February 14, 2011

How to spot a spinning black hole: Twisted space-time should be visible from Earth, say researchers

by Macquarie University

How to spot a spinning black hole: Twisted space-time should be visible from Earth, say researchers
(PhysOrg.com) -- An international group of astronomers and physicists – including Dr Gabriel Molina-Terriza of Macquarie University Sydney has found that rotating black holes leave an imprint on passing radiation that ought to be detectable using today’s most sensitive radio telescopes. Observing this signature, they say, could tell us more about how galaxies evolve and provide a further test of Einstein’s general theory of relativity.

General relativity tells us that very massive objects such as black holes warp space-time such that the path of any passing light is bent, an effect known as gravitational lensing. The theory also predicts that when a black hole rotates it will drag space-time around with it, creating a vortex that constrains all nearby objects, including photons, to follow that rotation.

Astronomers already have evidence that the supermassive black holes believed to lie at the core of many galaxies rotate. However, this evidence is indirect. The rotation of the Milky Way’s black hole, for example, is suggested by the velocity distribution of stars within the galaxy, but this approach is undermined because we don’t know exactly how much matter, particularly dark matter, the galaxy contains. Some believe that the Milky Way’s black hole is rotating very quickly while others maintain it is rotating much more slowly.

In the latest work, Fabrizio Tamburini of the University of Padova in Italy and colleagues instead show how to detect the rotation by measuring changes to the light from a distant star or from the disk of accreted material surrounding a black hole. They point out that a wavefront travelling in a plane perpendicular to the black hole’s axis of spin will get twisted as it passes close to the black hole, since half of the wave front will be moving in the direction of advancing space-time and the other half in the direction of receding space-time. In other words, the phase of the radiation emanating from close to a rotating black hole should have a distinctive distribution in space.

The researchers used a computer simulation to model the phase distribution resulting from the rotation of the ’s black hole and found that this variation ought to be visible from the ground. They say the way to measure it is to point an array of at the centre of the galaxy, using different telescopes to observe different segments of the approaching wave front, and then superimpose these segments to calculate their relative phase. This procedure would be repeated, each time the telescopes pointing to a different section of the tiny patch of sky surrounding the black hole.

Tamburini describes his group’s findings as “fundamentally important”, given, he says, that most massive objects in the universe rotate. In particular, he believes that studying the rotation of in active galactic nuclei can provide a lot of information about the evolution of these galaxies. And he maintains that his group could carry out such measurements within two years using an existing array of radio telescopes, such as the Very Long Baseline Array in the US, or the LOIS-LOFAR in Europe, were funding forthcoming.

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Astronomers calculate mass of largest black hole yet
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User comments

PS3
Feb 14, 2011
Holes only get bigger.. hawking is WRONG!
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AtomThick
Feb 14, 2011
Holes only get bigger.. hawking is WRONG!


Hey, don't get me wrong I can appreciate jokes ;) but what about holes made in water by a falling rock?
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ubavontuba
Feb 14, 2011
I'm not sure I buy the "twisted space-time" hypothesis, as this might imply subliminal hysteris between the mass, and the gravitational effect.

And, it might imply a resistance to motion between mass and spacetime.
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PS3
Feb 14, 2011
Holes only get bigger.. hawking is WRONG!


Hey, don't get me wrong I can appreciate jokes ;) but what about holes made in water by a falling rock?

you could compare the effect maybe but I don't think so because the BH would be like never ending rocks from powerful gravity to pull in stuff which should degrade space like any other hole material.
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Shootist
Feb 14, 2011
I'm not sure I buy the "twisted space-time" hypothesis, as this might imply subliminal hysteris between the mass, and the gravitational effect.


Frame dragging is a well recognized phenomenon. Spin a mass and it drags space-time along with it.

Everything has angular momentum. Find a black hole and you can be certain, it spins.
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ubavontuba
Feb 14, 2011
Frame dragging is a well recognized phenomenon. Spin a mass and it drags space-time along with it.
Sure. I'm just not convinced it will be optically detectable.
Everything has angular momentum. Find a black hole and you can be certain, it spins.
Oh, I don't doubt that.
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Jaeherys
Feb 14, 2011
As for a galaxy, our Milky Way Galaxy, to have a so-called Black Hole in the center, this is a possibility because stars die all the time, but the center of our Milky Way shows tremendous luminosity, active live stars. No "black" dead star eating away from the center. Another fantasy.


It has been shown that a supermassive black hole exists at the centre of our galaxy and many others. The orbital velocity of stars near the galactic centre require the mass of a black hole.

httpDELETE://en.wikipedia.org/wiki/Sagittarius_A*

Good image of orbits on this page, httpDELETE://www.astronomynotes.com/ismnotes/s9.htm
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kaasinees
Feb 14, 2011
I tried to post this question before ... it has been my impression that BHs do not rotate ... indeed it is part of the definition of a Black Hole ....

Where does this rotation come from?


The rotation probably comes from its own force. Just like the stars dynamics comes from its own force.
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AtomThick
Feb 15, 2011
I tried to post this question before ... it has been my impression that BHs do not rotate ... indeed it is part of the definition of a Black Hole ....

Where does this rotation come from?


The rotation probably comes from its own force. Just like the stars dynamics comes from its own force.


It might spin but are some other examples that don't require spin to wrap stuff arround it: for example the drain of a sink it surely doesn't spin but the watter still gets the form of a vortex arround it.
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soulman
Feb 15, 2011
ubavontuba said:
I'm not sure I buy the "twisted space-time" hypothesis

Shootist said:
Frame dragging is a well recognized phenomenon. Spin a mass and it drags space-time along with it.

ubavontuba:
Sure. I'm just not convinced it will be optically detectable.

But you just said that you don't buy the whole frame-dragging hypothesis. Which is it? Do you accept that spacetime can be twisted by a rotating mass?

ubavontuba:
...as this might imply subliminal hysteris between the mass, and the gravitational effect.

That makes no sense to me. Can you explain?

ubavontuba:
Oh, I don't doubt that.

Why do you doubt that everything has angular momentum?
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Jaeherys
Feb 15, 2011
@71STARS
@Jaeherys: You state "The orbital velocity of stars near the galactic centre require the mass of a black hole." Please explain.


Let's use the solar system as an example; imagine that the sun is invisible. Assuming we know the mass of the planets and their orbital velocities, you can determine the mass of this invisible sun using the equations on these pages,

httpDELETE://ceres.hsc.edu/homepages/classes/astronomy/spring99/Mathematics/sec10.html
httpDELETE://en.wikipedia.org/wiki/Elliptic_orbit
httpDELETE://en.wikipedia.org/wiki/Orbital_equation

Now back to the galactic centre, using the same equations and orbital velocities of the suns orbiting this "invisible" object, it is possible to determine the mass required to create (in this case) such high velocities.

Jake
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Ethelred
Feb 15, 2011
I tried to post this question before ... it has been my impression that BHs do not rotate ... indeed it is part of the definition of a Black Hole ..
No. Black Holes do not respond to human definitions in any case. This a case of mistaking the map for the territory AND using the using the wrong map legend.
Note the 'non-rotating body' in the definition.
That is NOT a definition. It is trying to do enough of the the math without doing ALL the math. It was a statement of the assumptions he was using NOT a definition. Physicists are often arrogant but I am not aware of anyone the things they can define things and make the behave according to their definition.

This is similar to the physics joke that is so deeply based in a VERY standard joke that only the punch-line is needed.

First assume a spherical chicken of uniform density.

Ethelred
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soulman
Feb 15, 2011
ubavontuba:
Oh, I don't doubt that.

Why do you doubt that everything has angular momentum?

Sorry ubavontuba, I read your comment to read "I doubt that", instead of "I don't doubt that". Mea culpa.
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Ethelred
Feb 15, 2011
Please read "Black Holes & Time Warps" by Kip Thorne, 1994 for a full understanding.
I read it. You didn't understand it.
Chap. 12: "Black Holes Evaporate" will clear up the demise of a dead star.
Read it again and see how bloody long that takes. Billions and trillions of years is just a VERY tiny fraction of the time involved.

There are NO black stars in the Universe because the universe isn't old enough. All stars are way above the background temperature of the Universe.
I assume that a "dead" star will rotate until it has depleted its course of existence, then shed itself into Empty Space. Agreed?
No. Stars are held together by gravity. They cannot just 'shed' themselves. They can blow up. They can black hole. They can cease burning and form white dwarf. The blow up and form a neutron star then suck down matter from a companion star and THEN black hole after they consume enough mass.

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Ethelred
Feb 15, 2011
There is simply no way to NOT have black holes in the Universe. IF you get enough matter in one place eventually you have enough gravity to stop light from leaving the mass. And it won't just magically evaporate because it is no longer fusing. Hawking radiation, assuming it is real, takes time. A long time. Billions of times the present age of the universes and more yet.

You know you could go look this stuff up. Kip's book is a bit old these days. And it doesn't say what you seem to think it does.

Ethelred
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Jaeherys
Feb 15, 2011
@ennui27 Virtual particles, where one particle is inside the event horizon and one outside, causes the particles to become real. The particle inside the event horizon is presumed to be negative which subtracts from the total energy of the black hole. The positive particle is then seen as hawking radiation, which has not been seen yet, afaik. So although the black hole is slowly radiating away, no matter is actually exiting the black hole.

httpDELETE://en.wikipedia.org/wiki/Hawking_radiation

wiki explains it better than I can.

Jake

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kaasinees
Feb 15, 2011
@ennui27 Virtual particles, where one particle is inside the event horizon and one outside, causes the particles to become real. The particle inside the event horizon is presumed to be negative which subtracts from the total energy of the black hole. The positive particle is then seen as hawking radiation, which has not been seen yet, afaik. So although the black hole is slowly radiating away, no matter is actually exiting the black hole.

httpDELETE://en.wikipedia.org/wiki/Hawking_radiation

wiki explains it better than I can.

Jake


It is already observed that black holes can leak radiation. It was observed by a blackhole eating a nearby star.
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Jaeherys
Feb 15, 2011
@kaasinees
That's just what daddy wanted to hear :D.
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Snowboarder
Feb 16, 2011
@71STARS

First of all no black holes have been predicted to explode.... ever. The only way for a black hole to "die" is through the process of evaporation postulated by Hawking. There are absolutely no other viable theories for how a black hole can lose mass/energy.

Hawking radiation works as follows. Two imaginary particles come into existence near the event horizon of a black hole, one normal particle, one anti-particle. Normally they destroy each other. But near a black hole two things can happen. If the normal particle is sucked in the anti-particle follows. No net gain/loss. If the anti-particle is sucked in it destroys a particle already in the black hole and the normal particle is shot out as Hawking radiation. The result is a loss of mass for the black hole. This is the only way for a black hole to lose mass.

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ubavontuba
Feb 16, 2011
But you just said that you don't buy the whole frame-dragging hypothesis. Which is it?
That's not what I said. My post was in reference to the headline of the article. I doubt it will be optically detectable.
Do you accept that spacetime can be twisted by a rotating mass?
Yes, but with reservations.
That makes no sense to me. Can you explain?
It's complicated, but briefly: Clocks are already at a virtual standstill around a BH. For the light to be thusly affected, It seems that orbital clock rates must be unevenly distributed, relative to a distant observer. Clocks might never stop on one side, and move backwards on the other. Causality might suffer.
Why do you doubt that everything has angular momentum?
I specifically stated otherwise.
Sorry ubavontuba, I read your comment to read "I doubt that", instead of "I don't doubt that". Mea culpa.
Okay.
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Snowboarder
Feb 16, 2011
@71STARS continued

Any black hole near even a small amount of matter will gain more mass than it loses through Hawking radiation. Even if it wasn't gaining mass, any black hole of a respectable size would take far longer than the 13.7 billion years the Universe has been in existence to evaporate.

You keep referring to black holes as dead stars that have burnt out as if they are simply stellar light bulbs that no longer function. It is vastly more complicated than that. When a star runs out of fuel it doesn't just burn out. The energy from fusion becomes no longer sufficient to stave off the effects of gravity and it collapses into a singularity. A singularity is not a burnt out light bulb, it is a collection of matter so dense that even the equations of relativity break down within it. A singularity does not behave in any way like a star.

You should either read more about the nature of black holes... or read more carefully :)
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soulman
Feb 16, 2011
Clocks are already at a virtual standstill around a BH.

Only from an external reference frame. If you were near a BH, your personal clock would tick away just as usual.
For the light to be thusly affected, It seems that orbital clock rates must be unevenly distributed, relative to a distant observer.

This is a consequence of different frames of reference and has nothing to do with BHs, per se.

Time flows at a different rate on the surface of the Earth compared to, say LEO, with countless transitions in between. But, if you measure time on Earth it will flow at 1sec/sec and it will likewise aboard the ISS. It's only when you compare the two clocks in the same frame of reference that you will see a difference.
Clocks might never stop on one side, and move backwards on the other. Causality might suffer.

How does it follow that clocks can go backwards?
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soulman
Feb 16, 2011
I don't understand why soulman rated Snowboarder's first comment "1"

Because he badly mangled the mechanism of Hawking radiation production. In hindsight, I should have rated him higher because he was spot on in the first part of the post (not dealing with HR).
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Ethelred
Feb 16, 2011
It is already observed that black holes can leak radiation
First we would have to actually observe a black hole. We have found things that we thing MUST be black holes but we have not actually observed Hawking radiation from anything.

It was observed by a blackhole eating a nearby star.
That is NOT Hawking radiation. That is radiation from an accretion disk and the very first black hole candidate, Cygnus X-1, was found from the X-ray radiation generated by the accretion disk.

Ethelred
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Ethelred
Feb 16, 2011
@Ethelred: Very politely, if you have read Black Holes & Time Warps, you would understand what I have said. Do you disagree with Prof. Thorne?
Not that I can recall. YOU seem to be disagreeing with him. And there is nothing polite in telling me not to reply.
1) Of course, Black Holes take a long time to demise, I never said they didn't. Many are still in existence at the present time.
You clearly don't get the time involved by MANY orders of magnitude. ALL stellar mass black holes that have ever formed MUST still exist except for those that have merged with other black holes to form larger black holes.
2) Yes, stars do "shed" a portion of themselves
While dying. Not AFTER becoming a black hole, neutron star or even a white dwarf. White dwarfs and neutron stars may just plain shatter in massive explosions but that is not shedding.

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Ethelred
Feb 16, 2011
Please read the life of a SUN (solar flares, prominences, accretion disk).
I have read those things. You either don't understand them or failed to say what you really meant.
) You state "There are NO black stars." This shows you have no idea what a black hole is! It is the implosion of a STAR to form a black hole.
Nonsense. I know what a black hole is and it ISN'T a star. It is, usually, a FORMER star and now it is just a place the light can enter but can no longer leave due to gravity. Calling it a black star is a sure path to being misunderstood assuming you do understand in the first place.
Pg 14: "Chandrasekhar pointed out in 1930 that STARS having a mass above a critical value, the so-called Chandrasehar limit, should collapse to become what we now call BLACK HOLES,
Which is NOT a black star. It is a place where light cannot leave. It has NO characteristics of a star anymore.

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Ethelred
Feb 16, 2011
when they have exhausted the nucler sources of energy responsible for their high temperature." Did you know that?
Yes little arrogant one. I read Kip's book in the year it was published and I really did not see much in it that I was not already aware of. I have known about black holes since the discovery of Cygnus X-1.

Your separation of dead black stars (because they no longer emit light) from the stage of black holes is either shocking or quite sad.
Your misunderstanding of black holes is quite clear. They are no longer stars.

No reply.
I see. You want to suppress dissent.

Ethelred
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Ethelred
Feb 16, 2011
Remember that some black holes are predicted to explode rather than fade away (according to mathematical calculations). Dead stars have many recourses of demise.
No. They are predicted to loose mass to Hawking radiation at an ever increasing rate as their mass decreases. For a stellar mass this would not happen till after the Universe is otherwise very cold and dead. Unless there really are quantum black holes we will never observe the end of a black hole.
Your nonsense reference to dead stars as "simply stellar light bulbs that no longer function" is your conclusion and very naive wording; not mine.
Perhaps you have not meant to write as if that was what you really meant. However everything you have written is leading all of us to that conclusion. You really need to write what you mean if you want to be understood. Try reading what you wrote and see what we are seeing.

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Ethelred
Feb 16, 2011
Your nonsense reference to dead stars as "simply stellar light bulbs that no longer function" is your conclusion and very naive wording; not mine.
Which is wrong. Black holes are the Event Horizon and not the hypothetical singularity at the core. Only a non-rotating black hole is expected to form a singularity and even a non-rotating black hole may not be able to collapse to smaller than the plank length.
What impression of my words gave you that idea?
Your arguing with me over saying black holes aren't stars would give that impression anyone with any logic.
but fading away is the prevalent choice; haven't you read that?
Not from you till now and its wrong anyway IF Hawking radiation is real the black hole would brighten as is decreased in mass which is not fading away.

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Ethelred
Feb 16, 2011
As for "I should read more carefully" the words written, I suggest that is exactly what you should be doing in this text.
No. He read what you wrote in a very reasonable manner. This post of yours is the first indication that you aren't Cranking and are simply VERY BAD at expressing yourself.

If you want to be understood you really need to write with one hell of lot more clarity and frankly your use of the term 'black star' makes it hard for anyone to think you don't mean a black star instead of a black hole. Non-standard SECRET definitions is a sure way to be thought a Crank.

So how about you clarify your position using standard terms instead of special definitions that only make a mess of things?

Ethelred
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omatumr
Feb 16, 2011
There are, of course, no Black Holes. Neutron repulsion prevents their formation ["Neutron repulsion", 19 pages, in press, 2011].

arxiv.org/pdf/1102.1499v1

Cosmologists have become as dogmatic and irrational in the 20th and 21st Century as the Religionists were in the 16th and 17th Century. E.g.,

youtube.com/watch?v=AQZe_Qk-q7M

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
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Ethelred
Feb 16, 2011
There are, of course, no Black Holes. Neutron repulsion prevents their formation
That is utter nonsense Oliver. Even if your hypothetical and contrary to evidence neutron repulsion was valid there would still black holes. If you get enough mass together in one place eventually you have a gravity field that is able to retain light. There is no need for a star to collapse to a singularity for this to happen as the event horizon increases in size faster then the radius of a mass of neutronium.

This has been pointed out to you before by others and you just plain pretended it never happened. This is typical Crank behavior and just one more of many that show that your simply aren't interested in testing your hypothesis.

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Ethelred
Feb 16, 2011
Cosmologists have become as dogmatic and irrational in the 20th and 21st Century as the Religionists were in the 16th and 17th Century.
The irony is overwhelming.

Go run the bloody numbers Oliver. See how a large a mass of neutrons can become before you get a black hole. Go read the results from the iron stacks while you are at it and notice the total lack of neutron decay. You don't have anything else to do so what if it takes you several months to work out the numbers. If you find you are right then its a good thing and if you find out that you are wrong you can stop wasting time and stop looking like the Arps do.

Heck you could even admit you are wrong and that woud be such a rare thing that it might go a long way to repair your reputation. You produced real evidence that a supernova was closely involved in the creation of this solar system. That is something real as opposed your idea that OUR sun was the supernova which is contrary to evidence.

Ethelred
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omatumr
Feb 16, 2011
No need to get excited. The Church of Certainty will tumble anyway.

Dogmatic religionists and dogmatic scientists are identical twins hiding under different cloaks of respectability.

That is the central lesson here:

youtube.com/watch?v=AQZe_Qk-q7M

and here: arxiv.org/pdf/1102.1499v1
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ubavontuba
Feb 16, 2011
Only from an external reference frame. If you were near a BH, your personal clock would tick away just as usual.

This is a consequence of different frames of reference and has nothing to do with BHs, per se.

Time flows at a different rate on the surface of the Earth compared to, say LEO, with countless transitions in between. But, if you measure time on Earth it will flow at 1sec/sec and it will likewise aboard the ISS. It's only when you compare the two clocks in the same frame of reference that you will see a difference.
Whoa! Hold up now! You're jumping all over the universe!

The article refers to two frames of reference. One, observing the other from a distance. Relevant to the article, it's the observer's frame of reference which I'm discussing.
How does it follow that clocks can go backwards?
It doesn't, which as I indicated with my causality remark, is why this experiment won't work.

continued...
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ubavontuba
Feb 16, 2011
I'm tempted to simply spill the beans right away (so to speak), but I think it might be more fun to ask some fun questions of my own...

It can be said that a black hole has angular momentum, but relative to a distant observer, is it rotating in real time?

What happens to backlight that passes very close to an intervening black hole's horizon? Will our distant observer see it?
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soulman
Feb 17, 2011
Whoa! Hold up now! You're jumping all over the universe!

That's the kind of guy I am.
...which as I indicated with my causality remark, is why this experiment won't work.

Except that your causality remark didn't make much sense, and is why I asked for clarification.
It can be said that a black hole has angular momentum, but relative to a distant observer, is it rotating in real time?

What's 'real time'?
What happens to backlight that passes very close to an intervening black hole's horizon?

What's 'backlight'?
I'm tempted to simply spill the beans right away

Please do, it might make more sense then your ambiguous questions and nebulous terminology.
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Ethelred
Feb 17, 2011
No need to get excited. The Church of Certainty will tumble anyway.
Not excited. I have no expectation that you will ever again become a rationalist. I am simply trying to encourage you to better yourself on the off chance that you will decide to change. Like many other Americans I think people deserve a chance to redeem themselves. Even you Oliver.

George Wallace changed and became a decent human being. So can you.

Dogmatic religionists and dogmatic scientists are identical twins hiding under different cloaks of respectability.
And the covers you on two counts as you are going on YOUR own dogma over actual evidence.

Run the bloody numbers. That is what REAL scientists do.

Ethelred
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Ethelred
Feb 17, 2011
One final word. My simple terminology has been smeared by someone named Ethelred.
Suggesting that you use standard terminology is not a smear.
Black Star: a dead/dying star that no longer emits LIGHT is my terminology. Color: black. Not to be confused with "black hole."
YOU were the one that sure seemed to be calling black holes, black stars. There are NO dead or dying stars that don't emit light UNLESS they are no longer a star because they Black Holed. It takes longer than the universe has existed by any dead star, which are white dwarfs, neutron stars, and the hypothetical quark star, to become so cold as to cease emitting light. Since there are NO black stars everyone quite reasonably thought you meant black holes and it didn't help that you were not clear in the first place.

This white dwarf is a candidate for the oldest white dwarf and it is still 3800K or 1000k hotter than a standard tungsten light.
httpDELETE://arxiv.org/abs/0804.1570

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Ethelred
Feb 17, 2011
Lecture notes for white dwarfs.
httpDELETE://www.astronomy.ohio-state.edu/~ryden/ast162_4/notes17.html

There NO black dwarfs yet in the universe and that means there are no black stars.

Not to be confused with the initial dark, invisible, dying star which causes the result.
There is no such thing. And you did NOT read about such a thing in Kip's book. Black holes come from stars that are not in the least black. Red Giants are not black.

@Ethelred: "explosion" of a black hole was calculated that if and when the hole would be so hot, it will explode, by Stephen Hawking.
He did no such thing. It just emits energy at a higher and higher rate till there is nothing left. That is not an explosion.

If you read the book (although you state you "really did not see much in it"), you missed pgs 435 & 436.
That book and many more. You do know that there are OTHER books don't you?

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Ethelred
Feb 17, 2011
I believe that should clear up any of my words that have been twisted.
Yes. It makes it clear you don't have a clue. I didn't twist anything. I just went on what YOU wrote. It is not my fault the you did not write what you intended. Nor is it my fault that now that you have finally written what you intended you STILL have it wrong.

There are NO black stars in our universe. We do have white dwarfs AND if FIVE white dwarfs were to conjoin without a mass loss in the process they would become a black hole. BUT no one has suggested that such a thing has occurred. Black holes could come from some supernova events but those suns that do that were NOT black. Mostly they are expected to come from Red Giants though Supernova 1987A seems to have been a Blue Giant before it went Supernova and it may have formed a black hole as there is no present sign of a pulsar.

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Ethelred
Feb 17, 2011
It's a shame to distort what a person says
Well I did not distort anything you said. I MAY have misunderstood but frankly so did everyone else. NO ONE thought you meant what you NOW say you meant. And it is still wrong.
Disagree; yes please.
I did.
Misstate; no.
I did not. YOU did. And you still don't get it. There are NO black suns no matter how you define them. Not in our universe at this time.

Reasonable criticism, like mine was, is NOT a smear. You were so busy turning a suggestion for more clarity into a nonexistent smear that you just plain ignored my pointing out to you that there are no black suns because no sun has ever gotten cold enough to be black. Nor has any black hole evaporated, unless there are quantum black holes, since the Universe is WAY too young. At present any stellar mass black hole is GAINING mass because the background temperature of the universe is higher than the temperature of any such black hole.

Ethelred
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omatumr
Feb 17, 2011
As noted earlier,

"Dogmatic religionists and dogmatic scientists are identical twins hiding under different cloaks of respectability."

With kind regards,
Oliver K. Manuel
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ubavontuba
Feb 18, 2011
That's the kind of guy I am.
Yeah, that's you - all over.
Except that your causality remark didn't make much sense, and is why I asked for clarification.
Well, it made sense to me, but I suppose it's hard to hear my inflection when you're reading (gentle sarcasm).
What's 'real time'?
Information update rate of the receiver (or observer, in this case).
What's 'backlight'?
Illumination from behind that which is being observed.
Please do, it might make more sense then your ambiguous questions and nebulous terminology.
The terminology I'm using is rather basic to the language. That you aren't understanding it, is disconcerting. Understanding "backlight" is particularly critical to understanding the concepts put forth in the article.

Do you actually understand the article?

Heck, you could've at least looked up the definitions, yourself. That you didn't bother to do so casts an unfavorable light on your ability to understand and process information.
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soulman
Feb 18, 2011
Heck, you could've at least looked up the definitions, yourself. That you didn't bother to do so casts an unfavorable light on your ability to understand and process information.

Yeah, that must be it.

Still waiting for the spilling of beans. I bet it won't amount to a hill.
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Ethelred
Feb 18, 2011
As noted earlier,

"Dogmatic religionists and dogmatic scientists are identical twins hiding under different cloaks of respectability."
As noted earlier and many times.

It is YOU that is being dogmatic.
It is YOU that refuses to look at evidence.
It is YOU that refuses to run the numbers that you should.

And it is you that backed a plasma universe post that totally disagrees with your own ideas and they did run the numbers. Got numbers that don't work so they try to pretend it never happened instead of dropping their incorrect theory. Might by why YOU refuse to run the numbers or look at the total lack of evidence for decay of bound neutrons.

And in this case you are backing person that not only thinks there are black holes which you claim exist he thinks there are black suns which really don't exist.

Ethelred
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ubavontuba
Feb 18, 2011
Yeah, that must be it.
Obviously.

Do you understand why backlighting is important in this case, yet?
Still waiting for the spilling of beans. I bet it won't amount to a hill.
I notice you didn't answer the question: Do you actually understand the article?

So, do you?
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Snowboarder
Feb 18, 2011
Because he badly mangled the mechanism of Hawking radiation production.


@soulman
Thought I had a decent understanding of HR in layman's terms. Can you explain/point the way to an explanation that is correct.

@Ethelred
Thanks for being the voice of reason. I have no experience/schooling in math/physics/science and I read this site in my spare time to try and be as knowledgeable as possible on these subjects I find so fascinating. Misinformation is frustrating.
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Quantum_Conundrum
Feb 19, 2011
Due to conservation of angular momentum, classical pre-Einstein physics would predict that any "singularity" formed by accretion should tend to rotate with arbitrarily infinite velocity as it's radius approaches zero.

However this will be limited by the effects of relativity, if relativity is even true, and if the laws of relativity don't break down inside event horizons.

The consequences of this is that all accretion-formed singularities rotate at infinitesmally close to the speed of light due to conservation of angular momentum.

They could only avoid doing so if they were at absolute zero, which nothing is at absolute zero.

Think of it this way. Light itself supposedly cannot escape the event horizon. But the "singularity" inside is smaller than the event horizon, and so it must be rotating equal or faster than the event horizon rotates.
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Quantum_Conundrum
Feb 19, 2011
A non-rotating black hole could only form in the case of a perfect 180 degree head-on collision of perfectly identical mass neutron stars with perfectly mirrored rotations.

The probability of this ever happening is virtually non-existent.

Due to conservation of angular momentum, if a collapsing star has any spin whatsoever, then the resulting black hole will eventually spin faster and faster as the singularity collapses, and will always get closer and closer to the speed of light as the "radius" decreases to zero.
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Quantum_Conundrum
Feb 19, 2011
He fool, what I wrote is consistent with the conservation laws.

This is the same reason ice skaters spin faster by pulling in their arms.
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nxtr
Feb 19, 2011
Who was it that first hypothesized that the universe just gets sucked into larger and larger black holes until it the last massive one rebirths as another big bang?
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ShelMar
Feb 20, 2011
@Ethelred
Nobody misunderstood what stars was saying, it was understood exactly as written.

Lets disprove his nonexistent "smear campaign" theory...

@71STARS(1st post)
Feb 14, 2011
Black holes are not 'holes' but simply black, dead stars. The person that made dead holes come to life with gravitational pull has created the biggest fantasy of our age. Picture a star dying, out of fuel, going black. That is a what is mis-called a Black Hole.

71STARS - Feb 15, 2011
@Ethelred:
Your separation of dead black stars (because they no longer emit light) from the stage of black holes is either shocking or quite sad. No reply.

cont...
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ShelMar
Feb 20, 2011
71STARS - Feb 16, 2011
Rank: 1.8 / 5 (8)
One final word. My simple terminology has been smeared by someone named Ethelred. Please know:
Black Star: a dead/dying star that no longer emits LIGHT is my terminology. Color: black. Not to be confused with "black hole."
Black Hole: the hypothetical RESULT of a dead STAR which implodes. Not to be confused with the initial dark, invisible, dying star which causes the result.
I believe that should clear up any of my words that have been twisted. It's a shame to distort what a person says.

Stars, apparently its your separation of dead black stars and black holes that is shocking or quite sad.
That should clear up any claim his words have been twisted. It's a shame to falsely claim a person distorted what you said.
Disagree;You can't. Misstate;You did. No reply.
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Skeptic_Heretic
Feb 20, 2011
One final word. My simple terminology has been smeared by someone named Ethelred. Please know:
Black Star: a dead/dying star that no longer emits LIGHT is my terminology. Color: black. Not to be confused with "black hole."
Except that is physically impossible. All known baryonic matter radiates energy in some wavelength. That wavelength or the intensity of radiation may be faint, in fact too faint for us to detect with current technology, or it may be drawn back to the origination point due to intense gravity.

There is no known mechanism by which matter can have a temperature of absolute zero. We haven't been able to do it in the lab, we haven't seen observational evidence for it, space time itself is of a higher energy than absolute zero.

In short, you're full of shit.
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Skeptic_Heretic
Feb 20, 2011
Skeptic H:I did not say ANYTHING about "a temperature of absolute zero"??
Which further exemplifies your very amateur understanding of the subject. As could be determined from my post, in order for baryonic matter to have zero emission it would have to be at a state comparable to absolute zero.
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Ethelred
Feb 20, 2011
Q. What do you call a dead and dying star that no longer emits light and/or light is being pulled back down to it, and light is no longer visible, and the star has not yet imploded to a black hole?
Nonexistent. There are no such stars. All stars, dead or otherwise, produce enough heat to be visible if the observer is close enough. Even the oldest white dwarf is hot enough to glow.

However if light is being pulled down then it IS a black hole and no longer a star.
Yes, any light trying to come off the surface will be pulled back DOWN to the star, but in the end stage you will not see any light whatsoever.
That is a black hole and not a star. It separated from the rest of the Universe by the Event Horizon.
My separation of a dying star and giving it a name before it implodes to a named black hole is causing a furor.
You separation is a fantasy because NO STAR IS BLACK. NONE. They ALL glow. EVERY ONE OF THEM. What is so difficult for you to understand about this?

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Ethelred
Feb 20, 2011
What is that name? What is that situation?
Since there is no such situation there is no name.
He seems to be the authority.
Is that a joke? I am NOT an authority. Just well read. I can back up what I say with sources OR I will say it is my opinion or even my WAG.
He has berated someone named Oliver, but what publications does he have on Neutron R.?
Since neutron repulsion as described by Oliver is a fantasy Oliver is the only person with papers on it. Papers that only Oliver sites. I have berated Oliver for trying to bully me like he has done to others but otherwise I have either simply asked questions he doesn't want to deal with or pointed out where REAL studies have been made that show him wrong. The iron stacks that were made to study proton decay would also have shown bound neutron decay. No such decay has EVER been observed. IF Oliver was right then such decay should have observed. Oliver stonewalls on this. Pretends I never mentioned it.

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Ethelred
Feb 20, 2011
It seems to be a great factor in the production of energy of the Sun.
Neutron repulsion, even if was something other than the Pauli-Exclusion Principle as Oliver thinks, would NOT be a power source. That is like calling a spring a power source. Neutron decays could be a power source IF was occurring in stars. There is no evidence to support the idea of bound neutrons decaying. Oliver just made it up.
Please Skeptic Heretic: Your lack of understanding of the temperature of a dying star is (to use your exact words) very amateur.
Yours seems to be based on stuff you made up as there is no evidence for black stars and the all stars that have not black holed produce light. from the link I posted above:
The oldest, coldest white dwarfs have L = 0.0001 Lsun and T = 5000 Kelvin.
Tungsten-halogen bulbs are only 3200K. At 5000K all the elements are a gas.

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Ethelred
Feb 20, 2011
Anyone knows radiation occurs at an extremely lesser level.
Then Mr. Anyone is wrong. All stars are hot enough to vaporize iron at the surface. An even solid iron can produce a lot of light.
It is so much so as to have the LIGHT be pulled down back to the star.
That is a Black Hole. You don't seem to get the concept.
We are taking about a SUN!
You are mixing up Black Holes and suns.

So to reiterate.

There are no black stars in this Universe. They all glow.

If a ex-star has such an intense gravity field that it sucks down light it is a Black Hole and no longer a star.

I never claimed to be an authority. It is Oliver that is claiming to be an authority that should not be questioned.

I have actual evidence on my side. Where is yours for the existence of black suns as opposed to black holes, white dwarfs and neutron stars. Please post a link to something that shows or at least implies their existence as that is our main, though not only, area of disagreement.

Ethelred
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Skeptic_Heretic
Feb 20, 2011
Please Skeptic Heretic: Your lack of understanding of the temperature of a dying star is (to use your exact words) very amateur.
Oh?
Anyone knows radiation occurs at an extremely lesser level.
What are you talking about level? In order to have a "black" star, you need no radiation. ie: Absolute zero. Since that is not possible, you're wrong. As you said
Please look it up.
jackass.
It is so much so as to have the LIGHT be pulled down back to the star. But you lack the understanding and seem to think that this equates to a "zero temperature"!!
No dipshit. That would be my understanding of a black hole, which cannot be a star as stars RADIATE.
We are taking about a SUN!
No, you're talking nonsense.
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Ethelred
Feb 20, 2011
In order to have a "black" star, you need no radiation. ie: Absolute zero.
I would settle for a star below the heat of glowing iron. Something below a 1000K or lower. Emiting light only in the infrared and lower region. I would be willing to call that a Black Star but there simply aren't any that cold. Even by the standard you are using if the star was down to backround levels that should do. Of course that is 2.8K and I am pretty sure the coldest expected brown dwarf, much less a dead star, would be much closer to 1000K than 2.8K

Ethelred
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lomed
Feb 21, 2011
The consequences of this is that all accretion-formed singularities rotate at infinitesmally close to the speed of light due to conservation of angular momentum.
It turns out that rotating black holes have ring singularities. You may have been refering to these, but your posts were sufficiently unclear (to me) on the subject that I thought I would mention them (note that GR does not accomodate intrinsic spin, so in general a point singularity in GR will have zero internal angular momentum).
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Snowboarder
Feb 21, 2011
Even an absolute layman without any physics knowledge sees through your presumptious, inappropriate behavior.


@frajo
I'm an absolute layman, and you're correct.

Somewhat off-topic question...

Can a sufficiently dense and massive amount of dark matter form a black hole?
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lomed
Feb 21, 2011
Can a sufficiently dense and massive amount of dark matter form a black hole?
Theoretically, enough of anything with positive energy density concentrated within a small enough radius will produce a black hole. For example, a black hole of 6.7 billion solar masses would have an average density (mass divided by the volume of a sphere with radius equal to the schwarzschild radius) less than that of air. So 6.7 billion solar masses of air in the same (spherical) volume it would fill at standard temperature and pressure on Earth would form a black hole. There is nothing to prevent dark matter from forming black holes, but its average density is extremely low (much less than normal matter in a galaxy). Also, as far as I know it does not interact strongly with anything including itself, so it is difficult for it to shed the angular momentum necessary to allow it to clump on stellar scales or be likely to be captured by pre-existing black holes
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Skeptic_Heretic
Feb 25, 2011
I'm waiting for an apology.
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Skeptic_Heretic
Feb 26, 2011
So, I AM RIGHT. A less massive star will exhaust its fuel with light being pulled back down to the surface and become DARK. Then it will shed its envelopes and remaining will be the core; the white dwarf....
I am not wrong on a dark star before a collapse and remaining white dwarf.
/double facepalm.
A black dwarf is a hypothetical stellar remnant, created when a white dwarf becomes sufficiently cool to no longer emit significant heat or light. Since the time required for a white dwarf to reach this state is calculated to be longer than the current age of the universe of 13.7 billion years, no black dwarfs are expected to exist in the universe yet,

There's the literature and definition of a black dwarf.

Go ahead and further continue to admit that you are wrong, and using incorrect terminology.
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Ethelred
Feb 27, 2011
. I WAS WRONG. I thought the star became exhausted before imposion to a black hole and was completely black.
At that point most have exhausted their exothermic fusible material. Most are red giants at that time. 1987A was a blue giant when it went bang. I don't that one is understood yet.
This does not apply to massive stars and supernovas.
Sure it does. They usually go off the main sequence and become red supergiants like Betelgeuse before going bang.
"Before exploding, the massive star was quite "normal", i.e.
Must have been talking about 1987A.
In reading that light is being pulled back down to the surface, this would, of course, apply to MASSIVE STARS but not covering the entire surface because when they exhaust their fuel, they explode immediately into the black hole stage.
No. That makes no sense at all. First stars have pretty much the same surface temperature range over the entire surface.

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Ethelred
Feb 27, 2011
Second at no time is the light 'sucked down' into a star where fusion is still occurring. Third 1987A is the only case I have heard of where a star went bang without a giant stage occurring. The problem there is that it is rare to see a supernova close enough to have an image of the original star so events like 1987A may be more frequent than is known.

Either way, red giant or straight to a bang, stars don't go through a black stage before a supernova.
It's wonderful to ask an expert and get true wording.
You had the truth from us already and you could have looked it up on dozens if not hundreds of sites on the web.
"Yes. Less massive stars can exhaust all their fuel and become dark.
Can in theory. None are yet black or even at red heat.
"white dwarf" (small and compact source) that, eventually, cools down to become completely black.
EVENTUALLY. None yet in the entire universe unless it is MUCH older than it appears to be.

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Ethelred
Feb 27, 2011
Such objects are well known to astronomers."
Well known to be THEORETICAL and not presently existing.
but they do not collapse; these are the so-called white dwarfs."
Yes. I know that.
So, I AM RIGHT.
No.
A less massive star will exhaust its fuel with light being pulled back down to the surface and become DARK.
Nonsense. And those people did not agree with you either. A less massive becomes a white dwarf and they told you that so that claim is utterly asinine and counter to reality and what you just quoted. ONLY BLACK HOLES absorb light. White dwarfs are WHITE they EMIT light. They do NOT absorb it. Not one single white dwarf has been cooling long enough to even reach red heat much less black.
Then it will shed its envelopes and remaining will be the core; the white dwarf.
NO. Less massive stars shed their outer envelopes and become white dwarfs WITHOUT BECOME BLACK at any time until LONGER than the universe has existed.

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Ethelred
Feb 27, 2011
Thank you to the experts.
And too bad you ignored them. They DID NOT tell that nonsense you just wrote. Not one of those quotes you posted agreed with that it. You clearly have reading comprehension problems at least when your pet ideas are involved.
I am not wrong on a dark star before a collapse and remaining white dwarf.
I am not wrong on a dark star before a collapse and remaining white dwarf.
Yes you are. The people you quoted did NOT agree to that silly claim.
Yes, an expert astronomer says "black dwarfs" are objects well known to astronomers, so their wording is obviously accurate.
Well known as THEORETICAL object and no has detected one nor is anyone expected to detect one as the Universe is not yet old enough to contain one.
Never be afraid to admit you are wrong.
You are half way there. You aren't admitting to being wrong about the existence of black stars? There aren't any in the entire universe.

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Ethelred
Feb 27, 2011
You simply don't have any understanding yet about the life cylcle of smaller stars such as our own sun. Red dwarfs such as Proxima Cetauri could be nearly as old as the universe and would still be only about half to two-thirds of the way along the main sequence.

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Ethelred
Feb 27, 2011
ttp://science.nationalgeographic.com/science/space/universe/white-dwarfs-article.html
Eventually—over tens or even hundreds of billions of years—a white dwarf cools until it becomes a black dwarf, which emits no energy. Because the universe's oldest stars are only 10 billion to 20 billion years old there are no known black dwarfs—yet.
ttp://www.eg.bucknell.edu/physics/astronomy/as102-spr00/web_pages/web8.html

ttp://en.wikipedia.org/wiki/White_dwarf
However, since no white dwarf can be older than the age of the Universe (approximately 13.7 billion years),[10] even the oldest white dwarfs still radiate at temperatures of a few thousand kelvins, and no black dwarfs are thought to exist yet.[1][5]
See. No black stars. Not yet.

Use the WEB Luke. It can inform you and keep you from ignorance.

It is also full of Cranks so use critical reasoning and multiple sources.

Ethelred
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