JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 The big bang model says nothing about that. I know it doesn't that's why it was a question . An infinite space, always was, always is and always will be , could not have a starting point, all observers from any geometrical position would observe infinite, there could not be a starting point?
Strange Posted May 4, 2017 Posted May 4, 2017 I know it doesn't that's why it was a question . An infinite space, always was, always is and always will be , could not have a starting point, all observers from any geometrical position would observe infinite, there could not be a starting point? Indeed. If space is infinite, then it has always been infinite. 1
Delta1212 Posted May 4, 2017 Posted May 4, 2017 I know it doesn't that's why it was a question . An infinite space, always was, always is and always will be , could not have a starting point, all observers from any geometrical position would observe infinite, there could not be a starting point? If space is infinite, it has always been infinite. That infinite space just used to be more dense than it is now.
Strange Posted May 4, 2017 Posted May 4, 2017 If space is infinite, it has always been infinite. That infinite space just used to be more dense than it is now. Just to avoid confusion, the contents of that infinite space used to be more dense than now.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 (edited) If space is infinite, it has always been infinite. That infinite space just used to be more dense than it is now. I would of thought the opposite personally and the space would of been less dense until some how gravity appeared? Edited May 4, 2017 by JohnLesser
Delta1212 Posted May 4, 2017 Posted May 4, 2017 Just to avoid confusion, the contents of that infinite space used to be more dense than now. Yes, given the conversation so far, I guess that would be important to specify.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 Just to avoid confusion, the contents of that infinite space used to be more dense than now. How can it be more dense?
Strange Posted May 4, 2017 Posted May 4, 2017 I would of thought the opposite personally and the space would of been less dense until some how gravity appeared? Well, the evidence shows that the density (and therefore temperature) used to be higher. And gravity has always been there.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 Well, the evidence shows that the density (and therefore temperature) used to be higher. And gravity has always been there. I must then presume that you are talking about observable universes inside an infinite space , i.e BH's
Strange Posted May 4, 2017 Posted May 4, 2017 I must then presume that you are talking about observable universes inside an infinite space , i.e BH's Well, obviously, we can only base our theories on what we can observe, i.e. the observable universe. However , the observable universe is not a black hole (I assume that is what BH stands for).
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 Well, obviously, we can only base our theories on what we can observe, i.e. the observable universe. However , the observable universe is not a black hole (I assume that is what BH stands for) How do you know our observable Universe is not a Black hole in an infinite universe? Let me explain your very own balloon analogy. The Observable Universe is expanding, Imagine dots on a balloons surface and the balloon inflates. That would not be entirely correct. Imagine a virtual box and inside the box it is dark. Now inflate the balloon with the dots on the surface as before, the universe is not expanding, the light point sources are extending allowing us to see further into the darkness of the box, That would be entirely accurate?
Strange Posted May 4, 2017 Posted May 4, 2017 How do you know our observable Universe is not a Black hole in an infinite universe? Let me explain your very own balloon analogy. The Observable Universe is expanding, Imagine dots on a balloons surface and the balloon inflates. That would not be entirely correct. Imagine a virtual box and inside the box it is dark. Now inflate the balloon with the dots on the surface as before, the universe is not expanding, the light point sources are extending allowing us to see further into the darkness of the box, That would be entirely accurate? I'm not good with analogies. But the first one sounds reasonably accurate (as long as you are only considering the 2D surface of the balloon as an analogy for 3D space.) The second sounds wrong. None of which has anything to do with black holes. The mathematics of a black hole is quite different from an expanding universe.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 I'm not good with analogies. But the first one sounds reasonably accurate (as long as you are only considering the 2D surface of the balloon as an analogy for 3D space.) The second sounds wrong. None of which has anything to do with black holes. The mathematics of a black hole is quite different from an expanding universe. The mathematics of Einstein fitted our visual Universe inside of a BH. The second one is much more accurate than the first one, the balloons skin is not actual there, the balloons skin is to show a light sphere, the sphere expands because the point sources are moving away from a central point, if you removed the point sources from the virtual light sphere the observable Universe would contract to the edge of the milky way.
Strange Posted May 4, 2017 Posted May 4, 2017 The mathematics of Einstein fitted our visual Universe inside of a BH. Citation needed. The second one is much more accurate than the first one, the balloons skin is not actual there, the balloons skin is to show a light sphere, the sphere expands because the point sources are moving away from a central point, if you removed the point sources from the virtual light sphere the observable Universe would contract to the edge of the milky way. The increasing size of the observable universe is not the same thing as the expansion of space. (Although it does depend on the rate at which expansion occurs.)
sunshaker Posted May 4, 2017 Posted May 4, 2017 My "2 pennies worth", In my view, "Space" is expanding at every point, So has you blow the balloon up, your allowing a place/volume for space to expand into, the space already in the box is/was continually expanding out of the box.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 (edited) Citation needed. The increasing size of the observable universe is not the same thing as the expansion of space. (Although it does depend on the rate at which expansion occurs.) Space itself does not expand, it is made of nothing, the light between bodies is stretched the more distance, space itself does not redshift, it is the light that redshifts that is being emitted/reflected by the receding bodies. The light is expanding relative to moving bodies, it is the same thing in my eyes. My "2 pennies worth", In my view, "Space" is expanding at every point, So has you blow the balloon up, your allowing a place/volume for space to expand into, the space already in the box is/was continually expanding out of the box. It would expand equally at every point if the surface existed, the surface only exists where the points are on the surface that doesn't exist. added - it may be easier to consider a ghost who has paint splatters on his surface and inflating the ghost. You can observe the splats but you can't observe the ghost. Edited May 4, 2017 by JohnLesser
Strange Posted May 4, 2017 Posted May 4, 2017 Space itself does not expand, it is made of nothing OK. Space doesn't expand, but the distance between things increases. Is that better? Note that distance is made of nothing but it increases. But I assume that's not a problem?
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 OK. Space doesn't expand, but the distance between things increases. Is that better? Note that distance is made of nothing but it increases. But I assume that's not a problem? Thank you Strange, yes that is much more accurate in description and I have no complaints. So is it right to assume that beyond our observable Universe there is more space that the ''balloon'' is ''expanding'' into?
Silvestru Posted May 4, 2017 Posted May 4, 2017 So is it right to assume that beyond our observable Universe there is more space that the ''balloon'' is ''expanding'' into? I thought from your analogy that the observable universe is the balloon itself.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 (edited) I thought from your analogy that the observable universe is the balloon itself. Technically yes, but you can't see the skin of the balloon you can only see the points on the balloon. Only the points reflect or emit light , we can't see anything else. If we removed all the point sources from the space, although there was light, it would be relative dark to you. Believe it or not the darkness you see between distant bodies is actually daylight. There is just nothing to see that is reflecting or emitting light. The balloons skin in my mind represents the light we cant see between bodies. Edited May 4, 2017 by JohnLesser
Strange Posted May 4, 2017 Posted May 4, 2017 So is it right to assume that beyond our observable Universe there is more space that the ''balloon'' is ''expanding'' into? It is generally assumed that the universe outside the observable universe is pretty much the same as what we see. There is no reason to think otherwise. Technically yes, but you can't see the skin of the balloon you can only see the points on the balloon. Fair point.
Delta1212 Posted May 4, 2017 Posted May 4, 2017 Thank you Strange, yes that is much more accurate in description and I have no complaints. So is it right to assume that beyond our observable Universe there is more space that the ''balloon'' is ''expanding'' into? The 2D surface of the balloon isn't expanding into anything. It is just getting larger. Same goes for 3D expansion.
JohnLesser Posted May 4, 2017 Author Posted May 4, 2017 It is generally assumed that the universe outside the observable universe is pretty much the same as what we see. There is no reason to think otherwise. Fair point. This is where multi-verse come in to affect, the realism of a multi-verse is what we are discussing now, if we can imagine several ''balloons'' floating around in a box in darkness, each balloon an isolated system but only isolated by the laws of light. They may view us as a black hole? The 2D surface of the balloon isn't expanding into anything. It is just getting larger. Same goes for 3D expansion. Scientific method proves for things to expand there has to be more space to expand into, I do not buy into this before the BB was nothing malarkey , evidence suggest otherwise.
Mordred Posted May 4, 2017 Posted May 4, 2017 Its more accurate to treat space itself as just the volume. However the standard model of particles reside in this volume of space. Expansion is a graviational and thermodynamic system. Though when you study enough you learn that GR also contains thermodynamics. Each particle species has a thermodynamic equation of state. This equates its potential energy (energy density/mass density/potential energy) to its pressure influence/kinetic energy. Details here. https://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology) In cosmology we treat everything we see as an ideal gas. Expansion follows all the rules of a homogeneous and isotropic adiabatic fluid. Universe geometry ie curvature is a relation between critical density to actual density. Details here. http://cosmology101.wikidot.com/universe-geometry page 2 http://cosmology101.wikidot.com/geometry-flrw-metric/ In GR curvature follows a different math relation. That of a vector map of kinematic freefall motion. Both forms of curvature are differential geometry relationships. In one case its a history of expansion density change in the latter case its a vector field mapping worldlines. (though density is intrinsic to GR as well). The FLRW metric also maps wordlines. Both treat space as simply the volume, we apply a set of coordinates to this volume, we add the time component to this coordinate map as this allows us to map how the density relations affect the wordline paths of light (null geodesics, freefall path of light). Universe geometry also affects light paths just as GR does. Both are affected by density gradient relations. (If you put together the above "What curves in spacetime is the density gradients influence upon the worldline paths of light) it is those paths that are curved. (through thermodynamic and gravity relations).
Pugdaddy Posted May 4, 2017 Posted May 4, 2017 Space is being created everywhere at once as a function of time. There is a doubling factor. That is why things further away move away faster. If you make a grid of space with say a galaxy "A" in one grid and another galaxy "B" in the grid next to it and another galaxy "C" in the grid next to that, after one doubling the galaxy "A" would see galaxy "B" twice as far away and galaxy "C" 4 time as far.
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