Moreta
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Post by Moreta on May 21, 2005 18:22:58 GMT -5
Interesting, but this always confuses me. When they speak of the size of the universe, are they implying that the size is equaled to the objects in space, such as galaxies, and that once we come to the end of the objects formed by the big bang, there is infinate empty space, or are they implying that once one comes to the end of the universe, it stops, and thier is no way to continue any further? I cannot see how space can come to an end, as there is always something ahead in the distance, I believe it to be infinate. Whether the universe is infinite or not depends on a few simple things, the main one being the amount of matter actually in our universe. Theres some universal constant called ummm... damn, just done this in Physics, should know it, but cant think of its name. Anyway, the size of this constant decides how old the universe is and I believe it is also affected by the amount of matter.
If it is greater than one then the universe will be what is called a "closed" universe. This means that 3 dimensional space itself is curved, rather like a sphere. Its impossible to imagine and in fact, the best way to put it into perspective is to imagine someone who is used to 2 dimensions, say living on a piece of paper then being placed on a sphere. They walk in the same direction and somehow end up back at the same place. This would mean the universe is not infinite and it therefore has a size. However, there is no such thing as "outside" the universe. The trouble is, when people picture the universe they imagine it like a bubble floating in nothingness but there is nothing outside the universe, the universe is everything even though it is finite. Again, a very difficult concept to get your head round, I know I struggle with it. A "closed" universe has enough mass to eventually halt the expansion and then the universe will get smaller and there will be what is affectionately nicknamed a "Big Crunch"
The second possibility is that the constant is less than one. This would mean the universe is a whats known as an "open" universe. It goes on forever. This is the infinite universe that everyone knows and can just about get their heads around. It will just keep on expanding and expanding forever as there is not enough mass to pull it back together. Eventually the universe will turn cold and lifeless as the stars and galaxies move further and further apart and the energy is spread over a wider and wider distance.
The third possibility is that the constant equals 1. Im not entirely sure what this actually means for the shape of the universe, all I know is that this is the condition for when there is exactly the right mass to halt the expansion but not pull it back together.
Although only about 10% of the mass required to make the constant about 1 has been found scientists still believe the constant probably does lie round about 1 which means there must be matter out there which we cant see or detect, which is how the belief of dark matter arose.
*Tries to remember exactly what she was getting at in the first place* Right, well maybe that gives you a better idea of how the universe can be finite or whatever...
Just a couple of other thoughts to leave you with. When people say the universe is expanding people imagine the galaxies travelling out into empty unoccupied space but it is in fact the fabric of space time itself stretching, rather like stretching a rubber band. Imagine putting three dots on a rubber band and then stretching it. The dots dont move across the band, the band itself gets stretched. This means that there is unlikely to be empty space outside the galaxies etc, there might be but it is incredibly unlikely if the Big Bang really is what happened since the universe started as a singularity, when it exploded (for whatever reason) matter would immediately have been at the edges with the expanding universe. That means eventually stars and galaxies, which expanded with the "edge" would form there and there would be no empty space after them because there is no after them since they are at the "edge" of the universe.
Oh and also I may have got the greater and less than one bits the wrong way round for the "open" and "closed" universes.
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xkamelx
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Post by xkamelx on May 30, 2005 15:31:20 GMT -5
Thanks Morry.
While all of that makes sense, I still have a hard time buying the universe is finite. The 2 dimensional example makes perfect sense, but how does that translate into a 4 dimensional universe, such as ours?
And while no one can really answer this, what is nothing? If the universe has a shape and size, what is beyond it? We may never be able to go beyond it because a straight line would in fact be a curved line due to the curvature of space time, but that still wouldn't be a true absolute straight line anymore then a trip around the world would be a straight absolute line.
If nothing exists outside of our universe, then what is nothing?
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Moreta
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Post by Moreta on May 30, 2005 17:32:02 GMT -5
Well theres two possible answers to that question Myke.
1. The usual answer: There is no outside. There is no such thing. Its not nothing, it simply does not even exist. Though its rather hard to explain, calling it nothing means you imagine a vacuum, a void... but thats not what it is, there quite simply is no outside.
2. Something like M-Theory is correct in creating a thirteenth (think its thirteenth) dimension in which universes "float". The universes can be all shapes and sizes and they exist in this thirteenth dimension. However, quite what the thirteenth dimension is Im not entirely sure... Iv never found that out
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syborg
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Post by syborg on Jun 30, 2005 11:17:07 GMT -5
The truth is scientists do not know enough about the universe and present information only on what they have observed and probably can never be a defiinite answer fior a long time, which is why they have theories. So people who enjoy science fiction/fantasy can come up with anything they like. The solar systems could be individual atoms, galaxies molecules and and the galaxies put together could really be structure of some living or non living thing.
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Post by k-jah on May 8, 2006 14:24:48 GMT -5
The Universe must have an end, because everything has an opposite, which is where anti-matter comes in. Which basically means your exact opposite is out there.
So what happens when you cross this barrier between opposites? You cease to exist, your matter does not belong in the opposite realm so you cease to exist along with everything else.
OR - When you mix opposites a new product is made, like hot and cold make warm (simple yes?) So you become "perfect" both your sides mix and you become you.
If any of that made sense I'm amazed.
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0 of 0
Admiral
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Post by 0 of 0 on Oct 17, 2006 20:48:02 GMT -5
I had no Idea that the universe was that big! I think that the realm of space goes on forever.
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Tobbles
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Post by Tobbles on Oct 19, 2006 10:26:44 GMT -5
This is pretty amazing but what i don't understand is how are people meant to be able to work all this out?! 165 billiion lightyears wide - We got some exploring to get on with.
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0 of 0
Admiral
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Post by 0 of 0 on Oct 21, 2006 17:57:23 GMT -5
So is the galaxy the universe? I'm a little confused.
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xkamelx
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Post by xkamelx on Oct 25, 2006 16:16:03 GMT -5
So is the galaxy the universe? I'm a little confused. No, a galaxy is a body of stars in the universe. We live in the milky way galaxy, which is about 100 thousand lightyears in circumference. Here is our galaxy: www.temporalreality.net/forum/galaxy.gifI added a red dot to show where we are, approximately, but keep in mind that we'd appear to be so small that our sun wouldn't even show up in that picture. This is a view of the universe, showing multiple, and seemingly endless galaxies. www.temporalreality.net/forum/universe.gifKeep in mind those are not stars you are seeing, but galaxies. I picked a random galaxy to point as ours to help give you a sense of where we would be in the universe, and how infinitely small. Now, imagine that picture of the universe repeating 10 billion times, with us being only that one small dot. Now, do you want to see something REALLY COOL, that gives a good example of galaxies and our universe? This video is the opening of the movie 'Contact'. It starts on earth and zooms out into our solar system, then eventually into our galaxy, then eventually outside of our galaxy into the known universe showing thousands of galaxies. www.youtube.com/watch?v=PLQF-4uyD4Yamazing huh?
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