Erasing the Bang and Hole singularities

[Martin]

Ashtekar and Bojowald are two of the most prominent people in Quantum Gravity research. Ashtekar was a co-founder of the LQG approach and Bojowald initiated the field of Loop Quantum Cosmology, where LQG methods are applied to help understand the big bang, inflation and features of the microwave background. In 2001 Bojowald showed that quantum gravity eliminates the classical big bang singularity and leads to a prior contraction phase. Now these two are working on a quantum gravity model of black holes and gravitational collapse (in a way the opposite of big bang expansion).

 

http://www.arxiv.org/abs/gr-qc/0509075

Quantum geometry and the Schwarzschild singularity

Abhay Ashtekar, Martin Bojowald

31 pages, 1 figure

 

SAMPLE FROM CONCLUSIONS SECTION

 

"Results of the last two sections support a general scenario that has emerged from the analysis of singularities in quantum cosmology. It suggests that the classical singularity does not represent a final frontier; the physical space-time does not end there. In the Planck regime, quantum fluctuations do indeed become so strong that the classical description breaks down. The space-time continuum of classical general relativity is replaced by discrete quantum geometry which remains regular during the transition through what was a classical singularity. Certain similarities between the [black hole] model analyzed here and a cosmological model which has been studied in detail [10] suggest that there would be a quantum bounce to another large classical region. If this is borne out by detailed numerical calculations, one would conclude that quantum geometry in the Planck regime serves as a bridge between two large classical regions. Space-time may be much larger than general relativity has had us believe."

 

 

In this paper the authors come close to saying that spacetime might re-bound from the pit of a black hole, forming another large tract of universe by another inflationary expansion. There is another paper in the works on this, reference [10]. The paper that is in preparation, by Ashtekar et al, is called:

Quantum nature of the big bang: An analytical and numerical study

"numerical" means they use computer runs as well as equations, to study the big bang moment when the classical Einstein model breaks down.

 

I understand that quantizing has been able to fix breakdowns in other classical models, to eliminate the glitches known as singularities. So if quantizing spacetime and its geometry-----in other words quantizing Einstein 1915 General Relativity-----succeeds in smoothing over the classical singularities at the instant of the bang and the pit of the hole, that will in some sense just continue the historical precedent.

 

fixing singularities (since 1900 when Max Planck fixed an infinity in the blackbody radiation curve) is one of the things quantizing has always been about

[Xyph]

So black holes are actually wormholes to other universes?

[Martin]

So black holes are actually wormholes to other universes?

 

you are quick Xyph, but I will be cautious and point out that nowhere do the authors SAY the word wormhole

and they are intentionally vague

 

and they also say that more analytical and numerical work is in progress, needed to confirm that kind of thing

 

also the first experimental tests of LQG will not occur until 2007 (or 2008 if there is some slippage) with a new orbital Gamma Ray Burst observatory.

 

and LQG will be shot down if a certain shift in the spike of a GRB is not seen.

 

and so on. so everything is very iffy and requires a lot of patience.

 

also maybe the word "wormhole" is better applied to microscopic brief connections between different parts of our space, rather than what A & B are talking about.

[Martin]

So black holes are actually wormholes to other universes?

 

one thing to say is that (if this BH-BB connection is right) then if you say it is a wormhole it must be a very ONE-WAY wormhole

 

the offspring universe, that branches off from ours at the BH, is entirely in the future

 

you can't come back from it.

 

once you pass the BH boundary, time points down to the pit, the forward lightcones designating the future point down into the hole, and going to the pit is as inevitable as tomorrow or next week (except that it happens faster)

 

and if there is this nonsingular "quantum regime" they talk about, where everything is fuzzy and matter and space arent distinct entities any more,

and if this quantum regime segues into an inflationary scenario endowing a new universe with space time and energy, then it is all one-way, you NEVER RECONNECT

 

there is only this one umbilical, no other contact, and it leads to a whole other tract of spacetime with its own kick-off inflation blast of energy and it is all in the future-----meaning that you CAN'T TURN AROUND and swim against time and get back

 

so whether it is a wormhole depends on what one means by wormhole, and if we call it that then the only thing to remember is the directionality.

[Bettina]

So the science fiction writers, Gene Rodenberry especially, may not have been that far out. Geez, I wonder whats next.

 

Thanks for the link.

 

Bettina

[Martin]

So the science fiction writers' date=' Gene Rodenberry especially, may not have been that far out. Geez, I wonder whats next.

 

Thanks for the link.

 

Bettina[/quote']

 

You are most cordially welcome Bettina, I also wonder what's next

[us.2u]

Isn't it just so fact is stranger than fiction...us.2u

[Skye]

So if you think of 4D space-time as a plane, and you have gravity as these kinds of indentations in the plane. In the case of a quantum gravity black hole the indentation sort of opens out at the bottom as you have the inflationary expansion. So then if you roll the unierse plane up into a big ball, with curved space-time I think this is what happens, you would maybe have something that looks like asexually budding yeast.

 

Some nice pictures of yeast budding off little baby yeast.

http://www.alltech.com/Resources/Yellow_yeastBig.jpg

http://www.schoolscience.co.uk/content/4/biology/sgm/images/yeast.jpg

http://microbiology.mtsinai.on.ca/mig/images/direct/fig05-dm.jpg

http://www.biology.mcgill.ca/faculty/vogel/assets/images/cells.gif

 

I guess the question, if I'm not completely mistaken here, is whether the little pieces of universe bud off like the yeast do.

[Xyph]

This is interesting. Would these universes have the same physical laws as their parent universes?

 

Will the life of the black hole dictate the duration of their Big Bang, or is this universe going to have a white hole continuously spewing matter into it's space?

[us.2u]

This is interesting. Would these universes have the same physical laws as their parent universes?

 

Will the life of the black hole dictate the duration of their Big Bang' date=' or is this universe going to have a white hole continuously spewing matter into it's space?[/quote']

 

As far as we know to date; relatvity has the same laws everywhere, we have not found the laws change anywhere to the contary as yet, but being open minded we all could be in for a shock; or maybe Relativity applies anytime anywhere...us.2u

[Martin]

Ashtekar could be feeling a bit uncomfortable now, because the A & B paper obviously opens a can of worms.

 

Scientists are not supposed to speculate, or if they do so occasionally they are supposed to say explicitly that it is just unsupported speculation. Other people in his field may well be telling him now that he wasnt sufficiently careful in how he worded things in this paper.

 

Xyph and Skye, your questions about this line of thinking are clearly good ones to ask, and I like the comments from Bettina and us-to-you as well. Quite a few people in the Quantum Gravity community (Ashtekar's colleagues) must now be asking questions and making comments like this.

 

And I suspect that Ashtekar and Bojowald do not have clear answers at this point. (there are other QG people working on this same thing and they probably wouldn't either)

 

There is a conference next month October 10-14, and Ashtekar is scheduled to give a talk about this on Friday, and he will get a lot of questions. It would have been fun to be there and watch the show, but it is in Berlin (a suburb called Potsdam) which is a long ways away from most of us I guess.

If anyone is in the area, here's Ashtekar's talk announcement with a summary:

http://loops05.aei.mpg.de/index_files/abstract_ashtekar.html'>http://loops05.aei.mpg.de/index_files/abstract_ashtekar.html

here's the main website with details about where etc.

http://loops05.aei.mpg.de/

and here's the full programme:

http://loops05.aei.mpg.de/index_files/Programme.html

 

I see something interesting. Right after Ashtekar speaks 10-11 Friday morning they have coffee (so more questions and informal discussion happens) and then a talk about TESTING quantum gravity models by measuring features of the cosmic microwave background.

 

The speaker after Ashtekar, Roy Maartens, is a cosmologist who has looked into the consequences both of string and LQG models (either or both of which could be wrong, obviously, and both of which urgently need testing) and Maartens has written about some possibly observable signature of LQG in the texture of the CMB which might (as more accurate data is collected) serve as a test. So has Parampreet Singh, and Singh and Maartens have collaborated.

 

The conference organizers have set it up in a way that takes some of the heat off Ashtekar and reduces potential frustration for the audience.

when they say how can you test this? he can refer to Maartens talk right after his. And the organizers scheduled only ONE talk instead of two in the main morning session 9-11, unlike on the other days, so people could focus on this, and put a coffee session after, so they could have a little time to digest and think about it.

 

It is basically a difficult situation. Ashtekar is a central figure in QG and co-initiated the Loop approach LQG, and he is going out on a limb and saying the shocking possibility that spacetime extends and re-expands beyond the pit of a hole and I suspect that he cannot answer any of the many questions that this raises

 

but at least there will be signatures in the CMB to look for that will help decide what kind of a (quantum gravity) event the Bang actually came from. It can't be merely a "singularity" (that just means a failure of the classical theory) it has to be a quantum spacetime dynamics thing and it must have left some traces of what it was. So Maarten's talk takes over after the coffee break.

Here is the brief summary in the programme:

 

http://loops05.aei.mpg.de/index_files/abstract_maartens.html

Prof. Roy Maartens

COSMOLOGY AND QUANTUM GRAVITY

"I will review the basic features of the standard, classical model of cosmology, which is based on General Relativity, and how this model accounts for observed properties of the universe. Modifications to General Relativity that are inspired by quantum gravity need to be tested against cosmological observations. This is one of the key tests for any candidate quantum gravity theory. I will discuss in general terms some of the difficulties involved in this aim, and what is needed from theorists in order to achieve this aim. In particular, I will compare some of the features of stringy cosmology and loop quantum cosmology."

[Martin]

This is interesting. Would these universes have the same physical laws as their parent universes?

 

We don't know. Lee Smolin has conjectured that the laws might be the same but some of the CONSTANTS in the laws might be slightly different (like the fine structure constant which in our universe is approx. 1/137' date=' and some of the mass ratios) because he thinks that some of the constants in the Standard Model of particle physics could be dynamically determined and could change in the transition from hole to bang. R. Gambini has provided some backup reasoning for this. But mainly we just don't know.

 

Will the life of the black hole dictate the duration of their Big Bang, or is this universe going to have a white hole continuously spewing matter into it's space?

 

No white hole, for the following reason. Our big bang exists only in our past. Theirs would likewise exist only in their past.

 

Once inside the event horizon of a black hole, TIME POINTS DOWN THE HOLE. Spacetime is skewed around. So the (former singularity, or quantum regime, or bridge at the) pit is not location in space but an EVENT IN TIME that crud that fell into the hole, the old sewing machines and television sets, conservative christians or whatever, experience for a moment.

 

presumably it is very hot and dense and blurred, matter blends with space and everything comes apart into uncertainty, but it only lasts for a moment and then you are a cloud of quarks or other confetti in the INFLATION stage of a new branch of the universe. but the main thing to remember is that I personally don't know and probably none of the QG people do either.

 

LQG could be wrong, observations could eventually refute it, but it seems (Ashtekar is saying) that the LQG model indicates that a black hole constitutes a place where THE FUTURE BRANCHES into two completely distinct futures: there is the future spacetime of whatever fell into the hole, and there is the future which we who did not fall in can look forward to.

[Martin]

... you would maybe have something that looks like asexually budding yeast.

 

Some nice pictures of yeast budding off little baby yeast.

http://www.alltech.com/Resources/Yellow_yeastBig.jpg

http://www.schoolscience.co.uk/content/4/biology/sgm/images/yeast.jpg

http://microbiology.mtsinai.on.ca/mig/images/direct/fig05-dm.jpg

http://www.biology.mcgill.ca/faculty/vogel/assets/images/cells.gif

 

I guess the question' date=' if I'm not completely mistaken here, is whether the little pieces of universe bud off like the yeast do.[/quote']

 

do the umbilicals eventually dwindle to nothing?

and what about when the black hole in our region of spacetime evaporates?

I dont understand this well enough to respond helpfully.

I have these same questions.

 

the pictures are evocative. they seem to grow in a "tree" structure

 

it is also possible that some microscopic planckscale process generates spacetime in a tree-like structure and that it only looks 4D to us (or spatially 3D to us) macroscopically.

 

so if you could explore space, or spacetime at very small scales you might find it was sort of "polymer-ish" rather than the usual euclidean or minkowskian model-----it might not seem 3D or 4D in any simple way

 

this yeast process is suggestive. but we can afford to wait and see what the QG people come up with, there will be a lot of papers and some brave souls will draw conjectural spacetime diagrams. I love watching this field of research, and wish them luck

 

thanks again for this yeast picture, I really like it

[us.2u]

Thank you martin for your interest I would've loved to go to Berlin but the expeses are too much for me...I hope you go & I'll be looking forward to your minutes...us.2u

[Martin]

Thank you martin for your interest I would've loved to go to Berlin but the expeses are too much for me...I hope you go & I'll be looking forward to your minutes...us.2u

 

I very much thank you for YOUR interest, us-to-you. I see you are in UK which is nearer than I am (US west coast). I would love to attend as well, but have other plans in October. maybe next year's Loops 06 conference.

[[Tycho?]]

Meh. This is basically in the same catagory as string theory, loads of math and equations, no observational evidence. I'll withhold my opinions until we get some evidence one way or the other if it actually works.

[Martin]

'']Meh. This is basically in the same catagory as string theory, loads of math and equations, no observational evidence. I'll withhold my opinions until we get some evidence one way or the other if it actually works.

 

In case anyone cares about tests of quantum gravity (currently predictions derived mainly from LQG) they might want to read

 

http://www.arxiv.org/abs/hep-th/0501091

Falsifiable predictions from semiclassical quantum gravity

Lee Smolin

9 pages

"Quantum gravity is studied in a semiclassical approximation and it is found that to first order in the Planck length the effect of quantum gravity is to make the low energy effective spacetime metric energy dependent. The diffeomorphism invariance of the semiclassical theory forbids the appearance of a preferred frame of reference, consequently the local symmetry of this energy-dependent effective metric is a non-linear realization of the Lorentz transformations, which renders the Planck energy observer independent. This gives a form of deformed or doubly special relativity (DSR), previously explored with Magueijo, called the rainbow metric. The general argument determines the sign, but not the exact coefficient of the effect. But it applies in all dimensions with and without supersymmetry, and is, at least to leading order, universal for all matter couplings.

A consequence of DSR realized with an energy dependent effective metric is a helicity independent energy dependence in the speed of light to first order in the Planck length. However, thresholds for Tev photons and GZK protons are unchanged from special relativistic predictions. These predictions of quantum gravity are falsifiable by the upcoming AUGER and GLAST experiments."

 

AUGER is currently recording data, and the GLAST satellite is scheduled for launch in 2007.

[Royston]

Please correct me if I'm wrong but if it's possible to equate models independant of a frame of reference, (that hold to relativistic values) then the old saying...'if we're part of the equation, then it's impossible to work out the equation', goes out the window.

[Martin]

... then the old saying...'if we're part of the equation, then it's impossible to work out the equation', goes out the window.

 

I don't understand your point, Snail. do you object to something in the paper that Ashtekar and Bojowald just posted? maybe if you point to some particular passage in their paper it would provide some traction on this slippery ground

 

To get the full article (instead of just the short summary) click on:

http://www.arxiv.org/pdf/gr-qc/0509075

 

the paper does present some unfamiliar ideas and it could well hold some paradoxes which require discussion---but right now I dont see what you mean

[Royston]

The diffeomorphism invariance of the semiclassical theory forbids the appearance of a preferred frame of reference' date=' consequently the local symmetry of this energy-dependent effective metric is a non-linear realization of the Lorentz transformations, which renders the Planck energy observer independent. This gives a form of deformed or doubly special relativity (DSR), previously explored with Magueijo, called the rainbow metric.[/quote']

 

I'm most probably misreading this passage, but have they created a model that isn't observer dependant (a frame that does not require an observer to equate relative position within that frame.)

 

If the universe is equated relative to an observers position then the observer is part of the equation, this is what I was getting at. If another model that's independant to the universe in which we reside...say a model of a blackhole is equated then a model of our universe can be reached that isn't dependant on an observer.

 

Sorry if that still doesn't make sense, and I will read the article. I've only been looking into physics for the last few months so please forgive my ignorance on the subject. I certainly wouldn't contest against these findings. From the few segments I do understand, this is very exciting.

 

I seem to have a habit of making things seem more convoluted then they are recently.

[Martin]

I seem to have a habit of making things seem more convoluted then they are recently.

don't be embarrassed you are doing fine

You are referring to something in the SMOLIN article, which is about TESTING quantum gravity. I just mentioned that article because Tycho seemed interested in having empirical tests.

 

More interesting is maybe the Ashtekar and Bojowald article about the Bang and Hole singularities (that maybe arent really there)

 

 

But going back to the Smolin article you quoted, the language may seem overly technical and confusing, but really he does not want to exclude observers.

What he is talking about is the idea of avoiding a PREFERRED frame of reference which is the old idea of 1905 special relativity that there is no one preferred observer singled out.

 

I think that physicists expect that there should NOT be a preferred frame and that in this passage Smolin, the author of the article, is just reassuring readers that yes everything is OK and there is no preferred frame

 

(no one observer who is right, and the others wrong, or at rest and the others moving----instead different viewpoints are allowed)

 

The reason that he has to be careful to reassure people is that there is a subtle effect of LQG which looks like it might serve to pick out a preferred frame of reference (and which some people used to suspect would do that) but which doesnt. Instead, what it does, is predict a very small deviation in the speed of light for very high energy GammaRays----the deviation is so small that would only show up after the light has been traveling for something like a billion years or more.

 

So the test (which starts in 2007) is to accurately record these GammaRay Bursts that came from a long ways off, and see if a small shift occurred between the low-energy peak and the high-energy peak of the pulse.

 

So everything is pretty normal, and not to worry, about OBSERVERS. What is not normal, and what will constitute a real test of some quantum gravity theories, is a tiny split-second delay between the peaks of the bursts, if that is observed.

[Royston]

Thankyou for the reassurance Martin, I tend to be quite rash as I've found people are more eager to put me straight...it's a quicker way to learn, anyway back to the article.

 

The Ashtekar and Bojowald article seems to echo Hawking's speech last year,

 

What I find quite sad is that the bangs formed from black holes would be impossible to equate unless you entered a black hole and observed the forming of these new universes.

 

If we rely on the forming of our universe as reference then we would be assuming there are multiverses similar to ours that obey all the rules (so far) implied by physics.

 

However if space-time breaks down before this formation, then the rules essentially could be completely different to how our universe started out.

 

What I'm fascinated with, is that if relativity holds at the start of these new universes space-time could be completely warped but still support uniformed shapes and maybe life...considering we're here this is a very strong possibility, and almost impossible to comprehend.

[Martin]

...If we rely on the forming of our universe as reference then we would be assuming there are multiverses similar to ours that obey all the rules (so far) implied by physics.

 

However if space-time breaks down before this formation' date=' then the rules essentially could be completely different to how our universe started out.

 

What I'm fascinated with, is that if relativity holds at the start of these new universes space-time could be completely warped but still support uniformed shapes and maybe life...considering we're here this is a very strong possibility, and almost impossible to comprehend.[/quote']

 

I'm thinking about what you said, Snail. I just don't have any definite answer to make right now.

 

there is a mechanism called inflation by which a highly warped curved small universe can flatten out during early rapid expansion

and Bojowald and several others have shown that the model they are using (called LQG) automatically provides that as a built-in feature.

 

This LQG feature was critically studied by a non-partisan cosmologist at University of Portsmouth named Roy Maartens, and it checked out---it wasnt just wishful thinking on the part of those who proposed it.

 

of course the WHOLE MODEL that the Ash-Bo people are using could be wrong----the first observational tests arent until 2007 and they could go against the model (Loop Quantum Gravity)

 

but it also might not prove wrong either

 

so I consider it at least a possibility that our universe expanded from the pit of a black hole in a previous universe.

 

(and that some of our black holes may have given rise to flat or at least not-too-badly-crumpled habitable universes in turn)

 

the thing is: this is not something to believe---the possibility is open, that's all.

 

if you want to see the article by the Portsmouth man, it is here:

http://www.arxiv.org/abs/astro-ph/0311015

[Royston]

there is a mechanism called inflation by which a highly warped curved small universe can flatten out during early rapid expansion

and Bojowald and several others have shown that the model they are using (called LQG) automatically provides that as a built-in feature.

 

This LQG feature was critically studied by a non-partisan cosmologist at University of Portsmouth named Roy Maartens' date=' and it checked out---it wasnt just wishful thinking on the part of those who proposed it.[/quote']

 

That's very interesting to say the least...and if correct, then I guess a lot easier to equate.

[Royston]

deleted