Did the "Shock-Wave" of Inflation expand faster than the speed of light?
If we first assume the universe started with a Big Bang, then there should have been a shock-wave extending out from the center. Science tells us that the shock-wave could not move faster than the speed of light. Did it?
Comments (65)
I think the shock wave you are talking about is space. As for travelling faster than the speed of light - the universe is about 14 billion years old while the diameter of the universe is about 90 billion light years. It is generally explained that movement associated with expansion of space doesn't count in the light speed calculation. I've never gotten that, but who am I to argue with Einstein?
If it was space before the big bang, and space after the big bang - then what changed? Plus, light still only travels at a defined velocity in space. Then did light travel faster before the big bang?
Not electromagnetic radiation.
There was no space before the big bang. As for the speed of light, I already explained as much as I know. And there was no light before the big bang.
I could live with that. It reminds me of a hypothesis I have:
When I go out on a moonless night and look up into a star-studded blackness, I intuitively know there is a metric shit-ton of light headed my way that I cannot yet see. It’s not that this light has yet to be generated. No, it was generated all right. It just hasn’t got here yet, unlike all the light that I do see, itself having left its star-point of origin so many lightyears ago.
It’s also not that it is the light to arrive shortly, from the same source as, but trailing behind the light arriving now, from a star or whatever. No, the unseen light was already generated from another source (Big Bang?) than what I can see, and its on its way but not yet visible. All the visible light (stars, etc.) are just out front, like us.
Now bear with me here. Scientists have told me that energy and matter can change, one into the other. But these scientists always leave time laying over here to the side, as if it could not likewise convert into energy or matter. But I thought, what if it could?
In that case, I think this light that I cannot see, but which I feel is headed my way, is actually the future (time) in the form of Dark Energy.
I also intuitively know there is a metric shit-ton of matter flying away from me so fast that I can’t see it. It does not and cannot reflect light back to me. I think this matter is the past (time). I think it is Dark Matter.
I also think that maybe this Dark Energy (the future), is not necessarily so far away that I can’t see it yet, but that maybe Dark Energy is, at least in part, blocked from my view from the fleeing past. Maybe Dark matter gets in the way.
But where I am in the here-and-now is the conversion point, where the future arrives and converts into the past, going from Dark Energy to Dark Matter.
To the extent physicists have calculated the amount of Dark Matter in the universe, as a percentage of the whole, maybe Dark Energy, or the future, accounts for the balance of the whole. Maybe we can thus determine the amount of time, or future we have left.
Sometimes it helps my thinking to consider particles. I like the idea of particles. While they don’t, in and of themselves, preclude the possibility of strings or waves, they work well as a tool in this idea of mine.
Where matter and energy can convert, one into the other, so too time and space can be tossed in the mix and likewise convert. The future can become energy, and matter, and now, and the past. Likewise, the past can become energy, and matter, and now, and the past.
So, a star that casts off its own light, say a photon, is looking at the backside of its own photon. It can't see it go, but go it does. If that star could some how run around and get in front of its cast-off photon and look back and see it coming, it would be seeing its own past. But if it got so far in front of its own cast-off photon that the photon was not yet visible, it would be, like us, not seeing the future before it got here.
Now, lets say that photon from that star were headed toward a near miss with the Earth, and I stepped out behind it to watch it whip by, I would see coming but not going. The back side of a photon is invisible. It’s the past that might be remembered but cannot be seen. The front side of that photon is only visible when it gets here, but until then it is invisible. It is the future.
I was a Recon Team Leader in the Marine Corps and sometimes we'd blow shit up. I'd take a brick of C-4 and roll and warm it in my hands until it was a ball. I'd stick a blasting cap in it, attach a fuse and set it off. It made a big bang. I'd imagine (and sometimes I could see) a shock wave. I'd figure there was some aspects of that C-4 on the outside of the ball that would precede the aspects from the center to follow. I knew that the outside stuff would not exceed the speed of the blast, and it would indeed start to slow in advance of the inside stuff. But it was nevertheless out front and the inside stuff had to catch up.
I'm thinking if you had a singularity on it's way to Heat Death, then maybe parts of it are waiting for the other parts to catch up. And when it does! Talk about light! In sum, I think we are all in a singularity, in Heat Death, and everywhere in between, all at the same time, past, present and future. But All is perceiving all aspects of itself. However, those aspects (like us) are regulated to providing our own perspective. So, while we are all together in a singularity, there must be space for all us aspects to perceive in. So we perceive we have space to perceive in. And we do. But from the perspective of All, it's All one; i.e. a singularity. Dark Energy and Dark Matter (the future and the past) hide the singularity from us, creating the perception of space to perceive in.
The idea that the speed of light is some final arbiter of this or that seems rather limiting to me.
The thread then proceeds by choosing various instances of shock waves and discussing how the question might be answered for each.
Then we have the problem that arrises from pop physics books that are for the most part written without the mathematical structure that underpins physics. Some readers think that is all there is to physics, that it's just conjecture, and so they throw in stuff such as that time might be converted to mass without any background theorising.
In both scenarios we have bits that work and bits that are junk. Such threads serve as bad examples of philosophical thinking, and worse examples of physics.
But the thread will run for a page or two as folk compare their misinterpretations.
I'll stop throwing ideas on the wall when "your people" quit talking about all the walls they are running into. Discuss among yourselves.
The trouble with physics and philosophy is that they are quite difficult. It looks easy, but one keeps finding out that one has gone astray. It looks lie folk are just making shit up - and indeed, some are; but the critique... there's the thing. If one comes here, one will be criticised.
Bringing this back to your post, Einstein didn't just guess that energy could be turned into mass, and vice versa; it wasn't quite just shit he made up. He derived it with the calculations he found after positing that the laws of physics should be the same for all frames of reference.
It followed, mathematically, from that assumption.
Can you provide something similar for you conjecture that mass can turn into time? How do we measure mass in seconds? Weeks in kilograms?
If this bursts your bubble, then welcome to philosophy.
I'm not complaining, so it certainly wasn't my bubble that was burst. In fact, your failure to address the sophomoric shit on the wall with a dumbed-down response on the merits that simple folks can understand leads me to believe you said too much. It must be frustrating for you to be in this arena with the likes of me. I'm surprised you're not back in a lab somewhere doing real work.
I'm new to this board, but I've been fooling around with philosophy for 45 + years. I don't get paid for it but I don't find that relevant (see my definition of philosophy in the recent thread on that point). I also find that philosophy has it's own wall(s). See the recent thread on self-evidence. I begged for help from the smart people, but crickets.
Then I hear physicists struggling with their own walls (dark matter, dark energy, spooky action at a distance, etc.). In fact, one of those walls seems to run counter to the fundamental, underlying principles of logic (a branch of philosophy?). How can this be here and there at the same time? Hmmm. I guess I better break out the calculator that doesn't seem to be working.
I hear about these physics walls in public, and not "pop physics books." I make up my own shit.
Finally, I don't derive anything, because I am not Einstein, a physicist, a mathematician, or anything close. Thus, I cannot provide you with something similar for my conjecture. I can, however, provide you with conjecture. If you can't make anything out of it, or explain it to a lay person, I'm sorry. Welcome to philosophy.
But I have to ask, what were you expecting in response to a post on a philosophy forum? Of course it was going to meet criticism.
It's what we do.
Same is in the other thread, I was expecting something to do with the merits of why my idea is wrong.
Probably not. You really have to dumb things down for me.
You're dreaming. A reverie such as this is not physics. Same goes for .
You're not very good at this. You should probably stick with the smart people and leave us monkeys to throw shit on the wall. (P.S. What was Einstein's position on dreams and reverie? Just curious.)
Quoting James Riley
Thank you, I've been doing it longer than you, so perhaps you will be able to achieve better results in a few years.
ad verecundiam? Or something similar having to do with time?
Are you admitting that time converts to matter? HAHAHAHA. Sorry.
No, what I meant was, your ability to dumb things down for us simple people is wanting. Either you don't know what "the merits" means, or you are just avoiding the schooling of me on Dark Matter, Dark Energy, or, in harkening back to the other thread, self-evidence.
If eternal inflation is true, then that inflationary epoch is the normal state of the universe, which is consequently MUCH much bigger and older than the part of it we’re familiar with. The universe as we know it is just a temporary little blip in that enormously larger universe, a tiny part that very briefly slowed down at random, dumping some of that enormous inflationary energy into all the other fields that the universe as we know it is made of. And over time, this part of the greater universe is gradually speeding back up and dissolving back into the rest of it, which has still been expanding at breakneck speed this whole while.
If two things are moving at whatever speed, or not moving at all, but space is added between them at a speed faster than light, are not those two things being separated from each other at a speed faster than light? If the "space speed" is not part of "thing speed" simply because space is adding, and the things aren't contributing, is there a distinction with a relevant difference? Aren't those two things moving apart faster than the speed of light, if only by the addition of space? Thanks.
Yep. For instance, if space is expanding at a steady rate (say doubling in size every unit of time), the two objects will get farther and farther away from each other at an "accelerating" rate, but neither will experience any acceleration: both will feel like they're coasting in an inertial reference frame, and actually if you tied them together such that they had to stay the same distance apart despite the expansion of space, then they would experience an acceleration (it would feel like there was antigravity pushing away from their common center, because they're basically being accelerated toward each other, but despite that are remaining the same distance apart).
Quoting James Riley
Yes, but that doesn't violate the laws of relativity, because those laws are only about things moving through space, not about space expanding.
We can see this in practice just looking out into space: farther away things are receding away from us faster than closer things, because space is still accelerating and a multiple of a long distance is much bigger than the same multiple of a small distance, and far-enough-away things are therefore receding so fast that light from them will never reach us (because it's not fast enough to cover more space than is being created in the time it takes to cover that), and that threshold is the edge of the observable universe.
I get that conceptually, but it seems in all those examples we are concerning ourselves with how the situation is perceived, or experienced, by the objects (or someone residing on the objects) as opposed to being an outside observer. As you say, it would not violate the laws of relativity, but if the experience was observed as we are doing in this discussion, conceptually, then that relative position would see two objects moving away from each other faster than the speed of light?
Another question: If everything is flying away from everything else (or, if space is growing between), isn't the relative experience of any one of those things that of stasis? What direction could one be going from anything without going toward something? To have space grow between, wouldn't it have to be still? and everything was flying away (as in space was growing between). Now this is going to probably sound stupid, but if, in your example of looking into space, aren't we seeing the same thing if we run around to the other side of the planet and look in that different direction into space? Or from any point on Earth into space? I guess what I getting at here is this: can we or are with between two different things with space growing between us and them in opposite directions? If there are no directions, wouldn't that make us the center of the universe?
I'm going to hit the rack now, and I'll check in tomorrow, but I appreciate your taking the time to address the merits.
Unfortunately true. :sweat:
:up:
Quoting Pfhorrest
:100: :clap:
In a sense, yes.
Quoting James Riley
Everything in space would observe itself as seeming to be at rest and at the center of the expanding universe; so yes, we do too, but not because of anything special about us.
Space isn't added between galaxies. All of space is expanding so the fabric of space between galaxies is stretching. The analogy generally used is to an inflating balloon. Two marks put on the balloon with a marker will move apart just because of the expansion of the balloon. Of course, space is a three dimensional compared to the two dimensional surface of the balloon. Or is it four dimensional?
The confusion which so often results when one means to examine the expansion of the metric of space is because we conflate this, or otherwise treat it as equivalent with objects moving within its boundary at an ever broadening distance from each other, notwithstanding that such an effect is coincident as well, rather than something more intrinsic to the space itself. Which is to say, that while there exists most clearly, and as has been well-established by the available evidence, a fundamental limit to the relative pace with which any object can move, so far as it possesses a definite mass, and indeed, even for those objects which are regarded as massless, and with the required energy-expenditure needed to maintain its movement at such a pace increasing to infinity asymptotically as it begins to reach this limit; when one considers instead the shift in the so-called metric of space, with this latter concept allowing us to define ideas of physical distance at all, then from an observer sitting idle at a fixed point relative to some other point occupied so far off as to make the scales at which this expansion occurs, apply, it will seem as though a superluminal velocity is attained. Such structures however, are said to thus fall outside the observer's light-cone, because the photonic-information which is encompassing of that part of space subject to expansion cannot reach the observer by virtue of its inability to overtake how far the associated point-source has receded from the observer's own line of view, in that its image is forever confined to the immediate wake of expansion. This is the reason for why, at least for those with a formal interest in the study of stellar dynamics, we speak only of those regions of the universe which are "observable", as even under the assumption that a telescope of infinite size and complexity could be constructed, because the very notion of distance on these scales is expanded upon so continuously, what may be sighted are only remnants of that which took place in the past, and even then, the photonic-signatures, or imagery, corresponding to a particular such event may require a greater period than the universe will ever exist for, to have even a chance of reaching our position so as to thereby preclude their reaching us outright. That these effects aren't dominant on a more local scale is in consequence of the force of gravitational attraction, which keeps those masses that are in fair proximity to each other tightly bound enough to minimize their respective recession; that empty-space is in contrast, much more prevalent on the supra-galactic scale is why expansion becomes so prominent, herein, and as compared to those scales which are locally based.
He didn't say specifically between galaxies. New space is being added everywhere. That's what it is for the fabric of spaced to get stretched: a length of space gets transformed into a greater length of space. There is now more space, so space was added.
You could quibble that it's really more like it's multiplied, but when you multiply positives the result is always the same as adding something would be. In any case, the amount of space -- everywhere, and so also between any two things -- is increased.
As I noted in my earlier argument, the effect of its expansion dominates at the scale of so-called cosmic filaments, which are some of the largest known structures in the universe and generally fall within the range of several dozen, to perhaps even a hundred megaparsecs in length. These structures consist of many unique superclusters, which themselves consist of tens to as many as thousands depending upon how one characterizes them, of unique galaxies in close proximity to each other, and as being gravitationally bound. This indicates, that the scale at which expansion of the metric of space dominates is nearly three orders of magnitude greater than what has thence been suggested.
It may sound disingenuous and that's fine, but I get that. And thank you for it. I don't argue for the sake of argument any more, and have not done so for years. I will ruminate some more and see what digestive gases produce. Gravity, or the place where inflation might overcome it, is something I want to think more about. Thank you all who took the time.
Is there space inside objects like planets? If so, do we see an increase in the size of the planets over time?
I am not at all certain of what you think to have implicated any disingenuousness on your part; my purpose was only to illustrate the specifics of that cosmology we are now reflecting upon, and thereby to contribute in some way to the broader part of its discussion. In these efforts of mine, I was motivated by nothing else than to inform, to teach, and while I do on occasion pursue argument for its own sake, this doesn't apply in the present case. But even if it did, to inform would have still been my foremost aim in doing so.
On an unrelated note, I seem to have made several errors, albeit minor ones in my initial response to your query, and while this is an expected thing, especially when using a mobile-device, I don't wish to give off the impression of illiteracy. Thus, they have since been rectified, even if in appeal to little more than my own semantic perfectionism.
Thanks, it's all good. I took you assistance in the spirit you intended. My implication was a defensive response to another teacher who wasn't so interested in my enlightenment.
I assumed as much after having glanced over parts of your earlier exchange, despite having chosen simply to overlook it. But, you shouldn't feel yourself to be at fault for the reason that the other party who was of involvement has a known habit of commenting on a thread, only to cause an undue tension. His writings seldom demonstrate much of an insight either, even in those few instances for which he makes a genuine effort to bring something of value to the discussion; I myself can attest firsthand to this pattern he has shown, though I don't feel his behaviors warrant such attention at all.
I suppose the time has thus come to move on.
Agreed.
There is space yes, but we don’t see small things (where even a galaxy is “small” for these purposes) expand because on small scales the forces holding those things together completely dwarf the force of expansion. It’s only on huge intergalactic scales that there is enough space relative to matter that the expansion of space outpaces the attraction of matter to itself.
I know it is trite, and cliché, to bring up the pot-smoking stories of our universe on the head of someone else's pin, or a universe on the head of our pin, but they sure come to mind in consideration of the space between the atoms of our Earth, so great as to allow a neutrino to whip on through, unimpeded by the tug of gravity holding those atoms together, or the space that is, by some other force, pushing them apart. How can that be? All while the giant and clumsy photon can barely pass through my green house panels, only to get locked up in the flimsy leaf of a fern, captured and forced into servitude of photosynthesis. And this, after lightyears of travel across the universe. What an ignominious ending. Or maybe not. Maybe a wonderful beginning. Jeesh! Another toke, bro. LOL!
Quoting Don WadeThe big bang theory does not posit an explosion into space from some point in that space. Any simple description on the web will tell you this. The expansion of the universe is not a speed, and is measured in different units. Pfhorrest seems to know the physics.
Science says no such thing. It makes no mention of a shock wave, which is something you get from say a star exploding in space. The universe isn't an object in space like a star.
Quoting T ClarkThe diameter of the visible part of the universe is about that. That volume includes all the material that can possibly ever have had a causal effect on us today. It doesn't mean we can see that far. Any light that has ever reached Earth up until the present has never been further from us than a proper distance of under 6 billion light years. Measured that way, the size of the visible universe is under a 6 BLY radius. We can only see these really distant galaxies because they were much closer than that distance back when they emitted the light that we're seeing now.
Indeed, definitions are fine so long as they are not definitive...
That is precisely the argument which I had sought to make earlier; while the so called light-cone of the universe is available to us, this applies only in part, and even under the assumption that a far greater portion of which could be sighted through some technological means, those photonic emissions made by the corresponding point-source are at such a distance that their image may not even reach us across the entire lifespan of the universe so as to thereby preclude their reaching us outright. Under all circumstances then, and unless the rate of expansion slows considerably enough to no longer appear superluminal, such images will be forever confined to the immediate wake of expansion.
Then what is the universe? That is, something other than it started with a big bang. Does the universe exist in space, or does space exist in the universe? Which came first, space, or the universe?
Again, the expansion rate is expressed in different units and thus is not a speed and cannot be meaningfully compared using a word like 'superluminal'.
Quoting Don WadeA reasonable definition, but still dependent on serveral assumptions such as your chosen interpretation of QM. An MWI guy for instance might say that the universe is the one universal wave function. Any follower of a realist interpretation (MWI being one of them) might say that the universe is all that is. I learn towards the RQM side, but I'm hesitant to say the universe is all that I measure since that confines it to the visible universe, and it needs to be meaningful to talk about more distant things, however much those things don't relate to us.
No model supports that. It is a naive interpretation that is quickly falsified.
Time as well since it is the same thing. Few can get their heads around time being part of the universe rather than the universe existing in time, which reduces its ontology to that of a mere object.
Great example of trying to think of the universe as being contained by time. The universe is not an object. Spacetime is part of the structure that is the universe.
With respect, your question appears to me a rather senseless one. The available evidence indicates that it began as a tightly bound singularity, of such density, and extremes of temperature, and so well-compressed that the traditional constituents of matter cannot be spoken of, at least not in a meaningful way when examining this state. Only during the Planck Era, having lasted for a duration of approximately 10^-43 seconds beginning after the start of expansion, when the forces of gravitation began to separate from the electromagnetic and nuclear forces with which they were formerly unified, did temperatures start to reduce enough to permit the formation of matter as we generally understand it. Though, even in this case, fully-defined atoms began to emerge only during the Inflationary Epoch at which temperatures reduced overall by a factor of nearly 100,000, and which itself had succeeded another transitory phase whereby the separation of gravity as a distinct force was completed. It was during the Inflationary Epoch that the seeds of the universe's large scale structure were sown on account of the Quantum Fluctuations which in the immediate moments when expansion first initiated, caused certain discrepancies in the distribution of matter, and thus a differing level of destiny across unique regions, to emerge, which were then amplified proportionally in their scale as the metric of space rapidly changed to accommodate something much larger.
It is thence a rather misleading characterization to say that the universe "started" with the Big Bang, as it always existed beforehand, just in a state so unlike anything we can conceive that one cannot speak of it meaningfully.
You seem to have misconstrued my words; I know it to be the case that the rate of expansion is expressed in units separate from that of more traditional ideas of velocity, but as seen from the perspective of a fixed observer, relative to some far off position which is of so large a scale as to make the effects of such expansion dominate, for all intents and purposes it does appear to the observer as though a superluminal velocity is attained.
Do notice how I qualified my statement with likening its chosen object only as appearance, rather than an absolute. As my argument certainly wasn't that this reference frame is somehow privileged, or the only one of merit. The purpose for which I cited it was instead to highlight how ideas of causality are meaningless in these cases because the light-cone of the observer is forever prevented from accessing the image of such distant point-sources, and nothing more.
The speeds expressed are relative to a non-inertial coordinate system and relativity theory doesn't forbid object or light from moving at speeds above c relative to a different kind of coordinate system, so none of this is particularly contradictory with anything.
Minkowski spacetime does contradict the geometry of the universe. Given Minkowski spacetime, light will eventually get from any location to any other. There are no event horizons. Not so with our universe, so Minkowski spacetime (typically assumed by any naive description of bang happening at a location and filling pre-existing empty space) cannot describe our universe.
I did, but there's not much appearance to it. We see redshift and brightness, both of which approach infinity and zero respecitively with subluminal local motion, and from that glean the speed. If we wait long enough, we see the object get smaller over time, but not so much that it appears to move super fast. Take GN-z11 which at redshift z=11 is the most distant galaxy know. Yet it subtends an angle that places it only about 3 billion light years away, making it appear to move quite slowly actually. Speed from appearances is a calculation relative to a model and a coordinate system, not something that can be directly measured just by looking at it.
I think that under a Minkowski inertial frame, the most distant object visible would appear almost 7 billion light years away. I mapped the universe to such a coordinate system as best I could once. It almost works if expansion is uniform and not accelerating, but there's simply no way to work dark energy into it.
Good grief, I never caught a suggestion of that in your posts.
You're talking about objects outside the visible universe? A few will become visible as that radius expands, but most never will. As a non-realist, I cannot say that any of those objects specifically exist relative to us, but someone positing an objective state of the entire universe would say that these distant objects do exist, any one of which is receding from us at an arbitrarily high rate.
I admire your effort in expressing your thoughts. I'm trying to grasp the the image, but there seems to be a "leap-of-faith" in the transition of events as you progress from a "tightly bound singularity". Maybe I'm missing it when you state "one cannot speak of it meaningfully". I'm looking for a continuous cause and effect but I'm just not visualizing it - and, maybe that's what you were pointing out?
I am aware of how on a practical level the degree of redshift of a point-source as experienced by a distant observer increases to infinity in correspondence with a like decrease in its observed energy. I am aware as well, of how because we are restricted in our ability to observe only any portion of the universe, and that one cannot physically catch sight of such superluminal motion, for the reason that the local photonic-emissions, such as you yourself noted, are receding from the observer's position at an even faster rate. It is in likely consequence of this physical inability, that notions of proper causality breakdown, and therefore are deprived of all application when examining these sorts of instances; and, while I cannot attest to the deficiencies of Minkowski Spacetime that you alluded to, nor the degree of redshift experienced in select cases, my purpose was to show why this sighting of so-distant an object is forbidden, such that it resolves into contradiction when one assumes its exercise of a causal influence on things within the context of the observer's respective light-cone.
Notwithstanding our dispute over the aptness of "Superluminal" as a descriptor, at least as pertaining to the current discussion, I am in agreement with and thus recognize as true, every concern you raised. In fact, on several occasions I myself made the same points, with an example of this being that we may never even have the opportunity to observe certain signals because to ever reach us, they must cross a greater distance than the duration over which the universe exists, or is otherwise expected to before it reaches a state of maximum Entropy, will allow for.
I assure you there applies no leap of faith when one restricts analysis to moments after the Big Bang occurred, rather than before; this is because of the latter's inability to be either modelled or conceptualized with our current methods, and that in such a state, every means available to us collapses on its head. Only insofar as we conceive of a Unified Field Theory, in which all the forces of matter and causal interaction are treated as one, and able to thereby be quantized on the smallest of scales, can we hope to move forward in our analysis of its earliest stage of development, when there was found only the associated singularity.
Context of argument, is of more relevance than anything else, herein.
On the other hand, an expansion of arbitrarily high compression of mass/energy (as posited by the BBT) would still involve a reasonably uniform distribution of mass and energy over all of spacetime, not at all meeting the stress energy tensor conditions of a black hole.
I think there is reason to note that while the conditions of that stress-energy tensor which is characteristic of a Black Hole are left unsatisfied in the case of a mass subject to an arbitrarily high-degree of compression, at least insofar as it is allowed to expand so as to not again revert into a singularity, certain discontinuities do emerge because of fluctuations in how it is distributed on the Quantum Scale; this, being a consequence of the Exclusion Principle, which induces a repulsion at the inter-atomic distance between any number of Fermions such that they are forced to occupy unique states and thereby be set at some distance from each other. Following a period of expansion, these fluctuations are amplified in scale according to how far the underlying metric of space has been lengthened. This same effect is responsible, so far as we know, for the large-scale structure of the universe and why in particular, bodies of mass tend to congregate in so-called Cosmic Filaments which extend in size to several dozen megaparsecs on average and themselves consist in hundreds of unique galactic-clusters. While the corresponding 'gaps' which emerged during the initial stages of expansion are now accounted for by 'Voids' of equal size to the aforementioned filaments, but consisting instead largely of empty-space.
As T Clark suggests, we should acknowledge proven undisputed evidence, and then distinguish it from theory and speculation. All are fine so long as we recognise what each element represents.
Science is confident about the minimum size of the universe today in absolute terms. It is also confident about what the speed of light can achieve in normal circumstances today. Clearly the maths which T Clark pointed out is self explanatory if you believe in the Big Bang. The universe must, in absolute terms, have expanded faster than the recognised maximum speed of light.
As I have pointed out in other threads, the principle that 'the speed of light was the maximum that could ever be achieved', was and remains speculation. It's not been a bad supposition for our limited circumstances and for our development of such things as atomic energy, but that doesn't have to extend to the cosmos.
When the evidence clearly says that, in certain conditions, it must be possible to travel faster than the speed of light in absolute terms, then we are fools to ignore it.
Indeed, in this respect, relativity is open to too many variables to provide a comment on this - when by its nature, any 'absolute factor' must take precedence over relative readings. The width of the universe is such an absolute - and a figure that wasn't available to Einstein.
The inflation of space was a notion dreamt up purely to preserve the notion of a fixed value for the speed of light as currently measured. It has no evidence to support it and only exists to preserve doctrine over substance.
The conversations on this thread have also blurred a number of other factors.
There is a difference between:- material moving outwards; a shock wave; and space itself expanding.
I feel that in normal language, suggestions of a shock wave would need some medium in which to generate the wave, (as others have suggested). You may argue that Dark Energy might constitute that wave, but Dark Energy is just theory and has no physical evidence to support it either. So it may not be correct - and I give an example of a simple alternate theory below.
However, for the moment, I'd like to set the context for all potential explanations. The 9 year results of the WMAP programme clearly stated that the dimensional lines run straight and are not bent as far as we can tell. Therefore by implication, they run to infinity and so space itself may genuinely be infinite.
Whether that means that space is 'something' rather than emptiness is hard to fathom. Finipolscie speculated that space may represent the framework for existence - quite apart from any material or energy that might occupy it.
His logic was along the following lines :-
If you were on the leading edge of the expanding material from the Big Bang and could see a location ahead of you which you can identify and move towards, then that space must exist in some form. He also pointed out various ideas that say there are a small number of core factors in existence which shape everything else. I think he said there were 6 - which he likened to settings on the 'control panel which governed the rules of existence'.
I have found other authors who make the same point. There 6 parameters, and each of them could, theoretically, have had any of a whole range of settings - each potentially resulting in very different manifestations of the universe..... but why they settled on the settings that they did, is unknown.
However we are also unsure of what makes existence conform to those settings, and therefore we speculate about a framework for existence, although we don't know how it might be imposed. It is this which suggests that space may be more than simply 'location' - and not just the material or unidentified Dark Energy which may occupy it.
The idea of Dark Energy was entirely driven by the finding that the redshift was increasing - from which people assumed that the expansion was accelerating. However, there is no need for Dark Energy if the original Bang-Crunch model of the universe is applied fully.
Think about it. The increasing redshift could just mean that we have entered the crunch part of the cycle in which case, Gravity would be causing that acceleration - there would be no need for Dark Energy.
What you're asserting then, is that the near entirety of [i]Inflationary Cosmology, as physicists apprehend it today[/i], is a facade.
Quoting Gary Enfield
Relativity, despite what its name suggests, is not a triumph of 'relative' readings over 'absolute' ones; despite that you haven't elaborated on what they even entail for you. Einstein geometrically interpreted the universe with a four-dimensional Lorentzian Manifold, whose metric tensor varies with time (again, the tensor equivalent of cosmological inflation). You can't straddle between two, antithetical narratives. Either abnegate General Relativity, and be a proponent of nonstandard ideas - or accept it, with all its known implications (inclusive of an expanding universe - wherein observed, absolute distances on a fabric can exhibit velocity differentials superior to [i]c, without the material on that fabric ever defying SR in localized regions)[/i].
Hi Aryamoy Mitra
Quoting Aryamoy Mitra
I am saying, very clearly, that Inflationary Cosmology was specifically proposed to preserve the notion of a fixed speed for light. It may be true, but it lacks any real evidence.
When it was pointed out that objects in space were not inflating, (which they should if space itself was inflating), then a 2nd round of gobbledygook emerged to try and justify the nonsense, despite the simple evidence. You are arguing for doctrine of substance - because you have no actual evidence for inflation as opposed to the basic implication of faster than light travel.
Quoting Aryamoy Mitra
I think I can just about guess what this jargon means - but you seem to be suggesting that I am jumping around between theories, when I am not. I am simply saying that the evidence of distance divided by time - when applied to absolute and agreed values, trumps vague notions based on doctrine over real substance.
As I said before. I acknowledge that your preferred theory may one day be given substance, but it hasn't yet - and the historical fact remains - it was dreamt up to preserve a fixed C
[math]Ds/Dt[/math] can parameterize unchanged spatial distances, on a Minkowski metric - not on a varying one.
Quoting Gary Enfield
I'm not contending that fixing C was one of SR's postulates; all I'm stating is that there exists a valid and demonstrable interpretation of cosmological inflation, that is consistent with that postulate.
For what it's worth, this isn't merely a preferred theory; it's what the majority of Physicists will attest to (not an appeal to authority, but a testament to its perceived credence).
I am curious as to how the current density would have any influence on either the physical possibility of expansion, or the degree to which it occurs. In what way then are these two factors correlated, in particular, or otherwise based upon a mutual relationship of causality?
Gary, I really like your post! In my opinion, It reflects a lot of insight.
Good thought. Add to that, if you would; What does the vision of "multiple" contractions and expansions do if we focus on the velocity of (light in space) during these periods. Then the question of; how far does the universe contract before it starts to expand. Lots and lots of questions about the model.
Quoting Don WadeYou mean a cyclic model? I'm not familiar with any such model that matches empirical evidence at the level of the accepted FLRW tunings. So I think you can make up any rules you want about what properties are preserved from one bang to the next.
I've never heard of a model that posits contraction that doesn't accelerate to some kind of crunch singularity. Doesn't mean such a model doesn't exist, but I've never heard of it.
The big bang and the big crunch kind of go hand-in-hand in some models. https://en.wikipedia.org/wiki/Big_Crunch . However, the jury is still out as to which models are more acceptable. Trying to get a grasp on the fundamentals of the different models is what makes cosmology a fun science - and is especially great for philosophy.
As far as we can measure, space is indistinguishable in size from an infinite size. If it is infinite, then it was still infinite in the past, and even at the beginning, if there really was a beginning. Imagine a grid on your screen where each square is 1 inch. Now zoom out from the infinite grid so that each square is just 1 pixel. Imagine you could keep zooming out until each square was much much smaller than a pixel. But the grid still fills your whole screen. There’s no edge to it to push out into anything else else: it’s just a very compact infinity of squares that expands into a much looser infinity of squares, but at any time it’s still the same size: infinitely large.
I am familiar with, albeit in a rather vague sense of how the so-called Cosmological Constant, with this latter term being interpreted in more modern treatments as encompassing the effects of 'Dark-Energy', has a great influence on the rate of universal expansion when possessed of a non-zero value and with a countervailing effect being accounted for by the forces of gravitational interaction instead; expectedly, it thus follows that their relationship to each other is one of competitive inhibition. I am familiar also with how the rate of expansion has since accelerated by virtue of gravitational forces exerting less of an influence than before, as the relative density of matter itself continues to decline, and that the associated factor, known as Hubble's Constant, will eventually reach its true value once the expansion becomes exponential. With the exception of what this particular value is, such as you communicated to me, all the information which has been proffered for my sake, I know of already. Certainly, this isn't to say I wish to sound disparaging, nor to overlook how much of a delight I found our exchange to be, just that I had hoped for a more thorough analysis of that relevance which current density has, as opposed to any other form of density, when modelling universal expansion.
In any case, that my role in society is of being a literal dropout, and with few prospects as it regards professional advancement, every one of those ideas which has been given mention for lies beyond my field of expertise. For this reason, I am sure you are still in a position to claim the advantage of that betterment of human-understanding which can be conferred only through a higher-institution, with respect to my own circumstances at least.