Do We Live in an Infinite Universe?

I thought that it is pretty much conceded that the expansion of the universe is accelerating. However, I gathered that there could still be a CC that is limiting the acceleration.Are you meaning then that the expansion could still at some point stop accelerating and start to collapse. If that were to happen wouldn't that have a profound impact on the flow of time. What would happen when the rate of collapse exceeds light speed in the way that expansion does now?Although I can't begin to understand it your suggestion that time and space is just a function of what is perceived by consciousness makes a lot of sense. Actually that is why I asked if galaxies that have expanded past the event horizon still exist. Isn't it also possible though that the gravitaional field could collapse in that scenario, resulting in Big Disintegration?

Yes, it is. I was talking from the theoretical model perspective. Ok, we've got to be more precise here then. The acceleration is driven by a field, we'll call A. If A is positive, the universe gets pulled in on itself; if it is negative it accelerates the universe apart, as observed.Now A could be made up of several things, but we'll just consider the important two: the Cosmological Constant,L (should be lambda but I'm too lazy to put in Greek) and some dark energy field, D.So A = L + D. Now L can be positive, zero or negative. D can be positive, zero or negative. But we can't tell them apart at the moment. So L could be doing the accelerating, or D or both. So there's often little point separating the two concepts. When I say CC, I mean sun of the two, which is an abuse of terminology on my part. Could do. The thing about L is it is constant. But D doesn't have to be, and could be reducing so that at some point the acceleration may cease, and the universe could even recollapse. It was once thought that it would, but entropy again seems to rule that out. Nothing much. Only towards the end would it become seriously noticable, and by then it would be the last thing on your mind That's not really what I was saying... although it is a discussion for another day. What I was saying was that the "flow of time" is a construct of conciousness. No. There is no gravitational field in that sense. There is curvature. It is the Universe, as a whole, and doesn't have much respect for horizons and c which are local concepts.

I think there is still some disagreement about the acceleration of the expansion. It MIGHT be a measurement error. More testing has to be done, but more evidence is coming up that the acceration is real.The universe might end in a big RIP ..

OK. I think I have that. However, (there is always a but isn't there? ) it seems to me then if L is a constant the only way that an expanding universe can contract is if D becomes more positive. Wouldn't any change in D likely be caused by the fact that with the acceleration wouldn't any change in D be caused by the fact that the dark energy field is becoming more diffuse, thus reducing its gravitational pull?If this is the case then wouldn't we expect that instead of starting to contract that we would arrive at a point where A is neutral and there would be a state of equilibrium which might leave us in a state of infinite time. If entropy is always increasing in an expanding universe then what happens at the point of max entropy. If the universe is contracting then doesn't that mean that entropy is decreasing. We have only known a universe with increasing entropy, what does the opposite look like if it is even possible? (By the way, my understanding of entropy is extremely limited, so if I'm talking nonsense don't be surprised and I won't have my feelings hurt if it is pointed out to me. ) If I can try rephrasing that are you saying that time is just the way that we perceive change as Barbour would say? (I think) If space and time are both illusions it sure becomes difficult to sort out reality from from perception. This I don't understand. Isn't the gravitational field largely what holds things together so to speak. With an expanding universe it would seem to me that the field would be weakened.When we look at the Earth the gravitational pull is constant because of the curvature of the earth. Are you saying that this would hold true for the universe in the same way when the dimension of time is included?It seems to me though that if the mass of the universe was increasing then the gravitational field would still be as strong. Wouldn't it be true that if the circumference of the Earth were to increase without any increase in its mass we on the surface would experience reduced gravity. (Beats dieting ) Why wouldn't this hold true for the universe as well?Thanks for the time you are spending with the layman's layman.

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Everybody is entitled to my opinion.

It's not exerting a gravitational pull exactly, but it may certainly reduce. Then again, it could get stronger as time goes on, which would give you the Big Rip scenario. It all depends on the particular dynamics of the field, and we are a very long way from determining that. This kind of field, outside of current Standard Model physics, is the sort of thing you expect from String Theory and similar. But don't think of it like a dust which thins out as such. It is more akin to an electromagnetic field through space-time, just with different properties. That would be cool: an asymptotic Einstein Static Universe. Such a model may well have been devised in the literature. It maybe worth a search. But again, the dynamics of D are far from determined. A bit before my time, Hawking and others thought this, which led to the time running in reverse picture (and the awesome Backwards episode of Red Dwarf ) Physically, this would be like an end to time at maximum expansion. But we're fairly sure now that entropy would just keep increasing in such a situation. No, that's too deep for today. True, but it's not what I'm saying (today). Merely that the flow of time is an illusion, not time itself. Imagine my good old globe, BB at North Pole, etc. There is the universe in all its glory: all time, all space, no flow of anything, no beginning, no end... just is. But if you look closely, you will see these little human threads, and you can see "time" ticking along them, starting at an end furthest north where these humans are born, and stretching south to where they die. They're not even all aligned. Two threads next to each other could have each "time" at a different point on the thread, so one thread thinks its having a 5th birthday in 1975, and the thread next to it thinks that it's getting married in 2012. Yes, in a sense. As the universe expands, the curvature decreases. But galaxies moving out of causal contact with each other is not going to make any difference to the gradual decrease in curvature. GR doesn;t really care how localise dthe mass is, it just wants to know how much mass there is in a particular volume. It's not a problem if you let that volume of space increase in size as the universe expands.

I keep running this through my mind trying to put the pieces together. One thing that seems strange to me is this: As you point out, A can function quite nicely with L being zero. Why did scientists reconsider the idea of L at all. Wouldn't it be more reasonable to think that A=D and that L is zero or non-existent?I realize that you consider this a possible solution but I don't see why it wouldn't be considered the most likely solution. If the universe is expanding I don't understand how any field, either gravitational or electromagnetic could be growing stronger. As I said wouldn't a more diffuse field be weaker?If it is an open universe I don't think that necessarily means an infinite one. It seems to me that the universe would meet some critical mass and self-destruct.I don't understand how the gravitational pull would grow stronger with expansion and I also don't understand why a stronger gravitational pull would cause the Big Rip. I would have thought that a stronger gravitational pull would help hold that whole shebang together.I read this and would like your opinion. It is short.Page not found | American Institute of PhysicsThanks
Greg

5% what we know
25% {matter} we know nothing of
70% {energy} ...But the equations balance ...An interesting side is what Einstein thought about "ether"
404 | TYPO3 Doku TUHHHe concludes: He has also IIRC said that we cannot disprove that an ether exists.

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Yes, and this is why I always jump in if someone says that there is no ether, no space-time background. Einstein found the ether in the form of the metric of General Relativity, it is just of substantially different character to the usual concept of ether held at that time.Today, with our everyday use of fields rather than particles or objects, it is simply taken for granted. I've not seen that. But we know of this ether only through General Relatvity (and related metric theories) and our other field theories. I guess it stands or falls on the merits of such theories. Even ideas of your own, such as adding another dynamical particle/field to account for dark matter, would simply be incorporated into this picture. You would need to deviate substantially from current ideas of space, time and particle physics to shake the idea of an "ether".Edited by cavediver, : No reason given.

RAZD's introduction of ether into the discussion seems to arrive out of the blue, so this comment may be off-topic, but anyway, the Einstein quote notwithstanding, this "ether" is of such a dramatically different character that to call it ether seems misleading and confusing. It's like after asking someone, "Did you find that inexpensive apartment in the city close to commuter lines you were looking for?" they reply with the answer, "Sure did! Although actually it's not in the city, it's in the country. And it's not an apartment, it's a house. And it's not close to any commuter lines, we'll have to buy a car and drive. And it's not cheap, it's costing us a bundle. But yeah, we found what we were looking for."As most would put it, there is a fabric to space/time, and it is of a wholly different character than the mythical ether that was at one time imagined to exist. Given the prominence of this ether in the history of physics, to put the ether label on the modern concept of space/time could only be confusing.So if someone (me, for example) were to say that the Michelson/Morley experiments demonstrated there was no ether, I definitely am not saying there's no space/time.Just a layperson registering my two cents for non-confusing terminology...--Percy

The MM experiments did not demonstrate that there is no ether. At most they demonstrated that the ether drift is too small to measure.The original concept of the ether was discarded as unnecessary. It was never actually proven to not exist.

True. The Lorentz-Fitzgerald Contraction was actually first proposed as a way to explain the null result of MM, before it found itself at the heart of SR.Will get back to Percy's comments later.

I too am curious about this. Layman alert, by the way, so correct me where I surely err. Einstein’s original CC (K) is still discounted today, no? His CC was to offset the implications of his own equations to make the universe static as I understood and is not needed in a universe that is slowing its acceleration. Now with the new accelerating model of the universe cosmologists introduced w as this dark energy field. Where does this relate to L and why do we need L in a currently losing battle with w? Is there still a theoretical need for a CC in an accelerating model or do we only need an energy field (w) overcoming gravity?

Too long a digression into the subject of the once-hypothesized ether would probably be off-topic, so I'll just say that I think you're seeking more precision than is appropriate in a statement that I specifically crafted to be as a layperson would be expected to say it.My point had nothing to do with the specifics of the ether and experiments directed at detecting it. My point was that I think it would be confusing to interpret comments about the ether as also being about the modern concept of space/time. It was intended as a response to this from Cavediver in Message 23, quoting more specifically this time: All I was saying is that if I were to say there is no ether, I definitely should not be interpreted as claiming there is no space/time background. I think ether should keep its historical definition as distinct from modern concepts of space/time, and that it would be confusing to do otherwise.--Percy

Everything we know by some form of observation could be considered our universe with a lower case u. All that "IS" could be considered our Universe with a capital U. Our universe is actually a pocket of space-time or POST and all internal laws of physics (Newtonian and Quantum) will behave pretty much as expected within out POST because the relative Aetheric density of our known universe is behaving, as we would expect it to.However our tiny little bubble or pocket in space that is made up of mass and energy and has the ability to interact with gravity, time, space, and light is nothing more than a point in space and time. An infinite Universe with an infinite number of POSTs like our little tiny universe is what is truly Infinite.So insignificant it must make one feel. Well when I then look at a solar or lunar eclipse, a rainbow or the Aurora Borealis, or the fact that our planet is just at the right distance from the sun to give us both a winter and a summer I am forced to wonder the real question of Infinity.Can something that is infinite be intelligently designed? To me I think more and more that it is just as plausible that an infinite intelligence could exist and create our little pocket of space and time as it could be for an 'infinite intelligence' to have created out tiny little planet all by itself?So what came first the chicken or the egg?
Did the creator of infinity exist before infinity or is the creator of infinity a byproduct of the infinity that it created. OR if infinity is taken it the most true context that it can be taken there is no smallest piece of matter or smallest piece of energy or largest spec of matter or energy. There is no smallest division of time or space that is not divisible nor is there a largest segment of time or space that can not be made larger or longer.Our POST, all we know about our universe, is likely traveling with speed through a much larger vacuum in space and along with most likely many other POSTs like ours they revolve around a central more dense center of density. Someday our POST will make contact with another POST and if the trajectories and speeds are opposite enough, the odds are that they will crash with a force and speed equivalent to they type of energy needed to vaporize all matter to an almost plasma state thus creating a pool of vaporized atoms to rebuild anew.

As far as Ether or Aether, it will be proven within 10-15 years to not only exist but to be the factor in the equation that ties the weak and strong subatomic forces to those of gravity and electromagnetism into a single unified field. Einstein stopped working on his Aetheric model not because he could disprove it but because he had many other things to work on. The proof of concept I think is easy. All we need is a cellular telephone satellite in orbit around the planet and a handful of equations showing the different amounts of energy required to keep it in orbit inside and outside of our local atmosphere.Once we can include the relative Aetheric density of our atmosphere compared to those items orbiting our planet to other areas with different Aetheric density’s we will find the constant that dictates the overall relative electromagnet attraction between any two 3d objects residing in a 3d pool of an infinite number of other 3d objects of varying mass and density. My instinct tells me that it is a number very much like pie I think. I say this because all objects as they exist relative to any other object should not be mapped using Cartesian coordinates. The true laws of the universe do not hold true to Cartesian coordinates but instead to a coordinate mapping system based on selfcentrispherical spherical coordinates. All calculations as to the laws of physics need to be done based as a set of interacting spheres inside a larger sphere being affected to some degree of precision by every other spherical electromagnetic (or gravitational) field within the relative vicinity.Newtonian Physics are close and works in most instances but if we really applied the scientific precision to our measurements that will become available over the next 1000 years right now we would see that other forces are at work that were never being taken into account. Quantum Mechanics and Particle Physics and the wave nature of energy and light also works in many instances. The bridge between the two will come to light once it becomes self-evident that all matter exerts electromagnetic interaction to all other matter and we can come up with the proper formula to include Relative Aetheric Density in the equations.To explain in a different way lets say that the atmosphere around our planet grew outwards by 25,000 miles a day due to new gaseous particles being added to our atmosphere like oxygen, nitrogen, xenon, or radon, etc. As our outer atmosphere grew larger the overall attraction that our planet could exert on the moon would increase. Once the atmosphere reached the moon (or more likely well before that ) the gravitational attraction would have been so great that the moon would have collided into the Earth.
I say that it is not the mass of the combined atmosphere that would make our moon break orbit but the conductive nature of the particles that are increasing the relative attraction of our planet to the moon more as a conduit. So what I guess I am saying is that the graviton is not a unique particle but a part of all particles and all masses and the relative Aetheric density of any object as well as the relative Aetheric density between any two objects needs to be included in any equations that refers to what we thought we understood about Newtonian and Quantum Physics. And its more than just that. Every significant pocket of density needs to be included in the equations each exerting their own level of interference and attraction (or repulsion) against the two objects included as the primary participants in the equations.