i've always had a nagging question about this theory; if the universe was some infinitesimal speck and that exploded in all directions (and the universe is supposedly in the shape of a pringle?), what was its catalyst to do so? things don't just explode without a force acting upon and no one has ever explained to me how this works out, and probably more importantly, where did this incredibly dense mass come from in the first place? and so i bring to you a hypothesis that may answer both questions, though i doubt it.\neinstein's theory of relativity postulates that if anything were to reach the speed of light (which he states is impossible) it would become as massive as the universe itself effectively taking up all the space in the universe. perhaps this would cause the universe to collapse in upon itself and become smaller and more condesed until it becomes that infinitesmal speck that explodes from stress of its intense density. it's sort of like a multitrillion year cycle i guess
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The Big Bang theory itself, doesn't say anything about the *cause* of the explosion. It describes only how the Universe evolved after the explosion took place. \n\nThe reason is twofold. \nFirst of all, the models physicists use to describe the Universe, like General Relativity and Quantum Mechanics break down in the extreme conditions immediately after the initial explosion. However, they do a very good job in describing the existing data afterwards. And with the recent high precision measurements by satellite of the cosmic background that is very impressive.  \n\nThe second reason is that GR and QM are only approximations of the correct theory. In fact they give different answers  in the region were they overlap. Fortunately this happens only in extreme conditions, close to black holes for instance. And, you guessed it, in the microseconds after the Big Bang.  \n\nConclusion: there is therefore a lot of room left to speculate. Not for the scientists though, because there are no data available for these initial moments of the Universe. No data means, nothing  to test theories on.
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You get into Quantum Theory with your intrigue and there is no evidence to support that the universe is not infinate.\n\nHOWEVER, according to the Big Bang theory there was nothing and then there was something in a centralized location millions (billions) of years ago. At the speed that the universe is spreading outwards there has to be an end to it and scientists are trying to get telescopes powerful enough to see to the beginning of time.\n\nWhat lays on the other side? Nobody knows.
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The universe, from your reference frame, would be length contracted into a single plane perpendicular to your direction of motion, thus enabling you to cross it by traveling no distance. Time for you would be stopped completely, thus you would travel this no distance in no time, at a speed of precisely c in your reference frame (light does that in every reference frame), despite the fact that by definition you are stopped in your own reference frame. Every other light ray would also travel at c in your reference frame and so would pass you in a finite period of time, except time would never move forward and so it wouldn't actually go anywhere. If you looked outside at the infinitesimally thin slice of universe, you would find that the area no distance ahead of your light ray is in the future of the origin (as viewed from any valid reference frame) and the area no distance behind it would be in the past. The beam you are riding on would have no frequency and would appear as a constant electric or magnetic field. Since the beam you are riding on is still traveling at c, it would therefore have infinite wavelength and so the field in question would permeate out to infinite distance in front of and behind you - not that it matters because there is no universe in either place. Speaking of the universe, every particle in it would appear to you to be infinitely massive and the universe would thus collapse on itself infinitely fast, if only there were time for it to do so.\n\nBy the way, there is a reason the speed of light is not considered a valid reference frame in special relativity. This is it.
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There are multiple possibilities:\na) The universe stops expanding, starts collapsing, and squishes back together (the "Big Crunch" theory)\nb) Basically the Big Crunch theory, except it states that  the universe will "bounce" back out again (the "Big Bounce" theory)\nc)The universe will eventually even out in temperature, and effectively freeze over, so no stars can shine (the "Heat Death" theory)\nd)Vacuum energy will eventually become so strong that every atom in the universe will tear at the exact same moment into traces of radiation (the "Big Rip" theory)\ne)Protons after 10^100 years will decay, leaving the same result as in the Big Rip ("Proton Decay")\n\nNote: Possibility "e" will happen regardless of any other of these possibilities, even though 10^100 years is a rrrreeeeaaaallllllllyyyy long time.
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From the physics point of view, our universe thus far is approximately 15 billion light years and expanding every second. Light year is the distance that light with the speed of nearly 300,000 Km/s travels in one year. This distance equals 9, 500, 000, 000, 000 Km (that light travels each year). Now, imagine how big our universe is!!\n\nAbout the second part, The space-time (space and time are inseparable) make our universe. They are both dynamic and the  fact that universe expands means both the space and the time expand. Now, in what do the space and time and our universe expand? This fact is not like other daily facts in our life, it is not possible to assign a place for space-time so that our universe expand in it. We cannot say there is something outside our universe because it is meaningless. These concepts are complex and require in-depth studies and deliberating.\n\nI hope these would be a little helpful...
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I hate to be the philosopher but that is why the question still reamins. No one can accuratly tell what lies beyond the boundries of the universe. Is there another? Is it just white noise? I believe that space is infinite and our "universe" could well be a part of a cluster of "multiverses". i was once told that the universe is expanding in the same way that a balloon is blown up. So what lies beyond our universe? I say space, space, and more space! \n\nIf our universe began with the "big bang" then that would mean that at some point the universe had collapsed upon itself, leaving empty space.
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The Big Bang \n\nAbout fifty years ago, American astronomers studying the galactic star clusters, stumbled on evidence that the entire Universe is blowing up before our eyes. According to their observations, all the galaxies in the Universe are moving away from us and from one another at very high speeds, and the most distant are receding at the extraordinary speed of hundreds of millions of miles an hour.\n\nFirst there was nothing and it blew up and then there was everything and scientists have calculated that it all happened in 1043 of a second. [The] echo of that explosion can still be heard bouncing around in space. Scientists claim that in the big bang all of the fundamental particles necessary for life were formed. All of the complexity we see around us is the result of this massive explosion.\n\n"The new finding hit the scientific world like a thunderclap." It meant that the idea of an ultimate beginning was no longer merely religious dogma. Science itself now indicated that the universe burst into existence at a particular time in the remote past.\n\nIn 1992 measurements by the Cosmic Background Explorer (COBE) and by the Hubble Space Telescope seemed to confirm beyond any reasonable doubt that the Big Bang cosmology is indeed correct. George Smoot, Professor at the University of California at Berkeley and Principle Investigator of the COBE team which made the discovery, said regarding these new observations, "What we have found is evidence for the birth of the universe . . . It's like looking at God."\n\nWorking backwards, the evidence implies that there was a time when the universe was infinitesimally small. The evidence from general relativity also indicates that it was not merely a case of the matter in the universe being concentrated at a particular location, but that space itself was this tiny. At a sudden instant in time all of the energy and mass in the universe was located at this infinitesimally small point and exploded. The currently observed outbound motion of the galaxies from each other is a continuing effect of that explosion.\n\n"The scientific community is prepared to consider the idea that God created the universe is a more respectable hypothesis today than at any time in the last 100 years," Frederic B. Burnham, science historian, declared.\n\nHowever, some die-hard secularists propose that the universe goes through endless cycles of expansions and collapses. Hence, eternity becomes nothing more than an eternal succession of big bangs followed by big crunches followed by big bangs followed by big crunches over and over again and again forever.\n\nBut this violates the second law of thermodynamics, the law of decay, that implies that the universe is in a process of gradual disintegration - running down, like a wound-up clock. And if it is running down, then there must have been a time when it was wound up. Once the big bang takes place and the universe begins its expansion, entropy starts to increase. From this point on it will never be able to go back to its original state.\n\nWhat's more, the first law of thermodynamics (the conservation of matter) implies that matter cannot just pop into existence or create itself. And therefore, if the universe had a beginning, then something external to the universe must have caused it to come into existence - something, or Someone, transcendent to the natural world.\n\nThe facts clearly indicate that the universe is not eternal, and it cannot originate itself The implication is that the universe began at a definite moment in time, in a flash of light and energy. Science has begun to sound eerily like Genesis 1: "And God said, 'Let there be light"' (1:3).\n\nThe evidence requires that we believe God formed the universe at His command, pointing to the importance of taking God at His word literally - from the beginning both of time and the Bible. Second, there is such a striking parallel between the Hebrews 1
321917
Quite an interesting question.  Well, it's true that the Universe is expanding, has been expanding since the Big Bang, and always will expand.  Plus, it's been doing so at the speed of light, so unless there's some way for us to travel faster than that, we're already too late to actually go (or send something) and find out what it's expanding into.  Point B can never reach the end.  Having said that, we're fairly sure that 'nothing' is beyond space.  Space is expanding into nothingness.  Of course, this is a hard concept since most of space has nothing in it anyway.  Yet even  when space is empty, it's still considered 'something.'  This empty 'something' expands into the nothingness.  Confusing, I know, but I can't think of a better way to explain.  Anyway, I don't believe there's a container that would stop the Universe from expanding.  I suppose it could be theoretically possible, but I'm not sure how.  I believe it will keep on expanding forever.
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Allow me to confuse you even more. \n\nTo begin with, the universe is not the result of an explosion. An explosion takes place inside something else, like a building, earth's atmosphere, etc.,  There is absolutely not one single shred of evidence that our universe began inside anything else.\n\nIn the first few instants of the universe there was nothing but spacetime and pure energy--no matter (mass) of any kind, including hydrogen. It wasn't until the universe was about 3 minutes old that the first low-mass atomic nuclei began to form, and another 400,000 years would pass before neutral atoms formed. Finally, after that 400,000 year point, the universe had cooled enough that hydrogen could first appear to fill the already existing spacetime volume of the universe.
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What is beyond the borders of the universe?\nIs it truly possible for the universe to go on forever? If there is an end, what’s on the other side?\n \nBefore we can address these questions, we must first define universe.  The word universe denotes all space and everything (matter, energy) contained within it.  The prefix uni means one.  The root verse means word, turn, or whole.  Thus our universe has traditionally been thought to be the one whole of all substance or matter.  Questions regarding our universe persist today.  Does it have a beginning and end, or does it go on forever and ever?  Is it linear or curved?  If it has limits of length or curvature, then what lies beyond the Universe?  If something lies beyond the Universe, then can’t we accurately call that the Universe?\n\nSome lay people and some scientists conceive of the universe as infinite space.  Others define the universe as finite, or limited (perhaps curved), space.  Still others incorporate the elements of matter and/or energy into their definition of the universe, as opposed to the space beyond matter and energy.\n\nGiven these concepts of our universe, some scientists conclude that the “totality of space could be infinite. Shrink an infinite space by an arbitrary amount, and it is still infinite. (Scientific American March 2005).”  \n\nAs to the notion that we live in an ever expanding universe, moving away from every other universe on the fabric of space-time, some scientists are careful to point out that “Andromeda, our nearest large galactic neighbor, is actually moving toward us, not away. Such exceptions arise because Hubble's law describes only the average behavior of galaxies (Scientific American March 2005).”\n\nIn accordance with your supposition that our universe is in another universe, “it has been hypothesized by some scientists that the universe may be part of a system of many other universes, known as the multiverse (http://en.wikipedia.org/wiki/Universe).” Modern astrophysicists talk about multiple "pocket" universes that branch off from one another.  Stephen Hawking points out that parallel pocket universes can have no effect on a real observer inside a single pocket, so, according to Hawking, they are theoretical baggage that should be eliminated from cosmology, the study of the origins of the universe.\n\nSome string theories define the universe as a three-dimensional space in an invisible space having more dimensions. This is, in essence, a universe within a universe.  Our zone, a “braneworld” could periodically bounce into another parallel braneworld.  This may create what would appear as a Big Bang from one perspective or a Big Bounce of alternating expanding and contracting universe from another perspective.  Such a cataclysmic event is thought to occur 300 billion years from now, resulting in the rearranging and creation of a new universe.\n\nBeyond the borders of the universe, there are other universes moving through a multiverse.  While scientists do not commonly believe that our universe goes on for an unlimited distance, despite its present expansion, they allow for the possibility that the multiverse may go on forever.  If there is an end to our universe, what’s on the other side is called the multiverse.  If there is an end to the multiverse, another term may need to be coined to describe what lay people commonly refer to as infinite space.\n\nSteve\n:-D
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*Edit2*\nBe careful! Most people that have replied to this question have obvious lack of knowledge in quantum field theory, relativity, cosmology, string theory and particle physics. I don't know where they get their facts from, but they are outdated and don't contain any correct information from ANY of the five fields I listed above. They do sound very matter-of-fact though. At least go to that www.superstringtheory.com website to see for yourself who is right and who is wrong.\n\nWhat you have loosely described is called the horizon problem. It was a huge problem for cosmologists and physics theorists to solve, and all the answers aren't quite in place yet, but I'll give you the jist and you can visit that website I mentioned to get the real goods on exactly why and how we know what we know.\n\nThe "big bang" was actually not an explosion, it was a rapid expansion, like a balloon being inflated. The universe started out as nothing but a seemingly empty vacuum that expanded so fast it released a whole lot of energy. This energy started out as extremely hot radiation that cooled into particles like quarks and gluons. These quarks and gluons then came together to form protons which then cooled further and formed atomic matter, which we are all familiar with (except for religious folk who don't want to think very hard, they like simple, three-word answers that start with "G" and require no thought).\n\nThe horizon problem, kind of like what you described, is that light can only travel at a fixed speed, but the universe is huge (over 50 billion light years across) and has NOT existed long enough to allow light to travel from one side to the other (the oldest light we see has travelled 40 billion light years even though the universe is only 14.5 billion years old - the discrepancy is due to expansion). In fact, it is unlikely that light from one side of the universe will ever reach the other side because the universe is expanding faster than the speed of light. \n\nWhat inflation also did is almost instantly expand the matter that now makes up the Earth so far away from the matter making up those early galaxies that the light from them is only just reaching us today. The light takes even longer to reach us than the distance to the galaxies because we are moving away from those galaxies faster than the speed of light. You might think this means the light would never reach us but this is not true because as the photon travels towards us, the expansion rate of the part of the universe it is traveling through gets slower and slower relative to us until the photon's speed is greater than the expansion speed and it zooms to us. Thus the galaxy might have started out only a few billion light years away but the expansion caused the photon to take 10 billion years to get to us, so we see these galaxies as they were 10 billion years ago.\n\nAs for the rest of the horizon problem: Studies of the cosmic background radiation show that the entire universe was isotropic in the beginning (that means it was almost the same everywhere). The cosmic background radiation is almost like a giant cast of the universe - it shows the shape and contours of many different properties of the universe when it was only about half a million years old. Anyways in order for the universe to be the same everywhere, it means the particles had to be all interacting with each other over a short distance, and inflation explains this very well. It makes the universe and all matter in it small enough that all matter is initially able to interact before being blown all outward in 3 dimensions like a balloon.\n\n*Edit*\nI just want to add that the universe is ~14.5 billion years old and the Earth is not travelling at the speed of light relative to spacetime, we zip around our galaxy at a few hundred kilometers a second and our galaxy whips around its cluster at an even greater speed, but not even close to the speed of light.
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The answer to your question lies with something called "inflation." The mechanics of inflation are very involved, but basically here's the gist of it: Long before the universe was even one second old it began to expand faster than the speed of light. Sounds like a violation of relativity, but it's not because at this point in the evolution of the universe there was no mass, only space-time which is not restricted by relativity. The bottom line is that with this FTL expansion rate, nothing could possibly pull the universe back into the initial singularity.\n\nFor a detailed look at inflation, check this website --> http://www.lifesci.sussex.ac.uk/home/John_Gribbin/cosmo.htm
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There is no scientific evidence about anything that happened before about 1 picosecond after the Big Bang.  At that time, all the particles that are now within our event horizon where concentrated in a sphere about 10^-13 cm in size, and they were very hot.  The evolution since that time has had consequences that can be studied by various methods.\n\n\nNote that the small volume occupied then by our now current event horizon was probably not all of the Universe.  The Universe may have been infinite then, and it may be infinite now.  \n\nWhat happened before that time is a matter of speculation.  We know that physics as we understand it breaks down at that point.  We do not have a complete theory of quantum mechanics and gravity that would allow us to do any real calculations about times prior to one picosecond.\n\nHowever, here is some speculation:  if you have an empty space that is inflating (as space seems to be doing now, because of the Dark Energy), and that space has ground-state energy quantuum fields in it, then every once in a long, long, long while you get something like a Big Bang.  Energetically, it's OK, because the total energy of the Universe may be zero: the positive stuff is cancelled by negative gravitational potential energy.  The event comes about due to fluctuations in the empty quantum fields, and the inflating space pulls the virtual particles apart and makes a Big Bang.  It's unlikely, but if you wait long enough it happens.
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My current belief is that there was time before time as we know it. Something "had" to exist before the cosmos as we now understand it. The Big Bang wasn't the first, nor the last. In order for that to occur, yes, I believe that it was the result of a black hole to end all black holes reaching its limit. It's a thin, untested theory, but it is what I am with until something better is derived. This is consistent with my answer to your later question. That is I haven't thought about the possibility of one universe existing within another. It is plausible in my mind though and interesting enough to think about it for years to come.
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i'm not sure how you consider it mathematically unlikely - where's your working for that?\n\nThe theory is that yes, the matter in the universe can from the dense plasma that expanded from the singularity that began the big bang.  Howver, if dark matter theory is to be believed, there is a lot of matter unaccounted for - but it is still likely to have originated from the Big Bang
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You have gotten some great answers up to this point.  I'd like to add yet another one...the pre big bang scenario re string/M theory.\n\nOne spin off of string/M theory is that parallel null universes are feasible.  Brian Greene pictures them as slices of bread in a cosmic, N-dimensional loaf of bread. [See source.]\n\nThese are "null" universes because, as far as we are concerned, from our myopic four dimensional world (the metric, observable universe one answerer talked about), these universes exist only in higher dimensions and cannot be observed in 4D.\n\nAccording to one hypothesis, based on string/M theory, two of these slices of bread collided.  That collision point is called the singularity where the big bang originated.  The energy such a collision could generate is one way to account for all the mass-energy postulated for our own known universe.\n\nOf course, as pointed out by other answerers, time and other physics phenomena in null universes may not exist as we know them in metric space.  Null universes are beyond our ken to understand and explain...now.  But who knows, with people like Hawkings, Witten, and others attacking the cosmos and its mysteries, we might just yet unlock the nature and existence of null universes and our own.\n\nPS:  Not all explosions are chemical explosions requiring air (oxygen) to work.  The atomic bomb, for example, does a really nice explosion by simply splitting atoms.   The sun makes spectacular explosions by fusing (putting them together) atoms.  Bottom line, the big bang is not a chemical explosion requiring oxygen.
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All the matter in the Universe was created as part of a "matter/anti-matter" pair out of the vacuum of space during the Big Bang. But there was a very slight imbalance, like 1 particle out of a billion survived and did get not annihilate with its anti-matter pair (not the huge imbalance the others have led you to believe).\n\nThis imbalance is due to a process called "Symmetry Breaking" or "CPT Symmetry Violation." This is a well understood process, not exactly a big mystery. (The mystery is why is there this asymmetry, not how this asymmetry happened.) Also, the fact that baryon numbers are not conserved in our Universe is not a big deal, because there is no reason to believe that it should be. The concept about baryon number conservation is very much outdated.\n\nGiven that all the matter came from a "matter/anti-matter" pair meant that all the matter in the Universe did not require any net energy to be created. As a matter of fact, most of the energy in the Universe is tied up in the vacuum as "Dark Energy" or "Vacuum Energy" (this makes up about 74% of the energy density in the Universe).\n\nI would say most physicists view the relationship between matter and energy as two manifestations of the same thing, somewhat like water and ice, where ice is just another phase of water.  Similarly, matter is just another "form" of energy, but more concentrated.\n\nYour mathematical interpretation of the matter-energy relationship as an integral compared to derivatives however doesn't make too much sense, because Einstein has already given us the mathematical relationship (and this has been tested and verified via nuclear bombs) E = mc^2, which tells us how much energy is locked up inside a piece of matter with mass, m.