Help me out here. The very shape - hypersphere - determines the Hubble Constant. That is an increase in radius expands space almost exactly as determined by observation of real astronomy. That is, just the mathematics of a hypersphere (no observation taken - just sums - the geometric property of a hypersphere). It's an obvious fact. An expanding hypersphere calculation gives our observed Hubble Constant.When we observe and measure distance from a curve surface, there is a limit to it and we call that limit the horizon.
But if you flatten that surface, the horizon retreats and disappears. It would appear as a straight line while retreating.
Can we detect a horizon out there? If we are in a hyper-sphere, we would have TWO horizons. Both horizons would appear as straight lines. With stars in between them.
But we don't see that. If space is expending, it's not curved.
I've always assumed, for a cyclical model, that one must extrapolate closer to t=0 than physics currently can address, hence outside the BBT, which is constrained by physics. It's metaphysics that seeks an oscillation point or moment.Helio, I just don't seem to be able to get across to you the concept that the backward extrapolation of the universe's apparent expansion does NOT have to go all the way back to some origin point in order to have an oscillation.
Ok. So if something weird like the universe is found to be contracting, then a cyclical model would make sense, perhaps? What test can we do to argue it will cycle even if this is true? Of course, if acceleration is confirmed, perhaps it is by now, then only a clear understanding of DE, and one that reveals it will diminish in time where gravity overcomes it to allow complete contraction, then perhaps the cyclical model will be more plausible. But a scientific theory requires more than supposition.The concept I am trying to get you to understand is that the actual conditions might depart from that backward extrapolation and even reverse while the universe is still quite large. It all depends on what you do with the free parameters in the equations.
The BBT more likely started with something other than a singularity, but who knows. If science discovers something, as mentioned above with DE, and the cosmos will contract, then that would be incorporated in BBT, similar to Inflation theory. All known phenomena end up in some theory. If a new phenomena falsifies a theory, then a new theory will be required, but the new one will be required to address all the already known phenomena as well or better than BBT. This is not likely, but I hope it's true.Perhaps you are saying that anything that does not go back to almost a single point in space is not "the BBT", and that therefore, any modification that reverses things before getting there is not "the BBT", but rather something else?
Actually it was never a "bang". It became such thanks to an opponent to it, Fred Hoyle, who was using a pejorative (w/ sizzle ) to diminish its worth, thus helping him argue his model (Steady State).If it doesn't have a "bang", then it isn't the BBT? But, "BBT" is just slang for the "Lambda-Cold-Dark-Matter" theory, and all I am doing is showing you that another formulation for Lambda could produce an oscillating universe, rather than a bang from almost a single point in space.
Agreed. But I'm trying to note to all that this is supposition, failing to meet the requirements of a hypothesis or theory. There needs to be evidence of oscillation and a way to test any claim. That may seem unfair for something as important as a cyclical model, but it doesn't prevent one from introducing ideas for it, similar to the views for a multiverse, which has a tiny bit of evidence for it, according to one author --- the cold spot in the CMBR.I am NOT saying that the universe must have oscillated, or that I have a theory that shows that it oscillates. I am just saying that an LCDM theory does not necessarily require that there were not and could never be any oscillations of the universe. The universe we observe now could simply be in an expansion part of an oscillation with a very long period - conceptually and "mathematically" in so far as the parameters of the LCDM model are really "known" from observations.
A better name would be nice, but whatever label we give it, it must be scientific and one that explains all the many observations. BBT does this so far.Calling it the "Big Bang Theory" seems to have blocked thinking about a lot of potential solutions.
Helio, I just don't seem to be able to get across to you the concept that the backward extrapolation of the universe's apparent expansion does NOT have to go all the way back to some origin point in order to have an oscillation. The concept I am trying to get you to understand is that the actual conditions might depart from that backward extrapolation and even reverse while the universe is still quite large. It all depends on what you do with the free parameters in the equations.
Perhaps you are saying that anything that does not go back to almost a single point in space is not "the BBT", and that therefore, any modification that reverses things before getting there is not "the BBT", but rather something else? If it doesn't have a "bang", then it isn't the BBT? But, "BBT" is just slang for the "Lambda-Cold-Dark-Matter" theory, and all I am doing is showing you that another formulation for Lambda could produce an oscillating universe, rather than a bang from almost a single point in space.
If that is what you are saying, then please consider that it is the name, not the math or physics, that we are arguing about.
Apart from one error you achieved a successful description of a hypersphere. The error you made was to state: ""You seem to understand that the "hypersphere" is a 4-dimensional version of a 3-D sphere, with the 4th dimension being experienced by us as "time"".Gibsense, I'm not understanding what you want help in understanding.
You seem to understand that the "hypersphere" is a 4-dimensional version of a 3-D sphere, with the 4th dimension being experienced by us as "time". As time goes on, it is like increasing the radius of the 3-D sphere so all of the x,y,z coordinates seem to be increasing in scale size in unison, like stretching a 2-D spherical surface, except that it is 3 dimensions.
The "horizon" issue is that we see light from things that are on the same surface as us getting stretched before it gets to us along the the surface as it has been expanding. SO, it started at a smaller time radius, and as it traveled along the expanding surface it gets stretched before reaching us.
That concept gets somewhat difficult to use for all considerations. Such as: on a 2-D spherical surface imbedded in a 3-D space, the circumference is 2 pi times the radius, and you would end up going around in circles if you follow a circumference far enough. That tends to suggest that in a 3-D hypersphere space imbedded in a 4-D space/time, there should be x,y,z space folding back on itself, that is, "curvature". But, we don't seem to be able to detect any curvature to real space/time. Maybe the radius is just too large for our measuring instruments to see. For one thing, light emitted far enough away never gets to us because it is traveling more slowly than the distance between it and us is increasing faster than the speed of light. In that sense, it is analogous to being "over the horizon" in time. But, it really isn't a perfect analogy.
I apologise. The "help me out" was in frustration that no one was prepared to comment on the fact that the Hubble Constant is predictable via simple geometry.Sorry, Gibsense - you said "help me out" and that is what I was trying to do with the description of the hypersphere as most of us think about it. With over 130 posts to this thread, I seem to have lost your description of what you think the hypersphere "really" is. Apparently, it is different, and apparently, you really don't want/need help in understanding how you think about it. Unless you have a concise description of your version, I have no way to proceed with a discussion of your concept.
But do you see that one is spawned from a given phenomenon, and the other is not? The other being spawned in the realm of cool ideas, but w/o any supporting evidence. Or am I missing something?Helio, I think you do get the concept. My point is that we really do not know how DE behaves with time (or other variables). So, just assuming that it is a constant or a monotonically changing variable is not really any different than assuming it is an oscillating function - it is all assumption at this point in our understanding.
Yes, but acceleration is observable and testable. Undoubtedly, more research will tweak the current acceleration rate. More observations of the Lyman-Alpha Forest will tweak the rates for earlier periods. All this will naturally tweak the BBT since it is based on GR, which is based on mass-energy.Thus, the prediction that the universe will expand forever is really just an assumption, based on the assumptions chosen for the current version of the LCDM theory. You can get a different prediction by choosing a different assumption for DE behavior over time
Agreed, but reason alone is not science. As she said, "Where's the beef?". FWIW, pushing past reason is something else, as well. "The heart has its reasons that reason cannot know." Blaise Pascal.Regarding the physics that would determine when an expansion/contraction reversal might occur, I do not see any reason why it would not be conceivable before the universe's radius was below the Planck value.
I know this sounds picky, but it doesn't hurt to mention that some people will conflate "belief" with objective evidence for it. Usually belief involves hope or faith, which is anathema to hard evidence found for a given scientific claim. I've heard some say we exercise faith whenever we sit in a chair, but I disagree since a simple FBD and a materials' handbook will negate the need for hope or faith in this circumstance.We already believe that gravity can crunch matter into a ball of neutrons, and some believe into a ball of quarks, before it even gets to black hole conditions.
Yes. You would enjoy reading about the early debates between Bohr, Heisenberg, Schrodinger, Einstein, etc. that happened during the same time period as Lemaitre's BB introductions.As an aside, I have a hard time with the concept of entropy not including the natural development of order in subatomic particles and atoms as they condense from what is postulated to have been pure energy. If everything really is just "waves" in "fields", why would those waves organize themselves into discrete quanta at all, and then build up such intricate organization as the chemistry and life we now experience? Seems extremely non-random to me.
I don't understand why this isn't obvious to all, since one view is science, and the other view is metaphysics. And it's not just GR that "struggles" with events prior to Inflation, or worse, the time prior to the first Planck unit of time, it's more a problem for both quantum mechanics and GR. But, on the other hand, they don't really struggle since neither go there, at least until they find a way to get there. You're asking snorkel divers to dive a thousand feet deep; they can't, and in this analogy, knowing what lies 1000 feet deep can only be found by the only means of getting there -- snorkeling. There is no means known to get us to, say, 1E-35 sec. Math is all we have for now, but Inflation theory does allow tests for it, but more in principle than our current technology will allow, AFAIK.Helio,
You seem to think that seeing expansion now and extrapolating all the way back to a single point (or almost a single point) is somehow better "science" (even though it involves postulating "inflation" as a way of overcoming Relativity Theory ramifications of that postulate), compared to thinking that the expansion many not be extrapolatable all the way back to a point (or almost a point) because Relativity theory alone would then not let it expand to what we observe today.
Right, I too have been saying this. Inflation theory is just one theory for what may have happened. It is carried forward in publications only because it is a surprisingly brilliant approach to explain the degree of isotropy, for instance. No doubt, many scientists will see it as ad hoc for the very reason you state; it lacks testability, so far. But, this is no cause to diminish the tenets of BBT, which explains so much of the universe after t=1E-12 sec, as confirmed by CERN.I do think that GRT is probably somewhat incomplete, but I don't agree that there is "testable" evidence of inflation.
Yet, most scientists, IMO, recognize the importance to Inflation Theory -- there are many versions, BTW -- as a fair possibility for what happened. They aren't going to toss their baby (BBT) with the bath water (no understanding of the initial conditions on or before the first Plance unit of time.).That is different from space "expansion" and "acceleration" as we currently measure with astronomy observations. Even the CMBR is so far removed from the postulated inflation that it does not really support it other than it seems to have come from a phase change of the matter in space. But, even that might not be the correct interpretation.
What part of BBT do you consider isn't science? It's improper to force any scientific theory to be contorted and stretched into regions where no science is capable of going. If a model does a fantastic job of explaining phenomena, then why wouldn't science support it, especially when no falsifications have come its way.I get annoyed with people continuing to claim that the BBT is "science" and that other considerations and concepts are not "science".
So, of which of the BBT lines of evidence found in the Big Bang Bullets do you see a red flag? When Einstein was given a paper of 100 prominent German and Austrian signers stating his General Relativity theory was wrong, Einstein simply said, "Why one hundred when only one is needed?"As a person who has considerable experience reviewing models of physical phenomena, I see a lot of red flags in the BBT.
Your opinion of what is overstated and what is not is opinion, not science. You need to produce objective evidence to support or diminish any given model.Hence, I object to people overstating the level of confidence that the BBT warrants in predicting the future or explaining the past. And, that type of objection, based on logic and fact IS SCIENCE.
Yes, because this is the time that correlates to all the objective evidence found from the results from CERN, at least according to one author. It's all over my head, admittedly.Helio, I am just going to stop trying to make the point that you keep ignoring. You insist on extrapolation of the observed expansion backward to something like 10^-12 second and a very tiny size.
Ok, what are your "lots of reasons"?My point is that there are lots of reasons to suspect that it was never that small,...
No. Inflation, as I have read about, only lasted for a trillionth of trillionth of a trillionth of a second. One author said this much, much, faster than light expansion rate brought the universe to the size of about a grapefruit. BBT modeling begins shortly after this since objective evidence currently does not exist...yet....particularly that it then requires something being called "inflation" to get large enough to expand into what we see today, because GRT would alone would not do that.
Nope. CERN results are not imagination. The CMBR was a prediction of BBT, where the expansion would cool to a point for Recombination to take place. Thus, there really is no argument or any real imagination to assume the universe was smaller since this was a prerequisite for the CMBR.The point you keep ignoring is that it doesn't take any more imagination to have the backward extrapolation of the expansion stop at a much larger universe, for some currently unknown reason, compared to the imagination that is required to invoke some unknown force called "inflation". Choosing inflation and calling every other possibility "non-science" is NOT THE SCIENTIFIC METHOD - it is political rhetoric.
There you go again, demanding "proofs" of science. You still don't understand that scientific theories never present truths or proofs. A theory, however, can be proven wrong, which is just another way of saying it's falsified. Sometimes models can be tweaked to get it out of a bar ditch, but sometimes it must be tossed-out completely, as the Chruch (Jesuits) did when Galileo proved (falsified) the Aristotle/Ptolemy/Thomist model with his discovery of the multiple phases of Venus (and later Mercury).And CERN had definitely not proven anything about what happened in the universe in the past.
Why are you forcing conditions on CERN that can't be tested? CERN is far from being able to test the phase events that may, or may not, have occurred "long" before t=1E-12s. Perhaps you have a different Inflation model in mind than the this, more original (Gamow), common one?All CERN has done is produce the same effects on subatomic particles as would be experienced at extremely high pressures and temperatures. That doesn't "prove" "inflation" at all.
Yesh! BBT is all about the universe being smaller in the past, large in the future (i.e. expansion). When the Universe was smaller, of course, it was necessarily hotter, per the theory. Physics is able to present a lot of information of what that would look like in the past as things were hotter and hotter. But, it has limits. Those limits, if we go beyond them, take us into metaphysics, or pseudoscience. BBT is not a metaphysics theory in spite of your incalcitrant efforts to make it so.It has only allowed quantum theorists to cobble together a partial theory about what MIGHT have happened if the universe ever was so tiny. And, it might apply to whatever is happening inside the event horizons of black holes.
Sorry, more metaphysics. The matter-antimatter proposed event is prior to 1E-12sec, right?But, that theory has some major holes, such as where is the antimatter.
Right. But you are looking for truth, which no theory is capable of revealing, IMO. A theory, as stated before, can't even be proven. The most accepted theory is the one that best explains phenomena. BBT does that well, unless it gets kicked into areas it can say nothing, such as a singularity moment.And, even if it is possible, physically, it is still just a theory (or maybe just a hypothesis) that it is what really happened.
Right, you are quoting me.It is not "unscientific" to question the theory. it is actually a scientific RESPONSIBILITY.
As I said, I am done here. There is no objectivity in the responses, just rhetoric. Others can make their own decisions after reading what we have both already posted.No. Inflation, as I have read about, only lasted for a trillionth of trillionth of a trillionth of a second. One author said this much, much, faster than light expansion rate brought the universe to the size of about a grapefruit. BBT modeling begins shortly after this since objective evidence currently does not exist...yet.
Just read what I said. Many scientists include it due to its elegance in explaining how the isotropy would be so smooth, and the horizon so flat. I argued that they call Inflation theory a theory. It should be seen separate from other, less suppositional, elements (e.g. CMBR) because of its lack of current objective evidence. Inflation theory elegance, though compelling, is incomplete without objective evidence, directly or indirectly, or even in principle.So, now you are claiming that "inflation" is not part of the BBT?!
It is essential to the BBT - it is actually the "bang" part of the BBT!
I am surprised given our mutual respect for one another, we haven't seem to be able to nail-down exactly where we disagree. My thought is that you want to hold BBT's feet to the fire at the events that took place prior to where physics can no longer address. Is this right? Where do we differ exactly?I still am not seeing an indisputable theory from the time the observable universe is extrapolated back in time to the size of a grapefruit.
Where does GR say the universe should contract? That went out the window in 1927, blessed by Einstein in 1931. [Suppositionally, they both thought the cyclical model was a real possibility, but they knew there was nothing to base that on other than some reasoning and guessing.]It still needs to expand when GRT says it should contract. If you aren't calling it "inflation", then you are calling it "dark energy".
Agreed. But mass and energy have equivalence. These values become incorporated into BBT. The result tweaks BBT but doesn't scar it. It was certainly a surprise to discover the likely acceleration, thus forcing the view of DE as the label used for it, but there are no paradoxes in Nature, so it's up to scientists to advance their science to explain why this is so.One way or the other, you have a theory that relies on 20 times more mass and energy than we have any explanations for.
This question belongs to those who are working on TOE. Such energy levels, AFAIK, are well outside the limits of CERN, so why would BBT be capable of explaining how that may, or may not, have happened. It hardly changes what we do know about BBT, right? Shall I list those bullets? BBT explains the observed phenomena. You seem convinced it must explain unobserved phenomena.Worse, the BBT (maybe not your version) does not know why there is not as much antimatter as there is matter, so, assuming the same amount of known energy types associated with antimatter, there is another 5% of the BBT that is missing in observations.
I know you're scientific, but you are mistaken when you imply that BBT is not robust because it doesn't answer the metaphysical questions that have arisen and also can't be tested within the realm of today's science. How is that fair for any theory?It is annoying that you call me "unscientific" when I question a theory that has so many holes it.
That's not what I've seen in your posts. Those "assumptions", as I try to note aren't observable. This may make it weaker in your view, but you mustn't ignore all the phenomena that it addresses robustly, and after thousands of tests, it is more robust than ever. It also helps allow the many suppositions, like antimatter-matter events. Though science does know something about matter and antimatter, the event you are mentioning is still outside the known laws of physics, at least for now.If you simply can't conceive of anything other than your version of the theory, then you are the one who is not being "scientific". All I have done is try to point out what are assumptions, vs observations.