nature of the universe questiom

ben89 · Dec 20, 2006

how can people say the univese doesnt have an edge when we probably just dont have telescopes powerfull enough to see the edge/

vogon13 · Dec 20, 2006

As the distance from us mounts, the red shift increases, and that decreases the intensity of the radiation we receive. It becomes more and more difficult to see things closer and closer to the 'edge'. You really have to ramp up the budget to make any dramatic increases in being able to peer ever further . . . <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

vogon13 · Dec 20, 2006

And, when you consider relativistic effects, and the effects the inflationary expansion period had on the early universe . . . . <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

ben89 · Dec 21, 2006

u saying what now? pleeze explain it 2 me like i dont know anything cuz ....well.... i dont know .... i wouldnt' be askin/

nexium · Dec 21, 2006

There is some possibility that more powerful telescopes will reveil what some people will say is the edge of the Universe. An important question is, what will the edge of the universe look like, if we see it. Vogon 13 explained that there likely is no edge and that we likely could not see an edge with more powerful telescopes, if there is an edge. Neil

ben89 · Dec 21, 2006

evrything is *if* i guess but its nice to think bout these things.... thanx nexium & vogon13/

SpeedFreek · Dec 21, 2006

It may be simpler to think of it like this. When we look at objects deep in space, we are looking backwards in time. The further we look, in whichever direction we look, the older things are. The furthest objects it would ever be possible to see would be the first visible objects in the universe. So.. the only "edge" we could ever see from Earth would be the beginning of the universe. But I doubt this is the edge you are thinking of. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

ben89 · Dec 21, 2006

no i was thinkin more like edge of a cliff kinda/ when your looking down & about to jump off or sumthin/ which i guess is so so so very very wrong way to think about it or picture the univese/ thanx speedfred for your answer/ beginning eqwals edge is cool/ its the sh****//

weeman · Dec 21, 2006

Because of the limits to the speed of light, even though it is the fastest thing in the Universe, I don't believe we will ever be able to see an edge to the Universe. Like Speedfreak is saying, the further we look in space, the further back in time we are seeing. Even though light can travel at 300,000 kps, it still has extraordinary distances to cover. There are two terms that can help visualize the Universe, the Observable Universe and the Material Universe. The Observable Universe is what we can actually see, and is limited to the speed of light. The Observable Universe is around 14 billion lightyears today. However, the Material Universe is how the Universe would actually exist in present day. The Material Universe might extend to 28 billion lightyears from Earth, or 50 billion, or maybe over 100 billion! Since we have to wait for light to reach us, I don't know if we will ever be able to see an edge to the Universe no matter how sophisticated our telescopes become. If indeed the Big Bang was a real event, our Observable Universe will always grow larger, but it will never allow us to see to the very edge of Space! <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

Mee_n_Mac · Dec 22, 2006

It may even get worse. If we believe the interpretation of the High Z team, the universe's expansion rate is accelerating. In the future we might not be able to see the far off galaxies and such that we see now. The night sky will slowly over time wink out and go dark. So look-up now ! <div class="Discussion_UserSignature"> -----------------------------------------------------Ask not what your Forum Software can do do on you,Ask it to, please for the love of all that's Holy, STOP ! </div>

SpeedFreek · Dec 22, 2006

There is a third term too! What we see is the observable universe which extends out from us around 14 billion light years in every direction, seeing further back in time, the more distant the object. Then there is the comoving universe which describes where everything in our observable universe is right now at this moment in time. The objects we see 13 billion light years away were in that position 13 billion years ago. The universe seems to be expanding, so by now those objects have been estimated to be up to 80 billion light years away by now. So that would make the actual size right now of the observable universe anything up to 160 billion light years across (but it won't look like that to us for another 65 billion years or so)! Lastly there is the whole universe, which includes the parts (if any) that are outside of our observable universe! Unless we live in a very special place in the dead centre of space and time, it is highly likely that we cannot see the whole thing. The light from the rest of the universe cannot reach us if its source is further away in light years than the universe is old and moving away from us. This means we have no way of knowing just how big the whole thing is! It is theorised that someone on one of the furthest objects 14 billion light years away, would see a similar thing to us - a universe extending around 14 billion light years in every direction! I should point out that all we have said in this thread is theory based on current observation. The big-bang isn't the only theory, but it is the most researched and accepted so far. <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

alokmohan · Dec 22, 2006

I think we should discuss observable universe only.Rest is possibly fiction,at least till now.

alkalin · Dec 22, 2006

Here’s an interesting site for some of these issues. http://www.atlasoftheuniverse.com/redshift.html I find some of these distance issues being presented are contradictory. If galaxies were very close to us when light left them, then they should be very bright and large.

ben89 · Dec 22, 2006

*apreciating* evryones comments right now/ your all so advanced/ as there r alot of stuff here i dont get but learning all the time thanx again/

weeman · Dec 22, 2006

<blockquote>In reply to:<hr /> It is theorised that someone on one of the furthest objects 14 billion light years away, would see a similar thing to us - a universe extending around 14 billion light years in every direction! <hr /></blockquote> You are right about this. In every point in space, if there is an observer, they should see their own observable universe that they are at the center of. If I hop in a ship and travel 5 billion lightyears, or 8 billion, or 10 billion, each of those places would essentially have their own observable universe. In response to Alokmahon, I'm not sure what you are saying when you say all else is "fiction". It is true that the observable universe is all we can see. However, the material universe is a very real thing. The light has taken time to reach us from distant objects, so we have to assume that those objects have moved in the time that their light has traveled through space. Is the material universe what you were referring to as fiction? <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

SpeedFreek · Dec 22, 2006

I think he was referring to my paragraph about the objects that may be beyond our observable universe. By beyond, I mean they were further from us in light years when the light left them than the age of the universe in years. When you refer to the material universe, you are describing the comoving distance. Where the most distant objects we see are now. Alokmahon isn't referring to this, he seems to be saying that everything outside our observable universe is a fiction. I would interpret that as saying it is unprovable, as we can never see outside our observable universe. If the estimates for the comoving distance are up to 70 billion light years or more, that could make our observable universe up to 150 billion ly or so across right now. But what if the whole universe is 300,000 billion ly across? If everything is moving away from everything else at large scales we would never see or know of any of the rest of the universe outside our small observable part of it. I recently read one theory where, if you imagine the whole universe to be the size of our galaxy, then our observable universe might in relation to that be only the size of a golf ball. I think Alokmahon might decribe that as a fiction too, as he is entitled to! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

weeman · Dec 23, 2006

I fully understand what you are saying about the comoving universe being unprovable. Most things in our universe will never be proved no matter how advanced our knowledge of science becomes. I had used an analogy in another post that helps understand why we will never be able to know anything beyond our observable universe. To know what is beyond our observable universe would be like standing in a room with no doors and no windows, and trying to come up with a plausible theory for what exists beyond the walls. So yes, it could be classified as fiction since it is the unknown. However, since light tells us that distant galaxies certainly do exist, then I guess thats why I don't really see it as being fiction. Of course, what we don't know is what state those galaxies exist in today. Do they still exist? How far are they from our position in Space? These are the questions that will most likely never be answered. The mind boggling part is that we don't know the speed of the Universe today. When we look 14 billion lightyears away, and we see objects moving at incredible speeds, that might be because we are looking to a time that was not long after the big bang, when the Universe was expanding faster. So for all we know, it could already be slowing down (if indeed we do live in a flat universe). However, many astronomers will also argue that we live in an accelarating universe. These are the things that are so hard to answer. Our observable universe might one day be able to tell the fate of the universe, but we might have to exist for billions and billions of years from now. <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

SpeedFreek · Dec 23, 2006

You still misunderstand I'm afraid. You look to be confusing the comoving universe with the possible whole universe! Its not the comoving universe thats unprovable, nor is it the comoving or material (as you called it) universe that was referred to as a fiction. Some confusion has arisen here, probably due to terminology. The comoving universe is not exactly "beyond" our observable universe. It is what our observable universe has come to be. As you said in your post, everything we see has to end up somewhere! Thats not the problem here. What Alokmahon was objecting to, was my references to the whole universe. This is what might be beyond the comoving universe. I was suggesting (and it has been suggested by many scientists) is that there is more universe out there than is contained in our observable (and comoving) universe. The universe might be so large that our observable (and thus comoving) universe may only be a small part of it. Imagine a point 1 billion years after the universe began. At this point the observable universe can only be up to 1 billion light years in diameter, because light has only had 1 billion years to go anywhere. So if we were around at this time we could only see 1 billion light years in any direction. The comoving distance would still apply, but the most distant objects from us have only had 1 billion years to expand away, and thus the comoving distance cannot be that much larger than the observable universe, and a lot smaller than it might be today. But imagine if, at 1 billion years old, the whole universe was 100 billion light years agross. We can only observe 1 billion light years in any direction (and estimate where those objects have moved to). Theres a whole other 99 billion light years of extra universe (and extra comoving distance!) that would always have been outside our observable and comoving universe! So we could now see an observable universe 14 billion li <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

weeman · Dec 23, 2006

I completely understand what you're saying. I do know the difference of observable universe vs. actual universe. Observable universe is limited to the speed of light. If light could travel at infinite speeds, and we saw all matter in the universe instantly, we might very well be able to see the "edge", if indeed it's not infinite <img src="/images/icons/smile.gif" /> I guess I did get confused with the terminology, I haven't ever really used the term comoving! So, who knows how wide the whole universe is? 1,000 billion lightyears? A quadrillion lightyears? <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

SpeedFreek · Dec 23, 2006

Ok no problems then! I was just a little confused by your previous posts where you said: In response to Alokmahon, I'm not sure what you are saying when you say all else is "fiction". It is true that the observable universe is all we can see. However, the material universe is a very real thing. The light has taken time to reach us from distant objects, so we have to assume that those objects have moved in the time that their light has traveled through space. and So yes, it could be classified as fiction since it is the unknown. However, since light tells us that distant galaxies certainly do exist, then I guess thats why I don't really see it as being fiction. Of course, what we don't know is what state those galaxies exist in today. Do they still exist? How far are they from our position in Space? These are the questions that will most likely never be answered. It seemed to me you were questioning why anyone would describe the comoving universe as a fiction, as in both cases you referred to visible distant objects or galaxies, and that even if we don't exactly know where they are now, you don't think of them as a fictional thing. Whereas I was referring to the possible universe outside the comoving universe, which as we agree is unknowable and therefore could be considered as a fiction. Phew! As long as we have cleared that up! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> _______________________________________________ SpeedFreek </div>

nature of the universe questiom

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