Astrophysicists duo propose Planck star as core of black holes

Feb 14, 2014 by Bob Yirka report
This artist's concept depicts a supermassive black hole at the center of a galaxy. The blue color here represents radiation pouring out from material very close to the black hole. The grayish structure surrounding the black hole, called a torus, is made up of gas and dust. Credit: NASA/JPL-Caltech

(Phys.org) —Two astrophysics, Carlo Rovelli and Francesca Vidotto, have uploaded a paper to the preprint server arXiv in which they suggest that a structure known as a Planck star exists at the center of black holes, rather than a singularity. This would suggest, they note, that black holes at some point return all the information they have pulled in, to the universe.

The current thinking regarding is that they have two very simple parts, an event horizon and a . Because a probe cannot be sent inside a black hole to see what is truly going on, researchers have to rely on theories. The singularity theory suffers from what has come to be known as the "information paradox"—black holes appear to destroy information, which would seem to violate the rules of general relativity, because they follow rules of quantum mechanics instead. This paradox has left deep thinking physicists such as Stephen Hawking uneasy—so much so that he and others have begun offering alternatives or amendments to existing theories. In this new effort, a pair of physicists suggest the idea of a Planck star.

The idea of a Planck star has its origins with an argument to the Big Bang theory—this other idea holds that when the inevitable Big Crunch comes, instead of forming a singularity, something just a little more tangible will result—something on the Planck scale. And when that happens, a bounce will occur, causing the universe to expand again, and then to collapse again and so on forever back and forth.

Rovelli and Vidotto wonder why this couldn't be the case with black holes as well—instead of a singularity at its center, there could be a Planck structure—a star—which would allow for to come back into play. If this were the case, then a black hole could slowly over time lose mass due to Hawking Radiation—as the black hole contracted, the Planck star inside would grow bigger as information was absorbed. Eventually, the star would meet the and the black hole would dematerialize in an instant as all the information it had ever sucked in was cast out into the universe.

This new idea by Rovelli and Vidotto will undoubtedly undergo close scrutiny in the astrophysicist community likely culminating in debate amongst those who find the idea of a Planck star an answer to the information paradox and those who find the entire implausible.

Explore further: Black holes do not exist as we thought they did

More information: Planck stars, arXiv:1401.6562 [gr-qc] arxiv.org/abs/1401.6562

Abstract
A star that collapses gravitationally can reach a further stage of its life, where quantum-gravitational pressure counteracts weight. The duration of this stage is very short in the star proper time, yielding a bounce, but extremely long seen from the outside, because of the huge gravitational time dilation. Since the onset of quantum-gravitational effects is governed by energy density —-not by size—- the star can be much larger than planckian in this phase. The object emerging at the end of the Hawking evaporation of a black hole can then be larger than planckian by a factor (m/mP)n, where m is the mass fallen into the hole, mP is the Planck mass, and n is positive. We consider arguments for n=1/3 and for n=1. There is no causality violation or faster-than-light propagation. The existence of these objects alleviates the black-hole information paradox. More interestingly, these objects could have astrophysical and cosmological interest: they produce a detectable signal, of quantum gravitational origin, around the 10−14cm wavelength.

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Modernmystic
1.3 / 5 (3) Feb 14, 2014
the Planck star inside would grow bigger as information was absorbed. Eventually, the star would meet the event horizon and the black hole would dematerialize in an instant as all the information it had ever sucked in was cast out into the universe.


One would think that the horizon would actually increase in apparent size as the singularity would decrease in size (if that's possible) because of the effects of gravity. Unless they're proposing something like degeneracy pressure that comes into play at the plank level.
SoylentGrin
1 / 5 (1) Feb 14, 2014
Dematerializing Planck star = Gamma Ray Burst?
Could they explain what sped up the Oh-my-god particle so much?
antialias_physorg
4.4 / 5 (9) Feb 14, 2014
One would think that the horizon would actually increase in apparent size as the singularity would decrease

Why? The diameter of the horizon is a function of the enclosed mass. Period. How big/small the entity inside is is irrelevant.
If the stuff inside it loses mass (due to Hawking Radiation) then the horizon will get smaller.

Dematerializing Planck star = Gamma Ray Burst?

Probably not because the time it will take for a black hole to evaporate via Hawking Radiation is MANY orders of magnitude longer than the current age of the universe.
SoylentGrin
4.8 / 5 (8) Feb 14, 2014
Dematerializing Planck star = Gamma Ray Burst?

Probably not


That's cool. I like the idea of GRBs being other civilisations trying out their Alcubierre drives anyway. =)
Tuxford
1 / 5 (6) Feb 14, 2014
More movement toward the obvious. Trying to distance themselves from years of proclaiming singularity nonsense. Galactic SMBH are stars! Just really massive, really dense stars, that can become unstable on occasion, ejecting massive radiations and expelling massive winds. So hurry up fella's, or prepare for singular intellectual embarrassment. Hawking sees the the handwriting on the event horizon.

(Yes, counter pressure eventually stops the collapse. A different physics is involved. One that eliminates the expanding nothingness, Huge Bang, finite age nonsense. Physicists must come around as the observational evidence piles up, or they are going to look rather foolish.)
TheGhostofOtto1923
3 / 5 (5) Feb 14, 2014
Probably not because the time it will take for a black hole to evaporate via Hawking Radiation is MANY orders of magnitude longer than the current age of the universe
Why? Evaporation is a function of the enclosed mass. Period.

A black hole with the mass of our sun will take longer than the age of the universe. Micro black holes should disappear instantaneously.
http://library.th...ore8.htm

Primordial black holes
"Being within the typical mass range of asteroids, this excludes those black holes too small to persist until our era and those too large to explain gravitational lensing observations"
Modernmystic
2 / 5 (3) Feb 14, 2014
Why? The diameter of the horizon is a function of the enclosed mass. Period. How big/small the entity inside is is irrelevant.


Well we don't know if it's relevant or not do we? My point was (if you'd read carefully instead of just being contrary for the sake of it) that current theory would suggest that since gravity overwhelms the scenario that the more matter added the more pressure is applied and the smaller the "singularity" would tend to be. UNLESS, like I said, they're implying some kind of new "counterforce" that comes into play at or around the plank level. For instance like degeneracy pressure keeps a white dwarf from collapsing further if the star is below a certain mass level.

Maybe it's a quark/gluon plasma, or maybe something more fundamental...a "string plasma"? I don't know, no one does, but it's fun to speculate.
Maggnus
5 / 5 (5) Feb 14, 2014
Well yes Ghost, assuming such micro black holes exist. So far, there is no evidence they do, and even Hawking has stated they are unlikely despite the maths backing their possible existence.
antialias_physorg
4.5 / 5 (8) Feb 14, 2014
Why? Evaporation is a function of the enclosed mass. Period.

We're not talking thermal radiation here. The radiation that a black hole of above solar mass has via Hawking radiation is in the nanoKelvin range. The current radiation from the CMB is at 2.7K. So currently black holes are getting orders of magnitude more radiation in than they are 'expelling' via Hawking radiation (i.e. they are growing - not shrinking...even if there is no matter to suck in in the neighborhood).

Until the CMBR drops below the temp of Hawking radiation black holes aren't going to be getting smaller.

Very small black holes are 'hotter'. A black hole with the mass of the Moon would be at roughly 2.7K and would start to get smaller (assuming no nearby mass to feed it). But those kinds of masses are too small to form black holes naturally.

Until a solar mass BH evaporates we're talking 36 orders of magnitude longer than the universe has existed. For larger ones MUCH longer.
reid barnes
2 / 5 (4) Feb 14, 2014
The black hole concept was devised to explain speeds of rotating stars from red shift measurements, rotating according to a hypothesized red shift-speed correlation, in order to maintain the gravitational cosmology model based on Einstein's general theory of relativity. However to maintain that model the red shift speed correlation hypothesis of Edwin Hubble was rejected in favor of the space-time stretching explanation of George LeMaitre in accord with the general theory of relativity. it was also theorized in order to maintain the gravitational model according to the general theory of relativity that the cosmos is expanding at the speed of light and accelerating. However, the general theory of relativity was based on non-Euclidean geometry, and something was overlooked when coordinates were included in the geometry; it turned out that the non-Euclidean geometry became self-contradicting, which invalidates the theory. It may be hard to accept that this mistake was made and no one realized it, but it is true, and though perhaps hard to accept, it is not hard to understand. You can understand it even if your math education did not exceed elementary geometry.
https://www.faceb...72097217
Osiris1
not rated yet Feb 14, 2014
A planck star would probably be super small.
TheGhostofOtto1923
1 / 5 (1) Feb 14, 2014
We're not talking thermal radiation here
Neither were the experts from whence I got the info.

"...a 1-second-lived black hole has a mass of 2.28 × 105 kg, equivalent to an energy of 2.05 × 1022 J that could be released by 5 × 106 megatons of TNT. The initial power is 6.84 × 1021 W.

"Black hole evaporation has several significant consequences:
Black hole evaporation produces a more consistent view of black hole thermodynamics, by showing how black holes interact thermally with the rest of the universe.

"Unlike most objects, a black hole's temperature increases as it radiates away mass. The rate of temperature increase is exponential, with the most likely endpoint being the dissolution of the black hole in a violent BURST OF GAMMA RAYS. A complete description of this dissolution requires a model of quantum gravity, however, as it occurs when the black hole approaches Planck mass and Planck radius."

-Primordial black holes could indeed be the source of gamma ray bursts.
TheGhostofOtto1923
1 / 5 (1) Feb 14, 2014
But those kinds of masses are too small to form black holes naturally
-And you didnt bother to read up on primordial black holes. So stay stupid.
antialias_physorg
4.2 / 5 (5) Feb 14, 2014
It seems they are severly restricted in mass
http://www.nature...-1.14551
And those that are much smaller would have long since gone boom.

It's also a question that if the early universe was that dense in a part where it collapsed into such a hole then that black holes should have found ample mass in the environment to feed on to grow big - even though they don't interact much with other mass due to their tiny size. .

For a primordial black hole to go boom now it must have stopped feeding and then somehow starved a few billion years. If at all they may account for the shortest GBRs but the longer ones don't really work for them.
http://arxiv.org/...5363.pdf

At current they're an interesting theory but without much in the way of observational evidence.
Nestle
3 / 5 (3) Feb 14, 2014
A Planck star would probably be super small.
The Planck units are broken with general relativity in the same way, like the general relativity models are getting broken with quantum mechanics - just pretty at the human scale range.
Feldagast
1 / 5 (1) Feb 14, 2014
Couldn't all the energy being sucked in and mass converted to energy be expelled somewhere else like they show in the sci-fi movies through a wormhole?
TheWalrus
4.8 / 5 (6) Feb 14, 2014
"The inevitable Big Crunch"? Are they refuting the accelerating expansion of the universe? I thought most physicists agree that the universe will die a heat death.
TheWalrus
5 / 5 (1) Feb 14, 2014
One would think that the horizon would actually increase in apparent size as the singularity would decrease

Why? The diameter of the horizon is a function of the enclosed mass. Period. How big/small the entity inside is is irrelevant.
If the stuff inside it loses mass (due to Hawking Radiation) then the horizon will get smaller.

Dematerializing Planck star = Gamma Ray Burst?

Probably not because the time it will take for a black hole to evaporate via Hawking Radiation is MANY orders of magnitude longer than the current age of the universe.


The event horizon is also a function of the black hole's spin. I read an article on that today. Basically, the faster the spin, the smaller the event horizon.
DonGateley
not rated yet Feb 14, 2014

The event horizon is also a function of the black hole's spin. I read an article on that today. Basically, the faster the spin, the smaller the event horizon.


I think that's because m=e/c^2 so rotation is energy is mass. In GR it's a "little" more complicated than that but from the outside of a black hole it's the end result.
Dr_toad
Feb 14, 2014
This comment has been removed by a moderator.
Mimath224
5 / 5 (2) Feb 14, 2014
Would seem to me that if we are to consider any type of 'star' existing inside a BH then surely the inside of the BH would be governed by a quantum process since stars follow this path. But then a Planck star would seem to be more like a Palnk 'atom', similar to the energies that prevent the electron from collapsing into the nucleus. But would not such a process be also present in neutron stars or am I being too simplistic here?
The other point that has always bothered me is the 'classical BH' destroying/taking information away from the universe. My analogy would be more like the BH acts more like the ultimate 'safe' where information is locked away but not destroyed.
Can't help feeling the article is suggesting some type quantum loop left over by the initial collapse.
h20dr
not rated yet Feb 15, 2014
Because a probe cannot be sent inside a black hole to see what is truly going on, researchers have to rely on theories.

As if we could send a probe...
antialias_physorg
4.2 / 5 (5) Feb 15, 2014
The event horizon is also a function of the black hole's spin.

What you'e thinking of is the ergosphere:
http://en.wikiped...gosphere
The ergosphere's shape is a function of the spin. The ergosphere is not the same as the event horizon. Only in non-rotating BHs are they identical - and I can't really think of any circumstance where you'd get a non-rotating black hole. BHs should all spin (close to) as fast as possible if the spin can counteract the collapse - which would make them another form of standrard candle, come to think of it.

I thought they said it was only at the Planck scale do the effects of the 'next level' of degeneracy pressure manifest.

That's the real interesting question: At what scale does another force kick in (if there is another one)?
Mimath224
4.7 / 5 (3) Feb 15, 2014
The event horizon is also a function of the black hole's spin.


2gm/c^2 is the basic calc for the eh (Schwarzschild radius), spin is not included. The possible confusion might be that some call the ergosphere an 'outer eh'. Depending on the nature of the BH the ergosphere and eh could coincide at the poles where the ergosphere could become flattened due to the spin.
TheGhostofOtto1923
1 / 5 (1) Feb 15, 2014
That's the real interesting question: At what scale does another force kick in (if there is another one)?
Well you can imagine (or maybe not) it's a question that scientists have also asked. So let's do a little research.

There may be:
-Quark stars and strange stars
-Electroweak stars
-Preon stars - "a proposed type of compact star made of preons, a group of hypothetical "point-like" subatomic particles, conceived to be subcomponents of quarks and leptons. Preon stars would be expected to have huge densities, exceeding 10^23 kg/m3"
-Boson stars
http://en.wikiped...tic_star

-All with predicted properties.
richardwenzel987
5 / 5 (1) Feb 15, 2014
Wouldn't the Pauli Exclusion Principle prevent matter from collapsing into a singularity?
IronhorseA
not rated yet Feb 15, 2014

That's the real interesting question: At what scale does another force kick in (if there is another one)?


And also, does it merely stop the collapse, or does it merely shunt it in another direction at right angles to the current three (or 4 including time). That's the problem with not being able to send a probe either into, or close enough to test Hawking's radiation hypothesis.
Nestle
2 / 5 (4) Feb 15, 2014
Wouldn't the Pauli Exclusion Principle prevent matter from collapsing into a singularity?
Yes, of course. From the same reason the dense aether model prohibits the formation of singularities. The gravity is formed with shielding of longitudinal waves of vacuum with massive objects (with space curvatures forming them, being more specific) - and when matter collapses into singularity, there is nothing to shield anymore. So far the most dense stars are considered the quark stars, but theorists already speculated about even more compact objects, like the preon and electroweak stars stuffed with neutrinos. IMO it's time to reconcile all these ideas into single one, because they're differ each other only infinitesimally from observational perspective. In particular, the neutrino star model appears promising for me, because it brings whole spectrum of black holes via AdS/CFT correspondence. Also, the oscillations of Planck stars proposed resemble the oscillations of neutrinos.
Nestle
1.8 / 5 (5) Feb 15, 2014
We can observe many similarities between small objects in the universe and the large objects, which are composed of them. In AWT it's a manifestation of projective geometry, known as a holographic principle and AdS/CFT correspondence. Even at the water surface the smallest density fluctuations known as a Brownian noise resemble the largest solitons spreading along it. These similarities are subtle for more complex objects close to human observer scale, but with increasing distance from it the dimensionality of both space-time, both objects observed decreases, so it manifests clearly. So if you cannot imagine, how the neutrinos or scalar waves do appear, the black holes are good model and vice-versa. For example, I don't think that the Planck stars do appear like the hollow sphere - but rather like the torus. Even the neutrinos do appear like the vortex rings in AWT model.
Nestle
1.8 / 5 (5) Feb 15, 2014
As we already know, the neutrinos come in two parity types, which are connected by their charge (1, 2). These vortices are otherwise quite symmetric. But we can suppose, that the neutral sterile neutrinos may exist too (3). If the black hole formed like this would rotate, it wouldn't exhibit a charge, but it would behave like the magnetic monopole instead. You may recognize it at distance, because the symmetry of black hole jets will be broken in this case. Such a black holes are rare, because they do represent an intermediate state between charged black holes with pair of jets and fully decayed quiet black holes without jets, which are residing inside of aged galaxies. Analogously, the sterile neutrinos are just an intermediate step during parity oscillations of neutrinos.
Nestle
1.8 / 5 (5) Feb 15, 2014
In addition the neutrinos are known to oscillate between generations. If the neutrino star would undulate in this way, its physical horizon may rise above the event horizon of black hole temporarily. Under such a situation we would observe the periodical bursts of energy, mostly in form of neutrinos and cosmic rays emanated in form of polar jets of otherwise quiet black hole. In LaViolette theory, such a bursts are quite common, they occur in black hole central to Milky Way and they may even affect the climate at the Earth. So that the model of Planck stars could be tested just with theory and observations, which the mainstream physics managed to ignore so long.
Nestle
2.3 / 5 (3) Feb 16, 2014
The schematic evolution of ideas about black holes. As we can see, both surface of internal singularity, both event horizon are becoming fuzzy, turbulent and they do converge against each other.
Drjsa_oba
5 / 5 (1) Feb 17, 2014
Why? The diameter of the horizon is a function of the enclosed mass. Period. How big/small the entity inside is is irrelevant.


Well we don't know if it's relevant or not do we? My point was (if you'd read carefully instead of just being contrary for the sake of it) that current theory would suggest that since gravity overwhelms the scenario that the more matter added the more pressure is applied and the smaller the "singularity" would tend to be. UNLESS, like I said, they're implying some kind of new "counterforce" that comes into play at or around the plank level. For instance like degeneracy pressure keeps a white dwarf from collapsing further if the star is below a certain mass level.

Maybe it's a quark/gluon plasma, or maybe something more fundamental...a "string plasma"? I don't know, no one does, but it's fun to speculate.


My point is that a singularity has no size or else it is not a singularity is it?
antialias_physorg
not rated yet Feb 17, 2014
Wouldn't the Pauli Exclusion Principle prevent matter from collapsing into a singularity?

If stuff stays in a form represented by a propbability distribution then at the very least the Heisenberg Uncertainty Principle should create a lower bound.

But since we don't know what kind of transformations go on in there it's anyone's guess.
Fleetfoot
5 / 5 (3) Feb 17, 2014
Wouldn't the Pauli Exclusion Principle prevent matter from collapsing into a singularity?


It does to an extent, that's why the collapse pauses at neutron stars, but higher pressure makes different mixtures of particles energetically favoured, and the exclusion principle has an upper limit related to the speed of light so eventually it fails.
Osteta
Feb 17, 2014
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Osteta
Feb 17, 2014
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Osteta
Feb 17, 2014
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Fleetfoot
5 / 5 (4) Feb 17, 2014
The most dense stars proved so far are quark stars, which are still composed of fermions, but the denser states composed of massive W/Z bosons are theoretically possible. The Fermi-Dirac statistics and the Paulic exclusion principle wouldn't apply for them, at least not in full extent.


Exactly, and ultimately the size of the central object becomes more related to the uncertainty principle than specific particle properties.
11791
Feb 17, 2014
This comment has been removed by a moderator.
RealScience
5 / 5 (6) Feb 17, 2014
We're not talking thermal radiation here
Neither were the experts from whence I got the info.

"...a 1-second-lived black hole has a mass of 2.28 × 105 kg, equivalent to an energy of 2.05 × 1022 J that could be released by 5 × 106 megatons of TNT.
...
-Primordial black holes could indeed be the source of gamma ray bursts.


While evaporating black holes would indeed release burst of gamma rays, those bursts would be much smaller than the gamma ray bursts we seem to see from billions of light years away.

The evaporation of a black hole slows with the cube of its mass, a black hole releases ~2x10^22J in it last second, ~8x 10^22J in its last minute, and ~1.5x10^23J in its last hour.

The cosmic GRBs release ~10^44 Joules in a short period - even 'ultra-long' GRBs release the bulk of their energy in less than an hour.

So evaporating black holes are simply too wimpy to be the source of cosmic GRBs.
rgrdnrjr
not rated yet Feb 18, 2014
How about the plank star being made up of leptons since the electroweak force can change quarks into leptons radiating energy? You could maybe pack them close enough to stop light from escaping forming a "black hole"and keep the Exclusion Principle.
ubavontuba
1 / 5 (1) Feb 19, 2014
The singularity theory suffers from what has come to be known as the "information paradox"—black holes appear to destroy information,
Or maybe they don't radiate and just keep the information forever...

...there, paradox solved. ;-D

rgrdnrjr
not rated yet Feb 19, 2014
siva at http://physics.st...rinciple says that black holes have many more quantum states that ordinary matter ~e^M^2 for fermions to occupy in a black hole.
william_thigpen7
not rated yet Feb 28, 2014
This seems a little convoluted to me. A singularity is a mathematical term and cannot exactly be observed in ordinary observations made by us from the earth using the tools we have now. If a singularity is the center of a black hole, it could be called between 0 and 1 dimensions, for all we know it could be more dimensions than we could ever know. But, If a star were to be at the center, then that suggests that the singularity of a black hole behaves about the same as the microstate acoustic black holes we can observe on earth and quantum mechanics as well as classical mechanics would be safe another day. However, even at a plank scale, the amount of energy needed to compress matter to that small of a size, while holding onto its ridiculous resistance to stable entropy would be more than I could ever say for sure. I am skeptical of the whole idea of something that solid state being the singularity, if anything is there, it's beyond our current definition of the black hole system.
taka
not rated yet Mar 25, 2014
Do not forget that there is nothing to stop matter when it reaches the center of Black Hole. But matter that is fallen in will have enough speed there to almost reach event horizon in other side. So, the center will be empty, matter is distributed all over inside of it. And as it will take infinite time for light to reach the event horizon there is infinite space inside actually. It is nothing else then Universe that is inside.
Fleetfoot
not rated yet Mar 25, 2014
But matter that is fallen in will have enough speed there to almost reach event horizon in other side.


No, that would necessitate moving way from the centre which is not possible. The radial direction becomes time-like inside the horizon so that would require the matter to travel backwards in time.