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    The big bang was not an Explosion: However an explosion is a metaphor for what the big bang was.
    By Hontas Farmer | May 1st 2011 04:40 PM | 49 comments | Print | E-mail | Track Comments
    About Hontas

    Currently I am a adjunct professor in physical sciences at the City Colleges of Chicago with a MS from DePaul University. My research focuses on...

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    The big bang was given it's name by Fred Hoyle, in order to make the theory sound absurd.  He metaphorically called it an explosion.   In the mist of time most people even some scientist lost the metaphor part of that and thought of it as an explosion.  Others then stopped using the metaphor because it confused people.   
    This is more of an entry about the use of language than physics.  That said here is the shortest possible argument for why the big bang was not an explosion for anyone who needs convincing:

    Explosions are the free expansion of material from higher, pressure, temperature and density to lower pressure, temperature and density in a short amount of time. 

    The big bang was the expansion of the space time manifold from a singular point at time equals zero to a four dimensional manifold growing with time.  In the process the contents of the universe expanded to fill the new space that was created after the big bang. 

    The big bang was not an explosion because no matterial was involved.  None existed yet. The big bang was the sudden expansion of space-time.  That is not the same as an explosion in any physical sense. 

    That said in terms of the accurate gramatically correct usage of the language in the sense that any English teacher would agree with writing the big bang "was" an explosion is correct. 

    What's in a name? 

    How many times in the last few weeks did someone say "tidal wave" only for someone nearby to say.  "They don't call them tidal waves.   They aren't called tidal because there is no tide involved.  They are called Tsunami's!"  (subtext... that the person saying "Tsunami" is smart")

    Odds are the person saying Tsunami has no idea that it literally means harbor wave.   Well, being really literal about it only a wave that hits a harbor is a tsunami.  Therefore that person is no more correct than the person they were seeking to belittle.  
    Even more I like the way that Richard Feynman puts it here. 
    TLDR:
    In terms of physics the big bang was not an explosion it was the expansion of space time.  In terms of the rules of the English language the closest metaphor for the event is to call it  an "explosion of space".  Just don't confuse that for the physics.    
    If you want to be a stickler for physical correctness then say that the big bang is this. 


    a(t) grows with time and causes three dimensional space in the universe to grow with time.  The beginning of this process at t=0 was the big bang.  
     

    Comments

    vongehr
    "Explosions are the free expansion of material from higher, pressure, temperature and density to lower pressure, temperature and density in a short amount of time.
    That is "expansion", fast maybe, but still nothing more. Explosion can have two different meanings, one being related to the burn front velocity in chemical reactions, the other being about the velocity distribution, i.e. Velocity~Distance From Center. The Hubble law makes the second definition fit well, which is partially why the name explosion is quite justified.
    "The big bang was the expansion of the space time manifold from a singular point at time equals zero"
    Never heard of inflation? Stop giving fodder to the religious by painting the BB as some creation event.
    "In the process the contents of the universe expanded to fill the new space that was created after the big bang."
    That is nonsense, since it would mean that contents move in order to fill, while in fact the matter content stays where it is.
    What is wrong? You had some decent posts a long while back!
    Hfarmer
    That is "expansion", fast maybe, but still nothing more. Explosion can have two different meanings, one being related to the burn front velocity in chemical reactions, the other being about the velocity distribution, i.e. Velocity~Distance From Center. The Hubble law makes the second definition fit well, which is partially why the name explosion is quite justified.
    Interesting. You see I was told by my thesis advisor that an explosion is an expansion of hot gasses by my thesis advisor and I will take his definition as being true enough. That said I see your point as well.
    Never heard of inflation? Stop giving fodder to the religious by painting the BB as some creation event.


    Inflation is not the same as the big bang.  Inflation began about 10^-36 seconds AFTER the big bang.  


    That is nonsense, since it would mean that contents move in order to fill, while in fact the matter content stays where it is.
    What is wrong? You had some decent posts a long while back!


    The problem with what you wrote is that it assumes that the distribution of matter that we have now was the same at the time of the big bang.  It wasnt' and did not have to be.  In fact the whole point of cosmic inflation is that it takes a wide variety of initial conditions and maps them to the extremely smooth matter-energy distribution we observe reflected in the CMB.  


    The space time started out isotropic but not the contents of the universe.  I don't blame you for not knowing that I had to think about it for a while to realize that myself. It's confusing because so much literature uses the words interchangeably. 
    Science advances as much by mistakes as by plans.
    vongehr
    No - the big bang is the reheating AFTER inflation. Nobody knows what came before inflation. Look it up on the links. Before inflation we know nothing - for all we know it could have been a pretty boring spacetime before.
    Hfarmer
    Nope before inflation we know from theory that the universe was a FLRW space-time, inflation inflated the universe exponentially by about 60 e-folds, then FLRW took over the rest of the way. 
    If this started at t=0 then inflation theory would actually not fit the data we have.  It would not be able to match the universe we see. 
    Science advances as much by mistakes as by plans.
    vongehr
    Where did you learn this stuff? It is never too late to change advisers, you know. Lets be very clear about something: Big Bang is defined via the backward extrapolation of the FLRW expansion observed. This leads to so called reheating after Inflation. That is why one calls the microwave background the "leftover of the Big Bang". Before all this happened inflation, which has so flattened and completely removed any traces from what was before inflation that we plainly have no idea about how curved the spacetime was before. We do not know! There cannot be any trace of the Big Bang left in the microwave background if the Big Bang came before inflation.
    So, maybe you or your adviser have some funny new ideas about what came before inflation - I hope it is something better than chaotic eternal inflation, because that one is a pretty good model. All fine, I encourage you guys, but please do not tell people about your crazy hypothesis being accepted science. The accepted science is inflation and then the reheating, which is the Big Bang. If you have some cute model, like bringing singularities back into the game before inflation although physics has just successfully gotten rid of them, have fun, but please do not confuse readers on a science website. Call your new singularity "Hontas Farmer pre-inflation super creation singularity", but do not call it Big Bang.
    Hfarmer
    Your wrong Sacha.  Since you don't want to believe a lowly negro I will refer you to "An introduction to General Relativity Spacetime and Geometry" by Sean M. Carroll.  
    These solutions all feature a singularity at a(t=0), known as the Big Bang.  It represents the creation of the universe from a singular state, not an explosion of matter into a pre-existing spacetime.  

    Inflation does not happen at t=0 neither does reheating.  While you are partially correct about the explosion-like nature of inflation and reheating don't confuse that with  "the big bang".  The bang is whatever the heck started it all and it preceded inflation by a fraction of a second. 
    Science advances as much by mistakes as by plans.
    vongehr
    Since you don't want to believe a lowly negro
    WTF??? You like to apologize maybe or is this going to be the last time I even give the slightest shit about anything you have to say?

    An introduction to General Relativity Spacetime and Geometry" by Sean M. Carroll.  
    These solutions all feature a singularity at a(t=0)
    That is exactly what I am saying, that the singularity is the GR solution without QM correction. Of course GR predicts singularities. Who ever doubted that? And your t=0 is a label. You may as well call it t=-0.467529 if you like. Doesn't change a thing.
    It represents the creation of the universe from a singular state
    Then go post on a religion, not on a science site. Your GR book is not all there is to modern cosmology.
    Inflation does not happen at t=0 neither does reheating
    Who ever claimed such? Did you even read my previous comments? Go to Ethan's "starts with a Bang" blog on SB if you do not trust me - he named his blog "Starts with a Bang" but explains about every other week that it did actually not.
    Gerhard Adam
    Since you don't want to believe a lowly negro...
    Where do you get off playing the race card?  You don't get to invoke racism whenever someone disagrees with you.  Besides Sascha, you owe everyone on this site an apology for such an irresponsible statement. 


    Mundus vult decipi
    Hfarmer
    Let me just make one thing clear Sascha.  I feel where you are coming from.   Before and indeed during inflation we probably cannot legitimately use any classical theory.  
    Inflation would have occured in a very energetic universe, with strong gravity, short time scales etc.  There is every reason to think that until we have a fully quantum theory of what went on we don't have a theory that's anything like correct.  

    Now astronomers would tell me sure the LCDM model is correct because it fits this data and that data and Spergel and the WMAP Blah blah blah.  However as a theoretical cosmologist that's just not enough for me.  Until every tiny perterbation and wiggle in the data can be explained from first principles in a simple and elegant manner we aren't anything like done. 
    Science advances as much by mistakes as by plans.
    vongehr
    "in a very energetic universe, with strong gravity, short time scales etc."
    Makes no sense. Inflation is pretty well described via GR and all kinds of slow roll potentials and quantum fluctuations that have been confirmed in the microwave background data. "energetic universe, strong gravity, short time scales" is pure esoteric woo. You might as well add "strongly oscillating spiritual field" to it.
    Hontas, I don't try to beat you down or anything, but I do insist that you clearly separate between what is your own opinions and what is by observation confirmed scientific fact. I am not a stranger to doubting accepted fact, however, when my opinion departs from what is scientific consensus, I make it very clear to my readers at what point what kind of motivated assumption of mine enters the discussion.
    Hfarmer
    Those are not just my opinions.  They are the motivations for every theory of quantum cosmology. 
    You cannot apply classical theory to the actual big bang or even inflation and think of it as anything but a stop gap until we have a better understanding of quantum theory at those energies and in the kind of environment that existed at that time.

    As for the slow roll potentials.   Do you mean single scalar, or double scalar?  You do know how unrealistic it is to expect a scalar field at this point when we haven't even observed one fundamental scalar field ever? (We are looking for one called the Higgs field but work done decades ago has shown that it could not be the inflation field.) 
    Science advances as much by mistakes as by plans.
    Hontas Farmer: "The big bang was the expansion of the space time manifold from a singular point at time equals zero to a four dimensional manifold growing with time. In the process the contents of the universe expanded to fill the new space that was created after the big bang. " ---------------------------------------------------------------------------------------------------------------- This is mostly untested conjecture and contains questionable absolutes, like an absolute begining of space-time and everything starting from a state of absolutely zero size, i.e., a "universal singularity". Below is a radically different interpretation of the solid evidence for global expansion of the OBSERVABLE universe, note the small "u". "In this review of Galactic and Metagalactic Scale phenomena we will discover that the entire observable universe constitutes a nearly infinitesimal region of one Metagalactic Scale object. The galaxies within this region are crammed together at very high densities. Galactic Scale objects are also chaotically moving at high velocities and this indicates an extremely high ambient temperature. The combination of very high temperature and density produces frequent galactic interactions and mergers. The mass spectrum of galaxies is relatively flat, unlike the abundance trends on the Atomic and Stellar Scales, and therefore significant numbers of moderately massive and very massive systems are present. The evidence for an extremely high-energy environment, the presence of substantial numbers of massive galactic systems, and the strong evidence for global expansion, all suggest a reasonably unique analogy to the interior of a supernova shortly after detonation. In this analogy, galactic systems play the role of fully ionized Atomic Scale particles and nuclei under very-high-energy plasma conditions. In what follows we will see that the [Discrete Scale Relativity] analysis leads inevitably to this radical reinterpretation of the standard Big Bang model for the “origin” of the “Universe”. " The above reinterpretation, including a determination of the Galactic Scale temperature, density and velocity distribution of the galactic "particles" can be found at http://www3.amherst.edu/~rloldershaw . Click on the link entitled "Galactic Scale Self-Similarity". This explanation of the Big Bang phenomena does not require "exotic" physics. The Big Bang is just routine physics taking place on a Metagalactic Scale. Bottom line: Let's not put all our theoretical eggs in one rickety old basket. Let's keep an open mind. RLO Discrete Scale Relativity; Fractal Cosmology
    Hfarmer
    Fractal cosmology eh.  Looking at your website you have clearly done allot of work on this.  While I have not the inclination to do an in depth review your work looks commendable.  You clearly have done the homework needed to say something important about cosmology and in a more concrete way than many others have said it. 
    The idea that this universe is just a small bubble nucleated off another universe in some way has been stated as simply conjecture by many cosmologist for many years.  What you have done is formulate what can be called a theory for just how that could be so.   

    That the structures of nature repeat themselves at different length (or time or energy depending on how you look at it) scales cannot be denied.  However I as a professional must stick to a rather narrow set of statements.  

    In this entry I stuck with the standard, classical big bang.  Within that framework which is accepted by all as being true within certain limits what I have said is right.  The big bang was not an explosion in the most literal physical sense of the word.  

    However as I have argued, equally correctly the word explosion was only ever a metaphor for an event that is simply beyond our experience.  No one has ever witnessed a big bang.  We just have a model that fits the evidence we have well enough.
    Science advances as much by mistakes as by plans.
    Howdy Hontas Farmer, Yes, I understand your position, and I think both models deserve thorough and skeptical scientific exploration, with an emphasis on testing the models against observations. The galactic dark matter issue, when resolved, will definitively tell us which is right and which is wrong. One VERY important point: Discrete Scale Relativity is extremely different from the untestable "multiverse" scenario derived from "string/brane theory". Discrete Scale Relativity is also extremely different from any "bubble nucleation" scenario derived from Eternal Inflation. Discrete Scale Relativity argues that the most fundamental description of nature will be a discrete conformal description. The implcations are far different than anything conventional cosmology, the Standard Model of particle physics, or the untestable postmodern pseudoscience has to offer. Look at the list of 38 fundamental properties that DSR can retrodict. Consider that DSR anticipated pulsar/planet systems. I think this bold new paradigm would be well worth some quality study-time. Who knows - you might ride that train to glory. RLO http://www3.amherst.edu/~rloldershaw Discrete Scale Relativity; Fractal Cosmology
    Just two ideas.

    The big bang should not be considered an explosion because when something explodes it's always because it does against a pressure already existing (atmosphere or other). It needs the preexistence of space outside the volume that explodes and that doesn't happen with the whole universe. We cannot really attach any force to the expansion of the universe because force against what? Then the question remains open: what was the physical cause of the expansion? Maybe it was just entropy-driven.

    We should not speak about things prior to the decoupling era from where the CBR comes as real: we don't have any experimental signal from before that time, or have we?

    Do you have any empirical evidence for your assumption that the observable universe is roughly equivalent to the whole Universe? If the observable universe is an infinitessimal, or even just a small, part of the whole Universe, then your argument would appear to be rendered invalid. RLO Discrete Scale Relativity
    If I rely on the observable universe I don't make assumtions about the supposed rest. It's you who'll need empirical evidence to proof the theoretical assumption that what we see is only a bubble in a miriad of bubbles! How we'll ever be able to falsify such hypothesis? We're talking about a science, an experimental science, aren't we?

    MikeCrow
    I think you have to consider them two different things, there might be more than one Universe, but it is not part of the space/time of our Universe. But we are still limited to seeing only the visible Universe of our space/time and it could be much larger (as I point out in the post below).

    This is how I picture it.
    Imaging floating in space in the early Universe right before photons decouple from the plasma(what Sascha calls reheating). Imagine that decoupling happened all at once, over the entire Universe. You'd see the edge of the plasma recede into the distance. After 1 year the edge would be 1 light year away (if there was no expansion), 13.7B years later it'd be 13.7B Light years away, it's z would be 0.
    However it's z is ~1100, and the Universe was at least some light years across when photons decoupled. Yet we can't see anything beyond the edge of the plasma.

    Assuming the entire Universe expanded equally, the bubble we can see would be only a small part of the entire Universe of our space/time.

    This does not take into account other possible Universes as described in the various Multiverse theories.

    I am interested in what the Physicists here think of this description.
    Never is a long time.
    Hfarmer
    What Sacha calls "reheating" preceeds "decoupling" by about 380,000 years.  Reheating is supposedly caused by the decay of the inflation field. (Whatever it is) into photons and other particles. 
    Reheating was needed and is expected because inflation as it expands the volume of the spatial part of the universe (look at the FLRW metric above to see what I mean) the pressure and temperature of the universes contents drops.  This cooling without reheating would not lead to the universe we see.  This reheating also plays a role in baryogenesis (the creation of ordinary visible matter and antimater).   This is followed shortly by what is called big bang nucleosynthesis the creation of a few elements heavier than hydrogen.    Which last a few minutes...

    Then there is a long dark period where the universe is filled with (leaving out dark matter) protons, electrons, and photons.  The protons and electrons will emit a photon and bind into simple hydrogen then be knocked apart releasing a photon.  The free path of a photon at this time was very short compared to any astronomically interesting distance.  So we basically can't see anything from this period or before using EM based astronomy.  

    The CMB is a image of the so called "surface of last scattering".  This is when decoupling took place.  The CMB photons are the last photons to scatter off that primordial plasma described above.  They were gamma rays when they last scattered and have red shifted all the way down to microwaves.  

    Understand?
    Science advances as much by mistakes as by plans.
    MikeCrow
    Yes, thank you.

    What do you think about my idea that the space/time of our Universe is much larger than the visible Universe because of the difference in z between the CMB and the farthest galaxies we've located?
    Never is a long time.
    Hfarmer
    Well.  Accepted astronomy has a very simmilar idea to that.  
    The farthest light we can see is about 13 billion years old.  That is the CMB.  

    The observable universe is going to be larger than 13 billion light years in fact it is about 93 billion light years .  So we really can't see most of the universe beyond seeing it's associated region of the CMB.  

    It is quite possible that some variant of what you have said is true. i.e. IN string theory the universe is thought to be embedded in a higher dimensional "M-Brane".  These occasionally collide creating a big bang like event.  Then there is the idea of a quantum time multiverse...in which every decision that gets made creates a new parrallel time line. etc. 
    Science advances as much by mistakes as by plans.
    MikeCrow
    The farthest light we can see is about 13 billion years old.  That is the CMB.

    But is that the accepted distance (13Blyrs)?

    My thinking is that with expansion, the CMB is further than 13Blyrs, I've read numbers in the 40-70 Blyrs for the radius of the visible(?) Universe.

    I think the CMB marks the edge of the observable Universe, but it's not the edge of the Universe(our S/T) itself.

    i.e. IN string theory the universe is thought to be embedded in a higher dimensional "M-Brane".  These occasionally collide creating a big bang like event.  Then there is the idea of a quantum time multiverse...in which every decision that gets made creates a new parrallel time line. etc.

    And most of these possible Universes are outside the S/T of our Universe.

    My view really does away with the Horizon Problem as well, as at decoupling the visible universe was a point. Now the inside of that point is 13B lyrs away plus whatever the amount the Universe has expanded since then (ie now 40-70B lyrs in total). Since the original point was part of a much larger S/T, all that other S/T has expanded as well, and represents the rest of our Universe that's beyond the CMB.

    I'm not saying much if any of this is 'right', but it's how I've integrated what I've read into a picture of the Universe.

    And since this is my solipsistic Universe, does anything else really matter ;)
    Never is a long time.
    MikeCrow
    I wonder if inflation can't be explained as the 'unfolding' of the 3 dimensions of space (or 4 of space/time) from extreme gravities. Collapsed dimensions are part of string theory (not that I am for or against it), but GR does generate mathematical singularities, isn't it a possibility that they're 'real'?

    It would seem to me that it wouldn't require any 'exotic' new physics.

    I also think the CMB with a z~1100 is an indication that the Universe is at least 100 times the size of the visible Universe (most distance galaxies with z~10).
    Never is a long time.
    Hfarmer
    Sure.   What your thinking of is the idea that space-time is a conserved quantity.  That at the big bang only so much of it was created.  The expansion of space is then just the unraveling of this coiled up space time.  
    In my own theory of quantum gravity I addressed that idea directly using by applying what's called Noether's theorem to the Lagrangian I derived.  Noether's theorem is a theorem which shows that there is a conserved current for every continuous symmetry of the lagrangian of a field theory. 

    Other theories if you apply Noethers theorem to them do contain such symmetries and they basically all say that things like the M branes of M theory or the spinfoams of Loop Quantum gravity have a limit to how much they can stretch.  That space-time like everything else is in finite supply.    

    It's a counter intuitive result and it not spoken of openly.   However not much in quantum theory is intuitive why would this be any different? 
    Science advances as much by mistakes as by plans.
    MikeCrow
    That's interesting, any thoughts to explain the current measured expansion if no new S/T is being created? I guess you think it is still curled up then?

    I've pictured S/T sort of like the surface of water under tension (ie not flat), large areas of empty space are 'uphill', and matter pulls it 'downhill'.
    Never is a long time.
    Hfarmer
    The universes space time is still curled up.  In this way of thinking the dark energy is just the potential energy of space time as it flattens it self out then opens it self back up.  Much like a rubber band being popped.   No new rubber is created.
    Science advances as much by mistakes as by plans.
    Hontas Framer: "Other theories if you apply Noethers theorem to them do contain such symmetries and they basically all say that things like the M branes of M theory or the spinfoams of Loop Quantum gravity have a limit to how much they can stretch. That space-time like everything else is in finite supply. It's a counter intuitive result and it not spoken of openly. However not much in quantum theory is intuitive why would this be any different? " ---------------------------------------------------------------------------------------------- It would be good, and properly scientific, to clearly distinguish between what is testable science in cosmology and what is pure speculation. The two are usually conflated in a most irritating manner. Much of the standard cosmology, and certainly the more recent pseudo-science like 10-dimensional M-branes theory, sounds to me like they are making it up as they go. And as Lev Landau said about cosmologists: "Often wrong, never in doubt". Amen, brother. RLO
    Hfarmer
    While the Lagrangians of quantum gravity theories are speculative... Noether's theorem isn't. It would still apply even to quantum gravity theories.
    Right. 

    Science advances as much by mistakes as by plans.
    But when you say: "The universes space time is still curled up. In this way of thinking the dark energy is just the potential energy of space time as it flattens it self out then opens it self back up. Much like a rubber band being popped. No new rubber is created.", you are mixing up the possible observational evidence for acceleration with a bunch of completely untestable theoretical modeling assumptions about the putative acceleration. Then you draw the conclusion that no new space-time is created. Do you see the problem here? If you qualify your statements so that observations and speculations are correctly identified, then it would be more scientific. Note also that there are at least 5 quite different interpretations of the observational evidence for acceleration, including that it be may due to incorrect assumptions about type I SN behavior, and that when the assumption of collisionless dark matter is removed and replaced with interacting dark matter, then the "dark energy" vanishes completely. There are other interpretations of DE and acceleration, as well, but I want my bowl of cereal. If we are scientists we should think and speak like scientists, and that means carefully distinguishing the observed from the purely speculative. RLO http://www3.amherst.edu/~rloldershaw Discrete Scale Relativity; Fractal Cosmology
    Hfarmer
    Actually no.
    The conclusion that no new space time is created comes from applying Noethers theorem to the published Lagrangian formulations of Quantum Gravity.  A consequence of all of those is not only quantizing space time---- but also quantifying it.  Space-time goes from being a stage on which things act, to the reactive medium in which everything else is embedded.  Space-time becomes just like anything else in the universe and in finite supply.  

    I know it's not going to be an easy idea for people to understand, even very educated ones. 
    Science advances as much by mistakes as by plans.
    big bang is not an explosion it is the mixture of one dimensions to other creating new dimention (time).because one dimension is always started at the end of other dimension.It may be possible before big bang there is no time exist but energy mainly contraction and expantion exist in different dimension .When they meet to each other the huge disturbance produce and time space generate it will possioble the universe goes to other dimension and produce new different dimension.

    Hontas Farmer, a question.

    Why did the period of inflation end? When inflation ends the universe should have minimum entropy.

    I cannot see any reason why it stopped unfolding space-time except for this particular reason.

    Hfarmer
    Who says the universe is done either inflating classically or as it put it "unfolding"?  Every observation we have now says the expansion of the universe is still ongoing.  It can even be suggested that from a point of view Billions of years in the future this period right now could look just like inflation does to us now.
    Science advances as much by mistakes as by plans.
    I think personally that astrophysicists are on the wrong track here.

    Energy/matter can neither be destroyed nor created. It can only change forms. As Sascha Vongehr already explained in his earlier postings about the nature of light, it is actually 'non-existent'. "Free" energy is a myth. On the quantum levels of existence matter is exchanging information. We call it entropy.

    Our universe is thought to expand forever due to Sn1 dimness in the past. But at the same time entropy goes to a higher state. This is not logical at all. A higher state of entropy can be explained easily when all matter is contracting finally forming the Big Crunch. It is not a state of disorder from the view of the universe. It is simply getting back to its original state.

    What happens when the last particle is collapsing in the singularity? It is the last piece of matter which is experiencing gravity. This is because all the particles in the singularity do not exert gravity on themselves. The black hole is spinning and the netto forces from outward and inward forces completely cancel each out. In fact you might say there is no force left. Momentum and gravity completely cancel each out. Here lightspeed comes in. We know that the arrow of time is dependant on c which is E/m . If there is a total equilibrium of energy which represents the entangled state of all matter at the final state (singularity) then there is no information to share anymore. All that is left is the momentum of the universe as a whole.

    mv^2/r= G m1m2/r^2 which simply states that the centripetal force in a system should equal the gravitational force if the system is stable.

    What happens is that temperature and space and time cease to exist. There is an inflationary period possible where the universe can expand again. But as information cannot be destroyed the universe remembers its momentum. At maximum possible expansion [Time] [Space] and [Gravity] are created again. The momentum from the universe is remembered by all particles. It is collapsing again because the net forces in this universe are zero - gravity and complete momentum should cancel each out. The universe is returning slowly back to its original state. Time is reborn - entropy rising.

    In the first stage after maximum inflation there is uniform low temperature. The universe is at its lowest possible state of entropy. When gravity is introduced there will be a slow warming up.

    After the Beginning:

    - lowest possible state of entropy
    - lowest average temperature
    - a maximum amount of information that can be exchanged
    - lowest speed of light (like in a BEC, the speed of light stops to almost zero)
    - the largest "spacial" volume
    - information cannot be lost - the momentum of a former universal singularity is therefore preserved (First law Newton)

    Near the End:

    - highest possible state of entropy
    - highest average temperature
    - a minimum amount of information that can be exchanged
    - highest speed of light (like matter in an entangled state where distance is nearly zero and the speed of light is ∞ )
    - lowest "spacial" volume

    The total amount of energy in the universe is not changing -> E^universe = mass^universe . c^2
    When c is not a constant then the mass of this universe is just AN EXPRESSION OF A SHRINKING SPACETIME. If the universe is a closed system and it is not affected by external forces, its total momentum cannot change. But momentum is not evenly distributed. It takes the universe a while ;-) to get back to its primary state.

    Momentum is barely visible at the Beginning -being distributed over the largest possible space, not showing to be in a hurry either. This changes when the speed of light is slowly rising.

    To achieve an entangled state you need to isolate the particles completely from this universe. So they can only see themselves in their little universe. When having reached exactly the same temperature (equilibrium) they are performing a perfect synchronous "dance". They are now at a maximum state of entropy. There is no information to change, distance becomes irrelevant.

    The reason light from SN1 being dimmer is that the speed of light was lower then at present, I think. This would imply that the universe is older then we think.

    Hopefully Hank will forgive me for giving some links here to the subject.
    I recently had a talk on the website from Luboš Motl - see http://motls.blogspot.com/2010/01/erik-verlinde-comments-about-entropic.... (63 comments) trying to explain what importance entropy has. Last 5 entries are mine, I think he got the point.

    My interest in entropy and gravity started in 2007 while enjoying a long conversation about the relation between entropy and gravity. See for instance http://www.nwtonline.nl/00/nt/nl/52_95/forum/39388/13/Entropie_op_kosmol...

    There was one guy who already fully understood the basics - Noppen Stefan. See his comments 11/09/2007 om 17:24 uur and 13/09/2007 om 22:45.

    Most important: Op 10/09/2007 om 21:11 uur Hoe manifesteert entropie zich in een zwaartekrachtveld ? / How does entropy manifest itself in a gravity field? His last sentence : Does a dropping stone in a perfect vacuum in a gravitational field emits heat or radiation?

    I had several comments in another post where I brainstormed what happens in an e-p pair collision regarding gravity since information cannot be destroyed. See "Nogmaals velden theorie" M.W.H. Bischot.

    The Forum is dead know, hopefully someone will realise its value. Will anyone read this? I really hope so.

    Han Vinke aka Hannes

    blue-green
    Are you presuming that there has to be a universal Big Crunch? I don’t think there is much support for that anymore. Two more quick questions to Han (and one to our Farmer) before I look into Han’s links, if time permits.
    #2: What is Sn1?
    #3: Being that you are from the Netherlands, why not bring us up to speed and relate your thermodynamic reasoning with the more compact reasoning of your countryman Verlinde, holographic principles, Unruh Radiation, Hawking Radiation and all that?

    Conservation of Information is more along the bedrock linear principles of quantum mechanics than along energy and momentum conservation as you imply. Conservation of energy and momentum can be derived from higher principles … mathematically, it is as trivial as Wheeler and Misner’s “the boundary of a boundary is zero” from old school algebraic topology (Gravitation: chapter 15 (1973) plus earlier papers on Geometrodynamics reaching back to 1962). Regardless of his many other talents, Wheeler was overly partial to a closed universe topology culminating with a Big Crunch.
    He would of embraced and published more on the newer thermodynamic approaches, IF he could have made it to Copenhagen for his 100th birthday in 2011. ((What say ye Ponta Hontas?))
    Hfarmer
    Nope.  The word big crunch is not appropriate for what I am talking about. The big crunch idea is a consequence of classical gravity in a universe where there is a certain amount of matter such that it's gravity "closes" the  universe.  In a closed universe of this kind the universe will expand, slow down, then fall back together and crunch.

    What I am talking about is that after a certain amount of expansion the universe just stops expanding.   What happens next?  I don't know?
    Science advances as much by mistakes as by plans.
    #2: What is Sn1?
    The unexpected dimness of Type Ia supernovae at redshifts z > ~ 1 . That is why we think the universe is expanding.

    #3: There is a difference in the amount of information to share (which is essentially represented by deltaS) and CONSERVATION of Information.

    I am only talking about a limit on the information that can be shared between particles - when it is reaching maximum there still is high temperature (represented by movement on a quantum level). I do not say that information is destroyed, on the contrary!

    At the final state all matter is in an entangled state - there is no need to share information. But there is no "chaos" here - all is dancing the SAME dance.

    Word missing: - when it is reaching maximum [ENTROPY] there still is high temperature.... , sorry.

    blue-green
    The Vacuum Energy Density is the Elephant in the Room. A week or two ago, our Discrete Fractal Relativity Relativist from Amherst had a mid-life crisis in this department and deleted his blog on the vacuum energy here along with all of the comments. Toss us a bone Sascha.
    Hfarmer
    Maybe he's looking for a way to disprove Noether's theorem.  For what I said that he objected to is  about as sound a mathematical fact as 2+2=4.   It's physically a very disturbing result since it fly's in the face of all our intuitions about the very notion of "space".  So much about both classic General Relativity let alone any of the theories that attempt a quantum gravity is conterintuitive...why would quantum cosmology be any different?
    Science advances as much by mistakes as by plans.
    There will be a crush and a big bang over and over again in my opinion.

    In my model above the period of inflation simply ended because the universe reached a state where it was not possible to expand anymore. It represents the lowest possible state of entropy therefore. As the second law of Newton shows entropy as a whole can only go up - to a state where it reaches a maximum.

    This maximum is a state where a matter in the final "singularity" stops collapsing because of mv^2/r= G m1m2/r^2 . So the singularity is not collapsing anymore - reaching highest possible temperature/entropy.

    The angular momentum of the universe "singularity" cancels out the forces of gravity - on the right side of the equation.

    Inflation could only start because the balance in the equation was reached at the final state, and gravity comes to an end. This allows for expansion, you could call it a "White Hole" .

    As long as the universe does not reach the final state where all matter has the same angular momentum you have "Gravity" acting like a force. You can see why it is closely connected to entropy.

    What we call "Space" is in my model dictated by entropy. Energy cannot leave this universe and entropy rises because the universe is collapsing.

    In current modelling based on the behaviour of type I SN we have to assume the universe is expanding forever. This must be if the speed of light is a constant during all ages. But entropy is rising - see the contradictory here?

    If you connect entropy with contracting space the logic is there immediately. If you press together a gas the temperature is rising - entropy is rising because you limit space.

    In my opinion entropy dictates our notion of what we call "Space" and not the the other way around.

    I had 4 years time to think about entropy and gravity.

    See also "tijd: een relativistische thermodynamische synthese ?" - e.g. "Time - a relativistic thermodynamic synthesis?" from Noppen Stefan. http://www.nwtonline.nl/00/nt/nl/52_95/forum/39510/5/tijd:_een_relativis...

    It is a great contribution (imho) to the relation between entropy, time and gravity.

    Hontas Farmer - please note - I do love Noether's theorem.

    We can see Landauer's principle here in the information stream. When delta S = highest there is little information to share. When delta S = lowest then there is a lot of information to share. Delta I (representing the informationstream) = inversely proportional to delta S over time.

    In a contracting universe we asymptotically go to a flat space from a third power order (volume) to a second power order (distance = r).

    We are loosing 3D information here fast until we reach the "final state" which represents an almost totally flat 2D space, as in FLRW metrics.

    Delta I is depending on the speed of light c during the process of a contracting space.

    c^current = c{x,y,z} / c{x,y}

    When the universe started to collaps delta S was at a minimum, delta I at a maximum and lightspeed at a a minimum.
    At the final entangled state delta S will be at a maximum, delta I at a minimum and lightspeed at a maximum.

    There is a close relation to delta I and what we call "the speed" of light.

    I have stumbled upon this highly interesting blog. Although I have an enquiring mind and have always been interested in theories of the universe, it did not take me long reading this blog to realise that I know absolutely nothing. But certainly you have wetted my appetite and now I have even more questions.

    What intrigues me is the question of what existed before the Big Bang. I am having difficulty with the idea of the expansion of space i.e. there was no emptiness because there was no space. Furthermore, what gave rise to all the energy that we have in the universe today?

    In my mind I picture absolutely nothing, and then in an instant a rapidly expanding universe. Or perhaps, I dont picture that. Instead I see a repeating cycle that is endless. This helps me out because then there is no beginning or ending. It is really hard to fathom that something began and there was nothing before.

    As scientists, you guys seem to have many theories that seem to satisfy your own need for answers. But yet the average person in the street would have great difficulty understanding you. And by-the-way, I am an atheist and so my questions are not leading to any religious comment. Even if there was a God, he/she would n't be able to conjure a universe up.

    Do you suppose, however, that the Big Bang event happened in only one place, a singularity, or is it just posible that our measurement of the universe is incorrect due to factors we don't know about yet, and in fact there have been numerous orgins of the matter we can all observe in the universe?

    Hfarmer
    You have some very good questions. 
    I am having difficulty with the idea of the expansion of space i.e. there was no emptiness because there was no space. Furthermore, what gave rise to all the energy that we have in the universe today? 
    The short answer is that we have run against the limits of all pre existing human language to explain this and need to resort to math.  That said, I will try.    The following is my own picture of the big bang. Other will disagree.

    Before the big bang there was a tiny tiny bit of space.  It would have been about one cubic Planck length in volume.  (Though it would not have been shaped like a cube...it would have been whats called a 24 cell.  It has some geometrically interesting properties. )  This is a tiny volume, and at lengths smaller than this measurement itself does not even make sense.  All that existed was quantum information in a very ordered and symmetric state.   All of this was encoded as pure energy in that tiny volume


    Then something, I don't know what broke that symmetry.  In modern physics particles are created when symmetry is broken.  We have seen this in the laboratory.  The difference between this and what we do in the lab so far is the scale and nature of the forces involved.  When this cosmic symmetry broke one "superforce" became (at least) four separate forces.  These forces are electromagnetism, two nuclear forces, and gravity.  


    Space did not expand....it was created along with gravity.  

    Space-time was created as the mediating "particle" for the force of gravity just as photons mediate electromagnetism.    

    What I have said and similar ideas are found in many papers about Loop Quantum Gravity, Casual dynamic triangulations, and my own theory Quantum Space-Time dynamics....which I realized latter was fundamentally equivalent to loop quantum gravity (As are all group field theories). 
     
    This big bang didn't happen any particular "place".  In the sense of where in the universe it happened it happened everywhere.  Everywhere and everything is part of the big bang.  As space is still growing the big bang is an ongoing process of expansion. 


    Other big bangs could have happened.  So far we have no generally accepted evidence of this.  There are some interesting observations of a "great" attractor and a dark flow in the universe.  Things which could be the effect of gravity from a near by universe. 



    As scientists, you guys seem to have many theories that seem to satisfy your own need for answers. But yet the average person in the street would have great difficulty understanding you.


    The problem is the things we study are inherently complicated.  Well us here at scientific blogging aka science 2.0 try very hard to make what we write enjoyable to the most people.   The very nature of these things works against us.  A smaller problem is if people feel you are dumbing things down for them they will be turned off, or insulted.   On top of that there are all the misconceptions about these things that we need to work through.   
    Science advances as much by mistakes as by plans.
    Hi Hontas, Thank you for your reply. You have given me plenty of research leads. I shall enjoy the reading. I would love to be able to understand this subject better.

    I read the first few exchanges in the comments (I realize they are more than a year old) between Hontas Farmer and Sascha Vongehr. I've just finished watching Leonard Susskind's Stanford University 8-lecture series on cosmology (on YouTube). Susskind adopts the same point of view as Vongehr espouses here: what he (Susskind) calls the "Big Bang" is an event that happened *after* inflation; inflation and everything that came before it is largely unknown territory, and inflation wiped out a great deal of information about earlier time. From the discussion, everyone appears to be talking about the same early-time cosmology; the differences appear to be just a disagreement as to what event to label "Big Bang".

    There appears to be agreement on reheating after inflation -- but I don't understand why it's necessary or where the reheating comes from ...

    Hfarmer
    I have not see Suskind's talk.  
    What I am talking about above is the standard way of thinking about the sequence of events. The big bang was "something" we don't know what, that started everything else that occurred after it. It was the initial but not inflationary expansion of space time.  Inflation comes very shortly after the big bang.  

    There is no reason they cannot be the same thing in the end.  There is no reason that the reheating after inflation could not be considered the true beginning of our actual knowledge about the early universe.  It's just not what most cosmologist mean by "big bang".  

    At Susskind's level he can say things like that and not be censured for it.  In the physics world of today one needs to show that they can walk the straight line before anyone will tolerate them going their own way.  


    Science advances as much by mistakes as by plans.