The Universe

91 posts

 I have a serious question about the Universe. I have heard two things, one is that the Universe is infinite and the other that it is growing/shrinking. How can this be? Is it something about different levels of infinity? Or is it just, for all intensive purposes VIRTUALLY infinite? The universe is a demention, and is really big, and that’s about all I can really say is it in a loop? or is it an infinite 3d plane? I have no idea as to the size, other than REALLY BIG The universe is expanding, in that if you take two points and measure the distance between them, and do it again at a later time, you’ll find that they are further apart the second time. We don’t really have much idea whether the universe is infinite or not. There’s _probably_ a finite amount of matter in it, but I don’t think we’ve found any upper bound on the volume yet. The universe is thought to be a four dimensional shape, so we can travel as far in one direction as we like, but we’ll never reach ‘the edge’, because we can only move in three dimension. Eventually you’ll get back to where you started, similar to a two dimensional being moving over the surface of a three dimensional object like a sphere. The Big Bang happened a finite amount of time ago and the universe is expanding at a finite speed, so it’s not really ‘infinite’, it’s just impossible for us to reach the edge of it. Calculations like those to work out the probability of life existing elsewhere in the universe assume it it finite, because otherwise there would have to be an infinite number of intelligent civilisations in the universe, as the probability of one evolving is greater than 0 (re. Us). > for all intensive purposes That should be ‘for all intents and purposes’. Sorry, but it always bugs me when people do that. I get that there is a finite amount of matter in the universe, for it can’t be created or destroyed, as with energy but if you keep going, at the speed of light in one direction will you eventually return to the same spot? Maybe you should try to think of it as a balloon that is being blown into. It will expand forever (excluding the pop). EDIT: Imagine the balloon is infinitely big. > *Originally posted by **[cuffofizz](/forums/9/topics/42400?page=1#posts-909199):*** > > Maybe you should try to think of it as a balloon that is being blown into. It will expand forever (excluding the pop). YEs but a baloon is finite. I can see how it can be growing or it can be infinite(sort-of on that second one) but I really don’t see how it can be both. I heard a math problem once about if you have an infinite number of rooms and an infinite number of guests you can increase the number of rooms all if you put them in every other room. Does that have anything to do with this? > *Originally posted by **[itipt](/forums/9/topics/42400?page=1#posts-909210):*** > > *Originally posted by **[cuffofizz](/forums/9/topics/42400?page=1#posts-909199):*** > > > > Maybe you should try to think of it as a balloon that is being blown into. It will expand forever (excluding the pop). > > YEs but a baloon is finite. I can see how it can be growing or it can be infinite(sort-of on that second one) but I really don’t see how it can be both. It can’t be. If something is infinite it cannot get bigger. The universe is not infinite. > If something is infinite it cannot get bigger. Something being infinite does not prevent it expanding. Suppose you have an infinitely long elastic band. You draw two dots on it. Then you stretch the elastic band. Those two dots move further apart as the elastic band expands. Very good analogy. You still have remember that infinity is just an idea. > *Originally posted by **[Jabor](/forums/9/topics/42400?page=1#posts-909237):*** > > If something is infinite it cannot get bigger. > > Something being infinite does not prevent it expanding. > > Suppose you have an infinitely long elastic band. You draw two dots on it. Then you stretch the elastic band. Those two dots move further apart as the elastic band expands. Yeah but if the universe were infinite, it would encompass _everything_. Given the fact that the universe is expanding, it must be expanding into something. Even if we’re expanding into a truly infinite nothingness, the very fact we’re expanding at all shows that there must be something ‘outside’ the universe, and thus that the universe is not infinite. I think. > Therefore, anything that is expanding cannot be infinite, because expansion implies increase, Suppose I have an infinite number of chairs, all in a row. With an infinite number of people sitting in them. Now suppose some more people want to sit down on those chairs. I can’t tell them to go to the end of the row and sit on the empty chair there, because there is no end. What I _can_ do is number all the chairs, and then get every person sitting down to get up and move to the chair who’s number is double that of their own one. That leaves half the chairs empty, so more people can sit down. We actually cannot observe what happens beyond a certain distance away in the universe. As in, light originating beyond that distance will never reach Earth. > Given the fact that the universe is expanding, it must be expanding into something! No! The universe is not expanding into pre-existing space. [http://en.wikipedia.org/wiki/Metric\_expansion\_of\_space](http://en.wikipedia.org/wiki/Metric_expansion_of_space) About a page down. The truth is, we don’t know how big the universe is because our technology is not yet at the level where we can measure it’s size, or how much of it is populated. The only thing we know for certain is that objects within the universe are distancing themselves from each other, indicating that the universe is in a state of expansion. What lies beyond, if anything, or if there even IS a beyond has been theorized by many, but is known by none. Whether or not the universe is infinite is also an unknown. Certainly for all intents and purposes we can call it infinite, because it is far larger than anything else by such a massive degree than no other unit of measurement can exist on the same relative scale using any practical manipulation of numbers. Is it possible that the universe is not in itself infinite but the matter inside it is still moving away from a central point from the Big Bang? I’d say that the universe is growing. There is no such thing as infinite, as everything is destroyed at some point. Energy can never be destroyed so in essence it is infinite I disagree. I think that it’s finite, however we can’t see all of it, because our planet isn’t where the big bang was caused (at least I think). The big bang happened everywhere. It’s not just a bunch of stuff moving away from each other – it is space itself that is expanding, and carrying stuff like planets, stars and galaxies along with it. I wonder if you could find out if where the Big bang happened I think it’s far larger than humanity can EVER reach. obviously this is entirely hypothetical