"Rethinking the origins of the universe"

Rethinking the origins of the universe
By Thania Benios, Office of Communications and Public Affairs, UNC-Chapel Hill
Published September 23, 2014 :

" Black holes have long captured the public imagination and been the subject of popular culture, from Star Trek to Hollywood. They are the ultimate unknown – the blackest and most dense objects in the universe that do not even let light escape.

And as if they weren’t bizarre enough to begin with, now add this to the mix: they don’t exist.

By merging two seemingly conflicting theories, Laura Mersini-Houghton, a physics professor at UNC-Chapel Hill in the College of Arts and Sciences, has proven, mathematically, that black holes can never come into being in the first place. The work not only forces scientists to reimagine the fabric of space-time, but also rethink the origins of the universe.
...
In 1974, Stephen Hawking used quantum mechanics to show that black holes emit radiation. Since then, scientists have detected fingerprints in the cosmos that are consistent with this radiation, identifying an ever-increasing list of the universe’s black holes.

But now Mersini-Houghton describes an entirely new scenario. She and Hawking both agree that as a star collapses under its own gravity, it produces Hawking radiation. However, in her new work, Mersini-Houghton shows that by giving off this radiation, the star also sheds mass. So much so that as it shrinks it no longer has the density to become a black hole.

Before a black hole can form, the dying star swells one last time and then explodes. A singularity never forms and neither does an event horizon. The take home message of her work is clear: there is no such thing as a black hole."
-the ^^above quoted^^ and much more at : http://www.unc.edu/spotlight/rethinking-the-origins-of-the-universe/
- also available at : http://uncnews.unc.edu/2014/09/23/carolinas-laura-mersini-houghton-shows-black-holes-exist/
- and : http://phys.org/news/2014-09-black-holes.html


Laura Mersini-Houghton seems to be "one of the worlds leading experts in the topic of Hawking Radiation, Black Hole Theory..." cite : 0:25 - 0:36 of video at top of link : http://college.unc.edu/2015/08/25/hawkingconference/

- Story and video by Rob Holliday, Office of Communications and Public Affairs - See more at: http://college.unc.edu/2015/08/25/hawkingconference/#sthash.3Xf86J3s.dpuf

" Folt, Hawking kick off historic physics conference"
" The Hawking Radiation Conference is co-sponsored by UNC-Chapel Hill, along with the Nordic Institute of Theoretical Physics (Nordita), co-hosted by KTH Royal Institute of Technology and Stockholm University; the Centre for Theoretical Cosmology at the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge; and The Julian Swinger Foundation. The gathering began Monday and runs through August 29. The conference is bringing together some of the world’s most accomplished theoretical physicists to discuss the question of whether singularities in black holes exist and whether Hawking Radiation has bearing on their existence. Laura Mersini-Houghton, associate professor of theoretical physics and cosmology in the College of Arts and Sciences at UNC-Chapel Hill whose work on black holes spurred new discussion among physicists, initiated the conference to continue the conversation."
- the ^^above quoted^^ and more at: http://college.unc.edu/2015/08/25/hawkingconference/#sthash.3Xf86J3s.dpuf

 

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Mersini-Houghton has been pushing her idea for years. It does not have much support.

 

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Plus her nonsense was discussed on this forum a few months ago.

 

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https://briankoberlein.com/2014/09/25/yes-virginia-black-holes/

Yes, Virginia, There Are Black Holes
25 September 2014/in Black Holes /by Brian Koberlein
Recent headlines have proclaimed “Black Holes Don’t Exist!” They’re wrong. Black holes absolutely exist. We know this observationally. We know by the orbits of stars in the center of our galaxy that there is a supermassive black hole in its center. We know of binary black hole systems. We’ve found the infrared signatures of more than a million black holes. We know of stellar mass black holes, andintermediate mass black holes. We can even see a gas cloud ripped apart by the intense gravity of a black hole. And we can take images of black holes, such as the one above. Yes, Virginia, there are black holes.

So what’s with the headlines? It seems to start with a link-bait article about a new work concerning the formation of stellar mass black holes. The paper hasn’t been peer reviewed, but it is an extension of an earlier work by the same authors that has been peer reviewed. The focus of both of these papers is on the firewall paradox, specifically how Hawking radiation might affect the gravitational collapse of a star to form a black hole.

The firewall paradox is something that arises when you try to combine black holes with quantum theory. In quantum theory there are limits to what can be known about an object. For example, you cannot know an object’s exact energy. Because of this uncertainty, the energy of a system can fluctuate spontaneously, so long as its average remains constant. In 1974 Stephen Hawking demonstrated is that near the event horizon of a black hole pairs of particles can appear, where one particle becomes trapped within the event horizon (reducing the black holes mass slightly) while the other can escape as radiation (carrying away a bit of the black hole’s energy). These escaping particles have come to be known as Hawking radiation.

According to general relativity, if you were to fall into a black hole, you shouldn’t notice anything strange when you cross the event horizon. Yes, you might feel strong tidal forces, but you’d feel those outside the black hole as well. But according to quantum theory if all this Hawking radiation is being created near the event horizon, then you should experience a firewall of quantum particles. The solution to this theoretical problem is still a matter of some debate. Some, such as Hawking and the authors of this new paper, feel that the Hawking firewall prevents black hole horizons from forming. Others, such as Sabine Hossenfelder argue that quantum theory doesn’t lead to a Hawking firewall. Just to be clear, I’m personally in the Hossenfelder camp.

In this new paper, the authors show that if the Hawking firewall idea is correct, then as a star starts collapsing at the end of its life, before it collapses into a black hole Hawking radiation starts kicking in, which pushes back against the collapsing star. So instead of collapsing into a solar-mass black hole, the star almost collapses into a black hole, Hawking radiation stops its collapse, and the stellar core then explodes. So the star dies in a supernova explosion, but no black hole is formed from its core.

This is interesting theoretical work, and it raises questions about the formation of stellar-mass black holes. But it doesn’t prove that stellar-mass black holes don’t exist, nor does it say anything about intermediate mass or supermassive black holes, which would form by processes other than stellar collapse. And of course the work depends upon Hawking’s take on firewalls to be correct, which hasn’t been proven. To say that this work proves black holes don’t exist is disingenuous at best.

So don’t buy into the hype. Black holes are real, this work is interesting, and the link-baiters should be ashamed of themselves.

Paper: Laura Mersini-Houghton & Harald P. Pfeiffer. Back-reaction of the Hawking radiation flux on a gravitationally collapsing star II: Fireworks instead of firewalls. arXiv:1409.1837 [hep-th]

As I have said many times, the evidence for BH's is overwhelming, and no one has yet explained the observable effects we see on spacetime and matter/energy in any other manner.
Like SR/GR and other mainstream accepted theories/models, BH's will always have their detractors and would be's if they could be's doing their best to invalidate such generally accepted models....Not referring to Laura of course as a "would be if she could be" but it should be remembered that we do have otherwise top notch scientists/physicists/cosmologists, that may stray from what is obvious to the majority, simply because of some obsession or agenda. One such "great" of course was Fred Hoyle......another Nikola Tesla.

 

http://arstechnica.com/science/2015...roversial-paper-exists-but-so-do-black-holes/

“Completely implausible”—a controversial paper exists, but so do black holes:

Mersini-Houghton’s work, even if accurate, leaves a massive, gaping question. If black holes really don’t exist, if they’re impossible, then what, exactly, have we been looking at this whole time?

Black hole skeptics might be quick to point out that black holes cannot be observed directly, due to their very definition. Black holes don’t reflect any light, they certainly don’t emit any, and any Hawking radiation would be far too weak to be observed, so there’s no way for us to directly observe a black hole.

“Yes, ‘black holes are observed,’” Jeffrey McClintock, an astrophysicist with Harvard University, told Ars, “but not in the way, e.g., that a planet, the Sun, or a neutron star is observed—all objects with material surfaces. There is no surface at all at the [event horizon], and anything found there is falling inward (relative to a local observer) at the speed of light. Moreover, according to [general relativity] the EH is a surface of infinite redshift, which means that distant observers like us cannot hope to see any radiation (excluding ultra-feeble and unobservable Hawking radiation) coming from the EH.”
more at the link:

 

Good and thought provoking question.

 

Certainly is, but you miss the proviso..NB: "even if accurate"
BH's remain a near certain entity in cosmology along with DM and DE, until someone is able to explain the relevant effects in a better light.

We had one "would be if he could be" who tried to explain it with what he fabricated as a Black Neutron Star. His work, and his maths, along with his weird claims were all totally demolished.

 

When on merges two "seemingly conflicting" theories and derives a result which conflicts EITHER with math or reality, then either one or both of those theories must be either wrong or incomplete.

Gravity bends light. Black holes exist. If your math shows either or both of these to be impossible, part of your math or your understanding is wrong.

 

If one considers the volume of the black hole to be the Schwarzschild radius then some black holes may be no denser than water, supermassive BH's possibly less than that, at least to an external observer. It is the singularity at the centre of the BH that is the "most dense objects in the universe", not the black hole itself - and I'd have thought that most refer to the black hole as being the volume encapsulated within the Schwarzschild radius?

 

Pretty correct in what you say. A BH in fact [all that is inside the EH] is mostly just critically curved spacetime, with the Singularity at the center.
Seemingly paradoxically, the more massive a BH is, the less dense it is.
Which is why density of a BH, is not often referred to.

Bingo

 

I used to think black holes had been directly observed, so for the benefit of readers who may still think this, I thought it might be useful to post the following discussion from NASA:

Scientists can't directly observe black holes with telescopes that detect x-rays, light, or other forms of electromagnetic radiation. We can, however, infer the presence of black holes and study them by detecting their effect on other matter nearby. If a black hole passes through a cloud of interstellar matter, for example, it will draw matter inward in a process known as accretion. A similar process can occur if a normal star passes close to a black hole. In this case, the black hole can tear the star apart as it pulls it toward itself. As the attracted matter accelerates and heats up, it emits x-rays that radiate into space. Recent discoveries offer some tantalizing evidence that black holes have a dramatic influence on the neighborhoods around them - emitting powerful gamma ray bursts, devouring nearby stars, and spurring the growth of new stars in some areas while stalling it in others.

http://science.nasa.gov/astrophysics/focus-areas/black-holes/
​

My next question would be: since she agrees that the object was once supermassive (as it does, she agrees, emit Hawking radiation), then "at that time" would it fulfill the definition of a black hole? As it emits Hawking radiation, and (arguably) shrinks, then at some point it would no longer be so influential on its local nebulae, shredding stars and building new accretion disks, etc.

Is it possible that she has proved that black holes are somewhat ephemeral . . . but otherwise perhaps reaching (at least for a "while") the state of a black hole which is massive enough to produce the observed phenomena?

Food for thought, in case I haven't missed the point by not studying her work before posting.

 

The facts are though, we see at this moment effects on spacetime and matter/energy etc, that can only be put down to something that has collapsed beyond its Schwarzchild radius.
Cygnus X-1 surpasses what effects a Neutron star could do. They conclude a gravitationally completely collapsed object, or a BH.

https://briankoberlein.com/2014/09/25/yes-virginia-black-holes/

 

The other factor is because of gravitational time dilation, we would never really see any BH in the process of forming, or evaporating for that matter.
bruce or OnlyMe may like to add more info in relation to your querie.

 

A few other points.....It appears she has been also pushing a multiverse model [nothing wrong with that] and also says she has proof of that.
She refutes the BB also and in the article in the OP says something about a Singularity never forming, which contradicts what GR tells us about compulsory collapse once the Schwarzchild radius is reached....well at least compulsory up to and including the quantum/planck level where GR reaches its limitations.

Another point was, " it produces Hawking radiation. However, in her new work, Mersini-Houghton shows that by giving off this radiation, the star also sheds mass. So much so that as it shrinks it no longer has the density to become a black hole."

As Aid said, it still had to have been a BH at least for a time and even if that was happening, time dilation at the EH would prevent us from ever seeing it, and secondly HR by its very nature is a small quantum effect, that only evaporates a stellar or SMBH over huge time periods.
Perhaps it had time to evaporate microBH's created at the BB, but that would be all.

I suggest if there was anything to her claim and her maths, we would have a lot more excited cosmologists/physicists running about like chooks with their heads cut off!

 

Since the actual observation is its effect on local objects, the explanation Dr. Mersini-Houghton has given (again pleading ignorance, since I have not studied her work) would not overturn the evidence (obviously) so I'm OK with the invisibility of black holes, understanding that time dilation and space contraction nearest to the gravity well (in the way it would probably affect detectable emissions) is similar to the effect expected from "collapse" of reality near an event horizon (space apparently contracted to nearly nothing, time apparently coming to a standstill). And in the imagery there is evidence of ancient remnants at an appreciable distance from the supposed gravity well (time having sufficiently elapsed for the star to be ripped apart and its remnants left in the wake, as the black hole moves in a contrary direction), as well as the exciting discovery of X-ray emitters left behind. Also, the black hole tends to orbit, as a pair of free bodies, the center of mass of the distributed matter it interacts with. So in some cases there may be a way to infer the rough amount of time elapsed since the most spectacular kinds of interactions.

I guess I need to read more to see how she treats the ephemeral nature of her black holes, in light of the evidence. I think her suggestion that the Big Bang is a sort of wave function at the horizon of a multiverse, which exerts gravity on our universe, is fascinating. In the other thread where Brian Greene is alternately being praised and skewered, I would connect this with his point that in cosmology and particle physics, there seem to be certain duals - he mentions the relationship between x and 1/x, which is reflexive in this sense (a cosmos "sees" a microcosm as 1/x and vice versa). Thus the black hole has as a sort of dual the quantum singularity (string) and so goes the basis of string theory. My point here is that, once we accept the wave function as a harbinger of "quantum weirdness" then her cosmic wave function would comport to this as "x is to 1/x".

More food for thought, with apologies to the experts, whose feedback is appreciated as well!

In fact I would like to know if she touches on my questions - does she mean they do not persist, or they do not exist at all? (I will try to find out.)

 

Let us know Aid.


Another rather important point.
In claiming and saying all she has, doesn't it imply that she has also "conquered" the holy grail of physics? A quantum gravity theory?
Isn't that a rather extra ordinary claim? And worthy of more headlines?

 

This G2 stuff was a big damp squib, the G2 ghost peacefully passed by, all predictions failed.

PS: The above quote is not attributed directly to Paddoboy, he had pasted a detailed link, without commenting anything on G2.

 

This is what she says in her paper. [taken in quote for clarity]

She is of the opinion that before the star core collapses below its EH, it bounces back....thus in principle no BH is formed.

 

And just as I referenced it, unlike you I do not plagiarise material.

 

According to her brand of mathematics.....As I mentioned claiming all this she would also have had to have a QGT.
I believe we can all safely move along, nothing to see here.

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