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## is Big Bang 100% true?

 Quote by voxilla 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.

 Quote by bapowell 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.

 Quote by voxilla 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.

 Quote by alexg 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 ?

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 Quote by voxilla 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.

 Quote by bapowell 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 ?

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 Quote by voxilla ... 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.

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.
 To Marcus or BaPowell: Thanks for yalls great explanations. As the original topic was speaking of, Pauli doesnt 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 Ive never heard of pair production occurring like this. Then again I dont 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.co...eir-limit.html

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 Quote by easyrider 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.
 Appreciate it man. But yeah, Im aware that that doesnt 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?
 The ban is lifted on me, would I get an infraction for telling ?
 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?

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 Quote by easyrider ... 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 any one 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!)
 Recognitions: Gold Member Science Advisor 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 dont know about.

 Quote by 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 dont know about.
Another very informative post Marcus. Can you can also explain what an instanton is? i dont think I understand it.