why would they think the expansion of the universe is speeding up?  The further out we look the further into the past we see, and the further out we go the faster galaxies are reciding, wouldnt that show that the expansion is slowing down?
207307
As the distance between galaxies increases, the gravitational attraction between them reduces, the momentum that the receding galaxies have makes them move at an apparent faster rate. Those galaxies that are strung close together being held together by their gravitational forces and hence their momentum is retarded by this gravitational force
608954
The current status of the universe actually does work like that.  Technically, with gravity the universe should collapse back upon itself and the big bang would occur all over again.  However, gravity is one of the weakest forces in the universe.  With that said, it has been measured that the universe is expanding and accelerating at a rate that exceeds the gravitational forces required to initiate the "big crunch."\n\n\nThere are two schools of thought right now.  One is that the universe will continue to decelerate but never completely stop or collapse upon itself.  More recent theories have stated that the universe appears to be accelerating.\n\nAs it stands now, I would say that it is safe to say that the odds are extremely low of the universe collapsing back to a singularity.\n\nSee the link below for some more information.
674304
The expansion of the universe causes distant galaxies to recede from us faster than the speed of light, if Comoving distance and cosmological time are used to calculate the speeds of these galaxies. However, in general relativity, velocity is a local notion, so velocity calculated using comoving coordinates does not have any simple relation to velocity calculated locally. In other words, the galaxies (or more accurately, galaxy clusters) do not physically move away from each other. Rather, the fabric of spacetime between them expands. This also explains the Inflationary epoch during the Big Bang, when the universe expanded from a size a hundred billion times smaller than a proton to approximately one hundred million light years in diameter in just 10-32 of a second.
440827
Yes, because the cosmological constant is a specification of a pressure that's constant in each unit volume of empty space.  So it "explains" an expansion over and above the expansion due to the velocity imparted by the Big Bang.  Einstein, after some thought, concluded that the CC = 0; in other words, that the expansion of the universe is due only to the initial kick of the Big Bang and is thus slowing down due to gravity.  But recent observations (of very distant supernovas) indicate that the expansion is not slowing down, but increasing.  This is consistent with a small but positive CC.  Other explanations are possible, though.  For example, there could be a "real" force exerting the outward pressure ("real" as opposed to the very mysterious constant pressure per unit volume); if this is true, such a force couldn't be one of the four known forces of physics, but would have to be a fifth one, and so has been called "quintessence."
424714
You misunderstand Einstein's Theory of Special Relativity. It doesn't say that you can't have something move faster than the speed of light. Only "information" can NOT move faster than the speed of light. By information, I mean any "signal", like electromagnetic waves (which includes light, radio waves, etc. etc.). Any material object within the Universe are also restricted by Special Relativity, since material objects also carry "information".\n\nFor the Universe or the fabric of spacetime to be expanding faster than the speed of light is NOT a violation of Special Relativity, and the Universe will not be moving backwards in time.\n\n--------------------------------------------------------\n\nEdit - Ok, here let me clarify why I said that Special Relativity (SR) does NOT apply to the expansion of the Universe:\n\nVelocity of something depends on which definition of distance we use. So, if we assume that the distance of an object at time t is the distance from our position at time t to the object's position at time t measured by a set of observers moving with the expansion of the Universe, and all making their observations when they see the Universe as having age t, then the velocity (change in D per change in t) can definitely be larger than the speed of light. This is not a contradiction of special relativity because this "distance" is not the same as the spatial distance used in SR, and the age of the Universe is not the same as the time used in SR.\n\nIn the special case of the "empty Universe", where one can show the model in both special relativistic and cosmological coordinates, the velocity defined by change in cosmological distance per unit cosmic time is given by v = c ln(1+z), where z is the redshift, which clearly goes to infinity as the redshift goes to infinity, and is larger than c for z > 1.718.\n\nFor the "critical density Universe", this velocity is given by v = 2c[1-(1/sqrt(1+z))], which is larger than c for z > 3. \n\nFor the "concordance model" based on CMB data and the acceleration of the expansion measured using supernovae, a flat Universe with Omega = 0.27 (this would be our Universe), the velocity is greater than c for z > 1.407\n\nAll this just means that for any expanding universe, there will be a value of z (i.e., redshift or cosmological distance) that will give the appearance of galaxies moving at velocities greater than c.
131678
==\nWhat all you study about universe is based on theories evolved out of observations.\n\nAs a general observation Universe is expanding.\n\nThe expansion of universe Begin with the big bang.\n\nThe rate of expansion is not exactly known.\n\nIt is observed that as much the universe is expanding, the distances among the bodies is increasing.\n\nBecause of increasing distances gravitational pull is decreasing and so the bodies are accelerating due to the force of big bang still preserved as a potential energy.\n\nIt is believed that at speed of light the objects become invisible so as muc the bodies get the speed of light they become invisible. This means that a rough limit of the visible univers exist.\n\nWhat was holding the universe?\n\nWhen there was no universe, naturally there was nothing to be hold by anything.\nThe creation itself is existence.
402740
The simple answer to your question of whether it is right to view the universe in age layers as it expands is:  No.\n\nIt is important to recall that our perceptions of the space-time continuum, in the context of the concepts of past, present, and future, are illusory at best and cannot be well quantified.\n\nAlthough it is often said that the universe "came into existence" and that this occurred "quickly" or over a "short span of time" this is at best a harsh encapsulation which is if you think about it simply a futile attempt to quantify the frequency at which the universe "As We Know It" experienced expansion(s) and/or the rate at which component parts of the universe became more distant in "space" in the context of "time."  \n\nIt is better to think of the universe not in terms of its "coming into existence" but rather in terms of its "existing" which is occurring as a persistent and ongoing process irrespective of whether the existing is occurring in the past, present, or future.  All "moments" affect all other "moments" in the space-time continuum.  In point of fact the notion of a "universe coming into existence" is in part a byproduct of our use of the senses to create a perception of discrete objects, or to establish topological boundaries, in order to make sense of and navigate our presence in the continuum.  \n\nIt is possible for persons to exist in realization with eyes opened to a world beyond time.  When this occurs, it is said that you are seeing with the eyes of the eternal soul, someone once told me.  However, before I stray too far from the substance of your question, let me simply conclude by saying the best answer is No.
485682
http://www.sciam.com/print_version.cfm?articleID=0009F0CA-C523-1213-852383414B7F0147\nhttp://universeadventure.org/\nhttp://en.wikipedia.org/wiki/Physical_cosmology\nhttp://www.astro.ucla.edu/~wright/cosmo_01.htm\nhttp://map.gsfc.nasa.gov/m_uni.html\n\nthis is actually a common misconception about the big bang. the universe is not expanding into anything. the universe is four-dimensional, but a two-dimensional version may be something like the surface of a sphere, and it is this surface that is expanding. the universe seems to be finite in size, yet it has no center and no edge. nothing, not even space-time, seems to exist "outside" the universe. the big bang was the entire universe, and everywhere in the universe was once the big bang.\n\nthe earliest, and oldest, radiation we can observe is the cosmic microwave background, and we see it in every direction we look, but the universe was much smaller at that time. the universe had expanded and cooled enuf for electrons and atomic nuclei, about 74 percent hydrogen and 26 percent helium, to combine and form neutral atoms. before this time the universe was much like a heavy fog, but when atoms formed, there were no free electrons to scatter light, and the universe became transparent. today, we see this light stretched to microwave wavelengths by the expansion of space-time.\n\nanything with a cosmological redshift of 1.7 is receding at light-speed, c.  anything with a greater redshift is receding faster than c.  the redshift of the cmb is 1089.  the cmb seems to be at least 78 billion light-years away, but the universe is only 13.7 billion years old.
324591
There is no actual proof as such although the evidence to support the theory is pretty convincing. The first piece of evidence is that the universe is observed to be expanding. Galaxies are observed to be receding from us. This is determined by the shift in their light to the red end of the visible spectrum. It's an effect you can hear with sound; as a vehicle approaches you blowing its horn you will hear the pitch of the sound change from high to low as it then travels away from you. It's called the Doppler effect. It aslo happens with light, only light changes colour from blue (coming towards you) to red (going away from you). The lightwaves are compressed and stretched just like sound.\n\nSince galaxies are moving away from us they must have been concentrated at one point in the distant past. That the singularity of the Big Bang.\n\nThe other piece of evidence is the background radiation of heat left over from the Big Bang. This was predicted to exist by proponents of the Big Bang, and was discovered accidentally in 1963. It's the leftovers of the tremendous heat generated by the explosion, and is 2.93 degrees above absolute zero.
498181
There is some controversy over that. It is difficult to account for the expansion of the universe if it doesn't. At least at the very beginnings of the big bang.
663877
Yes, in a way, looking at distant objects in our universe is like looking back in time.\nThe farther away we look, the older the image we are seeing is.\nAs fast as light travels, it still only travels at a finite speed and takes time to cross the VAST distances of interstellar (or even intergalactic) space.\nThings we wee in the sky could be billions of years old, we could be watching the formation of a new star (or for that matter, be receiving transmissions from an alien life form) that has since died long ago.
345483
Unfortunately, most laymen have an erroneous view of our universe stemming from the whole "big bang" concept.  They think of the big bang as an explosion of matter & energy into space from some central point, but this is incorrect.  The big bang was actually an explosion OF space, _not_ of stuff INTO space.\n\nAs such, there is no "beyond the edge of the universe" because there is no edge to the universe.  ANY point in the universe "looks" like it could be the center, because at every point space is expanding, pushing matter farther & farther apart.  The initial singularity that was the start of our universe, expanded to become all of space.  To answer your question about what's "beyond" space, the term really doesn't have any meaning.  It's like asking what's north of the north pole:  nothing.\n\nThe universe, if you could travel (much) faster than light, likely loops around itself.  Like travelling on the surface of a globe, no matter what direction you set out in you'd eventually come back to where you started.  However, because we CAN'T travel FTL (sorry, sci-fi fans), and because the universe is expanding at the rate it is, the reality is if you set out in one direction, you'd just keep travelling through more space.  As the universe continued to expand over the eons you'd notice the galaxies you pass becoming fewer and fewer, until eventually, many trillions of years into the future, you'd just be travelling through dark, empty space.\n\nHope this helps.  The first link below is an interesting future timetable of our universe.  The second is a very good and readable book that could probably explain better than I could about the big bang & origins of our universe.
319015
"...What are the dimensions (length, width, and height or thickness) of the physical universe (in light years)?..."\nThe universe can't be measured in terms of length, width, and height. Such parameters require some reference point from which measurements can be made, along with some distant boundary where the measurement would end. You simply can't do that with the universe because the universe is isotropic, meaning it's the same in all directions from any observing point. From Earth we can look outward in any direction and 'see' about 13.7-billion light years. From Earth that represents a boundary. Here comes the tricky part: if some alien in a galaxy 13.7-billion light years away from Earth looked outward in all directions (including back towards Earth) they'd 'see' a universe that appeared to be 13.7-billion light years in scope. In other words, the universe has no boundary. To have one it would have to be inside some "thing" else, and there's absolutely no evidence that such is the case.\n\nTo confuse the issue even more, if we had the ultimate telescope with limitless viewing power we still will never be able to see into the universe beyond a certain range. That's because at almost the same instant of the Big Bang the universe briefly expanded faster than light (this doesn't violate relativity because it was the space of the universe that did the expanding). In our 'normal' universe the speed of light is the speed limit which prevents us from ever seeing any of that inflation because it's moving away faster than the speed of light.\n-----------------------------------------------------------\n"...I've read that the universe is thought to be "saddle shaped..."\nMore recent observations point more towards the universe being geometrically "flat." This simply means that the universe appears to be infinite, that its space will expand forever while cooling more and more over the eons.\n------------------------------------------------------------\n"...What does it mean for example, to say that the universe is expanding at a rate of 70 kilometers per second per (x number of light years)?..."\nYou've described the so-called Hubble Constant. (70 km/sec/Mpc) It means if galaxy 'A' is 1 Mpc (1-million ly) away from us it's recessional velocity will be 70 km/sec. If galaxy 'B' is 2 Mpc away then it's velocity will be 140 km/sec It's important to keep in mind though that it's space that's expanding like that, not the galaxies moving THROUGH space; they just get carried along.\n------------------------------------------------------------\n"...I was not able to find a rate of acceleration of expansion..."\nI've been looking for a figure too. So far the only thing I've come up with is -3.15^36 /sec/sec  Darned if I know what the units of measurement are though. Maybe someone else on Yahoo can help us out with that.
361032
The essence of the Big Bang theory is pretty simple:  sometime billions of years ago the universe began;  everything now in the universe was created from energy/matter that was compacted into a really, really small volume/space, and indeed that really, really small volume/space was all there was to the universe at that moment; and since the universe began, it's been expanding.  These are the essential points of the theory.  Over time, we've added new details, such as pinning down the age of the universe to within a few hundred million years (last I heard, we thought it was 13.7 +/- 0.2 billion years old).  And a lot of theoretical and observational work have gone into investigating and refining the theory.\n\nAs to why we think that there was a Big Bang instead of, say, a universe which had always existed or a universe which came into being pretty much fully formed, the main reason and the reason we started thinking there was a Big Bang in the first place is because of very peculiar observations that we can make of distant galaxies.  This observation is that, except for a bunch galaxies which are both nearby and gravitationally bound to our own galaxy, all the galaxies we can see are moving away from both our galaxy and all other galaxies.  Also, the speed with which a galaxy is moving away from us depends directly on how far away from us it is (e.g. galaxies farther away from us are moving away from us faster than galaxies which are closer).  And the reason we first infered a Big Bang from this is that if you imagine running this movement backwards, doing a cosmic rewind if you will, then all the galaxies will be moving back towards each other, and eventually will all find themselves in the same place.\n\nSeveral years after this observation, a key predicition of the Big Bang theory was verified.  When the universe was young, it was also really hot and so for a time would have given off light all its own (I'm simplifying things a bit, but these are the essential facts as we know them).  It was predicted that some of this light should still be around.  And, lo and behold, at the very same time that people were making this prediction and beginning to think of looking for it, practically right down the road some experimentalists stumbled upon it accidentally.\n\nSo, in short and hopefully simple words, that's what the Big Bang is and why we think it happened.
417037
Ah yes, people like to give mumbo jumbo bullshiet answers to this question to confuse you further.\n\nThe thing is, we really have no idea. This is half the reason the answer is so confusing.\n\nScientists, like myself, have defined the universe as everything and like to say it isn't expanding into anything because, quite frankly, they don't know what's going on and it's easier to just define the universe as that for the time being. I don't know, neither does anyone else.\n\nFrom recent science, we know that the universe is absolutely finite, therefore it's size is increasing; it is getting larger. This can also be seen by looking at microwave radiation maps of the universe.\n\nSo then, what is it expanding into? Well, if ANYONE could answer this question, they would probably go down in history as greater than even people like Einstein, Newton, Galileo...but the reality is, we don't know. All answers to this question are purely spectical and usually formed to fit a belief system that has been adapted from that person.\n\n\nPersonally, it's probably expanding into more space, which probably contains an indefinite number of universes and extends infinitely.\n\nBut that is only my personal view. Just like all other views.
592502
There's a relative way to interpret your question as well.  \nWhen you look at the stars, you're seeing them because of the light that travels from them to you.  It takes time for the light to reach you.  So, you're not seeing the stars as they are "now".  You're seeing them as they were in the past.  They may not even be there any longer.  They may have gone nova or even supernova (if big enough), but the information of that event traveling at the speed of light hasn't reached us yet.  Just  remember it's all relative.  So, depeneding on which oberserver you ask and how you define certain terms...just how many stars that you can see are really there?
247610
The universe is expanding. The Hubbles observation was one of the important event in the history in which the experiment bit the theory! \nThe unit in it means that the far away galaxies are going away with certain velocity.