I want to just remind myself that the standard assumption is only based on Einstein's general relativity being correct.
The Fate of the Cosmos Isn't Necessarily Dependent on the Amount of Matter
- Thread starter common_sense_seeker
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Just some thoughts about that statement.
True, if there is a greater universe out there. If so then the landscape of the greater universe comes into play on a grand scale, but within any given arena (like our observable expanding arena) GR is perfectly adequate until that expansion is interrupted
. And after an interruption like the intersection of two expanding arenas, GR would again begin to apply to each overlap because a new arena forms from the overlap. GR can handle a collapsing arena or an expanding arena. It just doesn't allow for the eventuality that there are both going on out there at the same time in different arenas.
Also, assuming that the universe is homogeneous and isotropic on a grand scale as well as at the arena level, i.e. the cosmological principle, why wouldn't GR apply to cosmology on all scales. GR doesn't apply on the smallest scales so we need to be aware that there needs to be more work to unite GR and the Particle Model. Spacetime vs. energy density IMHO
, but that doesn't change what gravity does in cosmology, only how it works i.e. the mechanism.I was lost a little bit in your terminology. My knowledge of GR is somewhat limited and out-of-date though. It seems to come down to Luminet's chapter 5, 'Absolute or Relative Space'? Even this title is quite limiting in suggesting that only these two options are contenders. Is another combination of Newton's vision and Einstein's vision possible? I think it is. How to describe it in professional terms is difficult.Just some thoughts about that statement.
True, if there is a greater universe out there. If so then the landscape of the greater universe comes into play on a grand scale, but within any given arena (like our observable expanding arena) GR is perfectly adequate until that expansion is interrupted
And after an interruption like the intersection of two expanding arenas, GR would again begin to apply to each overlap because a new arena forms from the overlap. GR can handle a collapsing arena or an expanding arena. It just doesn't allow for the eventuality that there are both going on out there at the same time in different arenas.
Also, assuming that the universe is homogeneous and isotropic on a grand scale as well as at the arena level, i.e. the cosmological principle, why wouldn't GR apply to cosmology on all scales. GR doesn't apply on the smallest scales so we need to be aware that there needs to be more work to unite GR and the Particle Model. Spacetime vs. energy density IMHO
Newton's absolute space could be made richer by introducing the finite universe with a wraparound 'hypersphere'. This hypersphere could be expanding independently of the amount of matter in the cosmos. This is picture that I have. Is this so ludicrious? The hypersphere could have come into existence just before that of matter for example. Irregular activities within the 'outer' dimension could be influencing the fate of the cosmos, couldn't they?
My analogy is to think of a higher dimension that suddenly creates a void due it's irregular dynamics. This void expands and energy from the higher dimension finally penetrates our universe with a high energy build-up of radiating structure of matter. Because our brains have evolved to comprehend Euclidean space, there will always be the need of either tricks of mathematics or tricks of the imagination to comprehend the big picture. What will a computer simulation of creation look like? Can you imagine such a thing?
If a circular screen of the 1980's 'asteroids' game is thought of, where rocks suddenly appeared on the opposite side of the screen to where they went off is envisaged, then a trick can be used to represent the 4D topology. The amount of time taken for the asteroids to appear can vary. This is then a way of simulating the non-uniform shape of the 4D universe. I'm rambling a bit now, so I'll give you time to respond to what I've said in general.
I'm not requesting it yet but I might have to request scans if we can't talk this through without me reading chapter 5. I think I know what it might say.
This is from Newton: http://mysite.pratt.edu/~arch543p/readings/Newton.html
"Hitherto I have laid down the definitions of such words as are less known and explained the sense in which I would have them to be understood in the following discourse. I do not define time, space, place, and motion, as being well known to all. Only I must observe that the common people conceive those quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common."
Is the distinction in chapter 5 the same as Newton's, i.e. absolute, true and mathematical vs. relative, apparent and common. The physical picture of the real universe is absolute, true and mathematical while the common perseption due to observation can be relative, apparent and common?
This is from Newton: http://mysite.pratt.edu/~arch543p/readings/Newton.html
"Hitherto I have laid down the definitions of such words as are less known and explained the sense in which I would have them to be understood in the following discourse. I do not define time, space, place, and motion, as being well known to all. Only I must observe that the common people conceive those quantities under no other notions but from the relation they bear to sensible objects. And thence arise certain prejudices, for the removing of which it will be convenient to distinguish them into absolute and relative, true and apparent, mathematical and common."
Is the distinction in chapter 5 the same as Newton's, i.e. absolute, true and mathematical vs. relative, apparent and common. The physical picture of the real universe is absolute, true and mathematical while the common perseption due to observation can be relative, apparent and common?
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quantum_wave;
Apologies for switching subject but I've just had a daydream this morning concerning another lecturer of mine saying, some 20 odd years ago now btw, that the biggest puzzle in cosmology was the 'Missing Mass'. He then later corrected himself saying that it was really the missing Energy that was the mystery. This picture that I have seems to fit the bill with ease; the Missing Mass is the matter build-up before the big bang which largely annihilated itself, just leaving the universe we see today. The irreguarity of the annihilation is, I propose, due to the difference in timing of the arrival of wraparound gravity particles around the 'hypersphere'. This irregularity would have caused the opposing tightly balanced branches to crash past one another in a tumultuous cataclysm. The missing Energy is the collosal radiative power of the initial build-up of matter returning as a cosmological force of repulsion! I predict therefore that the expansion of the universe will continue to come in waves i.e. a Hesitant Universe just like Lemaitre calculated all those years ago..
I even have the image of 'god's hand' moulding the material of the hypersphere which would lead to the Creation. And I'm not even religious! :bugeye:
Apologies for switching subject but I've just had a daydream this morning concerning another lecturer of mine saying, some 20 odd years ago now btw, that the biggest puzzle in cosmology was the 'Missing Mass'. He then later corrected himself saying that it was really the missing Energy that was the mystery. This picture that I have seems to fit the bill with ease; the Missing Mass is the matter build-up before the big bang which largely annihilated itself, just leaving the universe we see today. The irreguarity of the annihilation is, I propose, due to the difference in timing of the arrival of wraparound gravity particles around the 'hypersphere'. This irregularity would have caused the opposing tightly balanced branches to crash past one another in a tumultuous cataclysm. The missing Energy is the collosal radiative power of the initial build-up of matter returning as a cosmological force of repulsion! I predict therefore that the expansion of the universe will continue to come in waves i.e. a Hesitant Universe just like Lemaitre calculated all those years ago..
I even have the image of 'god's hand' moulding the material of the hypersphere which would lead to the Creation. And I'm not even religious! :bugeye:
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quantum_wave;
Apologies for switching subject but I've just had a daydream this morning concerning another lecturer of mine saying, some 20 odd years ago now btw, that the biggest puzzle in cosmology was the 'Missing Mass'. He then later corrected himself saying that it was really the missing Energy that was the mystery. This picture that I have seems to fit the bill with ease; the Missing Mass is the matter build-up before the big bang which largely annihilated itself, just leaving the universe we see today. The irreguarity of the annihilation is, I propose, due to the difference in timing of the arrival of wraparound gravity particles around the 'hypersphere'. This irregularity would have caused the opposing tightly balanced branches to crash past one another in a tumultuous cataclysm. The missing Energy is the collosal radiative power of the initial build-up of matter returning as a cosmological force of repulsion! I predict therefore that the expansion of the universe will continue to come in waves i.e. a Hesitant Universe.
I even have the image of 'god's hand' moulding the material of the hypersphere which would lead to the Creation. And I'm not even religious! :bugeye:
You got a hold of some good stuff last night. I have a couple of thoughts about what you are conveying. I like to speculate and discuss other's speculations so whether the ideas come from dreams and even if they invoke the supernatural, they can lead to good discussion.In particular the missing energy is not resolved by the Big Bang. We left off the discussion on The Genius of Lemaitre thread after my post that included:
In that footnote the missing energy is introduced. It was considered missing if macro and micro realms were to be compatible. The Big Bang didn't resolve a previous condition of missing mass or energy, the discrepancy exists based on what we observe today. The discussion of dark matter arises from observation of galactic motion and dark matter offers a solution to the missing mass/energy question.QW said:
The galactic dynamics mystery is independent of the cosmological expansion mystery IMHO. I still think that the anti-gravity idea has good potential in at least being part of this cosmic dark energy that we observe.
Alright, repulsive gravity is an interesting idea but to discuss it you need to do so with some methodology. I suggest that you find a point in the mainstream consensus and them show how your idea is compatible or at least not inconsistent. Say that you start with the consensus I refer to as the standard cosmology, i.e. BBT with inflation. Your view of the circumstances preceding the Big Bang should be logically connected from those circumstances to the Big Bang. Just like everything that we observe has to be causally connected to the Big Bang in order to be part of BBT, the Big Bang itself must be causally connected to what ever preceded it.
I think we are along the same lines. I would like to do a computer simulation of this suggested build-up of matter, but it is beyond my capabilities now. The picture in my head seems easy to visualise, but when putting it down on paper it becomes more difficult.
Join the club. That difficulty is what the mainstream professionals are working on and you can bet that when there is a mathematically sound simulation of cosmology that shows how GR and QM work together it will be on TV
. Until then we can only convey our view of the physical picture in what I call word salad. That phrase is not meant to be derogatory in this usage but certainly it conveys the difficulty of discussing views and ideas with someone who cannot or will not speculate or discuss someones speculations. Those discussions belong in Pseudoscience where demands for quantification are off topic. Such demands serve their purpose in the hard science forums like Physics and Math, and Cosmology, and if things work properly those unquantified discussions end up here where they can be discussed more openly.
I also like your phrase repulsive gravity - thanks for that.Join the club. That difficulty is what the mainstream professionals are working on and you can bet that when there is a mathematically sound simulation of cosmology that shows how GR and QM work together it will be on TV
Until then we can only convey our view of the physical picture in what I call word salad. That phrase is not meant to be derogatory in this usage but certainly it conveys the difficulty of discussing views and ideas with someone who cannot or will not speculate or discuss someones speculations. Those discussions belong in Pseudoscience where demands for quantification are off topic. Such demands serve their purpose in the hard science forums like Physics and Math, and Cosmology, and if things work properly those unquantified discussions end up here where they can be discussed more openly.
Oh gees, don't give me credit for that. The Chapter in Lemaitre's book was called Cosmic Repulsion and your speculations parley that into Repulsive Gravity. That makes it your hot potatoI also like your phrase repulsive gravity - thanks for that.
. Besides, someone beat us both http://www.google.com/search?hl=en&q=Repulsive+Gravity&btnG=Google+Search&aq=f&oq=&aqi=.
Daah, I haven't even seen these links. I was embarassed at first but then when looking through I couldn't see the simple notion of the spinning helix structure acting as a mechanism to achieve 'repulsive gravity'. Or even the hypersphere I couldn't see mentioned..Oh gees, don't give me credit for that. The Chapter in Lemaitre's book was called Cosmic Repulsion and your speculations parley that into Repulsive Gravity. That makes it your hot potato
.
Then you are allowed to claim the term as it applies to your speculations. It becomes a part of the lexicon of your speculation
.I want to discuss the hypersphere with you. Would you mind doing a Google on it and picking a link that you think best describes your usage?
Sure, but I'll do it tomorrow; it's soon to my go against George my 9 year old godson, playing baseball on Wii. Bye for now.Then you are allowed to claim the term as it applies to your speculations. It becomes a part of the lexicon of your speculation
I want to discuss the hypersphere with you. Would you mind doing a Google on it and picking a link that you think best describes your usage?
The problem is that isn't how mass behaves.
Matter, or more specifically its gravity, curves space back somewhat, it tries to curl up space and so if you have enough of it you'd expect the universe to be closed. The gravitational effect which passes around a closed universe (like the toroidal one you are thinking of) doesn't manifest itself as space-time expansion. It might have the effect that it drags galaxies away from us but this is not synonymous with space-time expansion, it would actually be making the universe smaller. A universe which is undergoing accelerating expansion is open, it's not closed back on itself and things are being pushed apart from one another in all directions. This is quite different, even qualititatively, than pulling things together, even if they are being pulled together over the cosmological horizon.
Gravity from matter tries to constrict space-time, even if you've got a toroidal universe, so the overall size of the universe is decreasing. Dark energy, which fuels expansion, pushes things apart and makes the universe larger.
And you two are aware that a hypersphere is not the only compact 4 dimensional object, right?
With all due respect AN, I don't think that your input is going to help the proceedings between quantum_wave and myself. We are not adherring to the mainstream view of things, and so we have enough trouble defining our mental pictures without the hardline viewpoint being put in as a contender. I hope you understand that the comment isn't a personal one.The problem is that isn't how mass behaves.
Matter, or more specifically its gravity, curves space back somewhat, it tries to curl up space and so if you have enough of it you'd expect the universe to be closed. The gravitational effect which passes around a closed universe (like the toroidal one you are thinking of) doesn't manifest itself as space-time expansion. It might have the effect that it drags galaxies away from us but this is not synonymous with space-time expansion, it would actually be making the universe smaller. A universe which is undergoing accelerating expansion is open, it's not closed back on itself and things are being pushed apart from one another in all directions. This is quite different, even qualititatively, than pulling things together, even if they are being pulled together over the cosmological horizon.
Gravity from matter tries to constrict space-time, even if you've got a toroidal universe, so the overall size of the universe is decreasing. Dark energy, which fuels expansion, pushes things apart and makes the universe larger.
And you two are aware that a hypersphere is not the only compact 4 dimensional object, right?
I thought of a more specific term: Wraparound Archimedean Repulsive Gravity (WARG for short)!Then you are allowed to claim the term as it applies to your speculations. It becomes a part of the lexicon of your speculation
Here's a quote from Luminet to be getting on with;
Googling is a joke!!
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OK, you have WARG and I have QWC. I like the sound of yours and I guess mine should just be said Q W C. Otherwise it comes out sounding like quick and then the reference to quick sand looms out thereI thought of a more specific term: Wraparound Archimedean Repulsive Gravity (WARG for short)!
Here's a quote from Luminet to be getting on with;
“ "In 1917, Einstein constructed the first model of the Universe founded on his theory of relativity. He opted for a non-Euclidean geometry with positive curvature, allowing for a precise representation of a space that was both finite and limitless: the hypersphere, discovered by Bernhard Riemann a half-centuary earlier, which had the advantage of evading any edge paradox."
Googling is a joke!!
.Thanks for the quote from Luminet about Riemann space and avoiding the edge. That answers my question about your definition of "hypersphere" and we can agree on that usage. But to be up front, QWC is 3-D space with multiple and ever-changing arenas where time passes as a continuum that had no beginning and where everything is composed of energy. I guess you would say that WARG represents a finite universe with wrap around topography and repulsive gravity?
As for Google, I do get a laugh out of it but I keep going back.
We could be talking out our differences for a long time :argue:
My point is that unless you utterly throw relativity out of the window, you can't end up with something in which expansion can be viewed as an excess of matter. Too much matter = de Sitter universe. Too much dark energy = Anti de Sitter.