How can quantum fluctuations scale up to make something as massive as our universe?

We do not know the statistics of the distribution of properties & of attributes within a vacuum quantum foam (for instance, what is the distribution of the virtual masses of the virtual particles that pop in and out of existence.)

However a simple one-step scenario (aka the Tryon scenario) goes like this: once in a while a supermassive virtual particle happens to pop into existence. For some reason (to be established independently - a pre-extant quantum vacuum, etc.) quantum laws happen to apply to the environment into which this supermassive virtual particle pops.

A time quantum therefore applies in the vacuum, and the supermassive virtual particle happens to be *bigger* than allowed by the reigning time quantum under the Heisenberg relation - in other words the time conjugate answering to the supermassive particle would have to be smaller than the incompressible time quantum.

Heisenberg's equation would be then violated if the mass remained virtual , which nature does not allow to happen : to prevent this violation the supermassive virtual mass becomes instantly real: BANG.

There are also other scenarios.

I think that an exponential initial expansion, INFLATION (see authors like Guth and Linde), can make a small local fluctuation increase to the size comparable with the size of the present universe stage. This as far as size. May be, and only may be, that a replication ( as proposed by Dirac in 1937) of particles with their mass can explain the present mass of the universe. If you take a hypothetical Planck´s particle, obtained by making the speed of light, Planck´s constant and the gravitational constant as unity, you get a "world", a quantum black hole, that has the property of mass, size and characteristic time such that scaling them, by the same factor these three properties, we get the properties of mass, size and age of the present universe. The scaling factor is 10^61.

If you are online right now, then this show will be helpful in getting cleared

Mathematical and Philosophical refutations of the Kraussian claim and the standard view that the universe was 'created' out of quantum 'nothing'-ness

This is indeed a matter of great importance. The most robust approaches to a pre-big bang are still at the beginning of formalism. There are scenarios where the quantum fluctuation would have only one co-adjuvant role in baryogenesis. In this case the energy density involved in the Big Bang would come from another primordial property. The main factor for the expansion of the baryonic spacetime could be related to a non-homegeneity caused by some geometric bond (see for example alternatives models from Lemaitre-Tolman-Bondi cosmologies, as Top-Hat and Chamaleon-like mechanisms). Anyway, from the point of view of statistical physics, the scale factor involved in the quantum fluctuations should be treated from phase transition formalism. So one can find possible universality classes for amplification power of this magnitude. A question that comes from this approach would be, for example, which would be the order parameter and the partition function driving the bang process from the quantum fluctuations? How the inflation, from the perspective of an effective theory, is related to the quantum fluctuations?

That's a very good question, John. If you believe that there's a theory of everything, as I do, "a sequence of many phases" as you put it, is impossible. There can only be one set of physical laws.

Since the only real things in the universe are energy, space and time and the total amount of energy doesn't change, the evolution of the universe, from inflation to now including its future, must be due to changes in space and time. Interestingly if you realize that the constraints imposed by E=mc^2 apply to the universe itself and follow that through to determine how the universe evolves, everything falls into place.

For me, it's kind of astounding.

The answer is given by the following equations:

\sigma_E*\sigma_t >= \hbar/2 (Heisenberg's U.P.)

G_{\mu\nu}+\Lambda ds^2 = \kappa T_{\mu\nu} (Einstein's field Equation modified)

Due to the first equation, the uncertainty increases over time.

Due to the second equation, there is an energy density across free spacetime (which is an intuitive thing due to the electric and magnetic constant).

Is it not possible that still particles from the "outside" of the universe enter into the universe ?

By the way, through the expansion of the universe energy would be conserved.

The particles produced need not to be coming from the outside of the universe.

In the universe, large scales, energy is not conserved. See the cosmology book by Harrison.

Antonio, this is since Einstein's equations are not conserving energy ?

Your question asks how can quantum fluctuations scale up to make something as massive as our universe? You have to answer a different question....fluctuations in what? Before the big bang there existed neither matter, energy, space nor time, so by definition there could be no fluctuations in any of these entities. (If you claim there was something of a material nature “there” before the big bang, we are no longer talking about the ultimate origin of the universe).

Issam, I think you're right about what existed before our universe came into existence. But before then the energy that's present in our universe must have existed even though space and time didn't. It seems to me that the fluctuations John refers to must have been fluctuations in the energy itself without the presence of another medium. That may seem strange but we have another example of fluctuations that occur without a medium with the electromagnetic fluctuations which take place in spacetime rather than in a hypothesized ether. It's difficult to imagine energy fluctuations when spacetime doesn't exist but somehow they must have occurred. Can anyone else out there suggest how those energy fluctuations could have taken place without a medium? It's a puzzle to me.

Bill, you say that" the energy that's present in our universe must have existed even though space and time did't". If that energy existed before the big bang then once again we are no longer talking about the ultimate origin of the universe. Where did that energy come from? Further, we need to solve the question of how fluctuations can take place when there is no medium or no space time?

Those are very good questions, Issam. Before I say anything else let me say I don't know the answers and can only guess at some possibilities.

Without spacetime, the energy was "just there". It couldn't change but it must have been able to fluctuate or our universe would never have come into being. If multiverses exist, the energy could have been left over from another universe or possibly even have been "pinched off" from one of them ... there are a lot of theories. If ours is the only universe, perhaps you can loosely think of the energy as just being there fluctuating and "waiting" for the right fluctuation that would allow it to exist in spacetime and expand into our universe.

I think your last question is fundamental and crucial. I've read that most 19th century physicists KNEW that there had to be some kind of ether in order for light to propagate. But it turned out they were wrong. Hopefully we're in the same situation with regard to energy fluctuations when there's no spacetime.

@Bill: I can't accept your statement "Without space-time, the energy was "just there"." If energy was just there then once again we are not talking about the ultimate origin of the universe.

Further, there are weighty voices within science that are not enthusiastic about multiverse. Prominent among them is that of Sir Roger Penrose, Hawking's former collaborator, who shared with him the prestigious Wolf Prize. Of Hawking's use of the multiverse in the 'Grand Design' Penrose said: "its overused, and this is a place where it is overused. Its an excuse for not having a good theory."

Penrose does not, in fact, like the term "multiverse", because he thinks its inaccurate: "For although this viewpoint is currently expressed as a belief in the parallel co-existence of different alternative worlds, this is misleading. The alternative worlds do not really 'exist' separately, in this view; only the vast particular superposition.......is taken as real."

John Polkinghorne, another eminent theoretical physicist, rejects the multiverse concept: "Let us recognize these speculations for what they are. they are not physics, but in the strictest sense metaphysics. There is no purely scientific reason to believe in an ensemble of universes."

It is certainly far more elegant and economical to postulate one universe than postulating 10^500 different universes that are unobservable by us. Surely this is a much better "model".

Issam Sinjab: I agree with you. There is enough difficulty to understand our only universe. If you multiply by 10^500 (multiverse) the ignorance about them would be huge. This is only a way to increase lack of knowledgr to an enormous level. Better to keep where we are here: a see and touch, to a certain extent, universe.

We do not know what means time below 10**-43s and space below 10**-35m, except that they should become discontinuous, quantized. So, we do not know what means time zero and therefore what means time before zero.

Denis: My latest "findings" are that as you approach the "first" stage of the universe, a very small cosmological scale factor, the space-time interval ds becomes time like and of an enormous size. This would imply that the first "tick" of the universe, contrary to current belief, was very close to a mathematical "infinity": And of course one does not know what happens before this huge first mathematical time interval, no way. At this first stage the speed of light should have been very huge too. If things were this way, the Universe was born totally conected, with a huge time like interval and a huge speed of light to conect everything.

Hi,

I think that this question is out of the realm of science. We don't know what existed before the universe came into being (if there was a "before" at all) and therefore we cannot speculate about quantum fluctuations.

Ehud,

Isn't it the very essence of science to ask questions about things we don't know ?

The very argument you make above was used many times before - such as when Gerolamo Cardano mooted imaginary numbers, and Greek philosophers zero - seldom fruitfully ....

@Bill LaPorte-Bryan:

G=kappa*T + Lambda (X) g_\mu\nu

Since you claim for there to be energy without spacetime, the energy density is infinite and thus Lambda is Infinite:

G = kappa*T + infinity ds^2

G=infinite.

This would never allow the big bang to happen.

Abhimanyu, the concept of density requires the existence of spacetime since it refers to a certain amount of mass in a certain amount of spacetime. So if there's no spacetime talking about the density of anything is meaningless. The energy was "just there". I think I can imagine this but I can't imagine what happened that caused spacetime and our universe to come into being. But something did!

Chris,

Certainly. The very essence of science is to ask questions about things we don't know. I fully agree. Yet, some questions cannot be answered right now (and maybe never) and a smart scientist asks questions that can be answered. We recreated the energy density that existed in the universe some 10^-10sec (or whatever) after the big band and we still need to go ~20 orders of magnitude till we reach the time that is discussed here. I find extrapolations over such a huge range a wast of time.

Ehud,

Then you de facto agree with, and leave the field to, people who have a non scientific agenda, e.g. the pope who bid Stephen Hawking in 1981 to "not study the Big bang because it is God's work".

We can certainly agree to disagree.

(I'm not even going into the logic of not studying something because it is allegedly God's work.)

I don't necessarily agree either that a 'smart ' scientists asks questions that can be answered now or soon. As a case in point, a lot of unanswerable questions in string theory have had the non-linear but extremely beneficial effect of forcing many physicists to enhance their mathematical abilities, and also have answered a few off the side questions that had not even been asked in the first place.

Chris,

It has nothing to do with God. As I said, trying to figure out what happened at the moment of the big bang (or before it) requires extrapolating our knowledge by ~20 orders of magnitude. QM lays less than 10 OOM from us and GR 10 in the other direction. So why am I supposed to believe that we can say something meaningful about such a thing? We usually stop at the Planck scale saying that the new physics there may change things profoundly. So why are you willing to cross the "gravity barrier" and use our 21st century knowledge to speculate?

Physics is an experimental science. Sometimes we speculate on things that will be measurable in the far future, 50 100 years. But this type of physics will be subjected to experiments in zillion years if at all. So as far as I'm concerned this is some sort of theology (so maybe God is relevant). But I suggest we agree that we do not agree. I'm happy with such a conclusion

@Bill La -Porte Bryan: Its quite obvious that if I were to follow your logic, just "there" also requires the existence of spacetime. By the way, no spacetime and 0 spacetime are the same. So energy density WOULD BE infinite if there were energy without spacetime but "just there" would not be defined

That's exactly my point Ehud, maybe you should read posts more carefully. It has nothing to do with God, and it has all to do with society, as I was trying to convey.

My point is that it is irresponsible for scientists, who are a vanishingly small minority in society, to leave the public discussion of certain fields entirely open to non-scientific, and even sometimes obscurantist, folks with an agenda - who then dominate the narrative on certain subjects with their own, non-scientific interpretations.

Scientists do not operate outside society. I for one believe that the speculations of a Brian Greene, for instance, contribute to the enlightenment of society, and that we collectively would be all the poorer if he had chosen to keep silent, on the pretence perhaps that his field, string theory, is still largely closed to experimental proof.

Abhimanyu, perhaps "just there" is a bad choice of words. When I say that the energy of the universe was "just there" before spacetime came into existence at the beginning of the universe, the term refers to the existence of energy with no spatial or temporal characteristics. A way to think of it is as potential energy which has the potential to cause change if spacetime existed (which it doesn't).

I must admit it's not easy to imagine such a thing but I do believe it's conceivable and must have occurred. I don't think there's any alternative. The challenge is to figure out why such a situation isn't stable because, if it had been, spacetime wouldn't have been created and the universe wouldn't exist.

Hi Chris,

On one thing we agree: I should read posts more carefully :-)

I feel that we start repeating ourselves. I don't think that the fact that I do particle physics at energies of the order of TeV give me much head start over someone who is illiterate (ok, I exaggerate a bit). Had I been extrapolating Newtonian phys 20 o.o.m down I would have missed QM. SO I don't have the slightest cue what will we miss by going from LHC to Planck. True that others are talking nonsense when it comes to LHC phys (remember the mini black hole scare) but do we know if BSM exists? is it SUSY, ED or another thing? So physics ends near LHC and the rest is speculations (sometimes educated ones). But can you cope with the question "does the universe come from Quantum fluctuations?" I certainly cannot.

Ehud

I'm sure my theory is probably wrong, Abhimanyu but we do know the universe came into existence about 13.75 billion years ago and as far as I know nobody knows why. Sometime in the future somebody, certainly not me, will figure out what happened and as they start to share their conjecture it will seem crazy too.

Several people have commented that posing the question about cosmic fluctuations is not answerable using scientific methodology, and therefore should not have been asked in research gate. These people may be underestimating the potential discovery power of cumulative knowledge achieved through a series of many small gains. This method is often referred to as trial and error. Before a discovery, some problems seem insurmountable; but after a discovery the common expression is “Why didn’t I think of that.” It may be tedious at times; however, as an analogy from my many years of cave exploration have demonstrated, checking all leads, even unpromising ones, is necessary to find the interesting passages and to reach major discoveries.

In the quest to understand the Big Bang, the three most relevant disciplines have all experienced rapid scientific progress in recent years. They are quantum physics, M theory, and astrophysics. Each could lead to a plausible explanation of the cause of the Big Bang. Here I give examples of proposals for the cause of the Big Bang that could be discovered by scientist working in each specialty discipline.

1. As the knowledge base in quantum mechanics continues to grow it may be possible to either confirm or falsify quantum fluctuations as the cause of the Big Bang. It is my understanding that proponents such as Lawrence Krauss and others maintain that the uncertainly principle applies everywhere including outside of our universe and presumably outside all universes. Therefore, as quantum articles go in and out of existence and under very rare conditions they form a massive quantum article outside a universe that causes a big bang to form a new universe. This concept complicates the meaning of “universe” which brings up a different problem for later discussion. Other related quantum mechanics models are Loop quantum cosmology and Penrose's Conformal Cyclic Cosmology.

2. M theory (string theory) presents models such as M-Brane collisions (Steinhardt–Turok or Baum–Frampton) or other interactions among prior universes as the cause of the Big Bang.

3. Astrophysics and the advances in accurately measuring the cosmos have substantially influenced cosmology. This information has falsified many cosmological models, the most famous being the Steady State theory. The Big Crunch in which the entire universe collapses into a giant blank hole and then explodes into another universe has also been falsified. Astrophysics has given us an entirely new prospective with the discovery that dark energy is driving the expansion of the universe and separating everything that is not gravitationally bound. This means that the galaxies in most galaxy clusters will merge forming giant galaxies that will eventually be isolated over the event horizon from each other and the remaining universe. (Kentaro Nagamine and Abraham Loeb, 2002) Although our entire universe will not consolidate to form a new universe, the possibility that part of it might do so has not been eliminated. This idea states that the gravitationally bound galaxies in a cluster will consolidate into a single galaxy with an ultra supermassive black hole at its center and by some undiscovered process form a new universe. It would be interesting if someone would run a computer simulation to determine what will happen to these giant galaxies in the next several hundred billion years. If it is plausible that a very large galaxy in our universe could cause a future big bang then one might generalize that this is the method that caused the Big Bang.

4. Confluence of these disciplines could result in some other proposal not yet conceived.

John M. Wilson

Everybody has the right to ask any question. Similarly, everybody has the right to answer. Ultimately, By looking at the answers, it is you and only you who decide if your question should or should not be asked.

I think, that the uncertainty principle only belongs to relatively of small values of the energy. The h on the other side says that, in my point of view.

Dera John,

Would youmind putting this question if a professional way based on assumptions that lead to equations that one can attempt to solve. Without this this is a pure bla bla.

Ehud

Ehud:

There are several proposals that quantum fluctuations are the cause of the Big Bang. I have Roger Penrose’s book “Cycles of Time” 2010 beside me, so I will use his Conformal Cyclic Cosmology as an example. The CCC explanation begins on page 139 and goes to p 219. Also appendix A and B of this book provides additional and comprehensive supporting math for his theory; however, it is far too much information to quote here.

Penrose makes a credible case for how quantum fluctuations could make a new universe. What I could not find was any information on what would cause these fluctuations to happen in such a way that a very large universe would form. The probability of such an event occurring appears to be zero, which is why I asked the original question, hoping that I had over looked some critical information and someone would have an answer. Several people have provided some help but nothing yet regarding probability.

Quantum fluctuations appear to be spontaneous events. This is why I think large universe formation by this method is not going to happen.

The likelihood of a large spontaneous event is inversely and exponentially proportional to the complexity of the spontaneous event. The probability that an event will occur spontaneously can be determined by the number of independent components in the event or mass that are critical for the event to occur. The chances of a very large universe occurring spontaneously are essentially zero. The equation, F = 1/u2 describes the probability of numerous independent objects spontaneously combining to form a new consolidated object, where F = the probability of the formation of an object from independent units and u = to the number of independently functioning units.

John, while it may be highly unlikely that quantum fluctuations are the cause of the Big Bang, there is very strong evidence that that's indeed what happened. Let me quote from page 98 in Lawrence Krauss' book "A Universe from Nothing".

"The pattern of density fluctuations that result after inflation - arising, I should stress, from the quantum fluctuations in other-wise empty space - turns out to be precisely in agreement with the observed pattern of cold spots and hot spots on large scales in the cosmic microwave background radiation. While consistency is not proof, of course, there is an increasing view among cosmologists that, once again, if it walks like a duck and looks like a duck and quacks like a duck, it is probably a duck. And if inflation indeed is responsible for all the small fluctuations in the density of matter and radiation that would later result in the gravitational collapse of matter into galaxies and stars and planets and people, then it can be truly said that we all are here today because of quantum fluctuations in what is essentially nothing."

John Wilson, I've just finished reading Lawrence Krauss' book "A Universe from Nothing". It's excellent and you might want to read it too as it presents the best answer to your question I've seen.

Please also read a critique of Lawrence Krauss book by David Albert:

Bill, sorry, but I do not think at all that Lawrence's book is excellent. It does not make a compelling case at all, nor a complete case.

It's too bad, because Lawrence's earlier books (The Fifth Essence, as a case in point) were very very good.

Read my short review on Amazon (voted the most useful negative critique.)

I also agree with David Albert 's review (whose book 'Quantum Mechanics & Experience' is actually excellent.)

All I can say is that I liked the book. I read it as a science book and didn't pay much attention to his discussions about religious philosophy. I thought his science was current, solid, based on recent observations and experiments and well written. He rightfully labeled what's known and what were speculations. All in all, I found it very helpful.

But there are so many other scenarios for universes to be born ... not even touched upon in the book. As a snapshot of the current state of research on the subject, it is woefully inadequate. Since it is intended for laymen, it should at the very least *mention* possible scenarios that were simply totally ignored - why were they?

In terms of the current research on the subject matter - it is fascinating and wide-ranging. There are many 'eureka' moments out there, and having ignored them in this book is well-nigh inexcusable.

Benard Carr's compendium of 28 ground-breaking papers is, perhaps, a good place to start ("Universe or Multiverse"), but there are also a number of absolutely fascinating contributions in sundry current research papers, which should have been summed up or at the very least, mentioned.

Dear John

Penrose is a great physicist but even the best err from time to time. Let me explain once again why this is more fiction than science. We live in a meter-kg-sec environment. Things around us have a size of about a meter (km and mm count) weight ~kg etc. When you go 10 order of magnitude (OOM ) up you have masses that require GR. When you go 10 OOM is speed you must use SR. When you go 10 OOM in size you are compelled to introduce QM. I learn from this that one cannot extrapolate ones knowledge by 10 OOM .

I work at CERN on LHC and we go up to energies of ~ TeV. While this reproduces the condition in the universe very shortly after the big bang we are still much more than 10 OOM below the Planck scale where gravity should kick in and more than 20 OOM below the energies relevant to the universe at the big bang. So while it is perfectly ok to speculate about quantum fluctuations as a source to the universe it is pure fiction without any bit of science.

I wonder how many real physicist agree with me and how the others avoid these arguments.

@Bill-La-Porte Bryan: I do not consider that book (I read the preview on amazon) to be good at all because its explanations are un-mathematical and he keeps writing about religious stuff.

@ Ehud: I believe I am a "real" physicist and agree with you, except in your sentence ..." to speculate about quantum fluctuations as a source to the universe it is pure fiction without any bit of science. " My point is that the approach to nature using science as the tool may start with observation or with a scientific theory, to be validated by observation of its predictions. In a sense. to start with theories is not pure fiction because this would imply that science is pure fiction, and we know that it is not. In a general sense, experimenting is also speculating because you never know what would be the outcome, until you finish your experiment or measurement. Of course, everybody has the right to have its own opinions.

I want to make only one comment about what Lawrence Krauss says in his book. He proposes that virtual particle production serves as an analogy for how the universe came to exist.

Virtual particle production is a natural outcome of the Heisenberg uncertainty principle of quantum mechanics (HUP). This principle states, in part, that quantum fluctuations in the universe’s space-time fabric will generate particles, provided those particles revert to quantum space-time fluctuations before any human observer can detect their appearance. Typically, the particles so produced must disappear in less than a quintillionth of a second. Since these particles cannot be detected directly, physicists refer to them as virtual particles. Krauss suggests that the entire universe may have popped into existence by the same means.

However, this idea has caveats. To begin with, for a system as massive as the observable universe, the time for it to arise from nothingness (the space-time fabric) and revert back to nothingness (the space-time fabric) must be less than 10^-102 seconds (10 to the power -102 ) of a second. This episode is a bit briefer than the 14-billion-year age of the universe! -This can be easily calculated from HUP.

A second inadequacy in Krauss’ suggestion comes from another principle of quantum mechanics. The probability of a quantum outcome occurring increases in proportion to the passage of time. That is, the larger the time interval, the greater the probability that a quantum outcome, like the production of a virtual particle, will take place. This principle implies that if the time interval is zero, the probability for any quantum event is zero.

The Big Bang theory require that time has a beginning coincident with the beginning of the universe. Thus, the time interval at the beginning of the universe is zero. This eliminates quantum mechanics as a possible candidate for natural generator of the universe.

However, it would be naive for me not to mention other quantum calculations that indicate time itself must have preceded the Big Bang- see for example the below thread:

Issam, I agree with what you say about the inadequacy in Krauss' suggestion that virtual particle production serves as an analogy for how the universe came to exist. But in his book he explores another possibility that doesn't share the caveats you mention and therefore seems more likely to me ... namely, that ""quantum gravity not only appears to allow universes to be created from nothing - meaning, in this case, I emphasize, the absence of space and time - it may require them. 'Nothing' - in this case, no space no time, no anything! - is unstable. Moreover, the general characteristics of such a universe, if it lasts a long time, would be expected to be those we observe in out universe today." (page 170). Do you think that's possible, Issam? If you don't what are the caveats in this case?

Bill

I don't think you can create anything from nothing. This is total nonsense. Below is a summary of my answer to your question:

1- like I said before space-time is not nothing and so you cannot say 'quantum gravity appears to allow universes from nothing'. That is a self contradiction statement.

2-Laws of physics(quantum mechanics,gravity and quantum gravity) are certainly something not nothing.

3-It seems that both Hawking and Krauss appear to be telling us that the universe is created from nothing and something at the same time.

4-Neither Krauss nor Hawking give an explanation of where the laws of physics come from.

5-The notion that a law of nature explains the existence of the universe (or multiverse) is also self-contradictory, since a laws of nature, by definition, surely depends for own existence on the prior existence of the nature it purports to describe. The laws of physics cannot create anything.

6-Nothing does not exist in our universe!

7-Do we really have an up and running good theory of quantum gravity?

These issues are the subject of a question that I will be asking shortly on this platform.

Issam, I'm looking forward to your question. But, in the meantime, I copied the points you made and commented on them briefly: "1- like I said before space-time is not nothing and so you cannot say 'quantum gravity appears to allow universes from nothing'. That is a self contradiction statement." I agree space-time is something but it can be warped creating a gravitational field. I think that the idea that quantum gravity allows universes from nothing is not only not a self contradiction but rather a very profound thought.

"2-Laws of physics(quantum mechanics,gravity and quantum gravity) are certainly something not nothing." I agree.

"3-It seems that both Hawking and Krauss appear to be telling us that the universe is created from nothing and something at the same time." Their words are confusing perhaps to sell more books but what Krauss is saying is that if there are multiverses, which more and more physicists are coming to think likely, it's possible for them to be created from a state in which space-time doesn't exist. I agree with that.

"4-Neither Krauss nor Hawking give an explanation of where the laws of physics come from." Krauss suggests that they might be different in every universe and that makes sense to me. I think it's certainly possible.

"5-The notion that a law of nature explains the existence of the universe (or multiverse) is also self-contradictory, since a laws of nature, by definition, surely depends for own existence on the prior existence of the nature it purports to describe. The laws of physics cannot create anything." If the laws are different in each universe as each one is created from nothing then different laws can indeed "create anything" that's allowed by those laws.

"6-Nothing does not exist in our universe!" I agree and so would Krauss but that's not what he's saying. Rather he's talking about universes with something in them that are created from nothing.

"7-Do we really have an up and running good theory of quantum gravity?" Not yet. There may be no such thing and if there is one no one has found it yet.

Bill

I think there is much speculation in what Krauss is saying and speculation is just not science!

I agree it's speculation, Issam but at least Krauss is careful to say that he's speculating in that part of his book. I must admit I enjoy speculating and while speculation may not be science I do think it has a role to play. All of the scientists who have made major contributions to the field engaged in a lot of speculation along the way. Will you let me say that all science is speculation until it's proven by observations?

I am a humble man Bill! You have my up vote.

Read a few comments and thought I might as well chip in :P

The universe is really just a complex representation of nothingness for it would be irrational for anything to exist for the sake of existing, or to get neo-Aristotelian:

A=A, A-A=A-A, A-A=0;

And if A can be composite as that A=BC so A-A would then be BC-BC, also B=D+F so C(D+F)-C(D+F)=0 or so on ad infinitum.

In a perfect vacuum, I've heard that a positron and an electron spontaneously appear and negate, so (+)+(-)=0.

So how does this relate to us? Well, imagine an infinite (because of course limits to reality would be irrational because what would be beyond that limit?) macronothingness, that is constantly erupting (similar to the big bang) with macropositrons and macroelectrons negating each other across what would seem to us eternities while the structure of these to something as seemingly quantum as us on this pale blue speck would appear to be our universe which is at the end of the day, just the complex representation of macronothingness. The vast realisation of fractal nothingness, tinier than quantum and epic beyond the supergalatic or what we call home.

Dear John,

I think that your objections are well founded but....

I have one remark to voice after this whole long discussion. Before something exists we do not have the scale therefore we cannot say that something is large or small. You need to have something to compare it with. So before our physics laws started to work in this world the actual fluctuation was infinitesimally small at any comparable system. We cannot exclude any existence of anything before our experimental capabilities are taking us. If energy is so well conserved in our universe therefore it was given to us from whatever was before. This before must have existed in the same form as we exist today. If we assume that matter and space are coupled with each other and one creates the other than the only conserved thing remaining will be energy. Additionally, I personally am not convinced that physical constants are really constant during the course of world evolution from its initial state so I cannot even discuss the problem of scale that is necessary to fix in order to discuss how laws are or not relevant to what we discuss. I personally am siding with Issam on all his comments but he is too attached to what we see at present day. Speculation is one of the forms of hypothesis creation. They become science by Kunhnian process of testing and withstanding or being falsified.

Issam and Bill discussed whether "we really have an up and running good theory of quantum gravity? No we don't, and I think we are discussing issues for which we don't have the tools: neither the observations (of course) nor the theory. General relativity (GR) predicts the Big Bang, but its validity is limited to the Planck time when quantum mechanics (QM) sets in, and perhaps QM also has a limitation near time zero?

Some people have proposed a cyclic universe which really requires that you make some extraordinary "unphysical" assumptions about the physics at the turning point

To avoid the uncomfortable issue of a time zero others have proposed an infinitely coasting universe with small fluctuations where nothing happened until accidentally and improbably all fluctuations added up at one moment, causing the Big Bang.

In neither case will we ever find a trace of a proof because the Big Bang erased all knowledge of whatever preceded it.

Multiverses are another escape which cannot be observed nor proved, I think it is a populistic toy shop.

Spacetime may have more than 4 dimensions. That idea is closer to observations if dark energy needs it for its explanation.

What nobody seems to have mentioned here is the cosmic inflation, from which we do have some remaining information. If quantum fluctuations appear incredible to some in explaining all our massive universe, well, just equip your model of inflation with the right parameters, and you have it!

Another idea is to scale up the quantum black hole well known as Planck´s units. If you multiply (scale up) by 10^61 the Planck´s quantum black hole mass, length and time, then YOU GET OUR PRESENT UNIVERSE MASS, SIZE AND AGE !!!!!!!

The responses to my question about quantum fluctuations were most helpful. There is some disagreement over the certainty that a spontaneous quantum fluctuation caused our Big Bang. Linde makes a very persuasive case in several publications as to how this could happen. His chapter, “The Inflationary Universe” (pages 127-149), in Universe or Multiverse, edited by Bernard Carr, is concise and elegant. While Linde’s proposal is probably the best contemporary explanation of what caused the Big Bang, there is no verifiable evidence that a spontaneous quantum fluctuation did so, and the probability of this occurring spontaneously is small. Thus, quantum fluctuations could have but might not have been the cause of the Big Bang. There is enough doubt to justify pursuing all plausible leads, for sometimes the passage to the greatest discovery is not at all obvious until after it is discovered. One plausible explanation is that gravitationally bound galaxy clusters produce a dominant supermassive black hole singularity that would conform to the formula of quantum fluctuation as described by Linde, except that instead of a spontaneous beginning, the massive singularity causes a quantum fluctuation leading to a big bang. This process is similar to the Smolin proposal of bouncing black holes, except that with this hypothesis, the only black holes that “bounce” or burst from the universe are the ones that are formed from dominant supermassive black holes. These singularities, as Smolin describes, would function in predictable ways in forming universes rather than occurring as spontaneous events.

Had Linde and Smolin collaborated and made modest adjustments to their theories, it is plausible they could have developed a model of universe formation in which quantum fluctuations resulted from very large singularities that caused the Big Bang.

In an effort to encourage others to examine the possibility of gravitationally bound structures contributing to the formation of a universe possibility caused by a cosmic quantum fluctuation, I will present a paper on Monday, April 15, at the 2013 APS April Meeting in Denver in Session T14: New Direction in Astrophysics. By chance, this paper follows immediately after the one given by Richard Gauthier. This presentation is a condensed version of the class presentation, and the entire text is available at www.universeformation.org/APS2013APresentation.htm.

John, it is interesting to speculate that huge(?) singularity formed quantum fluctuations which ultimately caused Big Bang. But then what triggered these 'fluctuations' in the singularity? Also, by ;bouncing' massive black holes, do you mean that black-holes might contain universes of their own, with different space time than, say, our universe? Even if we have a theory to describe conditions before Big Bang (in fact quantum era-the Planck time), it will remain not much appealing than speculation as there will not be any convincing evidence- Observation.

Most people working with post-Big Bang physics concentrate on models of inflation which are to some extent predictive.

To discuss the existence of superclusters or black holes at the time of Big Bang I think is wrong: where did they come from in the first place?

John A. Wheeler "divided his own life into three parts. The first part he called 'Everything is Particles.' The second part was 'Everything is Fields.' And the third part, which Wheeler considered the bedrock of his physical theory, he called 'Everything is Information.'”

Black hole based thermodynamics and cosmology have provided support for two theories:

I. Information is conserved. _{(http://en.wikipedia.org/wiki/Black_hole_information_paradox)}

II. The holographic principle. _{(See http://en.wikipedia.org/wiki/Holographic_principle)}

However, although black holes provide the genesis/support for these theories, they are in conflict if we assume the following:

1. The conservation of information law is "true"..

2. The holographic principle is "true".

3a. The Hubble expansion of the universe is "true"

and/or

3b The volume of the universe immediately after the Big Bang was smaller than it is now.

The problem is: the information of the universe shortly after the Big Bang, as determined using the holographic principle, would have been less than it is today and, in an expanding universe, the information available to the universe must continue to increase. However, if the information of the universe increases, where does this information come? How could such an increase in information be consistent with a conservation of information law? It is my conjecture that the information reservoir comes first. Then, the Big Bang occurs, and expands, within this preexistent contextuality.

Rolf Landauer wrote: "Information is not a disembodied abstract entity, it is always tied to a physical representation." and, according to the Landauer Principle, the loss of access to information (entrophy) results in a heat penalty. _{See: http://en.wikipedia.org/wiki/Landauer%27s_Principle and according to a March 8, 2012 article appearing in "Nature.Note that the Landauer Principle has been experimentally verified. (See: Antoine Bérut, et al., "Experimental verification of Landauer's principle linking information and thermodynamics" Nature 483, 187–189 (08 March 2012) and http://www.physorg.com/news/2012-03-landauer-dissipated-memory-erased.html}

...and, if the loss of information access took a few milliseconds, may have also powered the inflationary expansion.

If you have a first quantum fluctuation, say a quantum black hole with the Planck´s units, AND apply the causal set theory that "replicates" these particles (a 10^61 replication) then you get roughly the physical properties of our present universe:

                                      Planck´s mass 10^-5 g  x   10^61   =   10^56 g

                                       Planck´s length 10^-33 c  x  10^61  = 10^28 c

                                       Planck´s time 10 ^-44s  x  10^61    =  10^17  s

Since the entropy goes like the area of the horizon, so to speak, the entropy of the present universe must be about 10^122 k, k Boltzmann constant as the unit of entropy, and so forth.