objekt by a sudden premisse-jump B] concentrating all matter and or mass to this imaginary massmiddlepoint.
Even a simple bar of some material is made to a blackhole by a system that has these premisses a and b.
But this could never come out of this system according to the same premisses.
If one keeps A and B for thruths because they are thruths in a certain system and the system is also kept for truth...Then the system can make anything real fysics. It,s real fysics. But fysics is not thát real.
in A)Yes, all matter and energy produce gravitational effects.
in B)Are you trying to define a singularity here? As far as I know, a motionless singularity is a point and a spinning one would form a 2D disc. I don't think a line would be produced in any circumstances.
in C)No, black holes are not the same thing as singularities. A black hole is a body where the escape velocity is greater than the speed of light (sort of). The radius at which it equals the speed of light is defined as the event horizon; the border beyond which nothing can escape (with information intact).
A singularity is what occurs when the force of gravity is so overwhelming due to high matter density, that no known barrier exists to stop the matter from collapsing so a single point. The existence of the singularity is not established yet. Its basically predicted by GR, but the maths fail when trying to describe a singularity, so we don't know for sure what happens. But, a singularity is not required for the existence of black holes.
The rest makes little sense.
That is not possible since electrons and proton would have to unite and compress.As to whether the mass actually concentrates to a single point is unknown at this point of time, but even if it doesn't this does not preclude the existence of black holes. Al that is needed for a black hole is for the mass to be contained inside the event horizon. For a typical stellar black hole, this works out to be a volume ~30 km in radius, for the black hole at the center of the galaxy it is a sphere ~22,000,000 km in radius in which a mass of ~40,000 solar masses is enclosed. The last would only require an over-all density close to that which exists at the center of the Sun.
[/quote]Which they do in neutron stars. The electrons and protons are forced together to form a single mass of neutrons. At that density, any neutron star larger than ~21 km in radius will be a black holeAnd that is simply wild speculation on your part. you are awfully quick to accuse others of that which you practice yourself.If they were to compress, then there would be no gravity. This is simply a wild assumption.
That being said, I'm going to put my moderator hat on:
This is the physics sub-forum, where we discuss established physics, if you wish to discuss your own personal ideas, the forum for that is the New Ideas and Hypotheses sub-forum.[/QUOTE]
Wait a minute. You are too quick too judge my comments. We are having a problem in communicating.
If electrons and proton compress into a neutron, then I have no problem with that, and the neutron does indeed have a gravitational force. I had interpreted your statements that they compress into a point. A point has no area and with zero area there can be no mass.
I guess that you don't like anyone to disagree with you, so I will no longer comment on anything that you say.
A and b are general used for both fysics ánd math : the massmiddlepoint is where all mass is often tought of as concentrated for objekts. It,s what you learn in mathclass at an early age. I suspect you have brought that into equations often enough. This is a paradox to A] that assumes an even spread for the molecules and electrons and the math uses this for the moment of inertia. But with using the same objekt centered massmiddlepoint for the moment of inertia.
Even knowing better if a premisse funktions in a system and things are brought in accordingly .... math on itself doesn,t know the difference between what a mathematician thinks as real or brings in as premisse. What is brought in as real for math is real to the math.
Ghrasp: Sorry. As always, you don't make much sense.
Did you even read his post? Let me quote the relevant bit: "As to whether the mass actually concentrates to a single point is unknown at this point of time". You agree on this bit at least. Read my post to Ghrasp as well. We simply don't know what really happens once matter collapses all the way.
You should not really think about particles as little balls floating around in a perfect vacuum.
BTW, Janus is no fool. He actually has the education to back up what he says.
@Ghrasp, having the mass at the center point of an object is a common simplification that gives accurate results for certain objects, but it's only a simplification, not what actually happens.
@sharpsword, there's nothing in the current understanding of mass that requires it to be spread over a volume, at least not at the quantum scale.
There is no evidence that a mass has zero volume. Maybe your understanding of mass does not require it, but you cannot provide real evidence of any mass of zero volume can you?
Lord in heaven, how many times must it be spelled out to you? NO WE CAN'T. The maths simply point that way and fails when the singularity forms and there is no known force that would stop the mass from collapsing all the way. That does not mean that that is what actually happens. Nobody knows. Who is insisting on their existence anyway?There is no evidence that a mass has zero volume. Maybe your understanding of mass does not require it, but you cannot provide real evidence of any mass of zero volume can you?
I am. Test and verify. No proof, no belief. You believe in something about which "Nobody knows" ? Your theory is abstract. Bohr admitted his theory was abstract, but it did correlate to some degree with measurements. In spite of his admission, physicists searched for "Bohr atoms" for many years without success. Keep searching for yours. If someone finds something, I would be most interested.
"... there exists invariants in the system of physics: ideas and laws which retain their meaning to all investigators and for all times, and to discover these invariants is always the real endeavor of physical research." --- Max Planck
Thank you for spelling it out to me.
We are aware of the location of several black holes, through their effects on nearby stars and X-ray signatures ( ie indirectly ). Now we can see, directly, neutron stars so we know these objects are not neutron stars and much more massive. In effect these objects are too massive for neutron degeneracy pressure to support them and they collapse until their escape velocity is greater than c within the event horizon. They then become invisible save for the effects of mass, charge and ang. momentum.
What do you propose they are if not black holes ?????
What sort of pressure mechanism do you propose to stop the collapse ????
Also keep in mind any explanation for these effects will have to be mathematically consistant.
So go ahead, you've been published as you say, provide plausible explanations.
I believe the expression is 'PUT UP OR SHUT UP'.
No need to get mad. I was voicing my opinion. My point is that you cannot easily test on objects in outer space. You are limited to observations and theories. In contrast, we can delve into matter are at various levels, and test theories. Most of the theories are based on the Doppler effect and the assumption that the changes in the Doppler spectrum infers either inflation or deflation of the universe. However, I find little information as to where the "particle" on which we live began with respect to the rest of the universe. Also, is the universe expanding as a sphere? If so, what is the thickness of the sphere, and where do we lie on it? Could the sphere be distorted? These are questions that I ask, and I can't find much data that backs up the observation theories. Astrophysicists are on thin ice when it come to proof, but they have very grand theories.
Since you don't like me comments, why do you read them? Try to find someone who tells you what you like to hear. Try to be professional and stay away from the personal comments. If something I say is wrong, then prove it.
Is black hole referring to "being black" or just some naming. I suspect the latter but the naming is questionable then....
A black cloud before a thunder is perfectly visible. The only reason black clouds are not sometimes is when all dark clouds take the light away from the sun.
A "black hole" won,t keep light from escaping as how a dark cloud for the sun gives a dark shade. So it seems neither a visible black or a dark shade then. What,s the meaning for using the term black hole then instead of "a hole". It,s a paradoxal naming ; information does not escape but it,s known to be black. If this is not known (just a naming) then - again - why the black in the naming ?
Last edited by Ghrasp; September 2nd, 2011 at 08:49 AM.
September 2nd, 2011, 11:23 AM
There is a proof of the singular nature of black holes, but it is being ignored. This proof was mentioned in an old paper by Michael Rowan Robinson. It can be found in ArXiv. I ran across it by accident and I do not remember the title or year of publicatiion. I emailed him to ask if he could remember the paper where he made the comment.
He said that it has been suggested that black holes, precisely and only because they are relativistic singularities, must posess an hyperbolic gravitational field. A singularity, as a single point mass with infinite density, must have a gravitational field that also tends to infinity as one approaches the center. The 2D profile of such a field, therefore, must be hyperbolic. Normally, when an object exists in spacetime, it presents with an overall parabolic field profile according to Newton's Law of Gravity. Such a field will fall off as 1/r2. But, a hyperbolic gravitational field will fall off much more slowly as 1/r.
In 1983 Mordehai Milgrom announced that he had discovered a new twist in Newton's Law of gravity. He studied a statistically significant number of spiral and other types of galaxies that had redshift measurements made of the rotational velocity distribution of their component stars. When he plotted velocity of these stars versus distance from the center, velocity did not fall to near zero as it should have at large r. Newton's Law was wrong!
Of course it was. Milgrom's galaxies had supermassive black holes embedded within them. The central black hole and even also the associated matter in the disk induced a hyperbolic gravitational field in spacetime even very far from the center, that is, as r tended to infinity. A hyperbolic field will tend to zero only very slowly at large r compared to a parabolic field. In fact, there is a near constant difference between a parabolic Newtonian field and a hyperbolic field generated by the same mass as r tends to infinity. This near constant difference accounts for Milgrom's very small residual centripetal acceleration constant that he used to mathematically summarize his findings as an addition to Newton's Law. Hence, he called his model "modified Newtonian dynamics" or MOND.
He did not respect the implications of supermassive relativistic black holes in the nuclei of his galaxies. In 1983, most scientists hardly even knew of them. So, Dark Matter was proposed to account for the MOND effect. But, Dark Matter is unnecessary. No enormous clouds of hypothetical "weakly interacting massive particles" or WIMPs are needed to account for the MOND effect. This has huge implications to the so-called Lambda/Cold Dark Matter model of the universe that is based on the Friedmann equations and the FLRW metric.
Science is missing an opportunity here. The existence of the MOND effect proves the nature of supermassive black holes as true singularities. One can mathematically prove that relativistic singularities must exist by means of the treatment of general relativity given by Schwartzchild. But, here is observational (experimental) proof that is as hard and undeniable as such proof ever gets. It is more important to find more ways to validate an all-encompassing theory like general relativity than it is to find ways to validate one particular favored model of the universe by inventing Dark Matter (and Dark Energy) to fix the gaping holes. This is the true meaning of the MOND effect. See LONETREE* PICTURES* &* NEW* COSMOS with MOND for more.
Again we get back to the hypothetical concept of point mass. That is an abstract idea that it not supported by measurement. Therefore, the entire concept of this definition of a black hole is based on a fundamental abstract notion. Nothing wrong with that as long as it is recognized as such. That is also the fundamental difficulty in trying to understand the universe on limited measurements from outer space. Any theory becomes feasible in that sense.
Didn't Gary just give an example of a measurement that supports the concept of point mass?Again we get back to the hypothetical concept of point mass. That is an abstract idea that it not supported by measurement.
Harold14370 has it exactly right. We don't expect our readers to actually be able to read, however.
As for my comment:
This goes to the whole question of the exclusive use of a single model of the universe that depends on the Friedmann equations and the FLRW metric. The consensus interpretation of the Lambda/cold dark matter model must clearly be flawed if it leads to the conclusion that the scientific method must be scrapped in order to save the model. Dark Matter and Dark Energy are ad hoc "add-ons" that are trying to find theoretical justification. Dark Enegy, in particular, is being called a supernatural or "unfalsifiable" hypothesis because no experiment can possibly directly challenge it, just like the existence of God hypothesis.
Heretofore, all hypotheses must adhere to the scientific method (the SM). Now, in order to admit Dark Energy, cosmologists insist that SM must be tinkered with and an unfalsifiable hypothesis allowed for the first time in history. If we do this, the Pope can re-ascend to the Throne.
All of the indirect "overwhelming evidence" for expansion rate acceleration and Dark Energy can be just as well applied to the concept that our inventory of matter and energy in our local universe is inadequate and that the mass of the global universe is at least 22.2 times as large as has been supposed (100%/4.5% = 22.2). The total mass of the universe has been and still is open to question. The Matter/Energy that we can inventory accounts for only 4.5% of the total needed to "flatten" the anisotropy pattern that is seen in the Cosmic Microwave Background radiation (CMB). This proposed revision in the "total mass" and the General Relativity (GR) concept of the black hole hyperbolic field will save not only SM, but the Friedmann Equations and the FLRW metric themselves too!
The "inflaton particle" from which the universe may have sprung was the mother of all black-holes (MOAB). As such, it must have possessed an hyperbolic gravitational field that existed timelessly according to Alan Guth's quantum principles. During the instant of inception of the differentiated universe that we can now detect, this hyperbolic field must have begun to degenerate. Space with time came into existence during this instant. The implication here of the prior existence of a sort of meta-universe is not explicitly acknowledged in any of the scenarios we read, but it is nonetheless an unstated assumption.
This space-time bubble's surface traveled up the MOAB's hyperbolic field gradient at a velocity hundreds or thousands of times the speed of light. This is Allan Guth's "Inflation". Matter/Light could keep pace with the inflation of space-time only as long as its temperature was several exponential decades of degrees Kelvin. As soon as Matter/Light began to condense and the fundamental forces began to differentiate, the inflation era ended. The collapse of the infinite density hyperbolic field began. The hyperbolic field has been collapsing by means of a time-dependent process ever since. It is this ongoing transition from a hyperbolic black hole gravitational field to a parabolic Newtonian gravitational field underlying the global universe that is being mistaken for acceleration and Dark Energy.
This is not speculation. This is not my personal idea. This is but one example of a different logical meaning of Allan Guth's inflation theory and General Relativity according to Schwartzchild and many others. When guided by correct meta logic, mathematical physicists will be able to validate this or some other theoretical interpretation of GR, the Friedmann equations and the FLRW metric. Then, with the demise of Dark Energy and Dark Matter, the scientific method will be saved.
Cosmologists are always wrong, but never in doubt. - Lev Landau
August 10th, 2012, 08:52 PM
The term "collapsing all the way" in regards to matter would imply that it has no actual substance. If matter has any substance at all then the radius of any amount could not be zero. I've always been puzzled by the application of the mathematics to create the singularity at the center of a black hole which is equivalent to the ultimate collapse of all the matter which enters it. But as the radius decreases relative to the volume of matter the force required to compress that matter would increase and at some point a)the matter would transform into energy and we'd have a "big bang" or b) the matter would become stable at some radius r relative to the mass of the matter.
Reading this thread makes me curious about black holes: Can they be squeezed? Can they be split?
Once the gravitational force is great enough to form an event horizon, there is no way that the gravitational collapse can be stopped, by anything or any force. And once the event horizon has formed, nothing, no matter how energetic can leave the BH (aside from Hawking Radiation).But as the radius decreases relative to the volume of matter the force required to compress that matter would increase and at some point a)the matter would transform into energy and we'd have a "big bang" or b) the matter would become stable at some radius r relative to the mass of the matter.
On second thought I dont think a black hole can be squeezed...Reading this thread makes me curious about black holes: Can they be squeezed? Can they be split?
But cant a black hole in principle get stretched and eventually split
by supermassive black holes on opposing sides?
No. Until the event horizons actually intersect, the gravity of each hole still keeps everything within the event horizon. Then when they do touch, they form a larger BH.But cant a black hole in principle get stretched and eventually split
by supermassive black holes on opposing sides?
This happens only because the maths used ( General Relativity ) does not account for quantum effects, therefore there is nothing preventing a total collapse into a singularity.
In reality, it seems reasonable to assume that as the energy density gets higher and higher during the collapse, quantum effects will become important; since we do not yet have a final theory of quantum gravity we cannot yet tell exactly what it is that really happens. There are a few interesting models ( like the Fuzzball hypothesis ), but we don't yet know if any of them has any physical meaning.
For all practical purposes this is nonetheless a rather moot point, because what happens beyond the event horizon is not causally connected to the rest of the universe.
Must they touch?
Cant they keep apart long enough for stretching to occur...eh: change of form of the event horizon?
What if they rotate around the black hole in the middle? Cant they form a stable orbit around it?
Shouldnt some change of form of their event horizons occur just before black holes merge?
How could that be tested? Actually I couldnt care less, I just cant help asking stupid questions
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