If space is a vacuum then ,what hold the galaxies up right?
967381
new research show that galaxies are held together by dark matter which until recently there was little or no evidence of,however i believe the massiveness of the entire universe is actually exerting pressure ever so slightly upon the galaxies and that force is squeezing them upon a tightly wound black hole which appears to be a gravitational force, but i compare it to all the water in a tub pressing itself gently into a whirlpool as it goes down the drain...yes it is gravity pulling it down the drain but if that same whirlpool was in space it would have more similarities to a black hole
601185
Space is the absence of matter, so if the universe didn't exist, there would still be space.
138404
Often when people are told that galaxies are receding from us, they assume that means we are at the center of the Universe.  However, remember that the Universe is homogeneous and isotropic.  No matter where one is, it looks the same in all directions.  Thus, all galaxies\nsee all other galaxies receding from them.  Hubble's relationship is compatible with a Copernican view of the Universe: Our position is not a special one.\n\nSo where is the center?  *There isn't one*.  Although apparently nonsensical, consider the same question about the *surface* of a sphere (note the *surface*).  Where's the center of a sphere's surface?  Of course, there isn't one.  One cannot point to any point on a sphere's surface and say that, here is the center.  Similarly, because the Universe is homogeneous and isotropic, all we can say is\nthat, in the past, galaxies were closer together.  We cannot say that galaxies started expanding from any particular point.
514889
Outer space extends to the end of the universe. Further, the universe is constantly expanding. No-one knows if anything is beyond the end of the universe.
630567
All  of them.\n\nActually, There is no such thing as a true vacuum...Period!\nA true vacuum has never been created, anywhere, where the atomic count is zero.\nThere is always atomic content left to fill the "vacuous" space. No one has ever been able to creat a true vacuum.\n(exerpt from a previous answer)\nContrary to popular belief, empty space is not empty, and it is certainly not a vacuum. \nresearch it, its true.\n"Empty" space actually contains an average of 1 hydrogen atom for every 32 cubic centimeters of space, this data is per NASA.\n\nIn our own Milky Way, space is more dense with 1 hydrogen atom for every 1 cubic centimeter.\n\nSo to answer your question, there are NO waves that travel in a vacuum.\n\nOne day the misinformation of space, or anything else, as a vacuum will finally die out.\n\n\nspread the knowledge
650212
The universe encloses all the stars and galaxies...so the answer is...we would see the universe. By the way, if I was that far out there and looking back, I'd be worried about what was sneaking up behind me.
13356
Some distant galaxies appear to be accelerating away from us, not just moving at a uniform speed. \n\nAnd the most distant galaxies are probably expanding away from us at more than the speed of light. This does not violate the special theory since no information is being transferred (see reference).
453550
It is an incorrect concept that space is full of nothing.  There are dust particles and gas molecules in space.  The solar wind from our sun is always blowing particles into space.  There is also a galactic wind that is blowing particles out into space as well.\n\nSpace is as close as we can get to natural vacuum, or nothingness but it still has a density of one atom per cubic meter.
380500
It's the matter in galaxies that provides enough gravitational force to prevent them from being flung apart by their angular momentum.  It's called dark because we can't see it
1097658
"Space air"?\nIt is really hard to decipher what you are trying to ask.\n\n"Space" is pretty close to being a vacuum (for all intensive purposes for us here on Earth), thus there is no "air" in space.\n\nThe concept of there being some type of medium in space which everything travels through (the idea of an "aether", the material which allowed light to propigate through empty space) has since been disproven over well 100 years ago by the Michelson-Morley experiment.
988250
space is not infinite  although to us it is pretty much,  confused  great.  the universe is currently expanding, whether it will always continue to do so is due to critical density and mean density of the universe.     if critical density = (3i x hubbles constant^2)/ 8piG      if critical density is greater than average density then the universe will contineue to expand forever although it wont ever become infinite because the recession of the galaxies is limited by the maximum speed of light, and the fact that the universe had a begining therefore has a limmited size. \nalso  if average denisty is greater than critical density then the universe will be closed (hyperbolic) and the gravitational pull of the galxies will cause the universe expansion to slow and eventually contract. if critical density = average density then universe expansion will slow down universe would be flat, Most cosmologists believe that the universe is open and will continue to expand, which is nice, heres something nice to think about that if the universe is exapanding at the speed of light and the universe has been around for 1/Ho   1/hubblesconstant then the unverse is about 13 biliion years old this is 4.16x10^17 seconds  times the speed of light  3x10^8 ms-1 is  1.248x10^26m  in one direction   if the universe is spherical  which it isnt but lets pretent it is for an easier calculation then the Volume of the Universe is  4/3 pi r^3    is 8.142x10^78m^3   which is quite alot of space. As the amount of volume that real mass takes up is insignificant at these measurement  we can forget about it.   On the other hand light follows the shortest routes as mass distorts space it is likely that this answer is a bit smaller.  Oh and the universe isnt spherical its more like a ball thats been sat on,    So in summary the universe is not infinite but it is pretty much as it is likely to be expanding at the invariant maximum speed of light so your never going to hit the edge, infact there isnt an edge im not sure would happen if you got to the edge before the first radiation from the beggining of the big band reached the edge,   But i dont think youd get there,  well about your car  at the moment if your car takes up 6m^3  then theres enough space in the universe to hold 1.3x10^78  cars   but theres not enough matter in the universe to make that much cars  for that so dont worry too much about it, also in 1 second the universes volume increases by lots  uhhh     ok if the universe was 8.142x10^78m^3   rite this second  and the universe is exactly 13 billion years  old  (which its not) then in one second later the universe would be bigger yeas thats right  bigger by           ok one second is too small to make any effect on the calcullation,  but if it was a billion years older then it would be 1.016x10^79m^3  thats 2.02x10^78m^3 more than it was a billion years earlier which means it expansion is well logarithmic exponential whatever, the next billion year the universe would expand even more in the same time,   soo  thats even more parking spaces, if u look hardenough im sure you wiil find some.    No wonder i dont have a girlfreind.
861922
It is not a vacuum.  The density of space is 0.1 - 1000 atoms/cm3.\n\nPlanets are made of condensed interstellar matter.
24590
The universe may or may not have a large three or four demensional structure, but it more than likely has an overall natural curvature based on it's density.  If the density of the universe is enough to overcome the expansion of the big bang, than general relativity predicts that space will have a possitive curvature, like that of a sphere.  If it's density is less than the expansive force of the big bang it will have a negative curvature, which is impossible to model in three dimensional space, but is often described as saddle like.  If the density is exactly right that the universe will slow in its expansion forever and never re-collapse, then space is probably flat.  This site could help...\n\nhttp://en.wikipedia.org/wiki/Shape_of_the_Universe
39702
expansion does not require an increase in mass in order to occupy a larger area.  all that is required is for whatever the object.  is for it to simply distribute itself over more area.  for example a balloon with out being blown up takes up conderably less area than one that is full.  note;  the balloon never actually gains mass.  the material its composed of has just been distributed over a larger area.  although the universe is substantialy larger and more complicated set of objects the analogy still applies.  oh, and it's not accelerating it's just expanding.  in order for it to accelerate it would require some source of propulsion like some kind of powerplant in a vehicle.  since astronomical objects aint' got none of that. they just keep truckin' right along at a steady, consistent rate.
299945
Space is infintie.  The universe,however, is not.
550511
Vacuum contains no particle (in classical sense) but lots of electromagnetic waves. photon (as a particle is a quantum mechanics concept) exists in vacuum. The problem with satellites around the sun is the heat radiation thats is emitted from the sun. Its difficult for instruments to work at that temperature. Things will melt though in vacuum.
332802
Actually, There is no such thing as a true vacuum...period!\n(exerpt from a previous answer)\nContrary to popular belief, empty space is not empty, and it is certainly not a vacuum. In fact, a true vacuum has never been created, anywhere, where the atomic count and therefore air pressure is zero.\nresearch it, its true.\n"Empty" space actually contains an average of 1 hydrogen atom for every 32 cubic centimeters of space, this data is per NASA.\n\nIn our own Milky Way, space is more dense with 1 hydrogen atom for every 1 cubic centimeter.\n\nOne day the misinformation of space as a vacuum will finally die out.\n\n\nspread the knowledge