Is the Universe in an Eternal Cycle of Expansion and Rebirth?

[procrastin]

hey all,

i'm going to be doing a presentation for my astronomy module, and i was thinking that i should talk about the idea of the universe being in an eternal cycle of expansion and rebirth.

i'll compare the expansion of a universe to a spring and harmonic motion. if the rate of the expansion is being reduced, then that may mean that there is a force which is decelerating this expansion. eventually the speed will be reduced to zero, from which point the bodies will then start moving in the opposite direction, with a negative acceleration. i believe that the "centre of the universe" may act as the point of equilibrium, meaning that the speed of the bodies will be at its peak.

the issue which i can see is what would cause the bodies in the universe to slow down and contract? what mutual force is there to cause everything to decelerate in the first place? will it be something to do with the Energy and energy density? a friend of mine also mentioned that the expansion/contraction will not be in a perfect sphere, which i neglected in my thought process. now I've come to the conclusion that instead of one large collision, there are smaller collisions throughout the universe.

this link will explain what i mean if i haven't made myself clear;

http://www.princeton.edu/pr/pwb/02/0506/0506-cyclicuniverse.htm

please point me out in the right directions if you have any opinions on this subject

thanks :D

 

[Xtensity]

I remember reading somewhere that the most probable shape for the universe is a donut. Actually I think there was a 1 million dollar prize to whoever figured it out, but the person who figured it out declined the prize. I can't remember many specifics on the whole situation though.

As for what causes it to accelerate and decelerate? Who knows, maybe we we'll understand if we ever get interdimension travel (:P). Isn't that kind of like asking, why do quarks randomly disappear from existence then reappear a short time later? As far as we know, it's the fundamental nature of them. What governs that? We could never know.

Also, I think I may have interpreted what you said wrong because you said "what would cause the bodies in the universe to slow down and contract". Is it not the fabric universe itself that will soon slow down and contract? Not the bodies?

 

[stakhous]

I would look into vacuum energy or dark energy for it’s speculated this energy is the cause of the universe's accelerated expansion and I believe inflation as well.

Additionally, researching the latest cosmological constant may shed light on to why the universe is expanding and not contracting and when if ever it will collapse into the big crunch.

Also in theory the Universe is Euclidian due to its isotropic uniformity and its shape(unlike a donut) should not violate elementary geometry( angels in a triangle add up to 180 degrees)

 

[cepheid]

hey all,

i'm going to be doing a presentation for my astronomy module, and i was thinking that i should talk about the idea of the universe being in an eternal cycle of expansion and rebirth.

It sounds like you're talking about the so-called "big-bounce" scenario. For what level of schooling are you creating this presentation?

i'll compare the expansion of a universe to a spring and harmonic motion.

The equations that govern the expansion are not those of a simple harmonic oscillator, although that's not a bad guess. I'm not sure what your math background is, but you might consider looking up the Friedmann equations in order to learn more. Very roughly speaking, these equations describe how the 'scale' of the universe evolves with time. One of the implications of the Friedman equations is that this evolution depends upon the different components that contribute to the energy density of the universe, such as matter, radiation, etc. The component that seems to be dominant at this point in time is something whose nature is not understood at all. It has simply come to be called, The Dark Energy. More on that below.

if the rate of the expansion is being reduced, then that may mean that there is a force which is decelerating this expansion. eventually the speed will be reduced to zero, from which point the bodies will then start moving in the opposite direction, with a negative acceleration.

That depends. The force that wants to slow down the expansion is just gravity. Therefore, the ultimate fate of the universe depends (partly) upon how much matter is present within it. This dependence is a direct result of General Relativity (which is where the Friedmann equations come from in the first place). It is simple to explain what the ultimate fates of universes without dark energy would be. There are three possibilities. If the density of matter in such a universe is less than some critical value, then that universe will continue to expand forever, and the expansion rate, although decreasing, will always be positive. If the density of matter happens to be exactly equal to the critical density, then that universe will also continue to expand forever and will once again be decelerating with its rate never quite reaching zero (but approaching it asymptotically). If the density of matter in the universe is greater than the critical value, then the expansion rate will decrease until it becomes zero, and then negative. In other words, the expansion will slow down, stop, and then reverse. The universe will begin to recollapse. This third possibility is essentially the same as the scenario you outlined, with one key difference. Without dark energy, there is no 'bouncing back.' Everything collapses down to a singularity and that's it. This is the so-called 'big crunch.'

I should emphasize that all of these scenarios have been ruled out by observations, which strongly favour the presence of dark energy. The dark energy makes it a bit more complicated to sort out what the ultimate fate of the universe will be (as compared to the neatness of the three cases presented above). However, in all reasonable models that include dark energy, the universe will continue to expand forever, and the rate of that expansion just gets faster and faster (i.e. the expansion is accelerating).

i believe that the "centre of the universe" may act as the point of equilibrium, meaning that the speed of the bodies will be at its peak.

The universe has no centre and no edges. Please don't ask me to explain this. There are numerous discussion threads on this topic in the Cosmology sub-forum. In fact, this thread should probably be moved to the Cosmology section (since that's what it is about).

the issue which i can see is what would cause the bodies in the universe to slow down and contract? what mutual force is there to cause everything to decelerate in the first place?

Again, it's called...gravity.

will it be something to do with the Energy and energy density?

Yes. As I've alluded to above, General Relativity says that anything that has energy gravitates. That includes "mass-energy."

a friend of mine also mentioned that the expansion/contraction will not be in a perfect sphere, which i neglected in my thought process. now I've come to the conclusion that instead of one large collision, there are smaller collisions throughout the universe.

Your final paragraph doesn't make much sense at all. What do you mean by the expansion "being in a sphere?" What collisions are you referring to? From what I can gather from this paragraph, you seem to be thinking of the "Big Bang" as an explosion of matter outwards from some "central point" in space, which is not correct at all. The big bang is a bit of a misnomer in that sense. Whatever it was, it happened everywhere in the universe, all at once. Rather than thinking of the expansion as being an expansion of matter outward through space (which is wrong), you might find it helpful to think of it as an expansion OF space itself. However, there is considerable controversy on these forums as to whether that's a good way to think about it, or whether it can be misleading (i.e. give the lay person wrong ideas about Cosmology). You have only to look at the numerous threads in the Cosmology section in which the merit of the so-called "balloon analogy" is debated in order to see what I mean.

 

[Xtensity]

Also I forgot to add, isn't the moment it collapses and restarts a "big bang" in itself. It's not really an alternate to the big bang, they're the same thing, just different names... at least that would be the most rational conclusion

 

[Pianoman14]

I thought that this theory was already proven wrong--or so I heard in a lecture I attended at CU.

Don't forget intelligent design as an alternative. The Big Bang is only a theory.

 

[Xtensity]

I thought that this theory was already proven wrong--or so I heard in a lecture I attended at CU.

Don't forget intelligent design as an alternative. The Big Bang is only a theory.

The thing I don't understand with intelligent design, and I don't understand why people don't understand this... in all religious books it doesn't say any detailed specifics. You think if a designer was intelligent, he would be intelligent enough to set it up in a scientific way.

I don't see what an intelligent designer has to do with it. Since with or without one, the "big bang" still could have happened, whether it was by nature, or by an intelligent designer. Which means discussing it here doesn't matter. Debating about dogma here is not allowed anyway.

A lot of science is only theories, but we can see the radiation from the big bang. We know something of similar to the description of a big bang happened because we can see the early traces of it.

 

[Pianoman14]

I was just suggesting Intelligent Design as an alternative to the Universe is being Eternally Reborn thory. I'm not out to prove it (well at least not in this thread)

The OP asked for my opinion on the subject, so...

I gave it.

 

[Burnerjack]

I would like to interject with this question if I may : Just after the (A) Big Bang, super massive amounts are in extremely close proximity, right? If so, why wasn't all this mass immediately returned to a great singularity, due to massive gravity fields? I find this paradoxical to say the least.
This paradox would pertain to a Big Bounce too, no?

 

[Borek]

I would like to interject with this question if I may : Just after the (A) Big Bang, super massive amounts are in extremely close proximity, right? If so, why wasn't all this mass immediately returned to a great singularity, due to massive gravity fields? I find this paradoxical to say the least.

It all depends on the Universe density and initial speed of expansion - please reread cepheid's post (three scenarios).

 

[Chronos]

Bah, blaming it on God is a copout, not an answer. Divine intervention [God] is the court of last resort. There are still far more questions than answers. I believe God is amused, yet fascinated, by our fumbling efforts to solve the puzzles set before us - thus explaining why God tolerates our existence.

Expansion is the current favorite to explain why the universe did not immediately recollapse after forming. But, hey, it doen't even make sense for it to come into existence out of a singularity. Injecting bizarre initial conditions is the only apparent explanation. Adding bounces does not 'cure' this conundrum, it merely assigns 'first cause' to some inherently unobservable pre-universe state [i.e., oblivion]. Pushing it under this rug is just a bit too evasive, clean and convenient for my taste.

 

[budrap]

Expansion is the current favorite to explain why the universe did not immediately recollapse after forming. But, hey, it doen't even make sense for it to come into existence out of a singularity. Injecting bizarre initial conditions is the only apparent explanation. Adding bounces does not 'cure' this conundrum, it merely assigns 'first cause' to some inherently unobservable pre-universe state [i.e., oblivion]. Pushing it under this rug is just a bit too evasive, clean and convenient for my taste.

Chronos, it sounds like you find the Big Bang scenario to be less than credible or am I misinterpreting your meaning here?

 

[cosvis]

Hi to all,
I also agree with the sentiments of Chronos, science should not become science fiction where unrealistic ideas are arbitrarily inserted into scientific speculations. New ideas should have some scientific proof or evidences or must be based on good theories. To speculate a Big Bang at the beginning of the universe, originating from a singularity, seems to me, to be too speculative. Leaving religion and meta physics out of our discussion, what we know is that at the beginning of the universe there existed finite energy and the universal laws that govern the evolutionary process according to which the universe evolved. We also know that all the energy, dark or light, which composes the universe, is eternal according to Einstein theory that energy can not be created or destroyed. We also know that energy consists basically of quanta particles, and thus I find it hard to understand that all this cosmic energy, all these quanta particles could exist in a singularity. Each quanta particle has space and consists of a definite quantity of energy eg. E = h f, where h is the Planck constant and f stands for the frequency of the photon. I am more inclined to believe that the first structure of the universe was huge big blob of energy, may be even a huge black hole, when its evolutionary process began forming first subatomic particles, atoms, molecules, galaxies and etc.
Yours Cosvis.

 

[Chronos]

I am totally on board with the big bang theory - after the first trillionth or so of a second. Of course time = zero is the juiciest part of the mystery. In my mind, not only physics, but, logic breaks down at that point. I consider 'branes' and 'bounces' as equally unlikely and unprovable as a creation event.

 

[nismaratwork]

I thought that this theory was already proven wrong--or so I heard in a lecture I attended at CU.

Don't forget intelligent design as an alternative. The Big Bang is only a theory.

How does the fanciful **** that is ID, in any way conflict with a BB event? A god could dictate any initial conditions it wants... it's people who feel the need for that to conform to their particular religious flavor. As for the "it's just a theory"... you just described all of theoretical physics, congrats. You then need to examine observational and other support for a given theory, and compare it to ID, which isn't even a theory, just a religious postulate with NO support.

 

[nismaratwork]

I am totally on board with the big bang theory - after the first trillionth or so of a second. Of course time = zero is the juiciest part of the mystery. In my mind, not only physics, but, logic breaks down at that point. I consider 'branes' and 'bounces' as equally unlikely and unprovable as a creation event.

We can't really imagine infinite cycles, nothingness, or infinity as a natural state, so pick your poison and it's going to kill human capacity for logic. That doesn't mean it cannot be modeled however, and that those models can't be a functional approximation of nature. I think that's the best anyone can realistically hope for.

 

[DavidGTaylor]

I have a problem with current BB theory. One of the big ideas about BB is that it is that the whole 'cosmic egg' started out as an infinitely compressed (or almost infinitely compressed) body that was composed of nothing but energy. There is a very big problem with that. Infinitely compressed would mean the gravity would all but stop photons/gluons/mesons to a stop. Whether it would do it through relativistic effects (that has gigantic implications I can talk about later) or through "potential energy". But potential energy is not an energy associated with zero rest mass [ZRM] particles. It is in the gravitational position of MATTER. Or the compression of MATTER. Even leaving that as too absolute, what potential energy does a particle have at the bottom of a gravitational distortion? If all the zero rest mass particles are brought near a stop, where does their energy go?

 

[bcrowell]

Don't forget intelligent design as an alternative. The Big Bang is only a theory.

And next time you want to make a lightbulb light up, don't forget voodoo as an alternative to Ohm's law. Ohm's law is only a theory.

 

[nismaratwork]

And next time you want to make a lightbulb light up, don't forget voodoo as an alternative to Ohm's law. Ohm's law is only a theory.

My lightbulbs work by harnessing the energy of sleeping elves!

 

[cosvis]

Hi Chronos and all,
I find the idea of zero time understandable from Einstein's relativity theory where he speculates that at the speed of light its time dimension has become zero (time dilation). Light or quanta particles travel at the speed of light thus they must exist in a special structure where time is zero. This connects also with Einstein theory that energy can not be created or destroyed. Thus, from a scientific point of view, energy is eternal and physical time only began when particles where formed that traveled slower than the speed of light.
Yours Cosvis.

 

[budrap]

I am totally on board with the big bang theory - after the first trillionth or so of a second. Of course time = zero is the juiciest part of the mystery. In my mind, not only physics, but, logic breaks down at that point. I consider 'branes' and 'bounces' as equally unlikely and unprovable as a creation event.

Logically you seem to be reasoning forward from the first trillionth of a second after the alleged Big Bang and saying it's all good from that point on. But the Big Bang theory was arrived at by reasoning backwards from the assumption that the observed cosmological redshift was caused by a recessional velocity and since that reasoning process culminates in an illogical absurdity isn't it difficult to credit the theory at all, especially considering the additional ad hoc modifications necessary to make the model subsequently conform to observation?

 

[DavidGTaylor]

Agreeing with Budrap: I am not going to try and argue with all the ways in which the current BB model conflicts with current physics (except the parts that were invented for the BB specifically) but what about this: the Planck constants are some of the most absolute values in Physics. A Planck Length is approximately:
1.616E-35m - the lowest definable dimension in the Universe - so how can you say the big bang started from an infinitesimal point? And if P-length is what you meant by infinitesimal, why can't you start playing with an initial Universe dimension of that value? You don't need to say "after the first trillionth" because there never was an "after". The Universe simply reached a point (we don't know where that is, really) it can't contract any more and begins to expand. Insisting that there was just a "beginning" without any postulates about: a)what existed before that beginning and b)what brought about that beginning not valid science. In the end, it is nothing more than thinly disguised science theology, the sort that cites Planck and Schwarzschild as prophets.
The fundamental of all science is that all of our existence is cause and effect. Just by dismissing the BB by saying its beginning is indefinable is not good science. Even the numbers submitted are not good Science. The number to use is not a "trillionth" of a second, the proper number to use is the a regular Planck Constant [6.6226] of a second!

 

[nismaratwork]

budrap, DavidGTaylor: You seem to be conflating the problem of the need for more complete cosmological theories, and the need for quantum-gravity with some fundamental flaw in the BB hypothesis. Let's say, for the sake of argument, that the BB precursor was the size of a Jovian planet, and there was time and physics, but not something we can describe with our current theories. Would that still offend your sensibilities? Observation DOES indicate, more and more, that the universe is expanding, and that BB theory does a fair job of describing the how. The exact nature of whether this occurred in the context of branes, or something else (or nothing) is a matter of pure speculation at this time.

 

[DavidGTaylor]

budrap, DavidGTaylor: You seem to be conflating the problem of the need for more complete cosmological theories, and the need for quantum-gravity with some fundamental flaw in the BB hypothesis. Let's say, for the sake of argument, that the BB precursor was the size of a Jovian planet, and there was time and physics, but not something we can describe with our current theories. Would that still offend your sensibilities? Observation DOES indicate, more and more, that the universe is expanding, and that BB theory does a fair job of describing the how. The exact nature of whether this occurred in the context of branes, or something else (or nothing) is a matter of pure speculation at this time.

My sensibilities aren't offended by anything I hear in this whole debate. If anything, I'm relieved. I have been researching this whole little BB affair for the past 3 years and you cannot imagine how many times I have come across - through the literature; on the net; from a very accommodating, helpful, yet very quick to anger researcher at the U. of Alberta.

The fundamental problem is this: we can make a reasonable postulate that 14 billion years ago, an event took place that began this particular edition of the Universe. But everything I have ever come across seem to cite some aspect of current theory that is undebatable. Isn't it POSSIBLE(?!?) that the BB was gigantically less violent that we currently think, and that all the evidence we see/interpret is simply the consequence of body/bodies that go through expansive and contractive phases?

Isn't it possible that on the contractive phase, the relativistic effects slow down all the zero-rest mast particle interactions, leading to the migration of more energy to matter particles, simplifying the elements in the process (because of the slowdown of gluons)?

Incidentally, what is 'budrap'?

 

[shredder666]

how would the thermodynamics work in a cycle like this?

 

[DavidGTaylor]

Thermodynamics is two basic principles - the first is that the amount of free energy (simply non-matter associated energy) will increase, and that the disorder of any system increases. What would happen in a cyclic big bang is that all the matter and energy of a system would come together (a "Big Crunch", or maybe just a "Big Mush"). Any complex particles/elements would slowly disintegrate as more and more energy of the system is forced into the matter by the combined gravitational and relativistic effects (again: all the zero rest mass particles would slow). The disorder of the system could be an absolute maximum of free nuclear and sub-nuclear particles moving at relativistic velocities. It maybe would even be that gravitons (technically zero rest mass?) would slow and the gravity would weaken enough to put a light speed limit on escape velocity. The nice thing about this idea is that it would mean that there could be engines of all sorts of sizes (ranging from nova's, supernova's, dwarf stars, seyfert galaxies and quasars) that would "simplify" elements. Though in some circumstances, it might even go the other way, and produce enough free energy in a confined environment (say a neutron star) where enough energy is enclosed to force together super-ferric elements. But it would eventually acquire enough energy from outside, and some of those super-ferric elements then would be expelled.
Their method of escape would use a relativistic consequence of high-gravity objects that I have been arguing with physicists/publications/fundamental-conservative-science-thought types for quite some time. It all revolves around something called relativistic perspective and the resulting equations, which means that relativistic distortions are fundamentally different when viewed from a DISTORTED viewpoint.

Nobody seems to care that I have confirmed my R.P. equations to 2000 decimal points (at least not any "respectable" Science publications) in a very full range of velocities. Isn't it occurring/accepted by anyone that relativistic distortions would have to use different equations when the body is moving at a relativistic velocity - i.e. one that the observers view as moving close to, or faster than the speed of light because of time distortion. Maybe there are more open minded types on this site that accept that obvious principle. For observers on any object moving faster than 211,985,281 m/s the combined velocity and time distortion would make it appear to them that they were moving faster than light. Does that mean that they've turned imaginary?

Sorry if I'm getting a little long-winded.

 

[twofish-quant]

I have a problem with current BB theory. One of the big ideas about BB is that it is that the whole 'cosmic egg' started out as an infinitely compressed (or almost infinitely compressed) body that was composed of nothing but energy.

No it doesn't.

 

[twofish-quant]

Isn't it POSSIBLE(?!?) that the BB was gigantically less violent that we currently think, and that all the evidence we see/interpret is simply the consequence of body/bodies that go through expansive and contractive phases?

Yes it is.

Isn't it possible that on the contractive phase, the relativistic effects slow down all the zero-rest mast particle interactions, leading to the migration of more energy to matter particles, simplifying the elements in the process (because of the slowdown of gluons)?

No it isn't.

 

[DavidGTaylor]

Yes it is.
No it isn't.

What is and what isn't?

In any event, are gluons immune to relativistic effects? The particles keep moving fast - at high enough temperatures each atom/nuclear particle/sub-nuclear particle become individual bodies because they are all moving so fast independently. The particles simply become more fragile. The fact that the slowdown of EM means that protons will no longer repulse one another as much, but it would also weaken the gluons. The whole structure of the body becomes more fragile. Any sort of impact with other particles/nuclei would have a destructive effect - and they would break apart. The orphaned particles would then pick up even more of the energy from those zero-rest-mass (ZRM) particles as they slowed down.

 

[twofish-quant]

What is and what isn't?

No the big bang is not a cosmic egg.

Yes it is possible that the big bang was the result of some cycle of expansion and contraction. It's also possible that the big bang was the result of cosmic turtles mating. It's also possible that I accidentally caused the big bang when in 2030, I accidentally flipped a switch at the LHC causing a wormhole to open in the past. Since we know nothing about what happened at the very beginning, anything is possible, and personally I find situations in which anything is possible to be quite uninteresting.

If you can come up with a good reason why the big bang *can't* be something, that's a lot more interesting.

No, it's not possible that relativistic effects cause particles to "slow down." Relativity doesn't cause things to slow down.

It is true that as things get hotter, they tend to break down, but this has nothing to do with relativity. Take a block of ice, heat it up, it melts. Heat it up even more, it turns into gas.

Also one mistake that people make about the big bang is that they assume that it much have exotic physics. In fact much of the standard model doesn't involve exotic physics. If you go to t=0, you can make up anything you want because no one has any clue what happens. If you go to t=300,000 years, the temperature of the universe is 3000 kelvin. Since we deal with 3000 degree gases all of the time, you can't randomly make stuff up, and so personally I find those problems more interesting.

When you talk about gluon reactions, you have a lot of room to make stuff up. However, the temperature of the universe very quickly goes to several million degrees and for those temperatures, you can do lab experiments.




In any event, are gluons immune to relativistic effects? The particles keep moving fast - at high enough temperatures each atom/nuclear particle/sub-nuclear particle become individual bodies because they are all moving so fast independently. The particles simply become more fragile. The fact that the slowdown of EM means that protons will no longer repulse one another as much, but it would also weaken the gluons. The whole structure of the body becomes more fragile. Any sort of impact with other particles/nuclei would have a destructive effect - and they would break apart. The orphaned particles would then pick up even more of the energy from those zero-rest-mass (ZRM) particles as they slowed down.[/QUOTE]