Big bang in a larger-verse?
A rarely discussed oddity (links embedded):
“the age of the universe is 13.77 billion years, with an uncertainty of only 0.4%” (temporality)
“the universe is flat with only a 0.4% margin of error” which “suggests that the Universe is infinite in extent”, “All we can truly conclude is that the Universe is much larger than the volume we can directly observe” (spatiality)
“The ensemble of O-regions that we discussed in this paper is very similar to the ensemble of universes in the many-world picture. An important difference, however, is that other O-regions are unquestionably real. There are infinitely many of them in our own thermalized region.” (spatiality)
... which, in turn, suggests that something is missing.
Perhaps something an established unification of relativity and quantum mechanics could shed light on?
More importantly, what’s your take?
“the age of the universe is 13.77 billion years, with an uncertainty of only 0.4%” (temporality)
“the universe is flat with only a 0.4% margin of error” which “suggests that the Universe is infinite in extent”, “All we can truly conclude is that the Universe is much larger than the volume we can directly observe” (spatiality)
“The ensemble of O-regions that we discussed in this paper is very similar to the ensemble of universes in the many-world picture. An important difference, however, is that other O-regions are unquestionably real. There are infinitely many of them in our own thermalized region.” (spatiality)
... which, in turn, suggests that something is missing.
Perhaps something an established unification of relativity and quantum mechanics could shed light on?
More importantly, what’s your take?
Comments (56)
Since we're talking cosmology, how can a universe that has expanded from a point explosion be anything other than a sphere, or at least spherish? How can a flat universe that started from a point 14,000,000,000 years ago be infinite?
And while we're on the subject, how can portions of the universe which were next to each other 14 billion years ago be more than 14 billion light-years apart now? I've looked up discussions of this and still can't figure it out.
Lacking anything interesting to present, and having lots of mouths to feed, science had become a never-ending series of fabricated stories.
It was not from a point but a volume of points. Or rather a volume of points changed their scale. They always had a size (and an energy density) from the start. Then that size expanded (and cooled).
Quoting T Clark
If two of these "points" were to either side of us back then, they are now to either side of us today. So we all swell together.
Next question is "swelled into what?". We want to imagine a collection of swelling points as swelling within some further embedding space.
Imagine instead every point was some compacted tangle of thread. Expansion of the point is the thread being stretched out so that it takes up more room. Imagine a whole volume of such points untangling together and creating an expansion that is also now very sparsely occupied by any thread.
The Big Bang can only be understood if you see the way it is both an expansion and a cooling. So if you want some intuitive mental image, you have to supply an analogy that represent both parts of that "explosion".
Quoting jorndoe
It doesn't feel like it makes a lot of sense talking about the initial conditions of the Big Bang as being either finite or infinite. Both alternatives feel metaphysically suspect. So something "beyond" these traditional choices may be needed.
What we know for sure is that the Big Bang did not start from just a single of Planck-scale point right at the beginning. And indeed, something like inflation is needed to guarantee that the initial region that "banged" was already humongously large.
But to then jump to that extent being "infinite" is a large assumption - if also a pretty natural one.
There are alternatives. The initial conditions could have been "infinite" yet finitely closed - like the surface of a sphere.
Or they could have been the opposite - open and "infinitely" finite in being utterly disconnected and hyperbolically curved at every point. So we might imagine a dust of points which are disconnected as they all curve away from each other with maximum energetic violence. They don't glue together to form a connected volume - a single actual space with shared dimensionality. And then the Big Bang is in fact the gluing together moment when the curvature (which physically would be the violent energy of the Planck density/temperature) started to connect and create a generalised flattening out.
Using the threads analogy, threads would start to connect to other threads and the whole "infinite" fabric would start to knit together and so share a common story concerning their stretching out and flattening out.
Quoting jorndoe
Yep. That was what loop quantum gravity approaches were looking at. An emergent spacetime knit together out of the pure potential for a cooling~expanding interaction. We start with an "infinity" of points so hot that they can't even connect. Then everywhere there is a phase transition like water crystallising to ice. The points start to align everywhere, flattening out and tying together, to form our familiar cooling~expanding spacetime metric.
And you know this how?
This is what I mean, science has become simple story telling. Just make things up as required. Single point. Volume of points (what the heck is a volume of points?). Etc, etc., Etc. Everyone satisfied now that science has explained it?
I was there. Saw it with my own eyes. Idiot.
Quoting Rich
A holographic quantum mind projection. Just without the "mind" part you like to add.
Science fiction.
This is a discussion of the most up-to-date consensus of the scientific community. Your beliefs, disbeliefs rather, are well known and you get plenty of opportunity to express them. That's a good thing. In this discussion you're just being disruptive and I wish you'd stop.
I'm a strong believer in people being able to have their say and I generally resist moderators getting involved, but I've flagged your post as harassment.
Thanks for your interesting response. When we say "infinite" do we mean infinite volume or infinite mass? Both? Or something else?
Quoting TimeLine
It seems that, by current findings, big bang inflation + expansion does not account for the spatial extent of the universe.
Admittedly I haven't gone through the motions/calculations myself, but that was my thinking with the opening post.
Quoting T Clark
The light speed limit applies to mass, not to spatiotemporal geometry (while going by relativity).
So, big bang inflation + expansion itself has "carried" things apart at seemingly superluminal speeds, if you will.
(If that's what you meant.)
Anyway, the three references in the opening post taken together, seems to indicate that the big bang was sort of "localized" spatially.
Even if the spatial geometry is not quite flat, it's close enough to suggest a (much) larger extent than what might have come about over some 14 billion years.
Maybe you're up to par with the latest, @apokrisis?
It would be both. For those arguing for an actually infinite extent, it would be just as unexpanded at every point, and so just as maximally dense and hot at every point, hence just as massive or energetic in its "explosiveness".
But as I said, any such extrapolation from our rather classical view of the Universe - one in which distances and energies have some relative value - really becomes quite moot if we are talking about an initial conditions where there just is nothing for distance and energy to be relative too, as yet.
So the infinity of the initial conditions would have to be infinite in some more general sense that we aren't good at describing in classical terms. A theory of quantum gravity would probably help that ... if not rely on that kind of re-conceptualisation.
Inflation definitely does. But then inflation is hardly a proven story. And also inflation can produce as big a common starting point as you like. Just leave inflation running a few more ticks of the clock and you get exponentially more growth.
So inflation is a free parameter. You can just dial it up as much as you need.
Then the eternal inflation article you referenced is another story again. It presumes inflation keeps happening forever and keeps spawning an unlimited number of big bangs. Ours is just one infitesimal region of the inflation that has cooled and slowed enough to bud off. There would be an unlimited number of other similar universes being created.
So the eternal and infinite version of inflation depends on an inflation event that spawns an unlimited number of big bangs. Ordinary inflation says our Big Bang suddenly took off and inflated a split second after it was first born. It wasn’t born inflating, but then inflation came along to make the universe sufficiently big and ensure that any local wrinkles were smoothed out and make the whole thing look as if it started off as perfectly flat and thermalised as possible.
So either inflation is eternal and we are a spot that dropped out of its exponential rate expansion with no cooling, to be a Universe with a steady rate expansion and cooling. Or inflation kicked in just after the Big Bang for a split second, which would still be enough to stretch out and flatten spacetime as far as the eye could ever see.
The idea in inflationary terms is that the total energy at the beginning was 0 where the negative contribution to the energy of the cosmic gravitational field - as in gravitational repulsion where the energy density produces these gravitational fields - cancels the energy of matter or the positive energy. Inflation thus becomes eternal because as mentioned earlier the matter is being created by the inflation but controlled by the non-uniformity. It would mean the pre-big bang would have been this singularity, where the big bang would occur and then inflation would drive exponential expansion and dark energy smooths the inflationary transition. There is no real answer as far as I know what the original value of omega actually is but inflation solves this problem as the universe is expanding faster and this exponential rate of expansion means that omega could be any number but that it will reach 1.
Einstein would agree that universe doesn't need to be Eucledean and why in general relativity cosmological constant can explain the flatness problem or the uniformity issue. Basically, if the universe is uniform or homogenous and cosmic microwave background is kind of proof of that, therein develops the geometric limitations and one of them is the flat universe. In general relativity, the flatness problem is calculated according to its mass density and critical mass density and this latter 'critical' or constant depends on universal inflation (that is, if the universe is flat (k=0) it is because inflation pushes omega to 1 (anything greater or smaller would make the universe curved or closed) and thus the curvature of the universe is being flattened by the expansion and this occurs a fraction of a moment after the big bang). The critical mass density makes the universe flat and the problem here is that pushing omega to 1 is actually unstable and it needs to be exactly 1 and even being off infinitesimally would mean that we would probably experience a crunch or infinity or basically there wouldnt be a universe, the conditions would not have allowed it.
The paper you have attached attempts to measure the universe as finite and this could be a problem with the big bang because it started with chaos and eventually smoothened that may contradict the second law. But, if we assume the big bang occurred as a ‘fluctuation’ and therefore an addition within one meta-system where there are a number of universes, this somehow resolves our problem (well, in a way). Have you heard about the possible reversibility of statistical thermodynamics with mirror universes where time can move both forward and backward? So cool.
Quoting apokrisis
Depending on the mass density, it could force omega > 1 and would therefore make the universe a closed system like a sphere or reduce omega < 1 and therefore the curvature would open and this is problematic viz., euclidean geometry. Flatness problem is when the geometry is a 1 exactly and perfectly between the two.
Observation says the geometry is almost perfectly flat with just enough hyperbolic curvature to count against any gravitational collapse (and so any reheating of the universe and its contents).
Thus I don’t understand what you are getting at here.
But if you think it did qualify my remarks in some meaningful fashion, could you explain in what way.
You say:
Quoting apokrisis
And then:
Quoting apokrisis
And I write weird? I think you are intentionally being dramatic because if now, apparently, you claim that my comment was a non sequitur as far as you could see it, where, exactly? I think you just want all the glory or something, hence why you are trying to answer questions directed to me. Alright, if you want to be ungenerous, let's do this.
Quoting apokrisis
Since we're talking non sequiturs, what is this "humongously" large you are speaking of? What are you comparing it to, exactly? Your shape and size of the universe is the observable universe of 46gly from earth and just to help ameliorate your understanding, the singularity - whilst it does not reference a single planck point - is a physically impossible point that we use to explain how the universe came to be. So the assumption is that the early conditions were infinitely dense at the size of 10^-28cm (with energies at 10^16 GeV) and that would mean that anything larger or smaller would blow the universe apart or suck it away.
Quoting apokrisis
What? First of all, inflation is pushing omega to 1 and the asymptotic curvature would therefore be flattened by the expansion, thus the curvature would equal 0 or at least be very close to 0 and this would cause infinite expansion. The symmetry between these points is explained by fluctuations in the anisotropy of the cosmic microwave background and so the universe is isotropic and homogenous; the best way to explain thermal equilibrium (actually the only as far as I know) is inflation.
My goodness. Is that what it is about? Hilarious.
Quoting TimeLine
Who mentioned singularities? I didn’t. And what is the relevance of a length scale 100,000x the Planck length? I’m not following you at all. This is another series of irrelevancies.
Quoting TimeLine
Inflation doesn’t have to balance the kinetics of its expansion with its gravitational attraction. So an Omega balance is irrelevant. Inflation is about a scalar field that stays the same energy density while expanding exponentially. Repulsion dominates and gravity is simply impotent.
You are mixing up quite different things.
To speak in your language, I mention singularities. Let's return back to the problem, shall we. What is this "humongously" large you are speaking of? What are you comparing it to, exactly?
Quoting apokrisis
Omega is irrelevant? Friedman just rolled in his grave. >:O We are talking about the universe right and all start at Einstein-de Sitter points. I already know that inflation is about the physics of scalar fields and matter, the particles that make up the universe following the initial phase of inflation are the quantum representation of Higgs fields. The problem though is not that the emergence of elementary particle masses that contains both positive and negative contributions together with a constant value at every space time point, because that is only attempting to explain quantum density fluctuations in scalar fields as a source of temperature anisotropies in CMB radiation. It ends at the de-sitter dSn point. If inflation is pushing omega to 1 with omega being the mass density divided by critical mass density, it means a universe with 0 matter density and critical mass density in the cosmological constant; the expansion of the universe is accelerating and the vacuum energy of this empty space has a mass density (which would mean that it is not actually empty). So Omega is relevant.
You are talking rubbish and I am probably one of the few people here who can see straight through you. How can a question that you are not answering be a garbled mess? This is the third time I am going to ask you:
What is this "humongously" large you are speaking of? What are you comparing it to, exactly?
You don't know, do you.
Science had no idea how things began, and it would be nice if they stopped pretending.
@apokrisis
Mommy and Daddy, please don't argue. It makes me and little Jorndoe so sad and afraid.
And now that bad @Rich man is yelling too.
I'm taking Apokrisis' side, this isn't relevant to the comment you replied to, and not least because it doesn't contain a thesis of any sort.
If you think so, then make your case properly. Don't waste my time with ill-written rambles.
Quoting TimeLine
Well in comparison to the light cone of our visible universe obviously. It has to be at least several times bigger for our own light cone to look equally thermalised in all directions. The famous cosmic background radiation.
And the original inflation story - not the one Linde is pushing that is the subject of the OP - speculated the extent of the scalar field would double every 10^-37 seconds or so. That was its exponential rate of growth. So presuming the decay of the grand unified field into the strong and electroweak fields happened at 10^-35 seconds after the birth of the universe, thus triggering the onset of inflation, followed by the further decay of the inflaton field by about 10^-32 second, then you could easily get 50 to 60 doublings into that fractional period.
So old school inflation says the visible universe is just 10^-55ish of the whole shebang. Hence the whole is "humongously larger", but not infinite, to use the technical description for that cosmic scenario.
Quoting TimeLine
You see how right from the beginning you were mangling the science. The free lunch story is that the kinetic mass of the universe nicely balances its gravitational potential. So the energy to drive expansion is matched by the energy wanting to re-collapse that expansion. However, gravity is held in suspension until the electroweak symmetry breaking releases a flood of gravitating particles via the Higgs mechanism. It is only then that the potential is actualised and collapse becomes a real issue. Mass can start to clump and unbalance the expansion.
So story one is inflation-less. You have a positive inertial expansion due to an initial energy density vs a countering negative gravitational contraction. To have then a flat outcome - a universe cruising towards the halt of a heat death at the end of time - these two tendencies have to be miraculously balanced from the first Planckian moment. And astronomical observation then found a lack of the necessary mass vs gravity balance. There wasn't enough mass to achieve the necessary amount of gravitational braking we could observe in a universe that looks as flat as it does. So Houston, we had a problem.
Then came inflation theory. Even with a perfect initial balance, there would still be the inevitable inhomogeneities of mass density due to quantum fluctuation. Something further had to kick in soon after the Planck scale birth to stretch the universe so big and flat it couldn't immediately collapse due to that.
On top of all that, dark energy was then discovered. That looks like a remnant inflation field - a faint continuing extra acceleration laid over the top of an under-weighted inertial expansion due to a "too thin" initial mass density. So some kind of inflation still rescues the general "Omega" picture of a perfect balance between the positive energy of inertial expansion and the negative energy of gravitational collapse. Counter-intuitively perhaps, the faint dark energy repulsion counts as a pervasive presence of an energy of pressure. And as energy has gravity, the missing gravitational braking could now be supplied to achieve a flat balance and arrive back at where we need things to be.
So you have managed to smoosh at least three separate cosmological stories into one garbled paragraph.
And luckily I'm one of the few people here who can see straight through that. :)
Quoting TimeLine
Inflation doesn't push omega anywhere. It washes out the early fluctuations that would have destabilised the show. So the problem is that overall, on average, the Big Bang could have had a perfect flat balance of omega = 1, but quantum fluctuations would have made it grainy. So it would have been unstable due to inhomogeneity. You need inflation just to deal with that separate problem.
Your own citation says this - carefully distinguishing between omega(m) and omega(lambda), or the critical density of the mass contents and the critical density of the dark energy:
Poor me. I have BB disagreeing with me. :-d
This is odd. It also explains nothing. It is all well and good that observable fluctuations and perturbations in scalar fields in the CMB radiation can explain the isotropy and homogeneity along with the massive size, as well as the expansion of the universe as accelerating, you stated that the initial region that "banged" was already massive. Going back 13 to 14 billion years, this makes no sense. If the universe was large and infinitely dense, you are merely comparing the size or shape to the observable universe.
As I have already said, I appreciate Guth' suggestion that the early conditions were about the size of 10^-28cm - the size of a marble - and with energy at 10^16 GeV the scalar field in this false vacuum state dominates the total mass-energy density enabling the volume to expand at a constant; the negative pressure enables it to grow exponentially and no energy is actually needed, or at least the energy of empty space (dark energy) and something we still have no clue as to what it is. In a fraction of a moment, the universe expanded at the speed of light, actually probably faster than light because there are no limitations to how far the universe can expand according to GR. Then the repulsive gravity begins to decay at 10^-33 seconds after the big bang and we get what we have now in the observable universe.
Quoting apokrisis
I get that inflation is the physics of matter and scalar fields and that the particles that make universe from initial conditions to the big bang is in the Higgs fields, but these separate suggestions are intentionally fused to help ascertain a number of other factors that have - like the flatness problem - but also have not yet been raised in this discussion; as mentioned earlier, the second law of thermodynamics and the arrow of time, the low-entropy early conditions, cosmological parameters and these problems in inflation also need to be considered, hence the fusion and I believe that I have already made it clear that I appreciate Guth.
Quoting apokrisis
From my understanding, it does; when you consider the effect of the cosmological constant as it explains the rate of expansion with time, particles that make up the universe following inflation are merely the quantum explanation of a Non-Zero Higgs field that forms elementary particle masses; it has positive and negative contributions at a constant at every space time point, which would mean that omega would equal to omega(m) + omega (lambda) as it explains the rate of expansion with time. I get what you mean, but there is no distinction.
What is it with your bad writing? Every sentence lacks logical argumentative structure. It's all a garble of buzzwords and not a proper response.
How do the fluctuations and perturbations in scalar fields in the CMB radiation "explain" the isotropy and homogeneity, and the massive size?
It is the fluctuations of the CMB we observe. Any scalar field responsible for inflation is then imputed via theory.
And it is the isotropy of the CMB we observe, thus making homogeneity a reasonable belief. And likewise, the massive size (much bigger than just the visible universe) a reasonable belief.
Likewise, how do the fluctuations themselves "explain" dark energy? The original observations that spoke to a cosmological constant were of surprising supernovae redshifts. It took another theoretical mechanism - the Sachs-Wolfe effect - to then "see" a background acceleration in the CMB data.
So you are name-checking familiar bits of the cosmological puzzle. But that's it. There isn't the logical connections that would show you understood how these bits of the puzzle slot together.
Quoting TimeLine
It is you who continue to fail to make a coherent response.
First, I stated that the initial region in the original inflationary story was very small. There was a pre-inflationary phase that lasted from the first Big Bang event - the symmetry-breaking that split gravity from a vanilla GUT force. Then this GUT force broke down into the strong and electroweak force an instant later, starting the inflationary period - according to the standard mainstream telling of this form of inflation.
So the usual tale is that the inflaton field was some kind of initial quantum fluctuation - about a teaspoon of matter. And then inflation was an exponential doubling in size of this field, without any dilution of energy density. It is quite easy to fit 50 to 60 e-doublings between the likely times for the GUT symmetry breaking and the next symmetry breaking - the Higgs/EW one - where inflation must have come to its end. Hence we can compare our visible universe region to the total inflationary expanse by counting up the number of supposed e-doublings. That gives us a 55 orders of magnitude difference. Plenty to do what inflation is meant to do in terms of the obseverable degree of isotropy and homogeneity in the CMB.
And all this is just what any popular science book on inflationary cosmology will tell you.
That you say: "This is odd. It also explains nothing," shows you have a flakey grasp of the cosmological arguments being made.
Quoting TimeLine
It is your sentences that make no sense.
What size do you think the observable universe was relative to the inflated universe back then just after inflation ended and recombination got visibility itself started?
If you could write proper sentences, then it would be clear what you think should be compared to what. You wouldn't rely on ambiguity to make it sound as if you had some valid criticism of my account.
Well that is just your first paragraph. And it continues the pattern of being so garbled that it is a huge waste of time untangling your out-pourings for you.
Quoting TimeLine
Are you implying I argued something fundamentally at odds with this? Again, you are sticking in a lump of text that does not contest what I said, and doesn't explain what you think you might be criticising when you accuse me of "This is odd. It also explains nothing."
Quoting TimeLine
Wow. What a dog-turd of a sentence.
OK. So there is a flatness problem - from observation we see the universe is as flat as possible. And there doesn't seem enough gravitating mass to brake an exploding big bang with such exact precision.
Another part of the flatness problem is that the density of any gravitating mass looks evenly thermalised. The universe in one direction looks the same as the universe in the other. And if we believe in the Big Bang, that raises a further issue of how our neighbouring regions could be thermally the same having never shared the same lightcone. We need a mechanism that explains that.
So two big problems. And inflation would help explain both.
You smoosh everything together, killing the logical story science wants to tell. You ought to be making it clear that you appreciate the parts of the puzzle when you write your replies. Otherwise there is no possibility of you making some actual counter-argument or criticism of the science as I explained it.
Your throwing in the arrow of time, entropy, cosmological parameters, etc, is just adding to the confusion you have already created.
More buzzwords that are irrelevant to any thread of argument you might be trying to sustain in your mystifying attack on me. If you think I should have added something further on these issues to explain the cosmology, then pin-point the difference they make. Otherwise it just seems you are trying to sound impressive by name-checking every damn buzzword you can think of. A childish rhetorical tactic.
Quoting TimeLine
No, you really don't get what even your own citation is saying if you believe that a distinction between omega(m) and omega (lambda) is not in fact a distinction mentioned for good reason.
And given that the simplistic focus of your attacks on me became about this issue of a "humongously larger" inflationary universe, how is this even relevant to that?
You are now conflating the issue of the late dark energy dominated era of the Cosmos with the brief inflationary event hypothesised to better explain its first moments.
Now I find it very reasonable that if there were inflation (a big if), then it is very appealing that dark energy may turn out to be a remnant effect of some kind. So future science may establish a connection.
But here, in your replies, you don't even seem to realise how your mind skips from one thing to the next without paying proper care to the distinctions involved.
You shit out another dog-turd of a sentence that is so scrambled that it can have no possible bearing on whatever it was that I was saying. It makes no definite argumentative point. And that has been the pattern of your every response so far.
Sorry to be blunt. But that's what you get for being blunt, isn't it?
Here, read. Now, I could turn around and say something like just because you go over the heads of others, doesn't mean you know what you are talking about or screaming like a little baby boy doesn't actually suddenly make you right but I am going to ask you once and once only, speak and question properly. If you do not understand something, it is you that has the problem and because you know a bit of physics, your attitude is nevertheless ungenerous.
Quoting apokrisis
I know. That is what I said.
Quoting TimeLine
Why do you repeat what I say and then scream that you don't understand?
Quoting apokrisis
What? I think you should probably take your own advice.
When you are so deep in a hole, stop digging. You've just cited a paper that is hypothesising about a non-inflationary scalar field that might explain some other issue - the dominance of matter over anti-matter after recombination.
So this scalar field would be a condensate that produces right-handed sneutrinos. It would be carried along for the ride like all other particle fields during inflation - inflation being produced by a different imagined scalar field that Guth dubbed the inflaton. https://en.wikipedia.org/wiki/Inflaton
The logic is the same as I outlined of course. And it is weird that you seem to want to continue to want to challenge that logic in some obscure fashion.
The logic is that observation shows that we have a problem and that then sets up the search for a mechanism that can fix it.
So the isotropic state of the CMB was a puzzling observation. Guth proposed a scalar field with a special property - some kind of repulsive spacetime expanding phase before it decays - as the possible solution.
Likewise, the paper you cited starts with the matter asymmetry problem. It is observed there is matter in the universe and so something is needed to explain how that asymmetry arose. Again, a scalar field - this time a more standard particle one - is being proposed as the get out jail card.
The paper makes this distinction in its first paragraph. It would have been impossible for you to miss it.
So because the inflaton can't explain the matter~antimatter asymmetry, something else after inflation would have to be the mechanism. Some particular particle condensate with a right-handedness that broke during recombination.
If you still think that your citation is any kind of argument against something I said - in particular, that observation of a problem is the reason we impute some scalar field as a mechanism - then you will have to explain yourself further.
Quoting TimeLine
And here you go with your usual hyperbolic attack as soon as you encounter the slightest pushback on your posts. But I'm sorry. You are giving me no reason to think you understand the issues in question.
The paper you just cited to "prove your case", again proves mine. And you can use your moderator position to hound me all you like. I'm not going to pretend you are correct about things when you aren't.
Quoting TimeLine
Remember that you decided to focus on my use of the term "humongously large". You were asking relative to what? I answered several times. Obviously the comparison was between the size of the visible universe at the end of inflation compared to the inflated whole.
So do you accept that as correct now? If so, why are you trying to pretend I was agreeing with something you said?
I know. That is what I said. That is, again, you agreeing with me by pretending that I am wrong and then re-phrasing what I said.
The problem is not that, Apokrisis, the problem is that you are intentionally and incorrectly misunderstanding my comments and then responding to an article I have given you by implying I meant something that I did not mean. It is impossible having this discussion with you because - from the get-go - you seem fixed on this notion that I am actually attacking you. I'm not. I am interested in what you have to say, but your behaviour and your responses have only made me lose my respect for you completely and I am confident that the reasoning behind that behaviour is because you are uncomfortable with my presence.
Attacking people as stupid or incomprehensible does not make you right; the louder one screams only makes other people quiet as an attempt to overpower them.
Quoting apokrisis
Indeed, and you went on a torrent of abuse because I sought an explanation, and an explanation you still have not given.
I’ve given you an explanation several times now. So you will have to explain what your problem with it is. Otherwise you are simply trolling.
Quoting TimeLine
Well explain how that cite meant anything.
How can I have intentionally misunderstand your comment “Here, read.” Clearly I understood. I read.
But what the hell do you think baryon asymmetry has to do with inflation? I’ve asked you to explain. Clearly having stuffed up again, you won’t. You will just huff about with wounded pride and pretend you have been done some dreadful wrong.
Quoting TimeLine
Uncomfortable with your presence? You have a vivid fantasy life apparently.
It is as simple as the fact that first you baffled me with your non sequiturs, and then you annoyed me with your strangulated prose, and finally I am tiring of your self-pitying tone.
I’ve asked you for a number of explanations. They have not been forthcoming. I’m not holding my breath.
Quoting apokrisis
This is your explanation:
Quoting apokrisis
How does that explain the problem? The "bang" of the big bang?
Quoting apokrisis
As I said, it is you that has no clue what he is talking about.
I was answering the question of how an inflationary universe could be considered large yet not infinite.
So again you are speaking in non sequiturs. Who was talking about the problem of the bang of the Big Bang? Where are you getting this latest misrepresentation from and what could it even mean?
Quoting TimeLine
If you believe that statement is wrong, provide a refutation with citations.
The whole scientific cosmology needs to discarded. It is fundamentally flawed because it was constructed with the sole purpose of proving a pre-ordained goal, i.e. that the Universe can come into being without resorting to anything but particles, which as it happens, no longer exist in physics. Hence a mess of construction and deconstruction, similar to modern culinary fads.
Hey, Baden. Rich is being bad again. I think his constant barging in to harass constitutes violence.
Apparently you are quite comfortable with non-stop ad hominem, but any commentary on the mythical basis of modern cosmology is totally verboten. The Emperor has Clothes!?
This thread is evidence of the mess that current scientific cosmology had found itself in. It speaks for itself and should be read and reread for all that it reveals.
And don't bother sending me any private messages. They are unwanted.
I should have used :-}. There is an infuriating thread going on called "Is Calling A Trans Woman A Man (Or Vice Versa) A Form Of Violence?" I was making a reference to that. I was trying to tease you and failed.
@TimeLine
I don't want to restart the battle, but I'd like to know how much of what you've discussed is at least theoretically verifiable either through direct observation or extrapolation from what we can observe. In particular, the existence of other universes within the possibly infinite universe. It has been my understanding that this particular version of the multiverse is unverifiable, thus meaningless.
Any argument based on inflation is speculative metaphysics. But it might be worth stepping back to think about how science can even operate at the limit of the observable.
You will never be able to experiment in some direct controlled and repeatable way - the gold standard - when it comes to investigating the origins of the Cosmos. That's obvious. Your apparatus to make measurements that could replicate the energies involved would turn into plasma, or collapse into blackholes, themselves.
So the only course is to identify the most fundamental constraints on any possible theory - like the fact the universe looks almost perfectly flat and thermalised from the beginning. And then you can search for a mathematical mechanism that would predict such an outcome.
Maybe that mathematics will just pop out of pure mathematical considerations themselves - like the permutation symmetries that have been so successful at predicting the fundamental particles.
Or else the maths will come from other physics internal to Universe - the kind of physics of mechanisms we can confirm via laboratory experiments, such as the kind of mechanisms that explain condense matter structures, or whatever.
So all we can hope to do is work our way towards the most fundamental known constraints on a final theory. And then make some judgement about which mathematical model best makes predictions that manage to fall within the bounds of that set of constraints.
So of course any final theory is "unverifiable" if we are insisting on some scientific method so strict that we know it could never be applied. But we can still be scientifically systematic in a way that respects the rules of some epistemically well-grounded game.
And exactly what the rules ought to be is a matter of loud argument in science. As it should be.
Inflation theory is an example of where the ease of producing mathematical models has fuelled an academic industry. Unconstrained imagination has been allowed to run riot to build CVs. Whereas really the fecundity of inflation as a research topic ought perhaps be sounding the alarm bells.
Hence we are now seeing the same kind of pushback that string theory got four or five years ago - http://backreaction.blogspot.co.nz/2017/10/is-inflationary-universe-scientific.html
And multiverse thinking is this issue on steroids.
As I say, what is happening is we are trying to paint the final theory into a corner. We are using what we know about the universe at an observable scale to narrow down a space of possibilities. Then in that corner, we explore all the mathematical structures that can fit into its tight space.
Yet it is a generic fact that every time we seem to trap a very particular kind of mathematics in the corner, it turns out to have unbounded fecundity. The same equations can still spit out an unlimited variety of alternative universes even if they seem to have only a few free variables to play with.
This is what happened with string theory. As the maths was perfected, it sprang a leak. It could generate a "practically infinite landscape" of alternative physical realities.
My view is that this shows the maths itself has a problem. We aren't good at modelling self-constraining systems. That is something that has only got going as a field of research this past 40 years. So we can't build models in which the constraints themselves emerge to rein in the very infinities that the maths will otherwise, in unconstrained fashion, generate.
After string theory, many expected loop quantum gravity to do just that. It has tried to apply a condensed matter mindset to the problem. But that also splintered into a great variety of possible mechanisms and as yet no breakthrough is being celebrated. Strings are even back in fashion.
So my answer is that inflation theory has the problem that it can sort of still be tested. For instance, better resolution of the CMB might detect the gravity waves that some inflation theories predict. Yet it is fundamentally a free parameter model. The "inflaton scalar field" is extreme hand-waving with no direct evidence. So if one version of inflation is falsified - we find no gravity ripples - the knobs of the basic model can be twiddled to predict that outcome too.
Inflation is not unverifiable and therefore meaningless. It just reflects the fact that we can paint the mathematical possibilities into a corner - which would be meaningful science - and yet maths tends to still have unbounded fecundity even when trapped in apparently the tightest physical spot.
So more attention has to be directed at this epistemic issue. Science ought to be favouring mathematical models that can predict their own emergent constraints, not just stay within some set of observable constraints while spewing out a vast variety of alternatives from within that confined space.
It's like the little boy exclaiming the emperor wears no clothes. Except this little boy is standing so far at the back of a tall crowd he sees nothing really. He just enjoys the sound of what he says.
I would not say meaningless. The study of cosmology itself deals with the universe at an extremely large-scale and so it is constrained by observable parameters where we rely on probabilistic or statistical models to predict possibilities. When we learn about those constraints, numerical variations or simulations can be methodically applied to enhance the accuracy of the formulations. We are taking steps toward understanding length scales or scalar quantum fields by formulating quantum theories that unify general relativity with length at a much larger scale and inflationary theory - particularly by Guth - has had some predictions verified and with an accuracy that legitimise the possibilities much more than say string theory or M-brane theory. Einstein' cosmological constant, for instance, is used in the equations that allow us to understand how gravitational fields can carry negative potential energy and as I was discussing earlier, verifies the parameters between mass density and critical mass density ? that make spacetime homogenous and isotropic. The observational findings from WMAP have shown data that verifies some aspects to inflationary cosmology and so it is about piecing pieces together.
As we continue the attempt to verify the components and geometry of the universe, we discover and learn like the recent gravitational waves that is an interesting leap in the right direction, although with LIGO is really about the verification of general relativity. So, there is Newtonian physics where gravity is a force that directs space, general relativity understands gravity as a field within 'space-time' and this field can be curved by mass; these gravitational fields are curved by planets and stars, for instance, but nevertheless locked into this geometry where space and time reacts by directing how matter should respond.
BICEP2 is also searching for these waves, but unlike LIGO where these interferometers have detected gravitational waves from collisions between black holes or pulsars over a billion years ago, BICEP2 is attempting to detect signatures left by gravitational waves much older than that (very early universe, around 14 billion years ago) by studying the light from the CMB, because if inflation happened there would be similar gravitational waves left from quantum fluctations that distribute a very particular kind of light-wave across the universe. While the initial findings were actually contaminated by space dust and other things, the problem is really the limitations of our equipment and not the inaccuracy of the equations. These waves are primordial imprints and so detection is extremely difficult, but verification of these predictions or the conditions of the universe are certainly on its way.