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Stephens Hawking's - 'Did God Create The Universe?'
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AugustusMinimus wrote: »The passage of time is completely a human interpretation of the time dimension though
That's what I was getting at
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AugustusMinimus wrote: »As I've said above, some believe that the unvierse is shaped like a 4 dimension sphere. We obviously can't imagine this as it's beyond our comprehension.
The easiest way to think of it is by dropping on dimension. So, imagine a universe where everyone is flat. There are only 3 dimenions, width, length and time.
This universe will be shaped like a sphere. Everyone will live on the surface of the sphere. The size of this universe will be limited to the surface of the sphere and obviously, this universe will have no edge.
The time dimension is then the axis from the centre of the sphere to the surface of the sphere. The expansion of the universe will be caused by the sphere simply getting bigger. The sphere will be growing along the time dimension. The big bang that created this universe happened at the centre of the sphere which is back in the past. The space inside the sphere represents the past. The space outside the sphere (which the surface is expanding into) represents the future.
The expansion of the this universe, which is the width and lenght dimensions growing outwards, creates time as these two dimensions are moving along the time dimension.
Obviously, this is just for a flat world. Now you've just got to imagine the same for our universe. Instead of the surface of this sphere being a flat world, the surface of the 3 sphere (which is our universe) is actually 3 dimensional and is everything we can see.
That's a very eloquent description, thank you 0 -
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That's a very eloquent description, thank you
A 3 sphere isn't the only theory everywhere.
Homer Simpsons favours the doughnut shaped universe, where everyone lives on the surface of a 4 dimensional torus (doughnut).
There is also the possibility of the universe being the shape of a klein bottle which is a 4 dimensional version of a mobius strip, which of course, only has one side.0 -
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I don't profess to know very much about it at all, but is the universe, or is it not, expanding in an outward direction?
No. If the universe was expanding outwards it would mean the universe was expanding into something other than itself a pre existing space if you will. the expansion of the universe is not described in motion but as the relative seperation of its parts. Objects in the universe are not moving away from each other, the space between them in increasing which is why distant objects can be expanding away from each other at speeds more than that of the speed of light.
Im not going to use the balloon or bread rising analogies because they only suffice to explain the apparent increase in distance between points with further expansion. in either instance the balloon or the bread is expanding in already pre-existing space
However i will take a stab at one. Say you are on a ship in the ocean and you look all around at your horizon, everything you can see right now we will call your observable ocean. in this instance the ocean is not expanding. The point at where you are viewing would appear to be the centre of your ocean. take another observer that resides far outside of your field of view and they can also say relative to them they are at the center of their ocean. to get the true center of the ocean in this exercise its obvious you need to know the boundaries of the ocean, you cant do any measuring without such dimensions.
Now what happens if that ocean is expanding while your trying to ascertain where the center may be?
The problem with expanding space is there is no edge, were not measuring space when we say our observable universe. we are measuring what we can presently see (in much the same way the person out at sea will see a different observable ocean relative to them at the horizon). For all intensive purposes given the rate of expansion and the observation that its not slowing down space could very well be infinite even if the universe is not.
I think the problem is some may assume that objects are actually moving or accelerating away from each other.
Dont think of it this way: (where the objects are moving away from each other)
Think of it this way: (just the dimension of space in between them that increases)
Although its very difficult to illustrate with images
The very fabric of reality could very well be a fixed size or have a limit but the dimension of space is not fixed.
Not to scale
Images uploaded with ImageShack.us0 -
No. If the universe was expanding outwards it would mean the universe was expanding into something other than itself a pre existing space if you will.
Obviously there's no pre-existing space for it to expand into, what I'm saying on the most basic of levels, is, is the universe getting larger with the passage of time? If so, surely in the past it was smaller? If time's arrow were reversed, would we not see the universe contract rather than expand?slade_x wrote:the expansion of the universe is not described in motion but as the relative seperation of its parts. Objects in the universe are not moving away from each other, the space between them in increasing which is why distant objects can be expanding away from each other at speeds more than that of the speed of light.
Yes, the space between objects is increasing with the foreward passage of time. Do you not think it's plausible to think that far enough back in time, the space between objects was much, much, much less, & that all matter in the universe existed at a single point?slade_x wrote:Im not going to use the balloon or bread rising analogies because they only suffice to explain the apparent increase in distance between points with further expansion. in either instance the balloon or the bread is expanding in already pre-existing space
True, its trying to word & visualise this stuff at the best of times
slade_x wrote:However i will take a stab at one. Say you are on a ship in the ocean and you look all around at your horizon, everything you can see right now we will call your observable ocean. in this instance the ocean is not expanding. The point at where you are viewing would appear to be the centre of your ocean. take another observer that resides far outside of your field of view and they can also say relative to them they are at the center of their ocean. to get the true center of the ocean in this exercise its obvious you need to know the boundaries of the ocean, you cant do any measuring without such dimensions.
Good analogy. But to take things stellar again, can't we observe & measure the expansion of space between objects? I'm not saying we can ever find the 'true center', but can't we at least establish from said measurements that there is an expansion in the first place, & deduce that a reversed expansion would likely indicate an origin?
None of this prob makes sense, I'm rubbish at trying to word this stuff & write down how I understand it in my mind
slade_x wrote:Now what happens if that ocean is expanding while your trying to ascertain where the center may be?
Again, I don't think there is a center 'position', because as you rightly say, to have a central position would require space in the first place.slade_x wrote:The problem with expanding space is there is no edge, were not measuring space when we say our observable universe.
Makes sense. Slightly off topic but it's something I've always wondered - when we say the universe is 13.7 Billion years old, that's only what we see of it, correct? Is it possible, to refer back to your ocean analogy, that there are points in the universe which we cannot observe, & never will be able to as they are so far away, the light from them will never reach us due to the expansion?slade_x wrote:we are measuring what we can presently see (in much the same way the person out at sea will see a different observable ocean relative to them at the horizon). For all intensive purposes given the rate of expansion and the observation that its not slowing down space could very well be infinite even if the universe is not.
That touches on my question above. Regards space being infinite, doesn't the CMB allow us to 'date' the universe? How does this picture fit in with an infinite space theory?slade_x wrote:I think the problem is some may assume that objects are actually moving or accelerating away from each other.
Dont think of it this way: (where the objects are moving away from each other)
Think of it this way: (just the dimension of space in between them that increases)
Although its very difficult to illustrate with images
The very fabric of reality could very well be a fixed size or have a limit but the dimension of space is not fixed.
Not to scale
Images uploaded with ImageShack.us
Good pics, cheers. But although the objects arn't moving away from each other, the distance between them is expanding isn't it? Take the lower diagram, if the two points were two galaxies ok...If you had a ship that could travel between them, and it did two trips. One from A to B, & one from B back to A. Surely the trip from B to A would take the ship longer, due to the expansion that's taken place since it initially set off from A to B?
Sorry if none of this makes sense, I find it all fascinating & love all this stuff 0 -
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Obviously there's no pre-existing space for it to expand into, what I'm saying on the most basic of levels, is, is the universe getting larger with the passage of time? If so, surely in the past it was smaller? If time's arrow were reversed, would we not see the universe contract rather than expand?
I didnt think this is what we are arguing as that is the reasoning behind most of the big bangYes, the space between objects is increasing with the foreward passage of time. Do you not think it's plausible to think that far enough back in time, the space between objects was much, much, much less, & that all matter in the universe existed at a single point?
One single point? And thats the problem with modern cosmology although the expansion of the universe does indicate that in the past the distances would have been less and theres no arguing with the observed expansion or the reasoning that yes in the past distances would have been less, there is no actual evidence to support the singularity as some physicists would say. there is evidence for expansion but no evidence that all matter existed at one infinitesimally small point. The proponents of the classical big bang theory even say they dont know what banged how it banged etc. So it remains one of many theories
It could very well be that our universe is a cause from something that occured in another, a place where our laws of physics as they are now were completely different(or something even stranger than that) and from that arose a reaction that our universe expanded from and physics evolved from there into what we have now. those universes may not even exist anymore as the very instability that caused the reaction makes them unstable and unable to last, so the total mass and energy of the universe could be a result from even two or more other universes. But that would be one idea of many. without any kind of proof its not a science but speculation as is the singularity but i do get the reasoning behind it& deduce that a reversed expansion would likely indicate an origin?
yes but an origin from where, this is the point. the origin of our universe did not come from within our universe because it didnt exist until its creation. this is unlike any of the analogies i can use which is kind of what makes them a little useless because it would only describe stretching or expanding a fabric in an already pre existing spaceMakes sense. Slightly off topic but it's something I've always wondered - when we say the universe is 13.7 Billion years old, that's only what we see of it, correct?
yes thats it, but the age of the universe is based on the big bang theory. the initial cooling period after it took place and the expansion since then is where that estimate comes from give or take .1 or .2 billion years. it is basically dating what we think its the intial evolution and then expansion of the universethat there are points in the universe which we cannot observe, & never will be able to as they are so far away, the light from them will never reach us due to the expansion?
Basically yesThat touches on my question above. Regards space being infinite, doesn't the CMB allow us to 'date' the universe? How does this picture fit in with an infinite space theory?
Well space continues to expand. No one knows if the end result will be an eventual contraction or if space will keep expanding so much so that the very space between atoms begins to expand (which there is already a hell of a lot of, and then eventually protons and neutrons being seperated by increasing space).
The energy (dark energy) or whatever it is thats driving the expansion is definitely not finite as it is ever increasing so space is ever expanding without knowing how long this will last the word infinite can come to mind.
Note: space at any moment in time may not be infinite but its potential to expand could very well be
If space continues to expand until the universe is practically torn apart an observer will still be able to use the cmb (increased sensitivity will no doubt be a requirement) and expansion to date the age of this construct since its going to take lots and lots of what we call time for that to happen. The very expansion itself is key to estimating how old the universe is as with time its going to keep going.Good pics, cheers. But although the objects arn't moving away from each other, the distance between them is expanding isn't it? Take the lower diagram, if the two points were two galaxies ok...If you had a ship that could travel between them, and it did two trips. One from A to B, & one from B back to A. Surely the trip from B to A would take the ship longer, due to the expansion that's taken place since it initially set off from A to B?
Yes using conventional propulsion systemsSorry if none of this makes sense, I find it all fascinating & love all this stuff
I wouldnt apologise for not making sense, many people as you well know questioned things with a different type of sense, we like to call this common sense now. just because one doesnt get a particular form of reasoning doesnt make it in correct as long as the method is scientific
Its very difficult to put a description of this sort into words. And i am by no means an expert but take for example the proposers of the higgs boson
basically a particle thats responsible for particles (for certain types which make the nucleus of atoms etc). So the very thing that causes volume and mass actually started out with volume and mass in the first place. Leading me to believe this higgs boson is not a particle as we define the word at all. When i think of mass i think mostly of energy. so the energy liberated from collisions in say the lhc is quantified and given a particle name for the amount of energy in the form of mass
On a fundemental level i see everything as energy which it is by einsteins equation mass does have an equivalence to energy and vice versa since they are the same thing. Mass being the manifestation of energy. now im not sure if that makes much sense to anyone even though were all aware of the mass and energy equivalence how about forgetting about mass on a fundemental level where everything is energy and mass is just our manifestation of how we see that energy. a particles mass is measured as energy.
Also as you may have guessed im not that big of a fan with the big bang theory in its entirety. the bit that gets me is the "singularity" which is not an explanation just something we have to assume.0 -
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