Debunking the Big Bang Theory: Colliding Branes as a Possible Alternative

[stglyde]

Markus,

In one of the quantum gravity books. It is mentioned that there are 4 roads to quantum gravity:

1. quantising General Relativity
2. quantising a different classical theory, while still having general relativity emerge as a low- energy (large-distance) limit.
3. having general relativity emerge as a low-energy limit of a quantum theory that is not a quantization of a classical theory
4. having both general relativity and quantum theory emerge from a theory very different from both

You have listings of many Quantum gravity models in your earlier post. Are they part of the above or are they new additions? How do you sort categorize each based on the above classifications?

I'm interested in 4. What models have you come across that is about both general relativity and quantum theory emerge from a theory very different from both, and which of them is your favorite, and why?

Thanks a lot for your help.

Oh. I think it's a bit off topic here. Maybe you can reply at the Planck Scale Physics thread where you enumerate the different QG programme at Beyond the Standard Model forum .

https://www.physicsforums.com/showthread.php?p=3685088#post3685088

But if you have any idea how many billions and billions and billions of galaxies are there.. let me know... and instead of using billions and billions and billions.. wonder if there is another word to use instead..

 

[stglyde]

Do you think it was once maybe about a Ping Pong ball size or a baseball size or building size or the size of Texas? What is your estimate from non classical GR calculations and theoretical projection of rewinding the universe down to smaller and smaller size?

Glyde, it's nice of you to ask! I appreciate you asking my opinion. There was a Nasa report called WMAP5 (cosmology implications from the 5-year WMAP data) which said that in the simplest case where the U had a finite size, with 95% certainty it would be AT LEAST 10 times larger than the observable portion. (And it could just as well be 100 or 1000 times larger, the estimate was just a lower bound that it had to be at least that.)

Their number was more precise than 10. I am just speaking approximately. Their lower bound was roughly that. I can get the link to the report if you want. It's online.

Many cosmologists think of the U as spatially infinite, and therefore it would be spatially infinite at the start of expansion. And they do their calculations based on that assumption. You get approximately the same fit to the data whether you say infinite or finite-but-very-large.

So the first thing is always to remember that when people talk cosmology OBSERVABLE universe is just a small portion of the full universe that one has to model with the equations or the computer simulator. What one models is the full thing and this can be spatially infinite (even already at "bang" time) or in any case very large.

Don't confuse observable universe with the whole thing. I'm sure you know this, but people forget. It has to be made explicit to avoid confusion.

In standard cosmology, as you probably know, the universe has no edge or boundary, and matter is distributed approximately evenly throughout. So if space is infinite volume then matter must be infinite---because it is throughout all space.
===================

That is just preliminaries. Are you OK with all that?

But you still haven't answered what could be the smallest size from extrapolating of all the cosmic data. Let's supposed the observable universe were just 10% of the true size but still they could all fit in a ping pong ball (remember our observable universe can fit into a hydrogen nucleus volume). Yet you said the initial ping pong ball was infinite. I understand there is no edge assuming the ping pong ball is 4 dimensional (space+time), but still any version of light or others there (supposed for sake of illustration they were not blocked) could cross the infinite universe round turn in a few seconds. This is what I meant by estimating the initial size. I was not imagining looking it from outside view because it's null or invalid and we could only describe internally within spacetime. So perhaps the best way to ask is to get estimate of how many seconds it would take for light to go around the universe at such ping pong ball size. Now with this context. So there is no refutation to the idea that the universe of billions and billions and billions (or is it zillions) were once the size of a ping pong ball, right? Or is it the size of Kansas? What's the most logical based on your opinion assuming the observable is at least 10% of the true size?

Many thanks for your helpful assistance making bare the essence of

"To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour."

 

[stglyde]

Glyde, this is something of a new line of questioning. I will try to carry it along so we don't forget it. Maybe someone else will respond in a useful way, who knows more and has thought more about it than I have.

But before I try to understand the new I want to finish the discussion of Planck energy density and how to picture it.

People have different conjectures about the start of expansion---the actual start, that very moment, is not covered by classical GR and standard cosmology. So people are working on various models and they typically do involve densities around Planck.

One very concrete and definite model of the start of expansion is the (LQC) BOUNCE and when they study different cases and either solve the equations or run the computer simulations with various inputs it typically happens that the bounce occurs when the density is 41% of Planck.

In effect we always face the need to picture Planck energy density, with whichever model.
If you iike to picture stuff in your mind, as many do. The simplest is to think of that density of LIGHT filling the universe. Imagine that ordinary matter boiled away into light already at lower density. Nothing that occupies any space is left. Only photons. You know from LASERS that you can put as many photons as you want on top of each other like sardines without limit.

The typical photon in the mix has wavelength equal Planck length. (the smaller the more energetic, the hotter the light). That is wavelength equal to 10^-35 meter. So within the space of a proton sized 10^-15 meter he has room for a lot of ripples. A proton is a huge space for these photons because, being such hot and energetic light their wavelength is very small. And they have no Pauli territoriality, they welcome each other's company.

So let's put some numbers. The energy equivalent of 22 micrograms (i.e. Planck mass) is 1.9 billion joules or in round numbers 2 billion joules. It's like the energy equiv of a tank of gas. It is the Planck energy unit.
So at Planck density, or at 41% of Planck energy or whatever, everything is pure energy and we can picture the U filled with very hot bright light with about a billion joules in each Planck volume. Or two billion, if we are imagining Planck density instead of 41% of it.


So a proton volume has 10⁶⁰ Planck volumes each of which contains a two billion joules of light. So it contains 2x10⁶⁹ joules.

Lets compare that with (the energy equivalent of) the observable universe. The Hubble distance is about 13.8 billion light years. If you type that into google you get
1.3 x 10²⁶ meters. Radius of the observable is about 3.3 times Hubble distance so say 4x 10²⁶ meters. I think that makes the observable volume about 2.5 x 10⁸⁰ cubic meters. You might check that with a calculator.
So what do we get if each cubic meter of today's universe has on average the matter equivalent of 0.22 nanojoules? I get around 5 x 10⁷⁰ joules.

In Wikipedia in the entry on Planck Density, it is said:

"This is a unit which is very large, about equivalent to 1023 solar masses squeezed into the space of a single atomic nucleus. At one unit of Planck time after the Big Bang, the mass density of the universe is thought to have been approximately one unit of Planck density."

Based on marcus calculation. 1023 solar masses would have 2x1069 joules of energy? Hope someone can confirm or calculate accurately.

Also how many 2x10⁶⁹ joules are there in 5 x 10⁷⁰ joules. Dividing them one would get 2.5 x 10 ¹ so I guess the observable universe can be contained in at least 3 protons or at least the volume of a helium isotope3 with 2 protons and one neutron)? Can anyone confirm this, thanks!

This has been quick and sloppy, it is not good enough to quote in another post. anyone who cares to do so could improve the accuracy and the result might change by up to an order of magnitude. But it gives the right idea. If you think of the proton volume as a room containing jillions of photons of very high temperature short wavelength light, and you imagine that the energy density is Planck,

then that proton volume contains about the same as the energy equivalent of the observable universe volume. This is admittedly kind of clunky. Anyone who wants is welcome to make it neater and more precise.

 

[stglyde]

But you still haven't answered what could be the smallest size from extrapolating of all the cosmic data. Let's supposed the observable universe were just 10% of the true size but still they could all fit in a ping pong ball (remember our observable universe can fit into a hydrogen nucleus volume). Yet you said the initial ping pong ball was infinite. I understand there is no edge assuming the ping pong ball is 4 dimensional (space+time), but still any version of light or others there (supposed for sake of illustration they were not blocked) could cross the infinite universe round turn in a few seconds. This is what I meant by estimating the initial size. I was not imagining looking it from outside view because it's null or invalid and we could only describe internally within spacetime. So perhaps the best way to ask is to get estimate of how many seconds it would take for light to go around the universe at such ping pong ball size. Now with this context. So there is no refutation to the idea that the universe of billions and billions and billions (or is it zillions) were once the size of a ping pong ball, right? Or is it the size of Kansas? What's the most logical based on your opinion assuming the observable is at least 10% of the true size?

Many thanks for your helpful assistance making bare the essence of

"To see a world in a grain of sand,
And a heaven in a wild flower,
Hold infinity in the palm of your hand,
And eternity in an hour."

Reflecting on all this. Remember we only knew the universe was expanding early this century and the expansion accelerating just in 1998. But the further away we look, at a distance just on the edge of the Observable universe, we can see the original fireball. So this means there is at least a fireball. Therefore in the initial Big Bang.. the universe really started from a dense state maybe less than the size of a milky way. Hence Big Bang is getting more and more plausible.. although we must not forget the possibility it may be all an optical illusion. Remember all information in a volume can be located in the area... so all this going on here may be projection from a distance surface as per Jacob's holographic bound. So we must not give up trying to think of alternatives to Big Bang. If anyone has encounter any promising avenues in the near future.. just be sure to drop us a line.

 

[Cosmo Novice]

Not quite. You would encounter same patch infinite amount of times. Read this, if you have time and will, interesting stuff!

Hello Calimero,

Although I agree it may be possible to encounter a "similar" patch of Universe, which may appear to be the same, it is in fact totally distinct from the other patch even if it was "identical". Ie: there would be no casual relationship between the two; so they are actually not the same part of "spacetime".

I would go further to say that any replication of all mass, energy, waves, spatial curvature and anything and everything else probably would exceed the sum of infinities. Thankyou for the discourse and appreciate the link although I have not found the time to read it.

Regards

 

[Imax]

Would you bet your life on it?

Big Bang proof supposedly came from:

1. Redshift
2. Cosmic Background Radiation
3. Deuterium and baryogenesis

If you look at spacetime as possibly forming a Compact Lorentzian Manifold, then time could have a curvature. Extrapolating linearly backward in time by 13.7 billion years could be meaningless. So no, I wouldn’t bet my life on it.

 

[stglyde]

I just finished watching Stephen Hawking Discovery Curiosity documentary. He said that in the beginning, there was nothing.. and somehow nothing produces positive and negative energy, the positive energy becomes the mass/stress/energy or the substance part of the universe and the negative energy becomes space. And herein lies the secret to the mystery of the Big Bang.

 

[thorium1010]

I just finished watching Stephen Hawking Discovery Curiosity documentary. He said that in the beginning, there was nothing.. and somehow nothing produces positive and negative energy, the positive energy becomes the mass/stress/energy or the substance part of the universe and the negative energy becomes space. And herein lies the secret to the mystery of the Big Bang.

I think Stephen hawking is going way overboard into speculation, instead of actual facts and observation. Where is the evidence for all that he said saying there was nothing in the beginning ?.That's the difference between pop science,speculation etc and actual science.

 

[stglyde]

I think Stephen hawking is going way overboard into speculation, instead of actual facts and observation. Where is the evidence for all that he said saying there was nothing in the beginning ?.That's the difference between pop science,speculation etc and actual science.

In the video, Stephen Hawking wanted to debunk the idea that the universe was created by someone or something. So he said the Big Bang created time and space, so there was no "before" prior to the Big Bang so how could anyone have created it when time was only produced by the Big Bang. But I remember Marcus saying the new consensus is that time and space already exist prior to the Big Bang and that it only expanded what already existed? But there was zero evidence for it too.

 

[thorium1010]

In the video, Stephen Hawking wanted to debunk the idea that the universe was created by someone or something. So he said the Big Bang created time and space, so there was no "before" prior to the Big Bang so how could anyone have created it when time was only produced by the Big Bang. But I remember Marcus saying the new consensus is that time and space already exist prior to the Big Bang and that it only expanded what already existed? But there was zero evidence for it too.

I am not an expert on the theory. Ideas and to some extent speculation are okay, BUT THEY SHOULD be backed by evidence. Discussion about creation or creator is not science, because that kind of philosophy , so far or in the future (IMO) cannot be proved or disproved.

 

[sirchick]

The problem i have is - if there was inflation in every point of space, then surely that causes a problem in explaining why it was not uniform.

Because as i would imagine ... everything would be occurring equally in every direction..

 

[bapowell]

And the big bang is not an explosion as such. I see it more like a perfectly sphere balloon being pumped up - everything on the surface of the balloon is being inflated outwards from every direction equally.

This is the right way to think about expansion.

And the air in a balloon is the dark energy which is in another dimension possibly which is causing the expansion of the universe that we see even today. That was a theory i had a while ago.

This is not the right way to think of it. The inside of the balloon, in fact, the higher-dimensional space in which the balloon is embedded, is superfluous. The curvature of the manifold, and hence, the gravity, is a property of the manifold itself, irrespective of the embedding. The hypothesized dark energy is a field defined on the manifold itself (the surface of the balloon); it results in an accelerated expansion.

In my opinion the big bang is an exploded black hole consisting of subatomic particles that can travel much faster than light (we are getting some real evidence about this at CERN).

Opinions don't matter in the face of evidence. This is science.

 

[voxilla]

Opinions don't matter in the face of evidence. This is science.

Yes, I'm a scientist, I wan't quotes to be fully backed up with evidence.
If you can prove my reasoning wrong than you are right.

 

[tfsc]

Yes, I'm a scientist, I wan't quotes to be fully backed up with evidence.
If you can prove my reasoning wrong than you are right.

You have to prove your reasoning has valid potential with evidence which you did not - for it to be taken with serious thought.

 

[voxilla]

You have to prove your reasoning has valid potential with evidence which you did not - for it to be taken with serious thought.

For the sake of science, don't we want to have a valid, verifiable theory that can explain black holes, the big bang, dark energy/matter, ... ?

Some theories only get validated many years after they have been postulated, mostly due the invention of new tools.

 

[bapowell]

If you can prove my reasoning wrong than you are right.

I cannot. But this is due to the extreme imprecision of your statement. If you would like to propose a more detailed explanation of your suggestion (which is teetering on the edge of forum rules, by the way) I'd be happy to explain why the universe most certainly is not a black hole with superluminal particles flying about. At face value, your suggestion exemplifies a lack of familiarity with modern cosmological theories and a misunderstanding of general relativity.

 

[voxilla]

I cannot. But this is due to the extreme imprecision of your statement. If you would like to propose a more detailed explanation of your suggestion (which is teetering on the edge of forum rules, by the way) I'd be happy to explain why the universe most certainly is not a black hole with superluminal particles flying about. At face value, your suggestion exemplifies a lack of familiarity with modern cosmological theories and a misunderstanding of general relativity.

Let's say a black hole can compress atomic particles into subatomic particles.

 

[alexg]

Let's say a black hole can compress atomic particles into subatomic particles.

Let's not, because it doesn't.

Atoms and subatomic particles are different things. One does not turn into the other.

 

[voxilla]

Atoms and subatomic particles are different things. One does not turn into the other.

For sure they are different, what happens if you smash atomic particles in a LHC ?

 

[bapowell]

For sure they are different, what happens if you smash atomic particles in a LHC ?

You sound incredibly confused. The LHC is not colliding atoms, rather, it is colliding hadrons (which are subatomic particles comprised of quarks, which are elementary). We do know that atoms can be compressed into subatomic matter -- this is what happens in the formation of a neutron star. It is, of course, less clear what happens inside a black hole. Even if black holes could somehow transmute atomic particles (how about we call them atoms?) into subatomic particles, how is this at all relevant to your claim that the universe is a black hole? Also, I'd advise you at this point to be careful about making overly speculative claims or proposals, as this is against PF rules.

 

[voxilla]

You sound incredibly confused. The LHC is not colliding atoms, rather, it is colliding hadrons (which are subatomic particles comprised of quarks, which are elementary). We do know that atoms can be compressed into subatomic matter -- this is what happens in the formation of a neutron star. It is, of course, less clear what happens inside a black hole. Even if black holes could somehow transmute atomic particles (how about we call them atoms?) into subatomic particles, how is this at all relevant to your claim that the universe is a black hole? Also, I'd advise you at this point to be careful about making overly speculative claims or proposals, as this is against PF rules.

Yes I already received a couple of infarctions, as I'm new to this forum I try to live by the rules.
In my understanding the LHC collides protons, which I call atomic particles (in case you call those sub atomic particles, the sub atomic particles I refer to are really sub sub atomic).
My point is that a black hole could compress those sub atomic particles into sub sub atomic ones similar to the transition of atomic to sub atomic in a neutron star. Is this more clear ?

 

[jambaugh]

...
My point is that a black hole could compress those sub atomic particles into sub sub atomic ones similar to the transition of atomic to sub atomic in a neutron star.

The boundary between "atomic" and "sub-atomic" has meaning based on the involvement of the strong nuclear force. You can't just stack "sub-"'s and assume it is meaningful. You must define what you mean by "sub-sub atomic" in some more rigorous way than a crude "kinda like" analogy.

 

[DaveC426913]

Yes I already received a couple of infarctions,

Yikes! You should consider reducing your stress level!

Protons are subatomic particles. They are comprised of quarks.

Yes, we can speculate what happens to matter when it is hypothetically infinitely compressed. But we just don't know.

 

[easyrider]

To Marcus or BaPowell:

Thanks for yall`s great explanations. As the original topic was speaking of, Pauli doesn`t exclude photons. ;)
And during the very early periods of the universe, neither of these would have applied at all of course since, as was said, all that COULD exist in such a hot, dense state was radiation. But, speaking in terms of the present day universe, can you still pack as many photons into the finite "box" as you want? Would there ever come a point where a black hole would form, or does that only apply to stars/baryons?

Also, you may have seen this link before but I wanted to get yall`s take on it as I've never heard of pair production occurring like this. Then again I don't follow particle accelerator experiments very much either. Specifically, they collided a stream of electrons and a very intense laser, and the result was pair production as said above. So does it really apply to ALL lasers even when they arent colliding with electrons? Thanks again.
http://physicsbuzz.physicscentral.com/2010/08/lasers-reaching-their-limit.html

 

[marcus]

But, speaking in terms of the present day universe, can you still pack as many photons into the finite "box" as you want? Would there ever come a point where a black hole would form, or does that only apply to stars/baryons?
...

I'm not an expert but I feel pretty sure about answering in this case. In the presentday universe the geometry is only expanding very slowly. So slowly that for practical purposes we can ignore it.

So we model BH formation in non-expanding surrounding space. And people use the Schwarzschild model and derive things like how big a mass do you have to cram into how small a space for the thing to collapse to hole.

That all depends on working in a non-expanding space.

So the basic answer is YES you are right. There would come a point. In todays conditions if you crowd enough photons together (enough energy in a small enough box) you will get a black hole.

It doesn't have to be a star that collapses.

But in the rapidly expanding geometry right after the start of expansion (even without quantum gravity corrections, e.g. repellent effects at extreme density) similar densities could exist without forming a BH.

 

[easyrider]

Appreciate it man. But yeah, I am aware that that doesn't apply to early Big Bang. Whats your opinion on pair production from a very intense laser? Will it really work like they said, i.e. once it gets to a certain energy density, pair production will always occur, destroying the laser in the process?

 

[voxilla]

The ban is lifted on me, would I get an infraction for telling ?

 

[easyrider]

Okay so Marcus, was there ever a time in the Universe where there was nothing but photons? Or was there always matter regardless of how far back one goes?

Also, so are you saying that the statement "many galaxies were squeezed into the size of an atom" is true or untrue? I thought that didnt quite qualify as a singularity, I thought that was just Planck energy density? Is Planck energy density/Planck density not possible?

 

[marcus]

... Is Planck energy density/Planck density not possible?

As I'm sure you realize, at this point the answer depends on what model you are using. Maybe I should ask you, are you interested in being told what the Loop cosmology model says about that? It is the one that AFAIK is the most completely worked out.

Here's a recent review article that covers a range of models, including Loop and including String cosmology. You could read the list and start a thread to see if you could get answers about the various models. No one should claim to know that anyone is right. They need to be tested against observational data.

http://arxiv.org/abs/1201.4543
Aspects of Quantum Gravity in Cosmology
Massimiliano Rinaldi
(Submitted on 22 Jan 2012)
We review some aspects of quantum gravity in the context of cosmology. In particular, we focus on models with a phenomenology accessible to current and near-future observations, as the early Universe might be our only chance to peep through the quantum gravity realm.
15 pages, 1 figure. Invited review for Modern Physics Letter A​

In case you are curious about what the Loop cosmo model says: in the simplest cases the bounce happens at 41% of Planck energy density. So 100% would not be achieved (to answer your question.)
But the model does not say in what forms the energy would be! One can postulate, put in various fields, and run the model (either by equation or numerically by computer.) I think there is little grasp at present of what forms energy would be in.

Warning: don't believe my picture of what Planck energy density is like. Maybe don't believe anyone's at this point. It's pure imagination. The mind just fills in a gap in understanding with something highly provisional until some more reasoned idea comes around.

I think of the energy by that time as primarily (perhaps entirely) in the gravitational field, that is, in the microscopic geometry. Highly energetic Plancksize features? a seething geometrical chaos? The distinction between real and virtual having long since been forgotten, a mob of gravitons each with great energy but with such small wavelength that you could fit more of them on the head of a pin than you might angels.

Why should I caution you not to imagine Planckscale energy density, since I do it myself. Just don't believe. (and surely you know enough not to do that!)

 

[marcus]

More seriously (perhaps) in some models the bulk of the energy density early on in is something called the "curvaton" field.

If curious about "curvaton" see:
http://en.wikipedia.org/wiki/Curvaton
"The curvaton is a hypothetical elementary particle which mediates a scalar field in early universe cosmology. It can generate [geometry] fluctuations during inflation, but does not itself drive inflation, instead it generates curvature perturbations at late times after the inflaton field has decayed and the decay products have redshifted away, when the curvaton is the dominant component of the energy density.
The model was proposed by David Wands and David H. Lyth in 2001."

You asked the kind of question that can only be answered speculatively. People have different ideas about how inflation worked and what fields were present during and after.
Damien Easson has been a co-author of George Smoot who got the Nobel for mapping the CMB. Easson has an idea of what field might have played the CURVATON ROLE.
http://arxiv.org/abs/1202.1285
Higgs Boson in RG running Inflationary Cosmology
Yi-Fu Cai, Damien A. Easson
(Submitted on 6 Feb 2012)
An intriguing hypothesis is that gravity may be non-perturbatively renormalizable via the notion of asymptotic safety. We show that the Higgs sector of the SM minimally coupled to asymptotically safe gravity can generate the observed near scale-invariant spectrum of the Cosmic Microwave Background through the curvaton mechanism. The resulting primordial power spectrum places an upper bound on the Higgs mass, which for canonical values of the curvaton parameters, is compatible with the recently released Large Hadron Collider data.
5 pages

IOW strange as it might seem, back when energy density was very high a lot of the energy might have been in the form of curvature fluctuations---energy might have been in the microscopic geometry itself, rather than in the form of photons (disturbances in the electromag field.) Maybe at very high energies geometric disturbances can interact with matter, there may be scattering reactions we don't know about.

 

[skydivephil]

More seriously (perhaps) in some models the bulk of the energy density early on in is something called the "curvaton" field.

If curious about "curvaton" see:
http://en.wikipedia.org/wiki/Curvaton
"The curvaton is a hypothetical elementary particle which mediates a scalar field in early universe cosmology. It can generate [geometry] fluctuations during inflation, but does not itself drive inflation, instead it generates curvature perturbations at late times after the inflaton field has decayed and the decay products have redshifted away, when the curvaton is the dominant component of the energy density.
The model was proposed by David Wands and David H. Lyth in 2001."

You asked the kind of question that can only be answered speculatively. People have different ideas about how inflation worked and what fields were present during and after.
Damien Easson has been a co-author of George Smoot who got the Nobel for mapping the CMB. Easson has an idea of what field might have played the CURVATON ROLE.
http://arxiv.org/abs/1202.1285
Higgs Boson in RG running Inflationary Cosmology
Yi-Fu Cai, Damien A. Easson
(Submitted on 6 Feb 2012)
An intriguing hypothesis is that gravity may be non-perturbatively renormalizable via the notion of asymptotic safety. We show that the Higgs sector of the SM minimally coupled to asymptotically safe gravity can generate the observed near scale-invariant spectrum of the Cosmic Microwave Background through the curvaton mechanism. The resulting primordial power spectrum places an upper bound on the Higgs mass, which for canonical values of the curvaton parameters, is compatible with the recently released Large Hadron Collider data.
5 pages

IOW strange as it might seem, back when energy density was very high a lot of the energy might have been in the form of curvature fluctuations---energy might have been in the microscopic geometry itself, rather than in the form of photons (disturbances in the electromag field.) Maybe at very high energies geometric disturbances can interact with matter, there may be scattering reactions we don't know about.

Another very informative post Marcus. Can you can also explain what an instanton is? i don't think I understand it.