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The edge of the universe

  • 13-12-2009 11:43pm
    #1
    luckyfrank
    Closed Accounts Posts: 1,054 ✭✭✭


    It's hard to believe that the universe is not infinite, i mean there is a place where the universe just stops and then there in nothing

    no matter no space no time, but surly if the universe is expanding it must be expanding into something that wasnt there before

    Ive read before that it's not the universe that's expanding just that the space within it is expanding if that makes sense

    Hypothetical question : If i was standing on the very edge of the universe with a tennis ball in my hand and threw that ball over the edge what would happen to the ball ?


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Comments

  • #2
    Brian CivilEng
    Registered Users, Registered Users 2 Posts: 1,031 ✭✭✭Brian CivilEng


    luckyfrank wrote: »
    Hypothetical question : If i was standing on the very edge of the universe with a tennis ball in my hand and threw that ball over the edge what would happen to the ball ?

    The ball would not move as fast as the universe is expanding, so the ball would not leave the universe. The universe will have expanded and where you are standing will no longer be the edge.


  • #3
    Mena
    Registered Users, Registered Users 2 Posts: 3,180 ✭✭✭Mena


    abitofacomedian wrote: »
    The ball would not move as fast as the universe is expanding, so the ball would not leave the universe. The universe will have expanded and where you are standing will no longer be the edge.

    All well and good, but what if you had a really strong arm, and managed to throw said ball faster than the universe is expanding?

    Interesting question by the way.


  • #4
    Rockshamrover
    Registered Users, Registered Users 2 Posts: 1,472 ✭✭✭Rockshamrover


    What would happen if there was another universe expanding towards ours and they met each other? Would they just merge or repulse each other?


  • #5
    marco_polo
    Moderators, Science, Health & Environment Moderators Posts: 10,087 Mod ✭✭✭✭marco_polo


    luckyfrank wrote: »
    It's hard to believe that the universe is not infinite, i mean there is a place where the universe just stops and then there in nothing

    no matter no space no time, but surly if the universe is expanding it must be expanding into something that wasnt there before

    Ive read before that it's not the universe that's expanding just that the space within it is expanding if that makes sense

    Hypothetical question : If i was standing on the very edge of the universe with a tennis ball in my hand and threw that ball over the edge what would happen to the ball ?

    Because something is finite does not mean that is has an edge, the surface of a sphere is a finite 2D space yet it has no edges.

    Try to imagine a 3D shape that has such a property, without your head exploding, and you have a finite universe with no edge. :)

    A finite n-dimensional (3 or more) space is called a torus

    A nice introduction paper here that is not too technical
    http://www.maths.lse.ac.uk/Personal/mark/topos.pdf


  • #6
    r3nu4l
    Registered Users, Registered Users 2 Posts: 17,399 ✭✭✭✭r3nu4l


    Mena wrote: »
    All well and good, but what if you had a really strong arm, and managed to throw said ball faster than the universe is expanding?

    Interesting question by the way.
    I'm not sure we could to be honest. The tennis ball would have to comply with our laws of physics and these laws are the only frame of reference that we have for what may be 'outside' our universe. So I don't know what Physicians or astrophysicists have to say about that. It's a great question :)
    Rockshamrover wrote: »
    What would happen if there was another universe expanding towards ours and they met each other? Would they just merge or repulse each other?

    Again, I think that depends on the properties of that other universe. If it was composed mostly of anti-matter then we might enjoy a huge explosion or something, if it was largely the same as our own universe then perhaps different gravitational effects would come into play to decide what would happen...


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  • #7
    Flamed Diving
    Closed Accounts Posts: 6,609 ✭✭✭Flamed Diving


    Why does it have to be expanding into something? For all we know, the universe is all the space there is, and by expanding more space is created. No "outside" space should be required.


  • #8
    A7X
    Closed Accounts Posts: 1,084 ✭✭✭A7X


    Flamed Diving wrote: »
    Why does it have to be expanding into something? For all we know, the universe is all the space there is, and by expanding more space is created. No "outside" space should be required.

    The problem is the human mind (at least mine) can't comprehend absolute nothing.

    It's so hard to think of absolute nothing. I said it to one of my friends before and all i got was him replying without think " Well there would just be nothing". But can you imagine it? I can't.


  • #9
    Flamed Diving
    Closed Accounts Posts: 6,609 ✭✭✭Flamed Diving


    A7X wrote: »
    The problem is the human mind (at least mine) can't comprehend absolute nothing.

    It's so hard to think of absolute nothing. I said it to one of my friends before and all i got was him replying without think " Well there would just be nothing". But can you imagine it? I can't.

    I can't remember the philosophical argument that explains why nothing, by definition, cannot exist, and therefore is merely an abstraction and does not require you to imagine it. Anyone?


  • #10
    Ingenuist
    Closed Accounts Posts: 68 ✭✭Ingenuist


    Question of the century OP


  • #11
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,488 Mod ✭✭✭✭Capt'n Midnight


    It's handy to think of the universe as the observable universe. It doesn't matter what is out there if there is no interaction with it.

    My understanding of it is that if there is anything further away than 13 Billion light years we will see more of it as time goes on since some of the universe isn't expanding at the speed of light. But it would take a LONG time for that to be apparent.


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  • #12
    stevenmu
    Moderators, Society & Culture Moderators Posts: 9,689 Mod ✭✭✭✭stevenmu


    The way I think of it, and I've no idea how correct this is, is that objects which occupy space conform to the shape and nature of the space they occupy. A little bit like one of those distorting mirrors, except instead of distorting just your reflection it distorts absolutely everything. So when you throw your ball it would appear to just go straight off towards infinity but would actually be following the curves around the edge of the universe.

    It's hard to explain but it was well illustrated by M.C. Escher (who had a knack for illustrating tricky concepts :)). Take a look at the main picture on this page. One of the basic concepts in it is that the angels in it are all actually the same size, the look smaller the closer to the edge they get from our perspective, but from the angel's own perspective they are the same size, what we see is the distortion of the 2D space they are represented in. If you were an angel in that picture and threw a tennis ball it would continue to infinity (the edge we see would be infinitely far away to them), from our outside perspective it would seem to get smaller and smaller never reaching the edge.

    Hope that makes some kind of sense.


  • #13
    Akrasia
    Registered Users, Registered Users 2 Posts: 22,599 ✭✭✭✭Akrasia


    Capt'n Midnight wrote: »
    It's handy to think of the universe as the observable universe. It doesn't matter what is out there if there is no interaction with it.

    My understanding of it is that if there is anything further away than 13 Billion light years we will see more of it as time goes on since some of the universe isn't expanding at the speed of light. But it would take a LONG time for that to be apparent.

    If the universe is expanding slower than the speed of light, what happens to the light that is moving towards the edge of the universe?
    does it just get bounced or turned back?
    If it was bounced or turned back then the edge of the universe would look like some kind of mirror?


  • #14
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,488 Mod ✭✭✭✭Capt'n Midnight


    Akrasia wrote: »
    If the universe is expanding slower than the speed of light, what happens to the light that is moving towards the edge of the universe?
    does it just get bounced or turned back?
    If it was bounced or turned back then the edge of the universe would look like some kind of mirror?
    as I understand it a lot of the light will be red-shifted to the microwave background of 3K

    time is relative to the observer, if you shine a light towards an object travelling away at 0.5c it will take a long time to get to the object and a lot longer to get back , if the object is travelling near the speed of light you won't see the light for a very long time, this is why there is a limit to the observable universe and as time goes on we can see further into the universe. Only a long time will tell if we can see further away than now.

    we can see objects 13.1 billion light years away or rather we can see what it looked like 13.1 billion years ago , it wasn't 13.1 billion light years away back in those days
    http://www.newscientist.com/article/dn17035-most-distant-object-in-the-universe-spotted.html


  • #15
    pug_
    Registered Users Posts: 636 ✭✭✭pug_


    I remember when I was in school, a long time ago now, our physics teacher was telling us about a theory. The basic idea was if you had a hypothetical telescope that could see to the edge of the universe without being restricted by the laws of physics what you would see is the back of your own head.

    I always liked that idea as it suggests the universe has no edge as such so isn't expanding the same way say a balloon when blown up. In this hypothetical scenario if a ball was thrown from your current position (as there is no edge of the universe to throw it from) and again could break all known laws of physics (hypothetical ball here folks) it would eventually hit you in the back of the head having travelled in a straight line across the entire universe to bring it right back where it started.


  • #16
    Kidchameleon
    Closed Accounts Posts: 5,482 ✭✭✭Kidchameleon


    r3nu4l wrote: »
    we might enjoy a huge explosion

    Cant imagine id enjoy that myself! :D


  • #17
    20goto10
    Registered Users, Registered Users 2 Posts: 1,210 ✭✭✭20goto10


    luckyfrank wrote: »
    Hypothetical question : If i was standing on the very edge of the universe with a tennis ball in my hand and threw that ball over the edge what would happen to the ball ?
    The universe is donut shaped, so it would come out the other side. But because we see the universe in only 3 dimensions it will appear to disappear and reappear on the other side as if by magic. The same concept applies for a 2D world. If you go off the screen in space invaders you magically appear back from the other side. But if it was seen in 3D you'd simply be looping around a conical.


  • #18
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,488 Mod ✭✭✭✭Capt'n Midnight


    20goto10 wrote: »
    The universe is donut shaped, so it would come out the other side. But because we see the universe in only 3 dimensions it will appear to disappear and reappear on the other side as if by magic. The same concept applies for a 2D world. If you go off the screen in space invaders you magically appear back from the other side. But if it was seen in 3D you'd simply be looping around a conical.
    AFAIK wwe aren't 100% sure of the shape of the universe
    it may be finite
    it may be far larger than we can see
    it may be infinite
    but I doubt it's a torus

    academic anyway, because if you shone a light at the edge of the universe it would take 13.7 Bn years to get there and 13.7 Bn years to arrive from the other side ( or be reflected ) even if the light was still visible in 27Bn years time, the universe would have still expanded further so my understanding is that we would never see the light we shone, just the light emitted from there.


  • #19
    20goto10
    Registered Users, Registered Users 2 Posts: 1,210 ✭✭✭20goto10


    Capt'n Midnight wrote: »
    AFAIK wwe aren't 100% sure of the shape of the universe
    it may be finite
    it may be far larger than we can see
    it may be infinite
    but I doubt it's a torus

    academic anyway, because if you shone a light at the edge of the universe it would take 13.7 Bn years to get there and 13.7 Bn years to arrive from the other side ( or be reflected ) even if the light was still visible in 27Bn years time, the universe would have still expanded further so my understanding is that we would never see the light we shone, just the light emitted from there.
    True it's only theory so far. There's a $1mill prize for the first scientist to prove the shape of it and apparently all the signs are the results will be its torus. I saw a documentary on it, I think it was horizon so I'm sure the information is out there on the google. One scientist even went so far as to suggest one of the stars in the night sky could well be light from Earth millions or billions of years ago.

    Besides that, one thing's for sure its not as it seems to us in our 3 dimensional universe.


  • #20
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,488 Mod ✭✭✭✭Capt'n Midnight


    20goto10 wrote: »
    One scientist even went so far as to suggest one of the stars in the night sky could well be light from Earth millions or billions of years ago.
    If that were true the Hubble should have found symmetry in the skies because our sun is only 1/3rd the age of the universe so the light would have gone around at least 3 times

    Also the microwave radiation background seems to be damn close to the age of the universe, so nah that doesn't add up for me


  • #21
    Alvin T. Grey
    Closed Accounts Posts: 1,169 ✭✭✭Alvin T. Grey


    The universe = everything. Therefor the property of "outside" has no meaning. It's like asking what happened before the big bang. You are trying to describe something in terms of a property that it does not have.

    I like to think of the universe as a train that lays it's own track as it goes along. And where does it lay those tracks? - strictly speaking the answer is "custard" (or any other term not even distantly related to the question). I know it makes no sense but to hairless monkeys like ourselves it wouldn't.

    So a comfortable lie that we can deal with, the answer would be "right where it laid them".

    Remember in terms of the edges of cosmology, we are using brains developed for spotting ripe fruit, and a language developed for telling other monkies where that is.


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  • #22
    the culture of deference
    Banned (with Prison Access) Posts: 2,196 ✭✭✭the culture of deference


    So if our universe is 27 to 28 billion light years wide and is shown to be torus shape, my question is will we ever get to see the opposite side of the big bang.

    Will we ever be able to physically visit or communicate with our nearset star systems in our own galaxy. Even if we do manage to design something that could get us there in 4 years, the time that will have passed on earth will mean that we will never be able to communicate simultaneously.


  • #23
    amen
    Registered Users, Registered Users 2 Posts: 2,781 ✭✭✭amen


    Even if we do manage to design something that could get us there in 4 years, the time that will have passed on earth will mean that we will never be able to communicate simultaneously

    nor could most of the planet for most of recorded history.. thats why we had diplomats. could do the same thing here.


  • #24
    FTGFOP
    Registered Users, Registered Users 2 Posts: 2,389 ✭✭✭FTGFOP


    The idea of the Universe looping back on itself makes me claustrophobic, even though it's billions of light years wide!


  • #25
    the culture of deference
    Banned (with Prison Access) Posts: 2,196 ✭✭✭the culture of deference


    amen wrote: »
    nor could most of the planet for most of recorded history.. thats why we had diplomats. could do the same thing here.

    If I visited proxima centauri as a diplomat and it took me 4 years to get there and 4 years back, hundreds of thousands of years would have passed on earth. It's not like the old days where your reps were only 5 years max away.

    Think of the changes on earth that could happen in than timeframe.


  • #26
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    I imagine the Universe as being a sphere of space which I imagine as being a vast number of points with a repulsive property such that every point in space is trying to move away from every other point and as a consequence, the Universe expands.

    It is the distribution of energy that is interesting here. Firstly, it will be seen that there is no possible state of equilibrium for such a system or, to put it another way, the state of constant expansion is equilibrium for such a system.

    But it is the relationship between the centre of the Universe and the edge of the Universe that gives rise to all the characteristics that we can observe.

    Imagine if we were able to confine a large number of electrons in close proximity to each other in the shape of a spere using some kind of field; imagine that the density of the electrons was such that they were almost touching each other. Since all the electrons are negatively charge they repel each other and under confinement, the stress caused by this force is more or less evenly distributed. Then we remove the confinement field.

    At that moment, the distribution of forces changes; electrons located at the centre feel a crushing force while electrons at the surface of the sphere are easily liberated from the system with a certain amount of energy. There is an energy gradient, centre to surface, that ensures that the sphere decomposes dissipating energy over time.

    Since electrons are being removed from the system, over time the strength of the repulsive force diminishes which means that electrons tend to leave the system with decreasing energy over time.

    Also, it should be noted that since there is no possible way to arrange a collection of spheres into a larger sphere such that there is an even distribution of forces throughout the system, (during confinement, our system would have generated heat at the centre), not all the forces will be acting perpendicular to the centre. This results in the development of structure within the sphere which evolves as the sphere 'evaporates'.

    In the electron model, the first electrons liberated represent the edge of the Universe and they define the volume of the Universe. Although the force of these electrons is still an active part of the overall system they cannot be overtake by others; the energy put into liberating the first electrons is slightly greater than the energy put into subsequent liberations. If you were able to recede from the system so as to maintain a particular perspective then you would observe it to have constant volume but also having a dynamic internal structure. No matter how much the system expands, there will be interaction between the parts.

    The thing is, matter can't exist at the edge of the Universe; matter consists of bound space which would rapidly expand at the edge instantly decomposing it into EMR, or perhaps neutrinos, energy which then goes to shape the edge of the Universe.

    I think this model neatly demonstates why galaxies near the edge of the Universe are accelerated to a higher velocity than ones closer to the centre too.


  • #27
    Hijpo
    Registered Users, Registered Users 2 Posts: 3,887 ✭✭✭Hijpo


    luckyfrank wrote: »
    no matter no space no time

    if humans didnt measure it, would time exist?


  • #28
    Allosaur
    Registered Users Posts: 128 ✭✭Allosaur


    Hijpo wrote: »
    if humans didnt measure it, would time exist?
    From a humans point of view, no. The rest of the universe might have something to say about that, but heck, their opinion doesn't matter.


  • #29
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    Hijpo wrote: »
    if humans didnt measure it, would time exist?

    Time is an effect of a constantly changing Universe; if we couldn't measure time then the Universe would be static.

    Measuring time is simply a process of counting events. Accurately. But 'time' is not intrinsically of any value to nature. Rather, it provides a measurement system that allows us to plot graphs that record rates of change and this in turn allows us to deduce interesting things about nature. Time is one of those interesting things.

    The three dimensions of space are easy to visualise; they correspond to the set of all points in the Universe. All deterministic processes have degrees of freedom in those dimensions.

    But the Universe does seem to have another directional component, things change in a particular direction, hot to cold, but seems unlike any of the other directions in space; a fourth dimension. But determinism has no degrees of freedom along this direction; this direction is a property of space itself and is the source of determinism. This property of space causes change that would occur even in the absense of deterministic processes and this underlying force of change determistically creates a 'sub-space climate' from which reality emerges.

    The fourth dimension, the t-axis, has a fundamental relationship with the Universe and could possibly represent the oldest law but what does that direction actully represent? And what is actually moving?

    When we observe the world around us we see processes at work that cause 'aging'. Things that are well used get worn out; life moves toward decay; entropy at work. We notice that we can relate periodic motion to rate of change; the number of sunsets per moon cycle is a very useful piece of information and thusly, we have a concept if 'time'.

    When we built our telescopes and peered out into the Universe, we realised that the cyclic nature of the Universe was extensive and, well, universal. Eventually, after assigning the fourth dimension as time, we were able to accurately model the behaviour of the Universe.

    But it may be that the 'time' designation is misleading to the extent that although the concept of time allows us to build accurate physical models, it fits so well that another more basic principle of the Universe could remain hidden from us.

    For instance, if the t-axis were related to the radius of the Universe, then just by thinking of the t-axis in terms of the radius you can show a relationship with the volume of the Universe and would be on the way to accurately defining a cosmological constant from which things like speed of light, gravitational constant and electron charge could be derived.

    By thinking in terms of time, albeit a useful concept, we may fail to see such a relationship.

    Plus it could be that the fourth dimension is a real direction and a real distance; the distance between in and out.

    That would be cool, wouldn't it?


  • #30
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Could it be, that what's on beyond the edge of the universe is simply the emptiness of the vacuum.


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  • #31
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 92,488 Mod ✭✭✭✭Capt'n Midnight


    krd wrote: »
    Could it be, that what's on beyond the edge of the universe is simply the emptiness of the vacuum.
    Nope

    even vacuum can produce energy fluctuations and create new particles


  • #32
    lasersquad
    Closed Accounts Posts: 58 ✭✭lasersquad


    Hi folks, 1st post...
    Capt'n Midnight wrote: »
    even vacuum can produce energy fluctuations and create new particles

    Yes, but if we allowed for super-perfect vacuum? A space that truly contains nothing and in which nothing happens?


  • #33
    Maximus Alexander
    Registered Users, Registered Users 2 Posts: 13,080 ✭✭✭✭Maximus Alexander


    lasersquad wrote: »
    Hi folks, 1st post...



    Yes, but if we allowed for super-perfect vacuum? A space that truly contains nothing and in which nothing happens?

    Would it not be simpler to go with current theories suggesting that the universe has no edge, than to conjure up new mechanisms to explain this never-ending void, where the rules are different to those in the observable universe?


  • #34
    lasersquad
    Closed Accounts Posts: 58 ✭✭lasersquad


    Of course not. It`d be quite boring and unscientific. Besides these "current theories" were also "conjured" at some point.


  • #35
    Maximus Alexander
    Registered Users, Registered Users 2 Posts: 13,080 ✭✭✭✭Maximus Alexander


    Yes but they were "conjured" on a basis of mathematics and observable evidence and work quite well to explain what we see.

    Suggesting that there is an unending void at the "edge" of the universe would require you to throw all of that away and start over. For no good reason, since there is nothing to suggest that such a void exists.

    If we were to just "allow" for this as you suggest, without a basis, that would actually be extremely unscientific.


  • #36
    lasersquad
    Closed Accounts Posts: 58 ✭✭lasersquad


    So, throwing ideas around and sometimes starting over from scratch is "unscientific"? That`s a good one ;)

    Current theories might work for observable universe - to a point. Apart from the obvious fact that by default our cute "void" is not observable, there are things like dark energy/matter - mysteries that are only being unraveled recently and are rather significant to the whole picture.

    Followed by other rather obvious things, like that from these many theories only one might be "right", some of them are based at least partially on speculation, folks at CERN have no problem talking about "new physics" in every other press release, etc, etc.

    But, if this is one of the forums where current science = religion (as in: can not be questioned) please say so - I`ll apologise for gatecrashing and disappear promptly.


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  • #37
    Maximus Alexander
    Registered Users, Registered Users 2 Posts: 13,080 ✭✭✭✭Maximus Alexander


    lasersquad wrote: »
    So, throwing ideas around and sometimes starting over from scratch is "unscientific"? That`s a good one ;)

    Current theories might work for observable universe - to a point. Apart from the obvious fact that by default our cute "void" is not observable, there are things like dark energy/matter - mysteries that are only being unraveled recently and are rather significant to the whole picture.

    Followed by other rather obvious things, like that from these many theories only one might be "right", some of them are based at least partially on speculation, folks at CERN have no problem talking about "new physics" in every other press release, etc, etc.

    But, if this is one of the forums where current science = religion (as in: can not be questioned) please say so - I`ll apologise for gatecrashing and disappear promptly.

    I'm sorry but the bolded part is one of those ludicrous things that gets bandied about a lot these days when someone has a random idea that flies in the face of rigorously tested theories.

    You seem to be reacting as though I have attacked you, when all I am doing is probing the basis for your hypothesis that the universe has an edge, beyond which there is an endless void governed by physics different from that which we observe.

    I could just as easily posit that the universe is contained within a giant teapot, sitting on someone's kitchen shelf, but that the walls of the teapot are outside of the observable universe, so we can't see them.

    Is your idea falsifiable? If so, how would we go about testing it? If we can't, then I would suggest that it is unscientific. Like religion.


  • #38
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    lasersquad wrote: »
    Hi folks, 1st post...



    Yes, but if we allowed for super-perfect vacuum? A space that truly contains nothing and in which nothing happens?

    Well, if we go with the big bang then it is easy to see how a medium containing all points trapped inside a medium containing no points might cause an energy differential that is enough to initiate a big bang.

    How would a pointless universe interact with points? Eternally I reckon.

    I sometimes imagine universal expansion in terms of pressurised space that is leaking away into a true void. As if space was a compressed gas contained in a slightly porous vessel. If gas were escaping through the wall of the container equally in all directions then the space inside the container would behave in a similar way to the observed Universe.

    I like this because it means two things; it provides a basis for defining an edge to the Universe and it means the Universe will continue to expand toward infinity forever.

    I might define the radius of the Universe as 'the distance travelled by the very furthest photon from the origin of the big bang'. Perhaps the photon is the only thing small enough to get through the porous wall? Perhaps the distance between photons at the edge of the Universe is related to its porosity?

    Which leads to us realising that the pressure inside the can will never be equal to the pressure outside and this has the interesting consequence that, in effect, the photons that define the edge of the Universe can be regarded as the wall of the can whose internal pressure is greater than the external pressure; infinity, the eternal movement of energy, constant change forever.

    In a way, the Universe is based on the relationship between 'inside' and 'outside' - the direction of expansion. Maybe photons have a life-span; if we viewed them as equivalent to pressurised cans on a much smaller scale but with identical characteristics to the Universe itself then when their internal pressure falls to almost equalise the external pressure, their momentum begins to approach zero; maybe that's what space is made of, cans that are almost empty. Perhaps the edge of the Universe is littered with the emptiest cans.

    And in the end, there can never be an equal distribution of energy in the Universe and that, I suspect, is the engine of change.

    Another interesting thing is that if you consider the eternal void as being experienced as the central point of the imperfect vacuum then the whole thing works in reverse; you would have a 'great attractor' at the centre of the Universe; a cosmic plughole where unimaginably vast amounts of energy are being dissipated. And again, infinity; there will always be big bang events at the centre.

    Additionally, one imperfect point in an otherwise perfect vacuum would have the same consequence; it's simply a matter of scale.

    How could gravity not exist?

    I think the idea of an outside and an inside actually helps to simplify the problems of the Universe.


  • #39
    Nabber
    Registered Users, Registered Users 2 Posts: 2,855 ✭✭✭Nabber


    The edge of the universe is a paradox. An edge would imply you have something to expand into. But if you can expand into it then there is something not nothing. If there is something beyond the 'edge' of the universe then where is it's edge? (Here we go again:pac:)

    So if our universe is finite, then how do you avoid a paradoxical edge? Perhaps a tube shaped universe forming a ring?
    If our universe is infinite. Then there is no edge, center or big bang. The 'expansion' we see is not expansion, but the distance between two objects getting larger.

    How do you get your head around infinity and pure nothingness?


  • #40
    Cú Giobach
    Closed Accounts Posts: 3,772 ✭✭✭Cú Giobach


    himnextdoor wrote: »
    I think the idea of an outside and an inside actually helps to simplify the problems of the Universe.
    The object of science isn't just to simplify problems by making stuff up with no evidence (or going against evidence) in order to make the problems go away.


  • #41
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Capt'n Midnight wrote: »
    Nope

    even vacuum can produce energy fluctuations and create new particles

    As I understand it. The particles can be created as long as the vanish immediately. And the particles do not fill the vacuum. It's mostly empty.

    Is it possible that the vacuum just goes on forever? And the universe doesn't have an edge - unless you consider the universe to be only the mass of created at the time of the big bang.


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  • #42
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    Cú Giobach wrote: »
    The object of science isn't just to simplify problems by making stuff up with no evidence (or going against evidence) in order to make the problems go away.

    You mean like renormalisation theory?

    I'm just brain-storming dude. I'm not looking for a Nobel prize.

    What 'evidence' did I go against?


  • #43
    Cú Giobach
    Closed Accounts Posts: 3,772 ✭✭✭Cú Giobach


    himnextdoor wrote: »
    You mean like renormalisation theory?

    I'm just brain-storming dude. I'm not looking for a Nobel prize.

    What 'evidence' did I go against?
    Need I remind you of this thread.


  • #44
    Andrew Flexing
    Registered Users Posts: 657 ✭✭✭Andrew Flexing


    My head hurts...

    my URBAN EXPLORATION YouTube channel: https://www.facebook.com/ASMRurbanexploration/



  • #45
    Helix
    Closed Accounts Posts: 17,661 ✭✭✭✭Helix


    lasersquad wrote: »
    Hi folks, 1st post...



    Yes, but if we allowed for super-perfect vacuum? A space that truly contains nothing and in which nothing happens?

    surely "something", which is what this super-perfect vacuum would be, can't contain "nothing". meaning that if a super-perfect vacuum existed outside the universe, it would therefore not exist?

    or is that just pedantry?


  • #46
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    luckyfrank wrote: »
    It's hard to believe that the universe is not infinite, i mean there is a place where the universe just stops and then there in nothing

    no matter no space no time, but surly if the universe is expanding it must be expanding into something that wasnt there before

    Ive read before that it's not the universe that's expanding just that the space within it is expanding if that makes sense

    Hypothetical question : If i was standing on the very edge of the universe with a tennis ball in my hand and threw that ball over the edge what would happen to the ball ?

    If the universe is closed (current evidence does not suggest this), the universe would have no edge, just as the surface of the earth has no edge. If you threw a tennis ball, it would eventually hit you on the back of the head.

    If the universe is flat, then it might very well be infinite.


  • #47
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Morbert wrote: »
    If the universe is closed (current evidence does not suggest this), the universe would have no edge, just as the surface of the earth has no edge. If you threw a tennis ball, it would eventually hit you on the back of the head.

    If the universe is flat, then it might very well be infinite.

    I don't know. Certain explanations, that could over simplified or completely wrong, of things like the Higgs field, make the claim that it came into existence just shortly after the big bang.


    If the universe is truly infinite - then that should allow for other big bangs, possibly hundreds of billions of light years away from our observable universe.

    I have heard our universe (our star system) described as a vacuum fluctuation - if it is, then there should be others. And if the true universe is infinite nothingness, then it could contain and infinite number of star systems that are also quantum fluctuations.

    I wonder is the vacuum dimensionless nothingness - that allows dimensions according to the rules of whatever vacuum fluctuation happens.


  • #48
    Morbert
    Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    krd wrote: »
    I don't know. Certain explanations, that could over simplified or completely wrong, of things like the Higgs field, make the claim that it came into existence just shortly after the big bang.


    If the universe is truly infinite - then that should allow for other big bangs, possibly hundreds of billions of light years away from our observable universe.

    I have heard our universe (our star system) described as a vacuum fluctuation - if it is, then there should be others. And if the true universe is infinite nothingness, then it could contain and infinite number of star systems that are also quantum fluctuations.

    I wonder is the vacuum dimensionless nothingness - that allows dimensions according to the rules of whatever vacuum fluctuation happens.

    The big bang was not a local event. Whether the universe is finite or infinite, the big bang "happened" everywhere.

    The Wavefunction of the Universe, a paper by Hawking and Hartle, describes a possible model of the universe as arising from "nothing" (a zero three-geometry), which might suggest a "foam" of emerging universes. That is the closest thing to "multiple big bangs" I can think of.


  • #49
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Morbert wrote: »
    The big bang was not a local event.

    We do not know that.
    Whether the universe is finite or infinite, the big bang "happened" everywhere.

    If you limit your frame of reference to the early universe, which is visible through the cosmic background radiation - clearly visible. Then the universe is finite.

    But there's nothing to conclude that space is not infinite nothingness.
    The Wavefunction of the Universe, a paper by Hawking and Hartle, describes a possible model of the universe as arising from "nothing" (a zero three-geometry), which might suggest a "foam" of emerging universes. That is the closest thing to "multiple big bangs" I can think of.

    Path integrals - when you have a hammer.


    I have an idea that the nothingness (I won't call it the vacuum) may have it's own uncertainty principle. Something that allows it to have an infinite number of dimensions but at the same time none. And something that allows it to expand at an infinite rate, and simultaneously contract at an infinite rate. Which sounds contradictory but it might be possible because it's not there. I've been thinking about this. If those two principles are correct, then it might be possible for the nothingness to have an infinite number of universes like our own - and universes with completely different rules and dimensions. But because of a strange kind of relativity - something that allows contradictory infinities - those universes would seem dimensionless to the nothingness.

    If the nothingness is expanding an an infinite rate, then the universes are shrinking relative to it at an infinite rate. If the nothingness is shrinking at an infinite rate, then a Doppler like effect makes the universes dimensionless. There wouldn't be a foam, the empty space would always appear completely empty. Even if you could escape one of the universes you wouldn't notice any difference - all your rules and dimensions are allowed. Your chances of seeing or entering one of the other universes would be infinitely small. And I think, if you could enter one, your rules and dimensions would be preserved but you may be forbidden from viewing or experiencing the dimensions and rules of that universe.

    You don't need Hawking's idea of a universe bubbling up and tunnelling its' way to a bigger space. It just doesn't need to.

    If the same kind of thing is happening in the vacuums in our universe, you can forget about using anything like Planck's constant - or any of our constants to estimate what might be there. You're not going to see a foam either - the chances of seeing anything may be infinitely small, and we may have nothing in our dimensions that can interact with the dimensions of those things.


  • #50
    mooliki
    Registered Users, Registered Users 2 Posts: 62 ✭✭mooliki


    krd wrote: »
    Something that allows it to have an infinite number of dimensions but at the same time none. And something that allows it to expand at an infinite rate, and simultaneously contract at an infinite rate. Which sounds contradictory but it might be possible because it's not there.

    Surely that's just philosophical meandering over the concept of "nothingness". No different from saying there's a cat sitting beside me that doesn't exist, that's both infinitely big and infinitely small, which is possible because it doesn't exist.


  • #51
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    mooliki wrote: »
    Surely that's just philosophical meandering over the concept of "nothingness". No different from saying there's a cat sitting beside me that doesn't exist, that's both infinitely big and infinitely small, which is possible because it doesn't exist.

    No, it isn't a philosophical meandering.

    You're in the same frame of reference as the cat. In your frame of reference the cat always remains the same size.

    And you've got the idea wrong - the cat can never be infinitely big.

    If the nothingness is contracting at an infinite rate in all directions - A Doppler like effect shrinks the cat to dimensionlessness. If the space is expanding, the cat is shrinking relative to the nothingness.

    The effect is, to the outside space, the cat's universe always appears dimensionless or of indeterminate dimensions. Within the cat's universe all kinds of dimensions and rules are allowed.

    The idea is not too different from the idea of quantum foam - but in my version, there is no foam. Recent results from Fermi Lab's Gamma ray telescope have shown the foam not to be there - or it wasn't detected. My idea is that all the stuff is still there, but the space will always appear empty.


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