Help stamp out the Big Bang!

[Martin]

I don't know of any evidence of a singularity existing in nature. AFAIK singularities exist in physical MODELS and it has happened that by improving the model so it fits the data better, you get rid of the singularity.

 

A singularity is a BROKEN PLACE in somebody's model of nature. Is everybody OK with this? Anybody want to object? Offer an example of a singularity that is known to really exist in nature? I'd be glad to hear of such a thing!

 

OK, what this thread is about is the following:

 

THERE IS NO EVIDENCE OF A SINGULARITY at the beginning of the universe expansion. It would be very peculiar because in the real world we dont see infinities, so why should there be infinities in the Planck regime at the beginning of expansion?

 

So as scientists we should try to stamp out this idea---it is sheer speculation---people should not talk like they take it for granted. We should replace it with openminded skepticism. There is no evidence FOR a singularity and also no evidence of NOT a singularity-----the model of the Planck regime at expansion start is not complete and has not been tested.

The old model has a broken place, at that moment, and the new model isnt finished and tested observationally. So the appropriate attitude, I would say, is "agnosticism"----don't take a singularity for granted.

 

THERE IS NO EVIDENCE OF SINGULARITIES IN BLACK HOLES EITHER. I will give a reference for that, if you would like one, in the next post.

 

So how is this with you so far, for starters? Does anyone have a different idea, like there is evidence of BH or BB singularities? Feel welcome to disagree!!!

[bascule]

Martin, I'm obviously a layman and have no real basis for having an opinion on any of this other than "what I like" from a purely arbitrary conceptual standpoint, or I'll like a person for their ideas (such as Lee Smolin) and go with what that person advocates.

 

I really like Lee Smolin's fecund universe model... and that eliminates the issue of singularities, does it not?

 

Oh, and I really like The Singularity, but that's a different matter entirely

 

I greatly dislike the idea that our universe is the One And Only Universe which began its life as a singularity and before that causality did not even exist. But then again I greatly dislike the Cosmological Argument/"first cause" explanations to the origin of causality.

[Martin]

here's a model of collapse to a black hole where there is no singularity

in other words these people have FIXED the broken place in Gen Rel's picture of a black hole

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

Quantum geometry and the Schwarzschild singularity

Abhay Ashtekar, Martin Bojowald

31 pages, 1 figure

Report-no: IGPG-05-09/01, AEI-2005-132

Class.Quant.Grav. 23 (2006) 391-411

 

"In homogeneous cosmologies, quantum geometry effects lead to a resolution of the classical singularity without having to invoke special boundary conditions at the singularity or introduce ad-hoc elements such as unphysical matter. The same effects are shown to lead to a resolution of the Schwarzschild singularity. The resulting quantum extension of space-time is likely to have significant implications to the black hole evaporation process. Similarities and differences with the situation in quantum geometrodynamics are pointed out."

 

remember that scientific theories are not primarily meant to be BELIEVED, but rather to be TESTED. I am not asking you to believe in Ashtekar Bojowald model of a black hole, simply to notice that it IS A MODEL and it does NOT INVOLVE the SINGULARITY that the classical BH model did.

 

It is characteristic of Ashtekar and Bojowald models that they have the correct classical limit away from the where the singularities were formerly located. There are some very slight quantum corrections which, it is hoped, will provide a means to test the models----i.e. give some signature to look for as adequate observation tools become available.

 

For further reference, here are some Ashtekar papers

 

http://arxiv.org/abs/physics/0605078

The Issue of the Beginning in Quantum Gravity

 

http://arxiv.org/abs/gr-qc/0605011

Gravity, Geometry and the Quantum

 

http://arxiv.org/abs/gr-qc/0602086

Quantum Nature of the Big Bang

 

These are mostly written for nonspecialists----some equations but much is accessible to general audience.

 

A reference work, for specialists, that the Max Planck Institute for Gravitation Research (Golm) has put online is Bojowald's encyclopedic 100 page article----with some animated computer graphics to show simulation BB results

http://arxiv.org/abs/gr-qc/0601085

Loop Quantum Cosmology

[Martin]

Oh, and I really like The Singularity, but that's a different matter entirely

yes! That singularity! The one in worldwide consciousness. that is a different sort of thing and COULD occur. it is something like how a butterfly coming out of a caterpillar's cocoon is a singularity for the butterfly but seems quite normal to an outsider.

 

I really like Lee Smolin's fecund universe model... and that eliminates the issue of singularities' date=' does it not?

...[/quote']

 

Yes in order to complete his picture, Smolin needs to assume that quantum gravity models will eliminate the BH and BB singularities that plagued Gen Rel.

 

In 1995 when he first proposed his idea it was something of a jump.

 

Now the Ashtekar Bojowald work eliminating the BH singularity can be seen as filling in a piece of Smolin's puzzle that he ANTICIPATED ten years earlier would be filled in. they did the equations and the computer calculations for him that he needed (but they do not talk about his idea they are just focused on understanding black holes)

 

so this is a case of various people's research seeming to converge

[Thales]

First off, Hello Everyone its good to be back.

 

Secondly, I agree Martin. I have long been a sceptic of infinities in nature. Singularities require gravity to cascade inward, onto a central point, therefore compressing it to an unimaginable size. But all of the other fundamental forces of nature have a threshold scale where their strength/relevence in equations becomes minute or so unimaginably huge that some other force is spawned to stop catastrophy.

 

The limits on the forces of nature, at varying scales, has borne out much of our current understanding. However the use of singularities as a stop gap measure, reaks of the dogma circlulating throughout history, where a god of some sorts was used to explain phenomena which had no other logically obvious means of explianation. The use of a singularity as the boundary at the beginning of time or at the centre of a Black Hole is merely a physicists way of placing the problem in the too hard basket and does little to add to the wealth of Human understanding.

 

Ironically the singularity has alot of relevence in helping to formulate the framework of modern cosmology, as the majority of work is focussed on removing the need for a singularity. So it has served its purpose by flagging any theory that leads to a singularity as incomplete.

[Martin]

First off' date=' Hello Everyone its good to be back.

 

...[/quote']

 

WELCOME BACK THALES! Long time no see. I remember you well from early days in 2004 when I first started coming here.

[ecoli]

weird Martin. I've always taken the big bang for granted. They shoved it down our throats at school. But, I like what you say about singularities not really existing. The idea of infinately folded space-time never sat well with me.

 

Nothing else in the universe is infinite, not even the universe itself, probably.

[mooeypoo]

It's quite amusing - a few days ago I stumbled upon an article discussing EXACTLY the matter of skepticism about the big bang. I think it's worth reading, the writer did an extensive attempt to understand if the big bang is a plausible theory, coming from the point of view of a skeptic on the matter.

 

He brings both good scientific results and awsome phylosophical / logical debate that shows why the Big Bang theory is quite a good one.

 

Here's a snippet of it:

For years I argued that there might not have been a Big Bang, since the evidence for it was rather poor. I encountered as a result a sea of snobbery and condescension from physicists. I encountered bias and closed-mindedness, and this was all the more reason to go on record against it. I found my experience was not unique: even some professional astronomers had been pressured to advocate the Big Bang in order to get telescope time, which makes or breaks every astronomer's career.[1]. This kind of arrogance was appalling.

 

As for myself, I asked for every piece of evidence available. But all I was ever given was a paltry handful of sometimes dubious facts that did not entail the conclusion drawn from them. Even if there was some other evidence, something "I could not possibly understand," it still violated all propriety and sense to expect me to believe in what was beyond my comprehension, or to attack me for this. Just as the mystic is not authorized to expect me to believe what only he has experienced, just as the Christian is not authorized to expect me to believe in the Resurrection without the evidence afforded to Thomas, so the cosmologist is not authorized to expect me to believe a theory that he cannot demonstrate to me as true, even if (indeed, even because) the evidence is such that "I cannot possibly understand."

 

Despite the rude madness I received from the physics community, I always kept an open mind and continued my investigations. And over the past two years enough evidence has arisen, and two physicists (Victor Stenger and Bjoern Feuerbacher) took enough trouble to patiently persuade me with genuine facts and argument, that I have "seen the light" so to speak, and changed my mind. Equally important was my careful reading of the apologetic works of Barry Parker and Joseph Silk.[2] I now conclude that the Big Bang Theory, in some formulation, is probably true. The odds are well in its favor. Why and how this is so I explain in this essay.

 

it really is worth reading. Here's the link:

 

http://www.infidel.org/library/modern/richard_carrier/bigbangredux.html

 

EDIT: Also, appearantly, in the article itself they're linking to another article they say is much more contemporary and full of better scientific proofs about the big bang:

"Evidence of the Big Bang" by Björn Feuerbacher and Ryan Scranton

http://www.talkorigins.org/faqs/astronomy/bigbang.html

 

Notice that according to this article -

The BBT is not about the origin of the universe. Rather, its primary focus is the development of the universe over time.

BBT does not imply that the universe was ever point-like.

The origin of the universe was not an explosion of matter into already existing space.

Interesting, it was quite new to me, and put things into order and gave me a very good view of what it actually is, isn't and why people tend to get the misconseption of it all.

 

 

~moo

[Skye]

Wait, does this also mean that as you look back in time organisms don't become infinitely small?

[Martin]

Hi Skye, Moo, Ecoli,

 

ecoli it is a problem that one's teachers feel they have to drill in the idea of a moment of infinite density, temperature, curvature

 

if you have younger brother/sister in highschool could show them this

just a recent press release from a group at Penn State

http://www.physorg.com/news66660003.html

 

not to argue with the teacher, because that will just confuse things, but learn what the teacher is saying and keep an open mind about whether it is right or not.

 

Skye my sense of humor is not sufficiently Antipodal for me to know how to respond. I visited your website one time----something about tropical storms and cats, that I dimly remember. Decided I'd better watch my step.

 

But frankly, yes, it DOES mean that. the little suckers (quarks, photons, whatever:-) ) are forbidden to shrink indefinitely. And in the simplest most workable quantum cosmology model gravity itself becomes repulsive at sufficiently high density, so there is even a mechanism to understand how the bounce occurs.

[Spyman]

Hi Martin,

 

So likely the singularities is going to be removed, personally I think that is good.

 

But that raises the questions about what is inside a Black Hole ?

 

I would like to visualize it, in my simple layman way . . .

 

If gravity becomes repulsive in the middle and sort of balances out the gravity from outside then:

 

- Will that make enough room for the matter ?

 

- What cind of matter will the BH consist of ?

 

- How will the matter be shaped inside EH ?

 

- Will this theory put new limits on BH sizes ?

[ajb]

I think you must distinguish between singularities in mathematical models and "real" singularities in nature. I think it is a general belief that there are no true singularites in nature.

 

Singularities in a theory lead to new theories. This has been the case with classical electrodynamics for example. Lorentz knew that the description of an electon classically has a divergence in the self-energy. That is the electon produces a field which backreacts on itself and produces unphysical effects. Also, they realised it would take an infinite amount of energy to assemble an electron. Classical electrodynamics is full of such infinities.

 

The resolution to these difficulties was a quantum theory of electrodyamics QED. There were originally infinities here also, much related to the infinites in the classical theory but they could be removed by rescaling of coupling conctants and masses; Remormalisation Theory.

 

So the hope that the infinites that arrise in General Relativity could be removed is very natural and is one of the motavating ideas for quantum gravity. Exactly what is quantum gravity is another question.

 

I think it was Hawking and Penrose that proved that within the framework of General Relativity the universe must have started from a singularity.

 

So I think the overal point is that theories and models can have singularities. Does nature? Probabily not.

[Skye]

Skye my sense of humor is not sufficiently Antipodal for me to know how to respond. I visited your website one time----something about tropical storms and cats' date=' that I dimly remember. Decided I'd better watch my step.

 

But frankly, yes, it DOES mean that. the little suckers (quarks, photons, whatever:-) ) are forbidden to shrink indefinitely. And in the simplest most workable quantum cosmology model gravity itself becomes repulsive at sufficiently high density, so there is even a mechanism to understand how the bounce occurs.[/quote']

Ok, I think you mean antipodean But if there is a point where gravity becomes repulsive, is there then a point where gravity is in equilibrium. Could we have a kind of gravitational steady state universe (in theory)?

[Martin]

Ok, I think you mean antipodean But if there is a point where gravity becomes repulsive, is there then a point where gravity is in equilibrium. Could we have a kind of gravitational steady state universe (in theory)?

 

That is correct. the catch is what you say: in theory

 

There are people who speculate about a new, highly compact, state of matter which could exist at the center of a black hole.

 

This would be at near-planck density where gravity is beginning to become repellant.

 

To me personally this idea is not very appealing. I more often hear about the BH singularity being replaced by a "bounce" which continue to form a new expanding spacetime region.

 

However there are several different Loop-and-related quantum gravity models and the important thing now seems to be to find predictions from them so that they can be tested and some can be eliminated. The most noteworthy nearterm test is the GLAST satellite planned for launch in 2007. It could eliminate some QG and favor others. (I am not expert about this but can give you links to papers if you want.)

Until there has been some testing it seems feckless to speculate about what QG theories is actually at the bottom of a black hole.

 

But the idea of gravity being in equilibrium with compaction, arriving at a further form of matter more dense than neutron matter is a good idea (point for Skye:-) ) and follows from the predicted transition of gravity to a repulsive force at high density. Interesting. It would not be at the zero gravity point but where gravity was just diminished enough to maintain the proper density of matter. I dont think (in my nonexpert humble opinion) that any QG theory is in shape to compute what that point is. But I think some are gradually getting there. Person to watch would be Martin Bojowald.

[Severian]

For the record, I agree with Martin on this. There is no evidence of any singularity in physics, whether that is the big bang or a black hole. The sigularity is merely an unconsious and unjustified extrapolation of perceived trends out of the observational realm.

[Martin]

For the record, I agree with Martin on this. There is no evidence of any singularity in physics, whether that is the big bang or a black hole. The sigularity is merely an unconsious and unjustified extrapolation of perceived trends out of the observational realm.

 

Good to have your confirmation on this!

[Skye]

Hmm well that's what you get when I post wasted.

 

Severian, what are your thoughts on this bouncing universe idea?

[reor]

Yay! Another one! Count me in!

I've been always wondering how they could say what extincted the dinosaurs, because of its date. The Big Bang would have to be even older, so, i was/am very sceptic about that. Though, it doesn't mean it's not valid.

[Martin]

...The Big Bang would have to be even older, so, i was/am very sceptic about that. Though, it doesn't mean it's not valid.

 

Hey reor, like your signature:D

I'm laughing.

 

I basically accept the big bang, just prefer the revised version worked out by Martin Bojowald.

Check Bojowald out, he got his degree with Hans Kastrup at Aachen and went to the MaxPlanckInst. at Potsdam (special branch called the Albert Einstein Institute). Recently moved to Penn State.

 

I will get a link. Young guy sort of slowly causing a revolution in cosmology.

he kept the big bang but got rid of the singularity, made it into a bounce from a previous contracting phase. have to go.

 

=======================

sorry about the delay, if you read German here is an article about Bojowald from Bild derWissenschaft

http://cgpg.gravity.psu.edu/research/articles/derumg.pdf

it is a little old (April 2004) but as a popular article it is OK I think

 

probably the two people that understand most about QG models both of the big bang and of black hole

are Abhay Ashtekar and Martin Bojowald

and that link is to some Ashtekar's personal website where he has a collection of links to popular articles and other more technical stuff.

 

Here is Ashtekar's page of semipopular writings about QG (quantum gravity) it has a couple of other articles in German from the Bild der Wiss.

http://cgpg.gravity.psu.edu/people/Ashtekar/articles.html

 

It just happens that in the case I think the journalism in BdW is better

If you do not like these, or only read English then I can find other links.

 

There was an article about Bojowald in the magazing "Nature" a year or so ago, but I dont have the link right now.

[SmallIsPower]

It's rare to see so many people in this forum saying "I just don't like the idea." That being said, I just don't like the idea of infinities, either. Infinite curvature seems to defy all reason. Inflation can be eliminated if the Universe was small before the Big Bang. I also like the idea of acceleating expansion based on laws we do know like magnitism and light pressure, rather than postulating dark energy. A small Universe would also explain superclusters but would it allow CMBR?

[Luciola]

So just for the sake of orientation:

 

You're basically saying, if the Big Bang theory isn't Wrong, but also isn't Right, we shouldn't be granting it Righteousness. As in, if something is both unfounded and mainly speculative, there should be no reason that (within the scientific method) it should be accepted as the answer to a yet unsolved problem.

 

Like saying that if that chair looks like there's an invisible cat in it, there is indeed an invisible cat in it, which sounds completely absurd, but is a good way to describe what the scientific community is doing in regards to singularities and the big bang theory.

 

Am I close to what you're proposing?

[Martin]

 

Am I close to what you're proposing?

 

I don't understand Luciola, but I'm pretty sure we are talking about different stuff.

 

Maybe you should read the posts at the start, and what Severian said, carefully.

 

The basic issue here is the SINGULARITY.

 

Scientists typically assume that singularities (infinities and suchlike glitches) do not exist in nature.

 

these little mathematical flaws, where a model fails to compute and gives crazy answers, exist in human MODELS of nature, not in nature.

 

but in the POP SCI mass market books, scientists trying to explain things to the public often talked as if the bigbang singularity actually existed.

 

The model has been corrected now----but the corrected model has not been observationally tested.

 

If you follow the new corrected model then you can work back in time to a point where there is VERY HIGH density (but not "infinite" density whatever that would mean)

 

and VERY HIGH temperature (but not "infinite" temperature whatever that would mean)

 

VERY HIGH curvature (but not "infinite" curvature whatever in heaven's name that could mean)

 

and then, as you continue working back into the past, it expands out again.

 

So the picture of the beginning of the expansion of our universe looks ALMOST THE SAME AS IT DID BEFORE 2001 when Bojo did the correction.

 

 

when you work the model back you get something that looks ALMOST EXACTLY THE SAME as the bigbang

 

(very dense, very hot, incomprehensibly hot really)

 

but YOU DONT GET A SINGULARITY and time did not begin there and you can keep on running the model back in time into a region that looks like a universe COLLAPSING

 

does that help?

[Martin]

Hi SmallIsPower, hi again Luciola.

I think the simplest way to describe the new corrected model is that it looks almost the same as the big bang except that it is a big bounce.

 

a moment when a collapse ended and an expansion began

 

so we don't really have to change our mental image of how it was when our universe began its current expansion (the only real change is that the model does not say that time began at that point, that point is just another point in history)

 

so since the mental picture doesnt change, maybe I shouldnt make such a big deal about it

 

the essential difference is getting rid of the singularity----that is no longer a necessary feature of the story

[Spyman]

the essential difference is getting rid of the singularity----that is no longer a necessary feature of the story

 

I think the change in philosophical thoughts about time and space is interesting.

 

Time is no longer created at the Big Bang, it is possible to calculate back to before BB.

Is it also possible/problable to have a continuing line of BBs by repeted bounces ?

 

How about space, it is there during the bounce and so also both before and after, but do they think space is small or big during the bounce ?

Is "all" space contracted with matter to a very small volume or only "local" space surrounding matter and affected by gravity ?

[Martin]

I think the change in philosophical thoughts about time and space is interesting.

 

Time is no longer created at the Big Bang' date=' it is possible to calculate back to before BB.

Is it also possible/problable to have a continuing line of BBs by repeted bounces ?

 

How about space, it is there during the bounce and so also both before and after, but do they think space is small or big during the bounce ?

Is "all" space contracted with matter to a very small volume or only "local" space surrounding matter and affected by gravity ?[/quote']

 

you can read more about it in the links here in this thread

 

the general idea is that a collapse-bounce-expansion does not happen INSIDE SOME LARGER AMBIENT SPACE. There is no surroundings. Space itself contracts (with whatever matter) and then gets to a very high density condition they call "the Planck regime" where gravity changes character and becomes repulsive, and then space stops contracting and begins expanding.

 

so what you said is basically right: all space contracts and bounces and then all space expands.

 

general relativity, and the recently developed quantum versions (still being worked on) are a dynamics of space. In those theories space behaves in a very dynamic way----it is influenced by concentrations of matter. So funny things like runaway contraction and runaway expansion are at least conceivable. It is pretty curious. Now it seems that even a "bounce" is possible. Even more curious.

 

I cant help you find out about this stuff. You pretty much have to read on your own. I can get you more links, if you tell me the kind of stuff you want to read. For example the articles in German by Rudy Vaas, that I gave a link to somebody else, those articles have been translated into English.

 

or there are review articles in Loop Quantum Cosmology, technical and thorough. I forget what is the right level.

 

But basically YEAH! Like you say I think the change in philosophical thoughts about time and space is interesting.

. It really IS! It's an exciting time to be watching physics.