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Post by Progenitor A on Nov 12, 2010 16:46:23 GMT 1
So you think planet Earth is in right smack bang in the middle of the universe, wow what’s the odds eh. I have said no such thing nor even suggested any such thing You seem a bit confused about the age thing. When you look at a photo of yourself as a baby you would not say “that was when I was older”. What we see at great distances is not what it is like now. Think of it like a photograph, the older the light we are detecting the younger the universe was then when the light left the object. This is why we call the CMBR the baby universe. The recessional velocity of a distant galaxy when the light we detect left that galaxy is something we can calculate by the red shift, but that is a historical record of the recessional velocity of that galaxy and because the universe is expanding that galaxy, now that it is older, has a much higher recessional velocity. No confusion at all (on my part)
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Post by typobrane on Nov 12, 2010 17:34:10 GMT 1
Naymissus by saying: “ The age of the universe is generally agreed to be about 14 billion years. Light can travel a distance of only 14 billion light years during that time.
Therefore what we see, (at the limit of our range of 'seeing' the Universe) is light that started on its progress to us 14 billion light years ago - that was approximately when the CMBR was created and CMBR is the limit of our 'visible' universe. As all other stars are younger (born later) than CMBR, then we can 'see' everything that radiates that has been created in the Universe.” You have inferred that we on planet Earth are in the middle as the CMBR appears to be the exact distance away in every direction.
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Post by Progenitor A on Nov 12, 2010 17:48:51 GMT 1
Naymissus by saying: “ The age of the universe is generally agreed to be about 14 billion years. Light can travel a distance of only 14 billion light years during that time. Therefore what we see, (at the limit of our range of 'seeing' the Universe) is light that started on its progress to us 14 billion light years ago - that was approximately when the CMBR was created and CMBR is the limit of our 'visible' universe. As all other stars are younger (born later) than CMBR, then we can 'see' everything that radiates that has been created in the Universe.” You have inferred that we on planet Earth are in the middle as the CMBR appears to be the exact distance away in every direction. No Typobrane, you seem to have inferred that. I have not suggested that. In fact, I am told that wherever is your position in the Universe the observation will be the same (except, presumably, at the exremity of CBMR or BB)
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Post by Progenitor A on Nov 13, 2010 8:23:59 GMT 1
.....So, based on this, we could eventually see ALL possible bulbs, we just have to wait long enough for the light from those bulbs to get to us. Not 'could see', we do see all of your 'possible bulbs'. You make it sound as if we are still waiting to see them all and that is false That is the simplest explanation I can give, and if any posters think they can refute the flashbulbs example................. Even your 'simplest explanation contains ambiguity - you really must address your English
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Post by alanseago on Nov 13, 2010 9:41:36 GMT 1
Even your 'simplest' explanation contains ambiguity, you really must address your English.
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Post by typobrane on Nov 13, 2010 11:27:22 GMT 1
Naymissus at #71 I started with a playful observation as I knew you did not intend to infer that we are in the middle of the universe but you did by saying "we can see all the radiating bodies that have been created since big bang"
If I inferred it then that's ok as I think the universe is infinite and so it does not mater what planet you are on you will always be in the middle. Just as well as it is often said that I am on a different planet.
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Post by Progenitor A on Nov 13, 2010 12:45:20 GMT 1
Naymissus at #71 I started with a playful observation as I knew you did not intend to infer that we are in the middle of the universe but you did by saying "we can see all the radiating bodies that have been created since big bang" If I inferred it then that's ok as I think the universe is infinite and so it does not mater what planet you are on you will always be in the middle. Just as well as it is often said that I am on a different planet. ;D Good one! But surely we can see all the radiating bodies that have been created since BB? Do you think that we cannot?
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Post by typobrane on Nov 13, 2010 13:40:10 GMT 1
I am sure we can't. It is not just the empty space part that I think is infinite but that the infinite space is filled very much like the part we can see.
When we look at a part of the CMBR we are looking at something that has now developed into a galaxy that like one of the ones we see near us or indeed like our Milky way. That galaxy will now be too far away to see. If there is anything in that galaxy that can look back at us it will not see us like we are now it will see the part of the CMBR that became us.
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Post by Progenitor A on Nov 13, 2010 18:15:58 GMT 1
I am sure we can't. It is not just the empty space part that I think is infinite but that the infinite space is filled very much like the part we can see. When we look at a part of the CMBR we are looking at something that has now developed into a galaxy that like one of the ones we see near us or indeed like our Milky way. That galaxy will now be too far away to see. If there is anything in that galaxy that can look back at us it will not see us like we are now it will see the part of the CMBR that became us. But isn't it the case that if the CMBR is vsible (as it is -t covers all of our far horizon) then everything that was created after CMBR, all that is younger than CMBR (CMBR is very near in time to the BB and hence is one of the oldest parts of the universe) then that everthing else radiant must be visible? Am I misunderstanding you?
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Post by typobrane on Nov 13, 2010 19:40:19 GMT 1
Naymissus yes you are I'm afraid and my shell from a tank will not help with this one. When we look at the CMBR in one direction we are looking at a distant moment in time and a distant place. When we look in the opposite direction at the CMBR we are looking at the same moment in time but at a different place. It would be the same for the BB moment if we could see it. This is not an easy concept for some people because we all think in different ways. Instead of thinking of the universe expannding from a tiny 3D ball think of it in 2 dimensions first and replace the dot with a big sheet a membrane a dimensional membrane that stretches out to infinity. Time for our universe starts at the membrane and not a point on the membrane. The next stage I doubt if you will not be able to visualise because you now have to imagine it as a 3D infinite brane (as in membrane)the vision collapses for most people at this point. It may be possible to think of it not as a point or an infinite 3D brane as I do but a finite 3D brane but that does not work for me.
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Post by typobrane on Nov 13, 2010 21:57:26 GMT 1
Perhaps it is better to think of it this way, once you have imagined the 2 dimensional membrane at the moment of creation it becomes infinitely thick.
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Post by typobrane on Nov 13, 2010 22:24:46 GMT 1
Everything in the universe has its origin at the same time so in a way everything is the same age. Things further away are not actually older or younger it is the light that is from an earlier time so we see things in the distance when they were younger there is no actual distance age relation it is a trick of the light. There are things further away than where we see the CMBR and they are the same age. What we see as the CMBR is now the same age as everything else. The image that the distant light brings to our eyes has not changed, apart from the frequency, the object it came from has.
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Post by Progenitor A on Nov 14, 2010 8:05:04 GMT 1
Perhaps it is better to think of it this way, once you have imagined the 2 dimensional membrane at the moment of creation it becomes infinitely thick. I know the feeling
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Post by speakertoanimals on Nov 16, 2010 13:41:27 GMT 1
Of course we can't.
You have to think of the Big Bang (or the later flash that becomes the CMB) as happening everywhere at the same time. So, any instant we observe, we see SOME of the CMB, just not from the same stuff as when we view it at a later instant.
SO for the stuff that lies beyond the present CMB we see, we will first see the CMB from there, once there has been enough time for the light to get to us, then later we see the galaxies etc created from the same stuff.
I think you're stuck on some idea of the CMB as being from a point or something, nothing before hence nothing beyond.
Go back to the flashbulbs example again, and take a very distance bulb. For signals radiating outwards from this bulb, we first have the CMB flash, which travels outwards like ripples on a pond. After the CMB flash, the matter that formed that bulb will form into galaxies and stars and start to shine. But the signals from that always lie behind the ripple that is the CMB from that point.
When we observe, we will see, at any instant, the CMB from objects whose CMB ripple has just reached us. We will also see starlight from objects whose CMB flash reached us earlier, but now the starlight ripples have had enough time to get to us as well. At a later time, the CMB ripples from objects further away will start to reach us, so that as time goes on, the CMB we see gets further and further away, with hence more and more objects closer than that CMB, those closer objects being the ones where we now have a chance to see their starlight.
Its because things are spread out in space that an event which happened everywhere at a single time can now be seen over all time. And also how events spread out in time (the CMB, first stars and galaxies) can now all be seen at the SAME time.
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Post by Progenitor A on Nov 16, 2010 17:19:19 GMT 1
Of course we can't. You have to think of the Big Bang (or the later flash that becomes the CMB) as happening everywhere at the same time. So, any instant we observe, we see SOME of the CMB, just not from the same stuff as when we view it at a later instant. SO for the stuff that insights beyond the present CMB we see, we will first see the CMB from there, once there has been enough time for the light to get to us, then later we see the galaxies etc created from the same stuff. I think you're stuck on some idea of the CMB as being from a point or something, nothing before hence nothing beyond. Go back to the flashbulbs example again, and take a very distance bulb. For signals radiating outwards from this bulb, we first have the CMB flash, which travels outwards like ripples on a pond. After the CMB flash, the matter that formed that bulb will form into galaxies and stars and start to shine. But the signals from that always insight behind the ripple that is the CMB from that point. When we observe, we will see, at any instant, the CMB from objects whose CMB ripple has just reached us. We will also see starlight from objects whose CMB flash reached us earlier, but now the starlight ripples have had enough time to get to us as well. At a later time, the CMB ripples from objects further away will start to reach us, so that as time goes on, the CMB we see gets further and further away, with hence more and more objects closer than that CMB, those closer objects being the ones where we now have a chance to see their starlight. Its because things are spread out in space that an event which happened everywhere at a single time can now be seen over all time. And also how events spread out in time (the CMB, first stars and galaxies) can now all be seen at the SAME time. Sorry old dear The first galaxies were created 400 million years after the CMBR, therefore if we can see the CMBR we can see all galaxies - there is nothing beyond CMBR (well 4000 years of expansion)
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